Technical Field

[0001 ] The present invention relates to a group of pyridinium enolates which demonstrate interesting photophysical properties, notably a significant Stokes shift coupled with strong absorption and emission profiles which enable these compounds to be used in light harvesting applications such as in solar concentrators. The invention also relates to solar concentrators utilising pyridinium enolates as the chromophore in the solar concentrator.

Background of Invention

[0002] As the world reacts to growth in global populations there is an increasing need to identify and exploit sources of energy to meet the expanding needs of a growing world population. In addition as a number of previously third world countries "modernise" their economies there is an even greater demand for reliable sources of energy. Accordingly, the earth is experiencing an increase in energy demand driven both by a growing world population and an increased energy demand per capita. These two factors are placing a significant strain on world energy supplies.

[0003] In addition as a result of world reaction to climate change, there is an ever- increasing desire to produce energy in an environmentally friendly and non-polluting way. As would be well appreciated there are a number of alternative and environmentally friendly energy sources that are under investigation and/or development such as wave energy, geothermal energy and solar energy just to name a few. Whilst each of these sources demonstrates potential in almost every instance there are issues that need to be resolved.

[0004] For example in respect to solar energy generation, whilst solar technology is relatively well advanced in that there are numerous solar cells that can be used to convert solar energy into electrical energy these cells are not without their own problems. For example, many solar cells are relatively inefficient in their conversion of solar energy that falls on the solar cell into electrical energy meaning that in order to approach meaningful levels of power generation levels large surface areas of the solar cell are required making their use as a renewable energy source prohibitive in some cases. [0005] In addition there is the issue that due to solar cells collecting (absorbing) light over a large portion of the electromagnetic spectrum, they are typically very highly coloured if not black and completely opaque which is not aesthetically pleasing and limits their potential applications.

[0006] One approach to overcoming this issue has been the development of solar concentrators which are devices designed to concentrate solar radiation in order to produce electricity. Solar concentrators (also known as luminescent solar concentrators in some reference texts) are designed to operate on the principle of collecting incident solar radiation over an enlarged area (typically the surface area of the concentrator) and then converting the collected solar radiation to electricity. In most cases, these concentrators utilise one or more compounds in the concentrator that absorb the solar radiation and then emit it through fluorescence in such a manner that the fluorescent light is directed towards a significantly smaller solar cell. The ratio of the surface area of the concentrator to the surface area of the photovoltaic cell is known as the concentration factor.

[0007] A typical concentrator consists of a substrate containing a fluorescent or phosphorescent molecule disposed on or in the substrate. In some embodiments, the concentrator consists of a transparent planar waveguide integrated with a fluorescent/phosphorescent compound dispersed in a polymer matrix within the waveguide. As light hits the waveguide the incorporated molecule harvests light through absorption. Subsequent emission of the absorbed light is focused to the edges of the waveguide by total internal reflection, where a photovoltaic cell is coupled to the concentrator to generate electricity. This form of device construct has led to technology aimed at harvesting solar energy from a myriad of surfaces as an alternative to direct capture and conversion by solar panels.

[0008] As a result of the desire to further develop this area of technology, there is a need to develop alternative compounds that have the required photo-physical properties to enable them to be used in these applications.

[0009] Research has determined that two key photo-physical properties of a compound that affects its performance in a solar concentrator are (1 ) photoluminescence quantum yield (PLOY) and (2) Stokes shift. A PLOY near unity and large Stokes shifts with a negligible overlap of the absorption and emission profiles are ideal properties for compounds for solar concentrators. Unfortunately, this combination of properties is not common meaning that there are limited choices available to fabricators of solar concentrators.

[0010] Accordingly, it would be desirable to develop compounds that exhibit these two properties so that they could be used in solar concentrators.

Summary of Invention

[001 1 ] The present applicants have therefore studied a number of compound families with the potential to exhibit these properties in order to identify potential compounds that could find application as fluorescent compounds in solar concentrators.

[0012] As a result of these studies, the applicants have identified a class of compounds that exhibit interesting photophysical properties allowing them to be used in solar concentrators.

[0013] In one aspect the present invention provides a solar concentrator comprising a substrate; and a compound disposed on or in the substrate, the compound having the formula (I):

Formula (I)

[0014] wherein each R is independently selected from the group consisting of H, F, CI, Br and I;

[0015] n is an integer selected from the group consisting of 0, 1 , 2, 3, 4, and 5; [0016] each R ¹ is independently selected from the group consisting of halogen, OH, NO ₂ , CN, SH, NH ₂ , CF ₃ , OCF ₃ , optionally substituted C Ci ₂ alkyl, optionally substituted CrCi ₂ haloalkyl, optionally substituted C ₂ -Ci ₂ alkenyl, optionally substituted C ₂ -Ci ₂ alkynyl, optionally substituted C ₂ -Ci ₂ heteroalkyl, optionally substituted C ₃ - Ci ₂ cycloalkyl, optionally substituted C ₃ -Ci ₂ cycloalkenyl, optionally substituted C ₂ - Ci ₂ heterocycloalkyl, optionally substituted C ₂ -Ci ₂ heterocycloalkenyl, optionally substituted C6-Cisaryl, optionally substituted Ci-Cisheteroaryl, optionally substituted CrCi ₂ alkyloxy, optionally substituted C ₂ -Ci ₂ alkenyloxy, optionally substituted C ₂ - Ci ₂ alkynyloxy, optionally substituted C ₂ -Ci ₀ heteroalkyloxy, optionally substituted C ₃ - Ci ₂ cycloalkyloxy, optionally substituted C ₃ -Ci ₂ cycloalkenyloxy, optionally substituted C ₂ -Ci ₂ heterocycloalkyloxy, optionally substituted C ₂ -Ci ₂ heterocycloalkenyloxy, optionally substituted C6-Cisaryloxy, optionally substituted C-i-C-isheteroaryloxy, optionally substituted C C ₁₂ alkylamino, SR ² , SO ₃ H, SO ₂ NR ² R ² , SO ₂ R ² , SONR ² R ² , SOR ² , COR ² , COOH, COOR ² , CONR ² R ² , NR ² COR ² , NR ² COOR ² , NR ² SO ₂ R ² , NR ² CONR ² R ² , NR ² R ² , and acyl;

[0017] wherein each R ² is independently selected from the group consisting of H, optionally substituted CrCi ₂ alkyl, optionally substituted C ₆ -Ci ₈ aryl, and optionally substituted C-i-C-isheteroaryl;

[0018] or a salt thereof.

[0019] In yet an even further aspect the present invention provides a compound of formula (la):

Formula (la) [0020] wherein each R is independently selected from the group consisting of H, F, CI, Br and I;

[0021 ] n is an integer selected from the group consisting of 1 , 2, 3, 4, and 5;

[0022] each R ¹ is independently selected from the group consisting of halogen, OH, NO ₂ , CN, SH, NH ₂ , CF ₃ , OCF ₃ , optionally substituted C C ₁₂ alkyl, optionally substituted CrCi ₂ haloalkyl, optionally substituted C ₂ -Ci ₂ alkenyl, optionally substituted C ₂ -Ci ₂ alkynyl, optionally substituted C ₂ -Ci ₂ heteroalkyl, optionally substituted C3- Ci ₂ cycloalkyl, optionally substituted C3-Ci ₂ cycloalkenyl, optionally substituted C ₂ - Ci ₂ heterocycloalkyl, optionally substituted C ₂ -Ci ₂ heterocycloalkenyl, optionally substituted C ₆ -Ci ₈ aryl, optionally substituted CrCisheteroaryl, optionally substituted CrCi ₂ alkyloxy, optionally substituted C ₂ -Ci ₂ alkenyloxy, optionally substituted C ₂ - Ci ₂ alkynyloxy, optionally substituted C ₂ -Cioheteroalkyloxy, optionally substituted C3- Ci ₂ cycloalkyloxy, optionally substituted C ₃ -Ci ₂ cycloalkenyloxy, optionally substituted C ₂ -Ci ₂ heterocycloalkyloxy, optionally substituted C ₂ -Ci ₂ heterocycloalkenyloxy, optionally substituted Ce-C-isaryloxy, optionally substituted Ci-Cisheteroaryloxy, optionally substituted C Ci ₂ alkylamino, SR ² , SO ₃ H, SO ₂ NR ² R ² , SO ₂ R ² , SONR ² R ² , SOR ² , COR ² , COOH, COOR ² , CONR ² R ² , NR ² COR ² , NR ² COOR ² , NR ² SO ₂ R ² , NR ² CONR ² R ² , NR ² R ² , and acyl;

[0023] each R ² is independently selected from the group consisting of H, optionally substituted CrCi ₂ alkyl, optionally substituted C ₆ -Ci ₈ aryl, and optionally substituted C Cisheteroaryl;

[0024] wherein R ¹ is not coumarin or a coumarin derivative; [0025] or a salt thereof.

[0026] We have found that compounds of formula (I) and (la) exhibit interesting photophysical properties which in many instances make them ideally suited to be used as chromophoric compounds in solar concentrators.

Brief Description of Drawings

[0027] Figure 1 shows absorption spectra of 1a 10uM in toluene. [0028] Figure 2 shows emission spectra of 1a 1 uM in toluene (excitation wavelength 374nm volt 700v).

[0029] Figure 3 shows normalized absorption and emission data of 1a in toluene.

[0030] Figure 4 shows absorption spectra of 1 b 10uM in toluene.

[0031 ] Figure 5 shows emission spectra of 1 b 5uM in toluene (excitation wavelength 350nm volt 600v).

[0032] Figure 6 shows normalized absorption and emission data of 1 b in toluene.

[0033] Figure 7 shows absorption spectra of 1 c 10uM in toluene.

[0034] Figure 8 shows emission spectra of 1 c 2.5uM in toluene (excitation wavelength 374nm volt 600v).

[0035] Figure 9 shows normalized absorption and emission data of 1 c in toluene.

[0036] Figure 10 shows absorption spectra of 1d 10uM in toluene.

[0037] Figure 11 shows emission spectra of 1d 5.4uM in toluene (excitation wavelength 374nm volt 550v).

[0038] Figure 12 shows normalized absorption and emission data of 1d in toluene.

[0039] Figure 13 shows absorption spectra of 1e 10uM in toluene.

[0040] Figure 14 shows emission spectra of 1e 6uM in toluene (excitation wavelength 374nm volt 550v).

[0041 ] Figure 15 shows normalized absorption and emission data of 1e in toluene.

[0042] Figure 16 shows absorption spectra of 1f 10uM in toluene.

[0043] Figure 17 shows emission spectra of 1f 5uM in toluene (excitation wavelength 374nm volt 550v).

[0044] Figure 18 shows absorption spectra of 1 g 10uM in toluene. [0045] Figure 19 shows emission spectra of 1g 10uM in toluene (excitation wavelength 374nm volt 550v).

[0046] Figure 20 shows absorption spectra of 1 i 10uM in toluene.

[0047] Figure 21 shows emission spectra of 1 i 10uM in toluene (excitation wavelength 374nm volt 550v).

[0048] Figure 22 shows absorption spectra of 1j 10uM in toluene

[0049] Figure 23 shows absorption spectra of 1 k 10uM in toluene

[0050] Figure 24 shows emission spectra of 1 k 10uM in toluene (excitation wavelength 374nm volt 550v).

[0051 ] Figure 25 shows absorption spectra of 11 10uM in toluene

[0052] Figure 26 shows absorption spectra of 1 m 10uM in toluene

[0053] Figure 27 shows emission spectra of 1 m 10uM in toluene (excitation wavelength 374nm volt 550v).

[0054] Figure 28 shows absorption spectra of 1 o 10uM in toluene

[0055] Figure 29 shows emission spectra of 1o 10uM in toluene (excitation wavelength 374nm volt 550v).

[0056] Figure 30 shows absorption spectra of 1 p 10uM in toluene

[0057] Figure 31 shows emission spectra of 1 p 10uM in toluene (excitation wavelength 374nm volt 550v).

[0058] Figure 32 shows the position of the thin film sample in the integrating sphere: a) sample in the beam line; b) sample out of the beam line.

[0059] Figure 33 shows the setup of distance-dependent EQE measurement.

[0060] Figure 34 shows Flowchart of the Monte-Carlo ray tracing simulation process. [0061 ] Figure 35 shows Thermal gravimetric analysis of 1a with decomposition commencing at 175 °C.

[0062] Figure 36 shows Thermal gravimetric analysis of 1 b with decomposition commencing at 350 °C.

[0063] Figure 37 shows thermal gravimetric analysis of 1c with decomposition commencing at 330 °C.

[0064] Figure 38 shows Thermal gravimetric analysis of 1d with decomposition commencing at 330 °C.

[0065] Figure 39 shows Thermal gravimetric analysis of 1e with decomposition commencing at 310 °C.

[0066] Figure 40 shows the absolute photoluminescent quantum yields of thin films 1a to 1e (5mM in PMMA).

[0067] Figure 41 shows a CIE chromaticity diagram based on the emission spectrum of the 1e (5mM) thin film.

[0068] Figure 42 shows the normalised absorption and emission spectrum of 1e with the external quantum efficiency (EQE) output data from the LSC solar cell device.

[0069] Figure 43 shows simulated optical quantum efficiency (OQE) and re- absorption fraction of the LSC device based on 1e in two concentrations plotted as a function of the geometric gain on a 1 mm thick square glass waveguide. The absorbance of all samples was set to 0.1 and a total of 100,000 photons were used in each simulation.

[0070] Figure 44 shows a graph of theoretically predicted absorption and emission spectra for compounds 1a-1f that indicate good reproducibility of experimental observations.

[0071 ] Figure 45 shows a graph of theoretical calculations for compound 1 a where chlorine and hydrogen atoms replace the fluorine substituents. Detailed Description

[0072] In this specification, a number of terms are used which are well known to a skilled addressee. Nevertheless, for the purposes of clarity, a number of terms will be defined.

[0073] Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to exclude other additives, components, integers or steps.

[0074] The term "optionally substituted" as used throughout the specification denotes that the group may or may not be further substituted or fused (so as to form a condensed polycyclic system), with one or more non-hydrogen substituent groups. In certain embodiments the substituent groups are one or more groups independently selected from the group consisting of halogen, =O, =S, -CN, -NO2, -CF ₃ , -OCF3, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, heteroalkyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkylalkyl, heteroarylalkyl, arylalkyl, cycloalkylalkenyl, heterocycloalkylalkenyl, arylalkenyl, heteroarylalkenyl, cycloalkylheteroalkyl, heterocycloalkylheteroalkyl, arylheteroalkyl, heteroarylheteroalkyl, hydroxy, hydroxyalkyl, alkyloxy, alkyloxyalkyl, alkyloxycycloalkyl, alkyloxyheterocycloalkyl, alkyloxyaryl, alkyloxyheteroaryl, alkyloxycarbonyl, alkylaminocarbonyl, alkenyloxy, alkynyloxy, cycloalkyloxy, cycloalkenyloxy, heterocycloalkyloxy, heterocycloalkenyloxy, aryloxy, phenoxy, benzyloxy, heteroaryloxy, arylalkyloxy, amino, alkylamino, acylamino, aminoalkyl, arylamino, sulfonylamino, sulfinylamino, sulfonyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl, sulfinyl, alkylsulfinyl, arylsulfinyl, aminosulfinylaminoalkyl, C(=O)OH, -C(=O)R ^a , C(=O)OR ^a , C(=O)NR ^a R ^b , C(=NOH)R ^a , C(=NR ^a )NR ^b R ^c , NR ^a R ^b , NR ^a C(=O)R ^b , NR ^a C(=O)OR ^b , NR ^a C(=O)NR ^b R ^c , NR ^a C(=NR ^b )NR ^c R ^d , NR ^a SO ₂ R ^b , -SR ^a , SO ₂ NR ^a R ^b , -OR ^a , OC(=O)NR ^a R ^b , OC(=O)R ^a and acyl;

[0075] wherein R ^a , R ^b , R ^c and R ^d are each independently selected from the group consisting of H, Ci-Ci2alkyl, CrCi2haloalkyl, C2-Ci2alkenyl, C2-Ci2alkynyl, d- Cioheteroalkyl, C3-Ci2cycloalkyl, C3-Ci2cycloalkenyl, CrCi2heterocycloalkyl, d- Ci2heterocycloalkenyl, Ce-C-isaryl, Ci-Cisheteroaryl, and acyl, or any two or more of R ^a , R ^b , R ^c and R ^d , when taken together with the atoms to which they are attached form a heterocyclic ring system with 3 to 12 ring atoms.

[0076] Examples of particularly suitable optional substituents include F, CI, Br, I, CH ₃ , CH2CH3, OH, OCH3, CF ₃ , OCF3, NO ₂ , NH ₂ , and CN.

[0077] In the definitions of a number of substituents below it is stated that "the group may be a terminal group or a bridging group". This is intended to signify that the use of the term is intended to encompass the situation where the group is a linker between two other portions of the molecule as well as where it is a terminal moiety. Using the term alkyl as an example, some publications would use the term "alkylene" for a bridging group and hence in these other publications there is a distinction between the terms "alkyl" (terminal group) and "alkylene" (bridging group). In the present application, no such distinction is made and most groups may be either a bridging group or a terminal group.

[0078] "Alkenyl" as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched preferably having 2-12 carbon atoms, more preferably 2-10 carbon atoms, most preferably 2-6 carbon atoms, in the normal chain. The group may contain a plurality of double bonds in the normal chain and the orientation about each is independently E or Z. The alkenyl group is preferably a 1 -alkenyl group. Exemplary alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl and nonenyl. The group may be a terminal group or a bridging group.

[0079] "Alkyl" as a group or part of a group refers to a straight or branched aliphatic hydrocarbon group, preferably a Ci-Ci ₂ alkyl, more preferably a CrCi ₀ alkyl, most preferably C1-C6 unless otherwise noted. Examples of suitable straight and branched d-Cealkyl substituents include methyl, ethyl, n-propyl, 2-propyl, n-butyl, sec- butyl, t-butyl, hexyl, and the like. The group may be a terminal group or a bridging group.

[0080] "Alkylamino" includes both mono-alkylamino and dialkylamino, unless specified. "Mono-alkylamino" means an Alkyl-NH- group, in which alkyl is as defined herein. "Dialkylamino" means a (alkyl) ₂ N- group, in which each alkyl may be the same or different and are each as defined herein for alkyl. The alkyl group is preferably a Ci-C ₆ alkyl group. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the nitrogen atom.

[0081 ] "Alkoxy" refers to an alkyl-O- group in which alkyl is as defined herein. Preferably the alkyoxy is a CrC ₆ alkyoxy. Examples include, but are not limited to, methoxy and ethoxy. The group may be a terminal group or a bridging group.

[0082] "Alkynyl" as a group or part of a group means an aliphatic hydrocarbon group containing a carbon-carbon triple bond and which may be straight or branched preferably having from 2-12 carbon atoms, more preferably 2-10 carbon atoms, more preferably 2-6 carbon atoms in the normal chain. Exemplary structures include, but are not limited to, ethynyl and propynyl. The group may be a terminal group or a bridging group.

[0083] "Alkenyloxy" refers to an alkenyl-O- group in which alkenyl is as defined herein. Preferred alkenyloxy groups are C C ₆ alkenyloxy groups. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0084] "Alkynyloxy" refers to an alkynyl-O- group in which alkynyl is as defined herein. Preferred alkynyloxy groups are C ₂ -Ci ₂ alkynyloxy groups. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0085] "Aryl" as a group or part of a group denotes (i) an optionally substituted monocyclic, or fused polycyclic, aromatic carbocycle (ring structure having ring atoms that are all carbon) preferably having from 5 to 12 atoms per ring. Examples of aryl groups include phenyl, naphthyl, and the like; (ii) an optionally substituted partially saturated bicyclic aromatic carbocyclic moiety in which a phenyl and a Cs-zcycloalkyl or C ₅ - ₇ cycloalkenyl group are fused together to form a cyclic structure, such as tetrahydronaphthyl, indenyl or indanyl. The group may be a terminal group or a bridging group. Typically, an aryl group is a C6-C18 aryl group. [0086] "Aryloxy" refers to an aryl-O- group in which the aryl is as defined herein. Preferably the aryloxy is a Ce-C-isaryloxy, more preferably a C6-Cioaryloxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0087] "Cycloalkyi" refers to a saturated monocyclic or fused or spiro polycyclic, carbocycle preferably containing from 3 to 9 carbons per ring, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like, unless otherwise specified. It includes monocyclic systems such as cyclopropyl and cyclohexyl, bicyclic systems such as decalin, and polycyclic systems such as adamantane. A cycloalkyi group typically is a C3-C12 alkyl group. The group may be a terminal group or a bridging group.

[0088] "Cycloalkyloxy" refers to a cycloalkyl-O- group in which cycloalkyi is as defined herein. Preferably the cycloalkyloxy is a d-Cecycloalkyloxy. Examples include, but are not limited to, cyclopropanoxy and cyclobutanoxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0089] "Cycloalkenyl" means a non-aromatic monocyclic or multicyclic ring system containing at least one carbon-carbon double bond and preferably having from 3-7 carbon atoms per ring. Exemplary monocyclic cycloalkenyl rings include cyclopentenyl, cyclohexenyl or cycloheptenyl. The cycloalkenyl group may be substituted by one or more substituent groups. A cycloalkenyl group typically is a C ₃ - C12 alkenyl group. The group may be a terminal group or a bridging group.

[0090] "Cycloalkenyloxy" refers to a cycloalkenyl-O- group in which the cycloalkenyl is as defined herein. Preferably the cycloalkenyloxy is a CrC ₆ cycloalkenyloxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0091 ] "Haloalkyl" refers to an alkyl group as defined herein in which one or more of the hydrogen atoms has been replaced with a halogen atom selected from the group consisting of fluorine, chlorine, bromine and iodine. A haloalkyl group typically has the formula C _n H( ₂ n ₊ i-m) m wherein each X is independently selected from the group consisting of F, CI, Br and I. In groups of this type n is typically from 1 to 1 2, more preferably from 1 to 6, most preferably 1 to 3. m is typically 1 to 6, more preferably 1 to 3. Examples of haloalkyl include fluoromethyl, difluoromethyl and trifluoromethyl.

[0092] "Halogen" represents chlorine, fluorine, bromine or iodine.

[0093] "Heteroaryl" either alone or part of a group refers to groups containing an aromatic ring (preferably a 5 or 6 membered aromatic ring) having one or more heteroatoms as ring atoms in the aromatic ring with the remainder of the ring atoms being carbon atoms. Suitable heteroatoms include nitrogen, oxygen and sulphur. Examples of heteroaryl include thiophene, benzothiophene, benzofuran, benzimidazole, benzoxazole, benzothiazole, benzisothiazole, naphtho[2,3- b]thiophene, furan, isoindolizine, xantholene, phenoxatine, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyrimidine, pyridazine, tetrazole, indole, isoindole, 1 H- indazole, purine, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, cinnoline, carbazole, phenanthridine, acridine, phenazine, thiazole, isothiazole, phenothiazine, oxazole, isooxazole, furazane, phenoxazine, 2-, 3- or 4- pyridyl, 2-, 3-, 4-, 5-, or 8- quinolyl, 1 -, 3-, 4-, or 5- isoquinolinyl 1 -, 2-, or 3- indolyl, and 2-, or 3 thienyl. A heteroaryl group is typically a C1 -C18 heteroaryl group. The group may be a terminal group or a bridging group.

[0094] "Heteroaryloxy" refers to a heteroaryl-O- group in which the heteroaryl is as defined herein. Preferably the heteroaryloxy is a CrCi ₈ heteroaryloxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0095] "Heteroalkyl" refers to a straight- or branched-chain alkyl group preferably having from 2 to 12 carbons, more preferably 2 to 6 carbons in the chain, in which one or more of the carbon atoms (and any associated hydrogen atoms) are each independently replaced by a heteroatomic group selected from S, O, P and NR' where R' is selected from the group consisting of H, optionally substituted C Ci2alkyl, optionally substituted C ₃ -Ci ₂ cycloalkyl, optionally substituted C ₆ -Ci ₈ aryl, and optionally substituted CrCi ₈ heteroaryl. Exemplary heteroalkyls include alkyl ethers, secondary and tertiary alkyl amines, amides, alkyl sulfides, and the like. Examples of heteroalkyl also include hydroxyd-Cealkyl, Ci-Cealkyloxyd-Cealkyl, aminod-Cealkyl, d- C ₆ alkylaminoCrC ₆ alkyl, and di(Ci-C ₆ alkyl)aminoCrC ₆ alkyl. The group may be a terminal group or a bridging group.

[0096] "Heteroalkyloxy" refers to a heteroalkyl-O- group in which heteroalkyl is as defined herein. Preferably the heteroalkyloxy is a C2-Cioheteroalkyloxy. The group may be a terminal group or a bridging group.

[0097] "Heterocycloalkyl" refers to a saturated monocyclic, bicyclic, or polycyclic ring containing at least one heteroatom selected from nitrogen, sulfur, oxygen, preferably from 1 to 3 heteroatoms in at least one ring. Each ring is preferably from 3 to 10 membered, more preferably 4 to 7 membered. Examples of suitable heterocycloalkyl substituents include pyrrolidyl, tetrahydrofuryl, tetrahydrothiofuranyl, piperidyl, piperazyl, tetrahydropyranyl, morphilino, 1 ,3-diazapane, 1 ,4-diazapane, 1 ,4- oxazepane, and 1 ,4-oxathiapane. A heterocycloalkyl group typically is a C2- Ci ₂ heterocycloalkyl group. The group may be a terminal group or a bridging group.

[0098] "Heterocycloalkenyl" refers to a heterocycloalkyl group as defined herein but containing at least one double bond. A heterocycloalkenyl group typically is a C2- Ci2heterocycloalkenyl group. The group may be a terminal group or a bridging group.

[0099] "Heterocycloalkyloxy" refers to a heterocycloalkyl-O- group in which the heterocycloalkyl is as defined herein. Preferably the heterocycloalkyloxy is a d- C ₆ heterocycloalkyloxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom.

[0100] "Heterocycloalkenyloxy" refers to a heterocycloalkenyl-O- group in which heterocycloalkenyl is as defined herein. Preferably the Heterocycloalkenyloxy is a C C ₆ Heterocycloalkenyloxy. The group may be a terminal group or a bridging group. If the group is a terminal group it is bonded to the remainder of the molecule through the oxygen atom. Compounds

[0101 ] As discussed above the applicants of the present invention have identified a class of compounds namely compounds of formula (I) and formula (la) that have interesting photo-physical properties that enable them to be utilised as components in light harvesting applications particularly in solar concentrators.

[0102] In the compounds of formula (I), n is an integer selected from the group consisting of 0, 1 , 2, 3, 4, and 5. In one embodiment of the compounds of formula (I) n is selected from the group consisting of 1 , 2, 3, 4, and 5, thus providing compounds of formula (la).

[0103] In one embodiment of the compounds of formula (I) and (la) n is selected from the group consisting of 1 , 2, and 3. In one embodiment of the compounds of formula (I) and (la) n is 1 . In one embodiment of the compounds of formula (I) and (la) n is 2. In one embodiment of the compounds of formula (I) and (la) n is 3. In one embodiment of the compounds of formula (I) and (la) n is 4. In one embodiment of the compounds of formula (I) and (la) n is 5.

[0104] In one embodiment of the compounds of formula (I) and (la) n is 1 and the compound is a compound of the formula (II):

Formula (II)

[0105] wherein R and R are as discussed above. [0106] The R ¹ group may be located at any suitable position on the pyridinium ring. In one embodiment R ¹ is located on the 2 position of the pyridinium providing compounds of formula (lla):

Formula (lla)

[0107] wherein R and R ¹ are as defined above.

[0108] In one embodiment R ¹ is located on the 3 position of the pyridinium providing compounds of formula (Mb):

Formula (lib)

[0109] wherein R and R ¹ are as defined above.

[01 10] In one embodiment R ¹ is located on the 4 position of the pyridinium providing compounds of formula (lie):

Formula (lie)

[01 1 1 ] wherein R and R ¹ are as defined above.

[01 12] In one embodiment of the compounds of formula (I) and (la) n is 2 and the compound is a compound of the formula (III):

Formula (III)

[01 13] wherein R and R ¹ are as defined above.

[01 14] In compounds of formula (III) the R ¹ groups may be located in a variety of positions on the pyridinium ring. In one embodiment the groups are located at the 2 and 4 positions of the pyridinium ring to provide compounds of formula (Ilia):

Formula (Ilia) wherein R and R ¹ are as defined above.

[01 16] In the compounds of the invention and in particularly with respect to the compounds of formula (I), (la), (II), (lla), (Mb), (lie) (III) and (Ilia) each R is independently selected from the group consisting of H, F, CI, Br and I. In one embodiment each R is independently selected from the group consisting of H, F and CI. In one embodiment each R is independently selected from the group consisting of H and F. in one embodiment each R is independently selected from the group consisting of H and CI. In one embodiment each R is independently selected from the group consisting of F and CI. In one embodiment each R is F. In one embodiment each R is CI.

[01 17] In the compounds of the invention and in particularly with respect to the compounds of formula (I), (la), (II), (lla), (lib), (lie) (III) and (Ilia) each R ¹ is independently selected from the group consisting of halogen, OH, NO ₂ , CN, SH, NH ₂ , CF ₃ , OCF ₃ , optionally substituted CrCi ₂ alkyl, optionally substituted CrCi ₂ haloalkyl, optionally substituted C ₂ -Ci ₂ alkenyl, optionally substituted C ₂ -Ci ₂ alkynyl, optionally substituted C ₂ -Ci ₂ heteroalkyl, optionally substituted C3-Ci ₂ cycloalkyl, optionally substituted C ₃ -Ci ₂ cycloalkenyl, optionally substituted C ₂ -Ci ₂ heterocycloalkyl, optionally substituted C ₂ -Ci ₂ heterocycloalkenyl, optionally substituted C ₆ -Ci ₈ aryl, optionally substituted d-C-isheteroaryl, optionally substituted CrCi ₂ alkyloxy, optionally substituted C ₂ -Ci ₂ alkenyloxy, optionally substituted C ₂ -Ci ₂ alkynyloxy, optionally substituted C2-Cioheteroalkyloxy, optionally substituted C3-Ci2cycloalkyloxy, optionally substituted C3-Ci2cycloalkenyloxy, optionally substituted d- Ci ₂ heterocycloalkyloxy, optionally substituted C ₂ -Ci ₂ heterocycloalkenyloxy, optionally substituted C ₆ -Ci ₈ aryloxy, optionally substituted C-i-C-i ₈ heteroaryloxy, optionally substituted d-C^alkylamino, SR ² , SO ₃ H, SO ₂ NR ² R ² , SO ₂ R ² , SONR ² R ² , SOR ² , COR ² , COOH, COOR ² , CONR ² R ² , NR ² COR ² , NR ² COOR ² , NR ² SO ₂ R ² , NR ² CONR ² R ² , NR ² R ² , and acyl;

[01 18] wherein each R ² is independently selected from the group consisting of H, optionally substituted CrCi ₂ alkyl, optionally substituted C ₆ -Ci ₈ aryl, and optionally substituted CrCi ₈ heteroaryl;

[01 19] In some embodiments, R ¹ is optionally substituted C Ci2alkyl. In some embodiments R ¹ is selected from the group consisting of methyl, ethyl, isopropyl, propyl, 2-ethyl-propyl, 3,3-dimethyl-propyl, butyl, isobutyl, 3,3-dimethyl-butyl, 2-ethyl- butyl, pentyl, 2-methyl, pentyl, hexyl, heptyl, and octyl.

[0120] In some embodiments, R ¹ is an optionally substituted C2-Ci2heteroalkyl group. In some embodiments, the C2-Ci2heteroalkyl group is selected from the group consisting of hydroxyd-Cealkyl, Ci-Cealkyloxyd-Cealkyl, aminod-Cealkyl, d- C6alkylaminoCi-C6alkyl, and di(Ci-C6alkyl)aminoCi-C6alkyl. Examples of possible values of R ² as C ₂ -Ci ₂ heteroalkyl include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl, methoxymethyl, 2-methoxyethyl, 3-methoxypropyl, 2- ethoxyethyl, 3-ethoxypropyl, aminomethyl, 2-aminoethyl, 3-aminopropyl, 4-aminobutyl, 5 aminopentyl, methylaminomethyl, 2-methylaminoethyl, 3-methylaminopropyl, 4- methylaminobutyl, 5-methylaminopentyl, ethylaminomethyl, 2-ethylaminoethyl, 3- ethylaminopropyl, 4-ethylaminobutyl, 5-ethylaminopentyl, dimethylaminomethyl, 2- dimethylaminoethyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 5- dimethylaminopentyl, diethylaminomethyl, 2-diethylaminoethyl, 3-diethylaminopropyl, 4-diethylaminobutyl and 5-diethylaminopentyl.

[0121 ] In some embodiments, R ¹ is selected from the group consisting of optionally substituted C6-Ci ₈ aryl, optionally substituted Ci-Ci ₈ heteroaryl and NR ² R ² .

[0122] In some embodiments, R ¹ is an optionally substituted d-d ₈ heteroaryl group. In some embodiments, the optionally substituted Ci-Ci ₈ heteroaryl group is a monocyclic heteroaryl group. In some embodiments the optionally substituted d- dsheteroaryl group is a bicyclic heteroaryl group.

[0123] In some embodiments R ¹ is an optionally substituted CrCi ₈ heteroaryl having a formula selected from the group consisting of:

[0124] each A ¹ , A ² , A ³ , A ⁴ and A ⁵ is independently selected from the group consisting of N and CR ³ provided that at least one is N;

[0125] each V ¹ , V ² , and V ³ are independently selected from the group consisting of N and CR ³ ;

[0126] Y is selected from the group consisting of S, O, and NH;

[0127] each R ³ is independently selected from the group consisting of H, halogen, OH, NO ₂ , CN, SH, NH ₂ , CH ₂ NH ₂ , CF ₃ , OCF ₃ , C Ci ₂ alkyl, C Ci ₂ alkyloxy, C Ci ₂ haloalkyl, C ₂ -Ci ₂ alkenyl, C ₂ -Ci ₂ alkynyl, C ₂ -Ci ₂ heteroalkyl, SR ⁴ , SO ₃ H, SO ₂ NR ⁴ R ⁴ , SO ₂ R ⁴ , SONR ⁴ R ⁴ , SOR ⁴ , COR ⁴ , COOH, COOR ⁴ , CONR ⁴ R ⁴ , NR ⁴ COR ⁴ , NR ⁴ COOR ⁴ , NR ⁴ SO ₂ R ⁴ , NR ⁴ CONR ⁴ R ⁴ , NR ⁴ R ⁴ , and acyl;

[0128] each R ⁴ is selected from the group consisting of H, Ci-C ₆ alkyl, and d- Ceheteroalkyl.

[0129] In one embodiment R ¹ is selected from the group consisting of:

[0130] wherein each V ¹ , V ² , and V ³ are independently selected from the group consisting of N and CR ³ ; and

[0131 ] Y is selected from the group consisting of S, O, and NH.

[0132] In one form of this embodiment each of V ¹ , V ² and V ³ are CR ³ and R ¹ is selected from the group consisting of:

[0133] In one form of this embodiment Y is NH and R ¹ is selected from the group consisting of:

[0134] In one form of this embodiment Y is O and R ¹ is selected from the group consisting of:

[0135] In one form of this embodiment Y is S and R ¹ is selected from the group consisting of:

In one preferred form R ¹ is a group of the formula

In one preferred form R ¹ is a group of the formula

[0138] In some embodiments R ¹ is NR ² R ² wherein each R ² is independently selected from the group consisting of H, optionally substituted C Ci2alkyl, optionally substituted C ₆ -Ci ₈ aryl, and optionally substituted CrCisheteroaryl.

[0139] In one form of this embodiment, each R ² is optionally substituted CQ- Ci ₈ aryl. In one preferred form of this embodiment each R ² is optionally substituted phenyl of the formula:

[0141 ] In the compounds of the invention containing an R ³ group each R ³ is independently selected from the group consisting of H, halogen, OH, NO ₂ , CN, SH, NH ₂ , CH ₂ NH ₂ , CF ₃ , OCF ₃ , CrCi ₂ alkyl, C Ci ₂ alkyloxy, C Ci ₂ haloalkyl, C ₂ -Ci ₂ alkenyl, C ₂ -Ci ₂ alkynyl, C ₂ -Ci ₂ heteroalkyl, SR ⁴ , SO ₃ H, SO ₂ NR ⁴ R ⁴ , SO ₂ R ⁴ , SONR ⁴ R ⁴ , SOR ⁴ , COR ⁴ , COOH, COOR ⁴ , CONR ⁴ R ⁴ , NR ⁴ COR ⁴ , NR ⁴ COOR ⁴ , NR ⁴ SO ₂ R ⁴ , NR ⁴ CONR ⁴ R ⁴ , NR ⁴ R ⁴ , and acyl; [0142] each R ⁴ is selected from the group consisting of H, d-Cealkyl, and d- Ceheteroalkyl.

[0143] Examples of preferred values of R ³ are H, halogen, CH ₃ , CH ₂ CH ₃ , OH, NO ₂ , CN, SH, NH ₂ , CH ₂ NH ₂ , CF ₃ and OCF ₃ .

[0144] In some embodiments R ¹ is an optionally substituted C ₆ -Ci ₈ aryl group. In one embodiment R ¹ is an optionally substituted phenyl group. The substituents may be located at any substitutable position around the aryl ring available for substitution as would be clear to a skilled addressee. Examples of suitable optionally substituted phenyl compounds include, but are not limited to, 2-methoxy-phenyl, 3-methoxy- phenyl, 4-methoxy-phenyl, 2-trifluoromethyl-phenyl, 3-trifluoromethyl-phenyl, 4- trifluoromethyl-phenyl, 2-chloro-phenyl, 3-chloro-phenyl, 4-chloro-phenyl, 4-bromo- phenyl, 2-fluoro-phenyl, 3-fluoro-phenyl, 4-fluoro-phenyl, 4-hydroxy-phenyl, 4-phenyl- phenyl, 4-methyl-phenyl, 2,4-dichloro-phenyl, 3,4-dichloro-phenyl, 2,5-dichloro-phenyl, 2,6-difluoro-phenyl, 2-chloro-6-fluoro-phenyl, 3-fluoro-4-chloro-phenyl, 3-methyl-4- chloro-phenyl, 3-chloro-4-fluoro-phenyl, 3-chloro-4-methyl-phenyl, 2-hydroxy-phenyl, 3-hydroxy-phenyl, 4-hydroxy-phenyl, 4-ethoxy-phenyl, 3-phenoxy-phenyl, 4-phenoxy- phenyl, 2-methyl-phenyl, 3-methyl-phenyl, 4-methyl-phenyl, 4-isopropyl-phenyl, 4- cyano-phenyl, 3,4-dimethyl-phenyl, 2,4-dimethyl-phenyl, 4-t-butyl-phenyl, 2,4- dimethoxy-phenyl, and 3,4-methylenedioxy-phenyl.

[0145] Certain substituents of the compounds of the invention may be optionally substituted as defined herein.

[0146] In some embodiments each optional substituent is independently selected from the group consisting of: F, CI, Br, =O, =S, -CN, -NO ₂ , alkyl, alkenyl, heteroalkyl, haloalkyi, alkynyl, aryl, cycloalkyi, heterocycloalkyi, heteroaryl, hydroxy, hydroxyalkyi, alkoxy, alkylamino, aminoalkyl, acylamino, phenoxy, alkoxyalkyl, benzyloxy, alkylsulfonyl, arylsulfonyl, aminosulfonyl, -C(O)OR ^a , COOH, SH, and acyl.

[0147] In some embodiments each optional substituent is independently selected from the group consisting of: F, Br, CI, =O, =S, -CN, methyl, trifluoro-methyl, ethyl, 2,2,2-trifluoroethyl, isopropyl, propyl, 2-ethyl-propyl, 3,3-dimethyl-propyl, butyl, isobutyl, 3,3-dimethyl-butyl, 2-ethyl-butyl, pentyl, 2-methyl-pentyl, pent-4-enyl, hexyl, heptyl, octyl, phenyl, NH ₂ , -NO2, phenoxy, hydroxy, methoxy, trifluoro-methoxy, ethoxy, and methylenedioxy.

[0148] Specific compounds of the invention include the following:

(Id)

(le) (If)

(ig) (lh) (li)

(lj) (lk)

(lm) (lo)

(lp)

Solar Concentrators

[0149] The compounds disclosed in the present application find application in solar concentrators. In their most fundamental form a solar concentrator consists of a substrate with a compound or compounds disposed on or in the substrate, the compound or compounds being chosen or selected such that they absorb incident light and emit light of a different (typically longer) wavelength.

[0150] Accordingly, the compounds that find application in solar concentrators are typically ones that exhibit a significant Stokes shift so that the emitted light is not itself absorbed by the compound in the solar concentrator as this lowers efficiency. In the basic form of solar concentrator, a substantial portion of the emitted light is trapped by total internal reflection within the substrate and guided to the edge of the solar concentrator where it is able to be absorbed by a photovoltaic cell that is optically coupled to the solar concentrator.

[0151 ] As will be appreciated there are a number of variations on the fundamental form of a solar concentrator and we refer the reader to US2009/0235974 which describes these devices in significant detail and describes a number of permutations on the basic form although we will attempt to include herein a discussion of some of the more relevant details.

[0152] A solar concentrator typically comprises a substrate and a compound either disposed on or in the substrate. Accordingly, the compound may be on the surface of the substrate or wholly contained within the substrate.

[0153] In this context, the applicants note that the term disposes is intended to be interchangeable with the term deposited. Accordingly, a compound may be disposed on a surface by methods such as evaporation, co-evaporation, coating, painting, spraying, brushing, vapor deposition, casting, covalent association, non-covalent association, coordination or otherwise attachment, for at least some time, to the surface.

[0154] The substrate may be any suitable material that the compound can be disposed on or in. Suitable examples include glass, polymeric films or layers and the like. Well known substrates for solar concentrators include polymethylmethyacrylate

(PMMA), glass, lead-doped glass, lead-doped plastics, aluminum oxide, polycarbonate, haiide-chalcogenide glasses, titania-doped glass, titania-doped plastics, zirconia-doped glass, zirconia-doped plastics, alkaline metal oxide-doped glass, alkaline metal oxide-doped plastics, barium oxide-doped glass, barium-doped plastics, zinc oxide-doped glass, and zinc oxide-doped plastics as referenced in the Us patent referred to above.

[0155] The size and shape of the substrate may vary widely with the dimensions and shape being chosen base on the end use application such as the overall desired size of the solar concentrator and its place of use.

[0156] In essence the substrate may be any suitable size determined by the end use location and the available space. The substrate can be any dimension. Nevertheless, the substrate in a solar concentrator is typically from 10 cm to 600 cm wide and 10 cm to 1000 cm long. In certain embodiments the substrate is from 10 cm to 400 cm wide and 10 cm to 600 cm long. In certain embodiments the substrate is from 10 cm to 300 cm wide and 10 cm to 500 cm long. [0157] The thickness of the substrate may also vary widely depending once again on the desired end use application. The substrate is typically from 1 mm to about 10 mm, more typically 1 mm to 5 mm, even more typically 2 mm to 4 mm.

[0158] As discussed above it is typical that the substrate is a solid substrate with the compound either disposed on a surface of the substrate or contained within the substrate. In one embodiment the compound is contained within the substrate by the compound being dispersed within the substrate itself such as where a compound is mixed with a polymeric material before being cast of formed into a film. In one embodiment the substrate is a polymeric matrix and the compound is incorporated into the polymeric matrix during manufacture of the polymeric matrix.

[0159] In some embodiments, the substrate is in the form of a container defining a contained region in which the compound, typically dispersed or dissolved in a carrier is contained.

[0160] In certain embodiments, the solar concentrator may include a wavelength selective mirror disposed on the surface of the substrate. A wavelength selective mirror is a mirror that allows light of certain wavelengths to pass through it but which at the same time reflects light at a second wavelength. The inclusion of a mirror of this type is desirable in solar concentrators as it can greatly increase the efficiency of the solar concentrator. Any suitable wavelength selective mirror may be used although it is typical that the wavelength selective mirror is tailored to the properties of the compound used in the solar concentrator. For example, the mirror is chosen so that the wavelength absorbed by the compound is able to pass through the mirror but the wavelength of the emitted light is not. In this way, any light emitted by the compound in the solar concentrator is trapped within the concentrator and will, therefore, be available for collection.

[0161 ] In certain embodiments, the solar concentrators are optically coupled to a photovoltaic cell in order to capture the light energy and to convert it to electrical energy.

[0162] The photovoltaic cell may be any suitable photovoltaic cell found in the art and may include one or more of the following: amorphous silicon (a-Si) and other thin film (TF-Si) cadmium telluride (CdTe); copper indium gallium deselenide (CIS or CIGS); dye-sensitized solar cells (DSC); Perovskite solar cells, and single crystalline gallium arsenide (GaAs) merely by way of example. In principle, any PV cell may be used with the solar concentrators described herein.

SYNTHESIS OF COMPOUNDS OF THE INVENTION

[0163] The compounds of the various embodiments may be prepared using the reaction routes and synthesis schemes as described below, employing the techniques available in the art using starting materials that are readily available. The preparation of particular compounds of the embodiments is described in detail in the following examples, but the artisan will recognize that the chemical reactions described may be readily adapted to prepare a number of other agents of the various embodiments. For example, the synthesis of non-exemplified compounds may be successfully performed by modifications apparent to those skilled in the art, e.g. by appropriately protecting interfering groups, by changing to other suitable reagents known in the art, or by making routine modifications of reaction conditions. A list of suitable protecting groups in organic synthesis can be found in T.W. Greene's Protective Groups in Organic Synthesis, 3rd Edition, John Wiley & Sons, 1991 . Alternatively, other reactions disclosed herein or known in the art will be recognized as having applicability for preparing other compounds of the various embodiments.

[0164] For example, the synthesis of the compounds of the invention may be carried out using the procedure in scheme 1 . Thus reaction of the appropriately substituted pyridine with octafluorocyclopentene under appropriate conditions with the addition of water and loss of hydrofluoric acid to the formation of the pyridinium enolate. This procedure may be modified by modification of either the pyridine starting material or the cyclopentene derivative to access almost all members of the family:

Scheme 1

EXAMPLES

[0165] The invention will now be illustrated by way of examples; however, the examples are not to be construed as being limitations thereto. Additional compounds, other than those described below, may be prepared using methods and synthetic protocols or appropriate variations or modifications thereof, as described herein.

Chemicals

[0166] All chemicals used in the following examples were laboratory grade and sourced from the following suppliers: Acetonitrile (Ajax Finechem), chloroform (RCI Labscan), ethyl acetate (Emsure), hexane (ACI Labscan), n-Butyllithium solution 2.5 M in hexanes (Sigma), magnesium sulphate (Chem-supply), 2-methylthiophene (Sigma), Octafluorocyclopentene (Tokyo Chemical Industry), Poly (methyl methacrylate) average Mw 996,000 by G PC, crystalline (Sigma-Aldrich), TBA PF ₆ (Sigma-Aldrich), Tetrahydrofuran (Chem-Supply), Toluene (Chem-Supply), Trifluoroacetic acid (Sigma). Chemicals were used as purchased without further purification. Solvents were degassed and dried over 3 A molecular sieves using standard laboratory procedures where appropriate.

Nuclear Magnetic Resonance

[0167] ¹ H NMR spectroscopy was performed on a Varian 400 MHz NMR Spectrometer using a pulse width of ττ/2 (1 1.25 ps), carbon decoupled and referenced against residual solvent. ¹⁹ F NMR signals were referenced against trifluoroacetic acid.

[0168] Proton chemical shifts are reported in parts per million (ppm) from an internal standard of residual chloroform at δ 7.26 ppm or dimethylsulfoxide at δ 2.50 ppm. All chemical shifts were recorded as δ values in parts per million (ppm) and coupling constants (J) were recorded in hertz (Hz). For reporting of an NMR spectrum, the following terms were used; singlet (s), doublet (d), triplet (t), multiplet (m), broad (br).

FT-IR spectroscopy (KBr disc)

[0169] FT-IR spectroscopy was performed on a Bruker Tensor 27 FT-IR spectrometer. Samples were prepared as KBr pellets. Signals are listed as wavenumbers (cm ^"1 ) with the following abbreviations: s = strong, m = medium and w = weak.

Elemental analysis

[0170] Elemental Analysis was conducted by the Campbell Microanalytical Laboratory and the Centre for Trace Element Analysis at the University of Otago, New Zealand. UV-Vis Spectroscopy

[0171 ] UV-Vis Spectroscopy was performed on an Agilent Technologies Cary 60 UV-Vis using Agilent Technologies standard quartz cuvettes (d = 1 cm).

Fluorescence Spectroscopy

[0172] Fluorescence spectroscopy was performed on an Agilent Technologies Cary Eclipse Fluorescence Spectrophotometer using Thorlabs Macro Fluorescence Cuvette with Stopper (d = 1 cm). Relative fluorescence quantum yields were calculated relative to 9,10-diphenylanthracene.

Thermogravimetric Analysis (TGA)

[0173] TGA was conducted on a Mettler Toledo TGA/SDTA851 ^e thermogravimetric analyser heating from 25 °C to 800 °C at a ramp of 1 0 °C min ^"1 under a flow of nitrogen (30 imL min ^"1 ).

Mass Spectrometry

[0174] MS experiments were performed on an Agilent 1 100 autosampler system coupled to an Agilent 6520 Quadrupole Time of Flight (Q-Tof) Mass Spectrometer controlled via the MassHunter software package B.05.01 . ESI solutions were prepared using HPLC grade acetonitrile and transferred to the electrospray source. One μΙ of sample was injected into the carrier solvent stream of 70 % acetonitrile (0.1 % formic acid) at a flow rate of 0.3 imL min ^"1 . Recorded m/z data were corrected using a reference mass by a dual-spray electrospray ionization source using the factory- defined calibration procedure. Mass spectrometer conditions: drying gas flow rate, 7 L min ^{"1 ;} nebulizer pressure, 40 psi; drying gas temperature, 300 °C; capillary voltage, 4000V; skimmer voltage, 65 V; Oct Rf, 750 V; scan range acquired, 100-3200 m/z.

[0175] All glassware used in reactions requiring anhydrous conditions was oven- dried and then cooled under nitrogen prior to use. Example 1 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) pyridinium (1a)

(la)

[0176] A solution of pyridine (70 mg, 0.89 mmol) in 2 ml THF was stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (158 mg, 0.745 mmol), 15.5% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solvent was removed in vacuo with the residue purified using column chromatography (silica, hexane: ethyl acetate, 10% to 60% ethyl acetate gradient flow). Slow removal of solvent from the product fraction yields pale yellow crystals (95 mg, 0.38 mmol, 51 .4% yield). ¹ H NMR (400 MHz, DMSO-d ₆ ) δ 9.26 (d, J = 5.7 Hz, 2H), 8.59 (t, J = 7.8 Hz, 1 H), 8.21 (t, J = 7.1 Hz, 2H). ¹⁹ F NMR (400 MHz, DMSO-d ₆ ) δ =-127.39. Elemental analysis (%) calculated, (found): C, 48.6 (47.32); H, 2.04 (2.32); N, 5.67 (5.45); F, 30.75 (29.04). Selected IR data (KBr, cm ^"1 ): 3442, 3127(w), 3082(m), 3053(w), 2959(w), 2922(w), 2851 (w), 1630(s), 1472(s), 1316(m), 1217(m), 1 1 19(m), 1066(m), 1014(m), 848(w), 770(w), 670(w), 614(w), 536(w). MS (ESI): m/z 248.0331 .

Example 2 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) 4'-Dimethylaminopyridinium (1 b)

[0177] A solution of 4-Dimethylaminopyridine (109 mg, 0.89 mmol) in 2 ml THF was stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (158 mg, 0.745 mmol), 15.5% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. Yellow crystals form on slow evaporation of the solution that are subsequently washed with cold ethyl acetate (130 mg, 0.45 mmol, 60% yield). ¹ H NMR (400 MHz, DMSO-d ₆ ) δ 8.34 (d, J = 7.05 Hz, 2H), 7.08 (d, J = 7.1 2 Hz, 2H), 3.22 (s, 6H). ¹⁹ F NMR (400 MHz, DMSO-d ₆ ) δ =-127.1 1 . Elemental analysis (%) calculated, (found): C, 49.66 (49.30); H, 3.47 (3.50); N, 9.65 (9.53); F, 26.19 (26.1 ). Selected IR data (KBr, cm ^"1 ): 3442, 3088(w), 1647(s), 1614(s), 1574(m), 1526(w), 1427(w), 1405(w), 1320(m), 1231 (m), 1 168(m), 1 1 19(m), 1052(m), 1012(m), 824(w), 766(w), 744(w), 619(w), 520(w). MS (ESI): m/z 291 .0759.

Example 3 - Synthesis of 1 -(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) 4,4'-bipyridine (1 c)

[0178] A solution of 4,4'-bipyridine (141 mg, 0.90 mmol) in 2 ml THF was stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (158 mg, 0.745 mmol), 15.5% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solvent was removed in vacuo with the residue purified using column chromatography (silica, hexane: ethyl acetate, 60% to 100% ethyl acetate gradient flow) to yield yellow crystals on slow evaporation of the solvent (95 mg, 0.30 mmol, 39% yield). ¹ H NMR (400 MHz, DMSO-de) δ 9.43 (d, J = 6.65 Hz, 2H), 8.87 (d, J = 5.81 Hz, 2H), 8.67 (t, J = 6.72 Hz, 2H), 8.05 (t, J = 5.91 Hz, 2H). ¹⁹ F NMR (400 MHz, DMSO-d ₆ ) δ =-127.25. Elemental analysis (%) calculated, (found): C, 55.57 (55.52); H, 2.49 (2.47); N, 8.64 (8.67); F, 23.44 (23.62). Selected IR data (KBr, cm ^"1 ): 3442, 3127(w), 2921 (w), 2850(w), 1700(m), 1624(s), 1540(w), 1479(w), 1453(m), 1412(w), 1381 (w), 1325(m), 1212(m), 1 130(m), 1058(m), 1017(m), 81 1 (w), 610(w). MS (ESI): m/z 325.0610.

Example 4 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) 3-Bromo-2-methyl-5-(4-pyridyl) thiophene (1d)

[0179] 3-Bromo-2-methyl-5-(4-pyridyl) thiophene was prepared as reported previously in G. Liu, M. Liu, S. Pu, C. Fan, S. Cui, Tetrahedron 2012, 68, 2267-2275.

[0180] A solution of 3-Bromo-2-methyl-5-(4-pyridyl) thiophene (160 mg, 0.63 mmol) in 2 ml THF and 1 ml water was stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (158 mg, 0.745 mmol), 15.5% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (100 mg, 37% yield). ¹ H NMR (400 MHz, DMSO-d ₆ ) δ 9.17 (d, J = 7.22 Hz, 2H), 8.34 (d, J = 7.26 Hz, 2H), 8.30 (s, 1 H), 2.52 (s, 3H). ¹⁹ F NMR (400 MHz, DMSO-d ₆ ) δ =-128.18. Elemental analysis (%) calculated, (found): C, 42.67 (42.95); H, 1 .91 (2.34); N, 3.32 (3.06); F, 18 (17.07); Br, 18.93 (18.20); S, 7.59 (6.82). Selected IR data (KBr, cm ^"1 ): 3442, 2924(w), 1701 (w), 1615(s), 1534(w), 1493(w), 1465(m), 1438(w), 1327(w), 1212(w), 1 125(m), 1065(m), 1014(w) , 839(w), 614(w). MS (ESI): m/z 421 .9480, 423.9459.

Example 5 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) 4-(5-methyl-2-thienyl) pyridine (1e)

Step 1 - Synthesis of 4-(5-methyl-2-thienyl) pyridine:

[0181 ] To a stirred anhydrous THF solution (20 mL) of compound 3-Bromo-2- methyl-5-(4-pyridyl) thiophene (141 mg, 0.56 mmol) was added dropwise a 2.5M n- BuLi/hexane solution (0.30 mL, 0.75 mmol) at 195 K under nitrogen atmosphere. After 30 min, 1 ml distilled water was added and the reaction mixture stirred for 1 hour. The reaction was slowly warmed to room temperature and stirred overnight. The product was then extracted with ether, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 5% to 20% ethyl acetate gradient flow) to give 75 mg 4-(5-methyl-2- thienyl) pyridine as a pale yellow solid in 77% yield. ¹ H NMR (400 MHz, CDCI ₃ ) δ 8.55 (d, J = 6.16 Hz, 2H), 7.41 (d, J = 4.54 Hz, 2H), 7.32 (d, J = 3.61 Hz, 1 H), 6.79 (d, J = 2.54 Hz, 1 H), 2.45 (d, J = 2.54 Hz, 3H), 2.54 (s, 3H). Selected IR data (KBr, cm ^"1 ): 3442, 2919(w), 1595(s), 1539(w), 1497(w), 1458(w), 1418(m), 1220(w), 1 165(w), 990(w), 805(s), 693(w), 467(m). Step 2 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1-yl) 4- (5-methyl-2-thienyl) pyridine

[0182] A solution of 4-(5-methyl-2-thienyl) pyridine (50 mg, 0.29 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (79 mg, 0.372 mmol), 7.8% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 60% to 100% ethyl acetate gradient flow) to give 55 mg product as yellow solid in 56% yield. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ 9.09 (d, J = 7.35 Hz, 2H), 8.28 (d, J = 7.34 Hz, 2H), 8.12 (d, J = 3.80 Hz, 1 H), 7.14 (d, J = 4.86 Hz, 1 H), 2.60 (s, 3H). ¹⁹ F NMR (400 MHz, DMSO-d ₆ ) δ =-127.17. Elemental analysis (%) calculated, (found): C, 52.48 (51 .95); H, 2.64 (2.96); N, 4.08 (3.78); F, 22.14 (20.22); S, 9.34 (8.59). Selected IR data (KBr, cm ^{" 1} ): 3442, 2917(w), 1701 (w), 1624(s), 1538(w), 1491 (w), 1458(m), 14389w), 1321 (w), 1217(m), 1 1 12(m), 1060(m), 1018(m), 842(w), 809(w), 762(w), 615(w). MS (ESI): m/z 344.0377.

Example 6 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) N, N-diphenyl pyridin-4-amine (1f)

[0183] A solution of N, N-diphenyl pyridin-4-amine (130 mg, 0.53 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (1 15 mg, 0.54 mmol), 7.8% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 70% to 100% ethyl acetate gradient flow) to give 150 mg product as yellow solid in 68% yield. ¹ H NMR (400 MHz, CDCI ₃ ) δ 8.77 (d, J = 7.10 Hz, 2H), 7.53 (t, J = 7.76 Hz, 4H), 7.44 (t, J = 7.41 Hz 2H), 7.29 (d, J = 8.22 Hz, 4H), 6.86 (d, J = 7.15 Hz, 2H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-125.87. Selected IR data (KBr, cm-1 ): 3442(w), 3108(w), 3055(w), 2924(w), 1708(w), 1640(s), 1619(s), 1519(m), 1490(m), 1424(w), 1394(m), 1320(m), 1220(m), 1 185(w), 1 167(w), 1 1 13(m), 1061 (m), 1015(w), 834(w), 777(w), 754(w), 705(w), 616(w), 508(w). Elemental analysis (%) calculated, (found): C, 63.77 (63.85); H, 3.38 (3.56); N, 6.76 (6.59); F, 22.14 (17.74); S, 9.34 (8.59). MS (ESI +): m/z 415.1095.

Example 7 - Synthesis of 1 -(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) N, N-diphenyl pyridin-2-methyl-4-amine (1 g)

[0184] A solution of N, N-diphenyl pyridin-2-methyl-4-amine (100 mg, 0.38 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (85 mg, 0.40 mmol), 7.8% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 70% to 100% ethyl acetate gradient flow) to give 1 10 mg product as yellow solid in 68% yield. . Selected IR data (KBr, cm-1 ): 3424(w), 3075(w), 2924(w), 2852(w), 1718(w), 1645(s), 1630(s), 1591 (w), 1515(m), 1491 (w), 1422(w), 1376(w), 1316(w), 1289(m), 1225(m), 1 180(w), 1 1 14(m), 1062(m), 101 1 (w), 851 (w), 812(w), 767(w), 709(w), 613(w), 519(w). ¹ H NMR (400 MHz, CDCI ₃ ) δ 7.69 (d, J = 7.46 Hz, 1 H), 7.53 (t, J = 7.65 Hz, 4H), 7.44 (t, J = 7.19 Hz 2H), 7.29 (d, J = 7.81 Hz, 4H), 6.70 (d, J = 9.75 Hz, 1 H), 6.65 (s, 1 H), 2.41 (s, 3H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-126 and -126.29. MS (ESI +): m/z 429.1 177.

Example 8 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) N, N-diphenyl pyridin-2,6 -dimethyl-4-amine (1 h)

[0185] A solution of N, N-diphenyl pyridin-2,6-dimethyl-4-amine (80 mg, 0.29 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (64 mg, 0.30 mmol), 7.8% in THF. The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 70% to 100% ethyl acetate gradient flow) to give 80 mg product as yellow solid in 62% yield. ¹ H NMR (400 MHz, CDCI ₃ ) δ 7.47 (t, J = 7.92 Hz, 4H), 7.36 dt, J = 7.22 Hz, 2H), 7.24 (d, J = 8.50 Hz 4H), 6.41 (s, 2H), 2.43 (s, 3H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-124.42 and -167.47. MS (ESI +): m/z 443.3641 . Example 9 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten-1- yl) p-phenylpyridine (1 i)

[0186] A solution of p-phenylpyridine (108 mg, 0.70 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (149 mg, 0.70 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (100 mg, 44 % yield). ¹ H NMR (400 MHz, CDCI ₃ ) δ 9.84 (d, J = 6.43 Hz, 2H), 8.1 1 (d, J = 6.47 Hz, 2H), 7.8 (d, J = 8.10 Hz, 2H), 7.64 (d, J = 6.88 Hz ,3H). ¹⁹ F NMR (400 MHz, CDCI3) δ =-124.42. Selected IR data (KBr, cm ^"1 ): 3437(s), 3130(w), 2922(w), 2923(w), 2851 (w), 1704(w), 1630(s), 1540(w), 1465(m), 1432(m), 1387(w), 1325(m), 1218(m), 1 1 15(m), 1061 (m), 1019(m), 851 (w), 772(w), 719(w), 681 (w), 616(w), 545(w). MS (ESI+): m/z 324.0643.

Example 10 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten- 1-yl) 4,4'-azopyridine (1j)

[0187] A solution of 4,4'-azopyridine (100 mg, 0.54 mmol) in 2 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (1 15 mg, 0.54 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 70 % to 100 % ethyl acetate gradient flow) to give 16 mg product as red solid in 8.4 % yield. ¹ H NMR (400 MHz, CDCI ₃ ) δ 9.84 (d, J = 6.43 Hz, 2H), 8.1 1 (d, J = 6.47 Hz, 2H), 7.8 (d, J = 8.10 Hz, 2H), 7.64 (d, J = 6.88 Hz ,3H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-126.97. Selected IR data (KBr, cm ^"1 ): 3447(s), 3126(w), 3037(w), 2923(w), 2852(w), 1716(w), 1617(s), 1449(m), 1326(m), 1222(w), 1 1 19(m), 1060(m), 1018(m), 842(w), 827(w), 615(w), 570(w).

Example 11 - Synthesis of Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l- cyclopenten-1-yl) 4-(2-thienyl) pyridine (1 k)

[0188] 4-(2-thienyl) pyridine was synthesised based on the paper J. Yang, S. Liu, J. F. Zheng, J. Zhou, Eur. J. Org. Chem. 2012, 2012, 6248-6259. A solution of 4-(2- thienyl) pyridine (120 mg, 0.745 mmol) in 8 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (159 mg, 0.75 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (100 mg, 41 % yield). ¹ H NMR (400 MHz, CDCI ₃ ) δ 9.71 (d, J = 6.91 Hz, 2H), 7.96 (d, J = 6.98 Hz, 2H), 7.84 (d, J = 3.69 Hz, 1 H), 7.79 (d, J = 4.95 Hz ,1 H), 7.32 (m, 1 H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-127.05. Selected IR data (KBr, cm ^"1 ): 3443(m), 3127(w), 2919(w), 2850(w), 1701 (w), 1628(s), 1529(m), 1490(w), 1462(m), 1417(w), 1360(w), 1325(m), 1213(m), 1 1 17(m), 1060(m), 1015(m), 856(w), 830(w), 712(w), 616(w), 540(w). MS (ESI+): m/z 330.0209. Example 12 - Synthesis of 2-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten- 1-yl) 2,4,6-tri(4-pyridyl)-1 ,3,5-triazine (11):

[0189] 2,4,6-tri(4-pyridyl)-1 ,3,5-triazine was synthesised based on the paper J. Wang, F. Xu, T. Cai, Q. Shen, Org. Lett. 2008, 10, 445-448. A solution of 2,4,6-tri(4- pyridyl)-1 ,3,5-triazine (200 mg, 0.639 mmol) in 8 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (400 mg, 1 .92 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. The solution was then extracted with ethyl acetate, dried with MgSO ₄ , filtered, and solvent removed in vacuo. The crude product was purified using column chromatography (silica, hexane: ethyl acetate, 20 % to 100 % ethyl acetate gradient flow) to give 10 mg product as red solid in 3 % yield. ¹ H NMR (400 MHz, (CD ₃ ) ₂ CO) δ 10.1 1 (d, J = 7.14 Hz, 2H), 9.55 (d, J = 6.85 Hz, 2H), 8.98 (d, J = 5.98 Hz, 4H), 8.74 (d, J = 4.41 Hz ,4H), 7.32 (m, 1 H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-127.95. Selected IR data (KBr, cm ^"1 ): 3445(s), 2960(w), 2921 (w), 2853(w), 1626(s), 151 1 (m), 1452(w), 1372(m), 1332(w), 1257(w), 1205(w), 1 122(m), 1058(m), 1019(m), 804(w), 638(w), 534(w). MS (ESI+): m/z 481 .0983. Example 13 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten- 1-yl) 4-(pyridine-4-yl)benzaldehyde (1 m):

[0190] 4-(pyridine-4-yl)benzaldehyde was synthesised using a previously reported method J. Kim, Y. You, S. J. Yoon, J. H. Kim, B. Kang, S. K. Park, D. R. Whang, J. Seo, K. Cho, S. Y. Park, Chem. Eur. J. 2017, 23, 10017-10022. A solution of 4- (pyridine-4-yl)benzaldehyde (130 mg, 0.710 mmol) in 4 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (148 mg, 0.71 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (100 mg, 40 % yield). ¹ H NMR (400 MHz, (CD ₃ ) ₂ SO) δ 10.15 (s, 1 H), 9.38 (d, J = 6.08 Hz, 2H), 8.64 (d, J = 6.89 Hz, 2H), 8.30 (d, J = 8.3 Hz, 2H), 8.15 (d, J = 8.14 Hz, 2H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =-127.073. Selected IR data (KBr, cm ^"1 ): 3448(w), 3133(w), 2922(w), 2850(w), 1700(s), 1627(s), 1526(w), 1491 (w), 1458(m), 1409(w), 1383(w), 1327(m), 1242(w), 1217(m), 1 178(w), 1 125(m), 1061 (m), 1023(m), 825(m), 735(w), 616(w), 548(w), 498(w). MS (ESI+): m/z 352.0592.

Example 14 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten- 1-yl) 2-(4'-pyridyl)benzo[b]thiophene (1 o):

(lo) [0191 ] 2-(4'-pyridyl)benzo[b]thiophene was synthesised using a previously reported method. (X. Zhang, W. Zeng, Y. Yang, H. Huang, Y. Liang, Synlett 2013, 24, 1687-1692.) A solution of -(4'-pyridyl)benzo[b]thiophene (105 mg, 0.5 mmol) in 4 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (104 mg, 0.5 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (90 mg, 47 % yield). s ¹ H NMR (400 MHz, Deuterium sulfoxide-d ₆ ) δ 10.09 (d, 2H), 9.04 (s, 1 H), 9.00 (d, 2H), 8.64 (s, 1 H), 8.56 (m, 2H), 8.02(m, 2H). ¹⁹ F NMR (400 MHz, Deuterium sulfoxide-d ₆ ) δ =-127.92. Selected IR data (KBr, m ^"1 ): 3441 (s), 3126(w), 3106(W), 2917(W), 2850(w), 1701 (w), 1622(s), 1541 (m),1524(m), 1465(m), 1384(w), 1331 (w), 1214(m), 1 120(m), 1060(m), 1019(m), 856(w), 833(w), 749(w), 616(w), 546(W). MS (ESI+): m/z 380.0364.

Example 15 - Synthesis of 1-(2-hydroxy-3,3,4,4-tetrafluoro-5-oxo-l-cyclopenten- 1-yl) 4-(4-hexylphenyl)pyridine (1 p):

(lp)

[0192] 4-(4-hexylphenyl)pyridine was synthesised using a previously reported method. M. D. Stephens, N. Yodsanit, C. Melander, Medchemcomm 2016, 7, 1952- 1956. A solution of 4-(4-hexylphenyl)pyridine (120 mg, 0.5 mmol) in 4 ml THF and 1 ml water stirred for 5 mins at 0 °C followed by the addition of octafluorocyclopentene (104 mg, 0.5 mmol, 7.8 % in THF). The solution was then stirred at 0 °C for a further 20 minutes before being allowed to warm to room temperature and stirred overnight. On slow evaporation of the solvent, the resulting yellow precipitate was collected and washed with cold ethyl acetate (106 mg, 52 % yield). ¹ H NMR (400 MHz, CDCI ₃ ) δ 9.76 (d, J =6.26 Hz, 2H), 8.07 (d, J = 5.92 Hz, 2H), 7.72 (d, J = 8.30 Hz, 2H), 7.43 (d, J = 7.68 Hz, 2H), 2.72(t, 2H), 1 .33(s, 8H), 0.89(s, 3H). ¹⁹ F NMR (400 MHz, CDCI ₃ ) δ =- 127.077. Selected IR data (KBr, m ^"1 ): 3443(m), 3127(w), 2955(W), 2923(m), 171 1 (w), 1621 (s), 1538(w), 1495(w), 1464(m), 1413(w), 1330(m), 1216(m), 1 123(m), 1062(m), 1022(w), 852(w), 820(w), 727(w), 616(w), 546(w). MS (ESI+): m/z 408.1584.

Example 16 - Fluoresence measurements

[0193] Samples of the compounds synthesised above were diluted in toluene at various concentrations and the photo-physical properties of the various compounds was determined. The results are illustrated in table 1 and Figures 1 to 17.

Table 1 - photophysical properties of compounds in toluene

[0194] (a) emission efficiencies relative to 9,10-diphenyl anthracene. [0195] Absorption spectra of freshly dissolved crystalline samples of 1a-1f in toluene display maxima ranging from 338 - 407 nm, with 1 b being the only derivative where the absorption maximum is hypsochromically shifted with respect to parent 1a (Table 1 ). The molar extinction coefficients of 1a-1 m vary significantly with thienyl derivatives 1d and 1e being the strongest absorbers (Table 1 ), while also being efficient fluorophores with an approximate 30-fold increase in quantum efficiency observed from 1a to 1e in toluene.

Example 17 - Thin Film Fabrication

[0196] The glass and quartz slides used in casting the thin-film samples were cleaned by sonicating sequentially in CHCI ₃ , acetone, NaOH (a.q.), distilled water, isopropanol and dried using a strong flow of N ₂ . All the thin film samples for the absolute PL quantum yield were prepared by drop casting 80 pL of 1a-1e and 1 % (w/w) PMMA/CHCI ₃ solution on top of 12.5 mm x 12.5 mm x 0.1 mm glass slides (quartz slides for 1a and 1 b). The concentration of the dyes in the casting solutions were calculated based on the solid volume of PMMA. The film deposition process was performed as follows. Solutions of the dyes and PMMA were drop casted on the quartz slides and left in a covered Petri dish to dry slowly over a 30 min period. During this drying process, the petri dish was placed on a spin coater and rotated at a very slow speed (100 rpm) to create an even drop casted film. After this slow drying process, the samples were heated for 30 min at 100 °C to remove residual solvent. A similar procedure was followed to produce cast films in polystyrene.

Example 18 - Absolute Photo Luminescent Quantum Yield Measurement

[0197] The absolute photoluminescence quantum yield of the samples in thin-film PMMA matrix or in polystyrene at different concentrations were conducted using an integrating sphere accessory (F3018, Horiba Jobin Yvon) on a Fluorolog ^® -3 fluorimeter. Figure (18) details the typical construction of an integrating sphere for the thin film sample measurement. The angle of the excitation beam line to the normal of the sample surface can be modified by the tunable sample holder. All spectra were measured under the correction of the light source noise, wavelength sensitivity and the transmittance of the filters. The photon counts of all the measurements on the Fluorolog ^® -3 fluorimeter were within the linear response range of the detector (less than 2x10 ⁶ cps).

[0198] The absolute PLQY of all samples described in this article were measured and calculated according to the experimental approach described by Porres et al. ^[5] Accordingly, the PLQY measured based on a integrating sphere can be defined by the following formula:

φ _ E _x -(l-A)E _x , _0Ut

" ^,J A I ,in where A is the percentage of the photons absorbed directly by the sample corrected by removing the secondary absorption from the sphere-reflected photons:

_{A =} Lx^c ₍₂ . _{5 )}

[0199] In the above formulae, E stands for the photon count from the emission spectra and L is the photon count from the scattering spectra. The index x and b are the samples and the blank respectively. The index of in and out reveal whether the sample holder is in the excitation beam line or out of the excitation beam line.

[0200] The PLQY values of the dyes in PMMA were generally higher than the corresponding toluene samples (Fig. 26). As with the dyes in toluene, there was a large variation in PLQY across the five compunds, with 1e having a quantum yield of essentially unity in both toluene and PMMA. These spectroscopic properties, in addition to the thermal stability > 310 °C of 1e (Figure 25) make it an excellent candidate for LSC applications that are discussed later.

[0201 ] The results of compound 1 f in various matrices is shown in the table below.

Table 2 - luminescence data for compound ^" If in various films.

Compound ^" If PMMA ^b 5 mM PMMA 50 mM PS ^C 5 mM PS 50 mM

PLQY (%) ^a 94 88 98 77 a. PLQY. Absolute photoluminescent quantum yields of compound doped in thin films of PMMA or PS;

b. PMMA means Polymethylmethacrylate;

c. PS means Polystyrene. [0202] As can be seen the absolute photoluminescent quantum yield of compound ^" If when doped into a polymer film is significantly higher than dissolved in toluene.

Example 19 - External Quantum Efficiency Measurements (EQE)

[0203] The LSC device for the EQE measurement was prepared by drop casting 1 imL of the 1e (50 imM) on a 2.5 cm x 3.75 cm x 0.1 cm glass slide. After drop casting, the device was left in a Petri dish for 30 min to allow complete solvent evaporation followed by heating at 100 °C for 30 minutes. The absorbance of the middle area of the LSC device was around 0.3.

[0204] The EQE of the thin-film LSC device were measured by an EQE Measurement Kit (Newport). The LSC was clamped by a Teflon sample holder and placed on a solar cell. The short bottom edge of the LSC was attached to the active area of the solar cell. The LSC device was excited by a 325 W Hg Arc light source. The size of the beam spot on the LSC device was kept at 0.5 cm to match the same condition in the calibration.

[0205] The PLQY of 1e was near unity at 5 imM concentration in a PMMA matrix, with good PLQY being maintained up to 80 imM in PMMA with the 30 imM sample showing 90% PLQY (Fig. 27). The spectral response of a silicon solar cell integrated with the LSC device containing 1e clearly showed light harvesting by the chromophore as can be seen by the matching device external quantum efficiency (EQE) and absorption spectrum of 1e (Fig. 28).

Example 20 - Monte-Carlo Ray Tracing Simulation

[0206] The Monte-Carlo Ray Tracing Simulation was carried out by MATLAB ^® running on a high-performance computer. The process of the simulation is described by the flow chart Figure 20. During the simulation process, all of the events, for example the re-absorption, reflection, escape cone loss, PLQY loss or releasing from edges, are recorded for assessing the performance of the waveguide system. The scattering losses are not considered in the simulation.

[0207] Monte-Carlo ray tracing simulation was also performed to predict the performance of the LSC device containing 1e in different concentrations (5 imM and 50 mM) and geometric gains (Fig. 29). The optical quantum efficiency (OQE) of each device decreased slowly against the geometrical gain (G), suggesting that the re- absorption effect was small in 1e based LSCs. The OQE of the 5 mM LSC maintained at around 63% for G = 75 which is similar in performance to the best visibly transparent LSC devices. Furthermore, the calculated flux gain increased almost linearly against the geometric gain up to G = 75 . At G = 45, the flux gain was 7.2 for the 5mM LSC sample. This result is comparable to reported benchmark devices operating in the visible range with flux gain of 7 to 1 1 at G = 45.

Example 21 - thermal gravimetric analysis

[0208] Thermal gravimetric analysis of compounds 1 a to 1 e was conducted on a Mettler Toledo TGA/SDTA851 ^e thermogravimetric analyser heating from 25 °C to 800 °C at a ramp of 10 °C min ^"1 under a flow of nitrogen (30 imL min ^"1 ). The results are shown in Figures 21 to 25.

Example 22 - computational analysis.

[0209] Comparison of all theoretical a) absorption spectra and b) emission spectra of 1a-1f ("Prediction"). All spectra were obtained with SCS-CC2 using the def2-TZVP basis set. Note: 1f absorbs and emits at wavelengths comparable to 1a (348 and 452 nm), while having the largest oscillator strength of all investigated compounds for the Si→S ₀ transition (f=0.728). Thus, it is predicted that it will have a Stokes shift similar to 1a and 1 c, but should have improved quantum efficiency. The results are shown in Figure 44.

[0210] Changes in the absorption spectra of 1 a were predicted, where CI and H atoms replace the fluorine substituents. The results reveal that these compounds should have similar absorption spectra to that of 1 a and it is reasonable to presume that a detailed computational investigation of several derivatives would reveal the same findings for both the absorption and emission profiles of these molecules. The results are shown in Figure 45