The present invention relates to a new method of functionalising diacetylene compounds, in particular to form diacetylene compounds that are capable of forming colour.

Background to the Invention

Certain diacetylene compounds are known to be capable of forming colour upon exposure to a stimulus, such as radiation. Typical diacetylene compounds for this purpose are disclosed in WO 2012/1 14121. There are many known methods to form these diacetylene compounds, including two-step methods such as those described in EP 2082890, EP 2553528, EP 2678742 and Chemistry of Materials, vol. 15, 2003, George et al., "Low molecular-mass gelators with diyne functional groups and their unpolymerized and polymerized gel assemblies" involving the formation and isolation of a highly reactive acyl chloride intermediate and subsequent addition of an amine or alcohol; the formation and isolation of an reactive intermediate mixed anhydride and subsequent reaction with an amine or alcohol is also known. These reactions enable the formation of non-symmetrical diacetylene compounds. Two-step methods for the formation of non-symmetrical diacetylene compounds are also disclosed in CN 103232358 and US 2001/0059867. JP2006063045 discloses the formation of a specific diacetylene compound comprising branched alkyl moieties, the diacetylene structure being selected specifically for the purpose of forming a gel.

However, problems with these known methods exist in that in the production of certain diacetylene compounds, small amounts of impurities in the reaction mixture can lead to the formation of unwanted products. Furthermore, over time, the diacetylene compounds produced by such methods often demonstrate low stability upon exposure to radiation under ambient conditions, i.e. unwanted colour formation may occur upon exposure to radiation under ambient conditions. In addition, these known methods often involve multiple process steps which make the process long and laborious, utilise hazardous reagents and can be difficult to reliably scale up for commercial use of the formed diacetylene compounds.

There is therefore a desire to provide a new method of forming diacetylene compounds, the method having improved reliability and efficiency in large scale production.

Summary of the Invention

Accordingly, in a first aspect of the invention there is provided a method of functionalising a diacetylene compound of formula (II) to form a diacetylene compound of formula (I):

T - - (CH ₂ ) _x -Q (I) wherein x is from 1 to 20;

O

jl

Q is selected from an amide having the formula ¾ NR R _anc | _{an ester} having o

, ¾A 3

the formula ^OR , wherein R ¹ and R ² are each independently selected from hydrogen, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, a Ci _-20 alkene group, a C _5-20 aryl group, a Ci _-20 alkoxy group, a hydroxylCi _-20 alkoxy group, a heteroaryl ring, a C _3- 18 cycloalkyl group, and (CH ₂ ) _Z -E-P, and R ³ is selected from hydrogen, a Ci _-20 alkyl group, a Ci _-20 alkene group, a C _5-20 aryl group, a Ci _-20 alkoxy group, a hydroxylCi _-20 alkoxy group, a heteroaryl ring, a C _3-i8 cycloalkyl group and (CH ₂ ) _Z - E-P, and y is selected from 1 to 20, z is selected from 0 to 10, E may be absent or present, and when present, E is selected from NH, O, and CH ₂ , and P is a protecting group; and

T is selected from hydrogen, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, and -(CH ₂ ) _x -Q wherein x, y and Q are as defined for formula (I); comprising the steps of reacting a diacetylene compound of formula (II) and a compound of formula (III): wherein T’ is selected from hydrogen, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, and - (CH ₂ ) _X -COOH wherein x and y is as defined for formula (I); and

L’ is selected from NR ¹ R ² and OR ³ wherein R ¹ , R ² and R ³ are as defined above for Q in formula (I); in the presence of a coupling reagent and optionally, a catalyst or base.

In accordance with a second aspect of the invention there is provided a diacetylene compound of formula (I) obtained by the method of the first aspect of the invention.

In accordance with a third aspect of the invention there is provided a method of functionalising a diacetylene compound of formula (II) to form a diacetylene compound of formula (I):

T - - (CH ₂ ) _X -Q (l) wherein x is from 1 to 20;

O

jl

Q is selected from an amide having the formula ¾ ^{NR R} , an ester having the o

, ¾A 3

formula ^OR , wherein R ¹ and R ² are each independently selected from hydrogen, a Ci _-20 alkyl group, a Ci _-20 alkene group, a C _5-2 o aryl group, a Ci _-20 alkoxy group, a hydroxylCi _-2 o alkoxy group, a heteroaryl ring, a C _3-i8 cycloalkyl group, and (CH ₂ ) _Z -E-P, and R ³ is selected from hydrogen, a Ci _-20 alkyl group, a Ci _-20 alkene group, a C _5-20 aryl group, a Ci _-20 alkoxy group, a hydroxylCi _-20 alkoxy group, a heteroaryl ring, a C _3-i8 cycloalkyl group, and (CH ₂ ) _Z -E-P, and z is selected from 0 to 10, E may be absent or present, and when present, E is selected from NH, O, and CH ₂ , P is a protecting group; and

T is selected from hydrogen, a Ci _-20 alkyl group, and -(CH ₂ ) _x -Q wherein x and Q are as defined for formula (I); comprising the steps of reacting a diacetylene compound of formula (II) and a compound of formula (III):

T' - = - = - (CH ₂ ) _X -COOH (I I) + HU (III) wherein T is selected from hydrogen, a Ci _-20 alkyl group, and -(CH ₂ ) _x -COOH wherein x is as defined for formula (I); and

U is selected from NR ¹ R ² and OR ³ wherein R ¹ , R ² and R ³ are as defined above for Q in formula (I); in the presence of a coupling reagent and optionally, a catalyst or base, and wherein the diacetylene compound of formula (I) is isolated by precipitation. Brief Description of the Figures

Figures 1a and 1 b show purity analysis of a diacetylene compound of formula (I) using MALDI-TOF mass spectrometry. The diacetylene compound of formula (I) analysed in Figure 1 a was prepared according to the method of the invention. The diacetylene compound of formula (I) analysed in Figure 1 b was prepared according to a prior art methodology.

Detailed Description of the Invention

The method of forming a diacetylene compound of formula (I) according to the invention is a single step method. By "single step method" is meant that the reagents are converted to the product in a single process, i.e. the diacetylene compound of formula (II) is functionalised in a single reaction to form the diacetylene compound of formula (I). This is a one-pot/step reaction. It will be appreciated that there are no intermediate stages in the process at which an intermediate compound is isolated and subjected to further processing.

It has advantageously been found that the method according to the present invention is particularly advantageous when scaled up for the production of diacetylene compounds for commercial purposes, demonstrating improved processability, as well as increased reliability and efficiency in producing the diacetylene compounds of formula (I). The method according to the present invention reliably enables the production of stable diacetylene compounds i.e. diacetylene compounds that will remain in a non-active form (be non-colour forming) upon exposure to radiation, such as ultraviolet (UV) radiation. This is advantageous for storage and transportation of the diacetylene compounds.

The diacetylene compounds of formula (I) according to the invention comprise a non-coloured state and coloured states, such as a first and second coloured state. Once in an active form, the diacetylene compounds of formula (I) are capable of transitioning from the non-coloured to a coloured state upon exposure to radiation. The diacetylene compounds of formula (I) can therefore be utilised in the formation of coloured images, generating colour upon exposure to radiation. For example, the diacetylene compounds obtained by the method of the invention can be used to form an image on or within a substrate to which the diacetylene compounds have been applied or incorporated within. It will be appreciated by a skilled person that upon exposure to radiation, the diacetylene compounds of formula (I) polymerise to produce a coloured state. Different degrees of polymerisation enable the formation of different coloured states of the diacetylene compounds.

“Non-active form” and like terms as used herein, refers to diacetylene compounds that are in a non-coloured state and will not undergo a transition from this non-coloured to a coloured state upon exposure to radiation, i.e. is non- colour forming. It will be appreciated by a skilled person that the non-coloured state of the diacetylene compound will have to be‘activated’ to an "active form" by application of temperature, before a transition from the non-coloured state to a coloured state of the diacetylene compound can occur through exposure to radiation. Accordingly, by the term“active form” and like terms as used herein, is meant diacetylene compounds that are in a non-coloured state and are capable of transitioning from the non-coloured state to a coloured state upon exposure to radiation.

“Non-coloured state” and like terms as used herein, refers to the state of the diacetylene compound in which the diacetylene compound is white, off-white or colourless i.e. clear, or has reduced or low visible colour, i.e. is paler in colour (a lighter shade) than a coloured state of the same colour. The non-coloured state of a diacetylene compound displays the natural colour of the diacetylene compound before any radiation or temperature is applied to it.

“Coloured state” and like terms as used herein, refers to the state of the diacetylene compound in which the diacetylene compound displays a colour, i.e. is substantially or highly coloured, in the visible spectrum and to a human eye. In relation to the term "coloured state", the singular encompasses the plural and vice versa. For example, although reference is made herein to "a" coloured state, the term encompasses one or more coloured states. It will be appreciated that the diacetylene compounds formed by the method of the present invention may have more than one coloured state, such as a first and second coloured state. By the term "colour" and like terms as used herein, is meant the colours of the visible light colour spectrum, i.e. red, orange, yellow, green, blue and violet, in addition to pink, purple, magenta, cyan and black and mixtures thereof. Both primary and secondary colours are encompassed, i.e. it will be appreciated by a skilled person that a coloured state formed by a diacetylene compound formed by the method of the present invention may have a primary or secondary colour. In the context of the present invention, the term may also be used to describe differing shades of each of the colours of the visible light colour spectrum, in addition to pink, purple, magenta, cyan and black.

“Transition" and "transitioning" and like terms as used herein, refers to a diacetylene compound changing irreversibly from a non-coloured state to a coloured state upon exposure to radiation. It will be appreciated that this is an intentional transition facilitated by the application of radiation. By the term "irreversibly" is meant that once the coloured state of the compound has been formed, a transition from a coloured state to the non-coloured state of the compound cannot occur to any significant degree.

"Diacetylene compound" and like terms used herein refers to a compound having a diacetylene moiety )

“Stable diacetylene compound” and like terms as used herein in relation to the diacetylene compound formed by the method of the present invention, refers to diacetylene compounds that remain in a non-active form, and therefore do not form a coloured state upon exposure to radiation under ambient conditions. "Ambient conditions" and like terms used herein, refers to the normal range of conditions of the surrounding environment to which the compounds are exposed, i.e. the range of temperatures, pressures and atmospheric conditions to which the compounds are exposed to during storage, use or otherwise. This includes solar radiation including electromagnetic radiation of X-rays, ultraviolet (UV) and infrared (IR) radiation. Typically, ambient conditions include a temperature of from 10 to 35 °C, a pressure of from 20 to 100 kPa, and the environment is typically an oxygen-containing atmosphere. The stability of the diacetylene compounds is exemplified by testing under artificial conditions by exposing the compounds to an artificial germicidal UV light. The diacetylene compounds will remain in a non-active form for at least 5 seconds, preferably at least 10 seconds, more preferably at least 20 seconds, and most preferably at least 30 seconds under these conditions.

The term "image" incorporates both single- and multi-coloured images.

"Monochromic" or "single-coloured image" and like terms used herein, refer to an image or text that is human or machine readable and has a single colour that is visible to the human eye. In the context of the present invention, when the non-coloured state of a diacetylene compound is white or off-white or colourless, the non-coloured state can form part of the monochromic image.

"Multi-coloured image" and like terms as used herein, refers to an image or text that is human or machine readable having multiple colours, i.e. displaying 2 or more colours that are visible to the human eye. In the context of the present invention, when the non-coloured state of a diacetylene compound is white or off-white or colourless, the non-coloured state can form part of the multi-coloured image.

"Radiation" and like terms as used herein, refers to energy in the form of waves or particles, and in particular, includes but is not limited to: electromagnetic radiation such as ultraviolet (UV), visible, near-infrared (NIR), and infrared (IR) particle radiation, e.g. alpha (a) radiation, beta (b) radiation, neutron radiation and plasma. By the term‘protecting group’ is meant, any organic chemical moiety that can be cleaved/removed from the diacetylene compound when exposed to certain conditions, including but not limited to: acid, base, heat, hydrogenation and reduction. Examples of suitable protecting groups include, but are not limited to: alkyl and aryl oxycarbonyl groups selected from tert- butyloxycarbonyl (BOC), 2,4- dimethylpent-3-yloxycarbonyl (DOC), dioctyl(((docosa-10,12- diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC), 9- fluorenylmethyl oxycarbonyl and benzyl oxycarbonyl, benzoyl, carboxy benzyl, and allyloxycarbonyl; cycloalkyls such as cyclododecane and cyclooctane; amide groups such as acetamide and trifluoroacetamide; phthalimide; triphenylmethyl; benzylidene; and p-toluenesulfonyl.

In the compounds of formulas (I), (II) and (III) used in the described method: x may be 2 to 12, preferably 2 to 10, and more preferably 2 to 8; o

Q is an amide having the formula ^* ^ NR ¹ R ² wherein R ¹ and R ² are each independently selected from hydrogen, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, a C _5-2 o aryl group, a C _3-i8 cycloalkyl group and (CH ₂ ) _Z -E-P, and y may be selected from 5 to 19, preferably 5 to 17, z may be selected from 0 to 8, preferably 0 to 6, E may be present or absent, and when present, is preferably NH, and P may be an alkyl or aryl oxycarbonyl group or a cycloalkyl, preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxy benzyl, cyclododecane, cyclooctane, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa-10,12- diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC), more preferably P is an alkyl or aryl oxycarbonyl group, and most preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxy benzyl, 2,4- dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa-10,12- diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC);

T is selected from a -(CH ₂ ) _y -CH ₃ linear alkyl chain, and -(CH ₂ ) _x -Q wherein y may be 5 to 19, preferably 5 to 17, x may be 2 to 12, preferably 2 to 10, and O more preferably 2 to 8, and wherein Q is an amide having the formula ^* ^ NR ¹ R ² wherein R ¹ and R ² are each independently selected from hydrogen, a -(CH ₂ ) _y - CH ₃ linear alkyl chain, a C _5-2 o aryl group, a C _{3-i 8} cycloalkyl group, and (CH ₂ ) _Z -E- P, and y may be selected from 5 to 19, preferably 5 to 17, z may be selected from 0 to 8, preferably 0 to 6, E may be present or absent, and when present, is preferably NH, and P may be an alkyl or aryl oxycarbonyl group or a cycloalkyl, preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxybenzyl, cyclododecane, cyclooctane, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa-10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 - diyl))dicarbamate (SOC), more preferably P is an alkyl or aryl oxycarbonyl group, and most preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxybenzyl, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa- 10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC);

T is selected from a -(CH ₂ ) _y -CH ₃ linear alkyl chain and -(CH ₂ ) _x -COOH wherein y may be 5 to 19, preferably 5 to 17, x may be 2 to 12, preferably 2 to 10, and more preferably 2 to 8; and

L’ is NR ¹ R ² wherein R ¹ and R ² are each independently selected from hydrogen, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, a C _5-20 aryl group, a C _3-i8 cycloalkyl group, and (CH ₂ ) _Z -E-P, y may be selected from 5 to 19, preferably 5 to 17, z may be selected from 0 to 8, preferably 0 to 6, E may be present or absent, and when present, is preferably NH, and P may be an alkyl or aryl oxycarbonyl group or a cycloalkyl, preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxybenzyl, cyclododecane, cyclooctane, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa-10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 - diyl))dicarbamate (SOC), more preferably P is an alkyl or aryl oxycarbonyl group, and most preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxybenzyl, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa- 10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC).

Preferably, the diacetylene compound formed by the method of the present invention has the formula (IV): wherein x is from 1 to 20, such as 2 to 12, preferably 2 to 10, and more preferably 2 to 8;

O

jl

Q is selected from an amide having the formula ¾ NR R _anc | _{an ester} having o

, ¾A 3

the formula ^OR , wherein R ¹ is hydrogen and R ² and R ³ are each independently selected from a cyclopropyl group, a -(CH ₂ ) _y -CH ₃ linear alkyl chain, and (CH ₂ ) _Z -E-P, y being selected from 1 to 20, preferably 5 to 19, and more preferably 5 to 17, z being selected from 0 to 10, preferably 0 to 8, and more preferably 0 to 6, E may be absent or present, and when present, E is selected from NH, O, and CH ₂ , preferably NH, and P is a protecting group, preferably an alkyl or aryl oxycarbonyl group or a cycloalkyl, more preferably selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxy benzyl, cyclododecane, cyclooctane, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa-10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 - diyl))dicarbamate (SOC), still more preferably an alkyl or aryl oxycarbonyl group, and most preferably P is selected from tert- butyloxycarbonyl (BOC), benzoyl, carboxy benzyl, 2,4-dimethylpent-3-yloxycarbonyl (DOC), and dioctyl(((docosa- 10, 12-diynedioyl)bis(azanediyl))bis(ethane-2, 1 -diyl))dicarbamate (SOC); o

Jl

preferably Q is an amide having the formula ¾ ^{NR R} wherein R ¹ and R ² are as defined above for Q in formula (IV), more preferably R ¹ is hydrogen and R ² is a -(CH ₂ ) _y -CH ₃ linear alkyl chain, y being selected from 1 to 20, preferably 5 to 19, and more preferably 5 to 17; and

T is selected from -(CH ₂ ) _x -Q wherein x and Q are as defined for formula (IV), and a -(CH ₂ ) _y -CH ₃ linear alkyl chain, y being selected from 1 to 20, preferably 5 to 19, and more preferably 5 to 17, preferably T is -(CH ₂ ) _x -Q and x and Q are as defined for formula (IV); comprising the step of reacting a diacetylene compound of formula (V) and a compound of formula (VI):

T' - = - = - (CH ₂ ) _x -COOH (V) + HL’ (VI) wherein T is selected from -(CH ₂ ) _x -COOH wherein x is as defined for formula (IV), and a -(CH ₂ ) _y -CH ₃ linear alkyl chain, y being selected from 1 to 20, preferably 5 to 19, and more preferably 5 to 17, preferably T’ is -(CH ₂ ) _x -COOH and x is as defined for formula (IV); and

L’ is selected from NR ¹ R ² and OR ³ wherein R ¹ , R ² and R ³ are as defined above for Q in formula (IV), preferably L’ is NR ¹ R ² wherein R ¹ and R ² are as defined above for Q in formula (IV), more preferably R ¹ is hydrogen and R ² is a -(CH ₂ ) _y - CH ₃ linear alkyl chain, y being selected from 1 to 20, preferably 1 to 20, more preferably 5 to 19, and most preferably 5 to 17; in the presence of a coupling reagent and optionally, a catalyst or base.

It will be appreciated by a skilled person that the diacetylene compound of formula (I) or (IV) may be symmetrical i.e. T is -(CH ₂ ) _x -Q and the values of x and

Q are the same on both sides of the diacetylene moiety ( c=c-c=c— ^ ^ _or the diacetylene compound of formula (I) or (IV) may be unsymmetrical, i.e. T is different to -(CH ₂ ) _x -Q, or T is -(CH ₂ ) _x -Q and the values of x and Q are different on either side of the diacetylene moiety of the diacetylene compound. Preferably, T is -(CH ₂ ) _x -Q and the values of x and Q are the same on both sides of the diacetylene moiety, such that the diacetylene compound is symmetrical.

It will be appreciated by a skilled person that the diacetylene compound of formula (II) or (V) may be symmetrical i.e. T is -(CH ₂ ) _x -COOH and the value of x is the same on both sides of the diacetylene moiety ( c=c-c=c— ^ ^ _{or the} diacetylene compound of formula (II) or (V) may be unsymmetrical, i.e. T is different to -(CH ₂ ) _x -COOH, or T is -(CH ₂ ) _x -COOH and value of x is different on either side of the diacetylene moiety of the diacetylene compound. Preferably, T’ is -(CH ₂ ) _X -COOH and the value of x is the same on both sides of the diacetylene moiety, such that the compound of formula (V) is symmetrical. The skilled person would recognise that a wide array of coupling reagents are suitable for use in the method of the present invention. Examples of suitable coupling reagents include, but are not limited to: phosphonium coupling reagents such as benzotriazol-1 -yloxy-tris(dimethylamino)-phosphonium hexafluorophosphate, benzotriazole-1 -yloxy-tripyrrolidino-phosphonium hexafluorophosphate (PyBOP), bromo-tripyrrolidino-phosphonium hexafluorophosphate, 7-aza-benzotriazol-1 -yloxy-tripyrrolidino-phosphonium hexafluorophosphate, ethyl cyano(hydroxyimino)acetate-0 ₂ )-tri-(1 -pyrrolidinyl)- phosphonium hexafluorophosphate, and 3-(diethoxy-phosphoryloxy)-1 ,2,3- benzo[d]triazin-4(3H)-one; aminium and uronium-immonium coupling reagents such as 2-(1 H-benzotriazol-1 -yl)-N,N,N’,N’-tetramethylaminium tetrafluoroborate, 2-(1 H-benzotriazol-1 -yl)-N,N,N’,N’-tetramethylaminium hexafluorophosphate, 2- (6-chloro-1 H-benzotriazole-1 -yl)-N,N,N’,N’-tetramethylaminium

hexafluorophosphate, N-[(5-chloro-1 H-benzatriazole-1 -yl)-dimethylamino- morpholino]-uronium hexafluorophosphate N-oxide, 2-(7-aza-1 H-benzotriazol-1 - yl)-N,N,N’,N’-tetramethylaminium tetrafluoroborate, 2-(7-aza-1 H-benzotriazol-1- yl)-N,N,N’,N’-tetramethylaminium hexafluorophosphate (HATU), 1 -[1 -(cyano-2- ethoxy-2-oxoethylidene-aminooxy)-dimethylamino-morpholino]-u ronium hexafluorophosphate, 2-(1 -oxy-pyridin-2-yl)-1 , 1 ,3,3-tetramethylisothiouronium tetrafluoroborate, and tetramethylfluoroformamidinium hexafluorophosphate; and carbodiimide coupling reagents such as dicyclohexylcarbodiimide (DCC), 1- ethyl-3-(3-Dimethylaminopropyl)carbodiimide (EDAC), bis(trimethylsilyl)carbodiimide, diisopropylcarbodiimide (DIC), N-cyclohexyl-N’- (2-morpholinoethyl)carbodiimide methyl-p-toluenesulfonate, N,N’-bis(2- methylphenyl)carbodiimide, bis(2,6-diisopropylphenyl)carbodiimide, N, N’-di -tert- butylcarbodiimide, and 1 ,3-di-p-tolylcarbodiimide.

It will be appreciated by a skilled person that all references to carbodiimide coupling reagents are to be interpreted as also covering the salts of any given carbodiimide coupling reagent. For example, by 1-ethyl-3-(3- Dimethylaminopropyl)carbodiimide (EDAC), the salts 1 -(3-dimethylaminopropyl)- 3-ethylcarbodiimide hydrochloride and 1 -(3-dimethylaminopropyl)-3- ethylcarbodiimide methiodide are also encompassed. Preferably, the coupling reagent is a carbodiimide coupling reagent selected from 1 -ethyl-3-(3-Dimethylaminopropyl)carbodiimide (EDAC), bis(trimethylsilyl)carbodiimide, diisopropylcarbodiimide (DIC), bis(2,6- diisopropylphenyl)carbodiimide, bis(trimethylsilyl)carbodiimide, N,N’-di -tert- butylcarbodiimide and dicyclohexylcarbodiimide (DCC).

The skilled person would recognise that a wide array of catalysts are suitable for use in the method of the present invention. Preferably, the catalyst is present. Examples of suitable catalysts include, but are not limited to: organic N- heterocycle materials, such as 4-Dimethylaminopyridine (DMAP), 1 - Hydroxybenzotriazole (HOBt), Hydroxy-3, 4-dihydro-4-oxo-1 ,2,3-benzotriazine, N-Hydroxysuccinimide, 1 -Hydroxy-7-aza-1 H-benzotriazole and Ethyl 2-cyano-2- (hydroximino)acetate).

Preferably, the catalyst is 4-Dimethylaminopyridine (DMAP).

It will be appreciated by a skilled person that when a catalyst is not utilised in the method according to the present invention, the reaction may be left to proceed for a longer period of time. Ideally, the reaction is left to proceed until a yield of the diacetylene compound of formula (I) of over 50% is obtained.

When a catalyst is not utilised in the method according to the present invention, the method may take place in the presence of a base. The skilled person would recognise that a wide array of bases are suitable. In the context of the present invention, "base" refers to non-nucleophilic bases. Such bases will not interfere with the desired reaction outcome. Examples of suitable bases include, but are not limited to: non-nucleophilic bases such as non-nucleophilic tertiary amine bases including trimethylamine (TEA), N-methylmorpholine (NMM), N,N- diisopropylethylamine (DIPEA), 1 ,5-diazabicyclo(4.3.0)non-ene (DBN), 1 ,8- diazabicyclo(5.4.0)undec-7-ene (DBU), 2,6-di-tert-butylpyridine and tributylamine, and other non-nucleophilic bases such as pyridine. Preferably, the base is trimethylamine (TEA).

The reaction takes place in a solvent. It will be appreciated that the solvent is selected based on reaction kinetics, in addition to the solubility of the compounds and the coupling reagent utilised in the reaction. The solvent may be a single solvent or a mixture of solvents. The solvent may comprise water, an organic solvent, a mixture of water and an organic solvent, or a mixture of organic solvents or biphasic systems. Suitable organic solvents include, but are not limited to the following: dimethylacetamine (DMA), dimethylsulfoxide (DMSO); aliphatic solvents such as hexane and cyclohexane; esters such as ethyl acetate, butyl acetate, and n-hexyl acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and solvent naphtha 100, 150, 200; ketones such as acetone, cyclohexanone, methylisobutyl ketone, and methyl ethyl ketone (MEK); glycol diethers such as diethyl ether and rmethylfe/f-butyl ether; cyclic ethers such as tetrahydrofuran (THF) and 1 ,4-dioxane; chlorinated solvents such as chloroform, dichloromethane (DCM), carbon tetrachloride, methyl chloride, methyl chloroform, hexachloroethane, hexachloropropene, tetrachloroethane and dichloroethane; and combinations thereof. Preferably, the reaction takes place in tetrahydrofuran (THF) or chloroform or mixtures thereof.

The reaction will occur at any suitable temperature. It will be appreciated by a skilled person that this will be dictated in part by the solvent in which the reaction takes place. Suitable temperatures may range from -120 °C to 100 °C. Preferably, the reaction will occur at a temperature of from -10 to 80 °C.

In the method of the present invention, the diacetylene compound of formula (I) is isolated by precipitation. By "isolated by precipitation" is meant that following reaction of the diacetylene compound of formula (II) and the compound of formula (III), the diacetylene compound of formula (I) (end product) is formed as a solid suspended in solution, i.e. a precipitate, and can be filtered from the solution. Alternatively, following reaction of the diacetylene compound of formula (II) and the compound of formula (III), the diacetylene compound of formula (I) (end product) is soluble in the reaction solution, but may be caused to precipitate by either pouring the solution of the end product into an anti-solvent (a solvent in which the end product is not soluble), or by pouring an anti-solvent into the reaction mixture, thus causing the end product to precipitate as a solid which may be filtered from the resultant solution. There is no use of column chromatography or extraction into organic solvent as an isolation method. The end product of the method of the present invention i.e. the diaetylene compound of formula (I) is a solid precipitate. There is no gel formation.

To summarise the advantages of the present invention, the method:

• reliably produces stable diacetylene compounds;

· involves fewer process steps than known methods, in fact, the method is simply a single step process;

• demonstrates improved processability;

• does not use highly reactive reagents or intermediates resulting in improved safety and reliability;

· does not need to use low temperature additions which may be expensive and time consuming;

• is not an exothermic reaction, leading to improved safety;

• provides diacetylene compounds that are easier to process after functionalisation as they are quicker to filter, resulting in a lower total process cost;

• has the potential for reagent recycling; and

• is cleaner, i.e. the reaction product comprises fewer impurities.

All considerations relating to the method according to the first aspect of the invention are reiterated for the diacetylene compound of the second aspect of the invention and the method according to the third aspect of the invention.

Chemical Definitions

The term "Ci _-20 alkyl" denotes a straight or branched hydrocarbon chain containing no C=C bonds, and having from 1 to 20 carbon atoms. For parts of the range Ci _-20 alkyl, all sub-groups thereof are contemplated, such as C _{M O} alkyl, C _{5-i 5} alkyl, C _5-i0 alkyl, and Ci _-6 alkyl. Preferably, the Ci _-20 alkyl is a C _4-2 o alkyl, more preferably a C _6-2 o alkyl, even more preferably a C _8-2 o alkyl, and most preferably a C ₈ -is alkyl. Examples of said C _8-i8 alkyl groups include, but are not limited to: n-octadecyl, n-hexadecyl, n-tetradecyl, n-dodecyl, n-decyl, n-octyl and branched isomers thereof. The alkyl groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkene", "C _5-2 o aryl", "Ci _-20 alkoxy", "hydroxylCi _-2 o alkoxy", "a heteroaryl ring", and "C _3-i8 cycloalkyl".

The term "Ci _-20 alkene" denotes a straight or branched hydrocarbon chain containing one or more C=C bond and having from 1 to 20 carbon atoms. For parts of the range Ci _-20 alkene, all sub-groups thereof are contemplated, such as Ci-io alkene, C _{5-i 5} alkene, C _5-i0 alkene, and Ci _-6 alkene. Preferably, the Ci _-20 alkene is a C _4-20 alkene, more preferably a C _6-2 o alkene, even more preferably a C ₈ -2o alkene, and most preferably a C ₈ -is alkene. Examples of said C _8-i8 alkene groups include, but are not limited to: n-octadecene, n-hexadecene, n- tetradecene, n-dodecene, n-decene, n-octene and branched isomers thereof. The alkene groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkyl", "C _5-20 aryl", "Ci _-20 alkoxy", "a heteroaryl ring", "hydroxylCi _-20 alkoxy" and "C _3-i8 cycloalkyl".

The term "C _5-20 aryl" denotes a monocyclic or polycyclic aromatic unsaturated ring system having from 5 to 20 carbon atoms. For parts of the range C _5-20 aryl, all sub-groups thereof are contemplated, such as C _5-i0 aryl, Ci _0-i4 aryl, and C ₆ -s aryl. An aryl group is preferably a "C ₆ -i ₂ aryl" group and includes condensed ring groups such as monocyclic ring groups, or bicyclic ring groups. Examples of C _6- i ₂ aryl groups include, but are not limited to: phenyl, biphenyl, indenyl, naphthyl or azulenyl. Condensed rings such as indan- and tetrahydro-naphthalene are also included in the C _5-20 aryl group. The aryl groups may be optionally substituted with other functional groups. The aryl groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkyl", "Ci _-20 alkene", "C _5-20 aryl", "Ci _-20 alkoxy", "hydroxylCi _-20 alkoxy", "halogen", "a heteroaryl ring", and "C _3-i8 cycloalkyl".

The term "Ci _-20 alkoxy" denotes a straight or branched Ci _-20 alkyl group which is attached to the remainder of the molecule through an oxygen atom. For parts of the range Ci _-20 alkoxy, all sub-groups thereof are contemplated such as CMO alkoxy, C _{5-i 5} alkoxy, C _5-i0 alkoxy, and Ci _-6 alkoxy. Preferably, the Ci _-20 alkoxy is a C _M2 alkoxy, more preferably a C _{M O} alkoxy, even more preferably a Ci _-8 alkoxy, and most preferably a Ci _-6 alkoxy. Examples of said Ci _-6 alkoxy groups include, but are not limited to: methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso- butoxy, sec-butoxy, tert-butoxy, n-pentyloxy, iso-pentyloxy, sec-pentyloxy, n- hexyloxy and iso-hexyloxy. The alkoxy groups may be optionally substituted with other functional groups. The alkoxy groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkyl", "Ci _-20 alkene", "C _5-2 o aryl", "Ci-2o alkoxy", "hydroxylCi _-2 o alkoxy", "a heteroaryl ring", and "C _3-i8 cycloalkyl".

The term "hydroxylCi _-20 alkoxy" denotes a straight or branched Ci _-20 alkoxy group as defined above that has one or more hydrogen atoms replaced with hydroxyl and is attached to the rest of the molecule through the oxygen atom of the Ci _-20 alkoxy group. Examples of said "hydroxylCi _-20 alkoxy" group include, but are not limited to: -OCH ₂ CH ₂ OH. “Hydroxy” and“Hydroxyl” refer to the -OH functionality. The hydroxylalkoxy groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkyl", "Ci _-20 alkene", "C _5-20 aryl", "Ci _-20 alkoxy", "hydroxylCi _-20 alkoxy", "a heteroaryl ring", and "C _3-i8 cycloalkyl".

The term "C _3-i8 cycloalkyl" denotes a non-aromatic, saturated or partially saturated monocyclic ring system having from 3 to 18 carbon atoms. For parts of the range C _3-i8 cycloalkyl, all sub-groups thereof are contemplated, such as C _3-8 cycloalkyl, C _{5-i 5} cycloalkyl, and C _5-i0 cycloalkyl. Preferably, the C _{3-i 8} cycloalkyl is a C _3-i0 cycloalkyl. Examples of suitable C _3-i0 cycloalkyls include, but are not limited to: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. The cycloalkyl groups may be optionally substituted with other functional groups. The cycloalkyl groups may be optionally substituted with one or more functional groups, including "Ci _-20 alkyl", "Ci _-20 alkene", "C _5-20 aryl", "Ci _-20 alkoxy", "hydroxylCi _-20 alkoxy", "halogen", "a heteroaryl ring" and "C _{3-i 8} cycloalkyl".

The term "heteroaryl ring" denotes a monocyclic heteroaromatic ring comprising 5 to 6 ring atoms in which one or more of the ring atoms are other than carbon, such as nitrogen, Sulphur or oxygen. Typically, the heteroaryl ring will contain up to 4 heteroatoms, more typically up to 3 heteroatoms, more usually up to 2 heteroatoms, for example a single heteroatom. The said heteroaryl ring may be attached to the rest of the molecule through either a heteroatom or a carbon atom of the ring system. Examples of heteroaryl groups include, but are not limited to: furyl, pyrrolyl, thienyl, oxazolyl, isoxazolyl, oxadiazolyl, imidazolyl, oxatriazoly, thiazolyl, isothiazolyl, tetrazolyl, pyrazolyl, pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl and thiadiazolyl. In some embodiments, the heteroaryl ring contains at least one ring nitrogen atom. The nitrogen atoms in the heteroaryl rings can be basic, as in the case of an imidazole or pyridine, or essentially non-basic as in the case of an indole or pyrrole nitrogen. In general the number of basic nitrogen atoms present in the heteroaryl group, including any amino group substituents of the ring, will be less than five. The heteroaryl rings may be optionally substituted with other functional groups. The heteroaryl rings may be optionally substituted with one or more functional groups, including "Ci- ₂ o alkyl", "Ci _-20 alkene", "C _5-20 aryl", "Ci _-20 alkoxy", "hydroxylCi _-2 o alkoxy", "halogen", "a heteroaryl ring", and "C _3-i8 cycloalkyl".

"Halogen" refers to fluorine, chlorine, bromine or iodine, preferably fluorine and chlorine, most preferably fluorine.

The terms“unsaturated” and“partially saturated” refer to rings wherein the ring structure(s) contains atoms sharing more than one valence bond i.e. the ring contains at least one multiple bond e.g. a C=C, CºC or N=C bond. The term “fully saturated” refers to rings where there are no multiple bonds between ring atoms.

“Optional” or “optionally” means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not.

All of the features contained herein may be combined with any of the above aspects and in any combination.

For a better understanding of the present invention, and to show embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following experimental data.

Examples Example 1 : Formation of a diacetylene compound of formula (I) (Compound 1 )

Compound 1 was formed according to the scheme below:

[i] 10,12-docosadiynedioic acid (DCDA) (diacetylene compound of formula (II));

[ii] 1 -ethyl-3-(3-Dimethylaminopropyl)carbodiimide hydrochloride (EDAC) (coupling reagent); [iii] 4-Dimethylaminopyridine (DMAP) (catalyst); and [iv] dodecylamine (compound of formula (III));

[v] Compound 1 (diacetylene compound of formula (I)); and [vi] 1 -(3- (dimethylamino)propyl)-3-ethylurea (by-product).

The reaction takes place at room temperature (around 25 °C). 5.03g of DCDA was dissolved in 200 ml_ of THF in a beaker. The solution was stirred for 10 minutes to produce a clear solution with a small amount of red insoluble solids.

5.62g of EDAC was added to a round bottomed flask fitted with a stirrer bar, followed by 0.163g of DMAP, and 5.38g of dodecylamine.

The solution of DCDA in THF was filtered into the round bottomed flask using filter paper. An additional 100 ml_ of THF was then used to wash the filter paper and ensure all of the DCDA was transferred to the round bottomed flask.

The round bottomed flask was stoppered and stirred overnight. The resulting solids were then vacuum filtered onto paper, transferred to a beaker and slurried for 2 hours in 200 ml_ of water. The resulting solids were again vacuum filtered onto paper, returned to the beaker and slurried in 200 ml_ of acetone. The resulting solids were again vacuum filtered onto paper, and then transferred to a dish to be dried. The solids were dried overnight in a vacuum oven at 20 °C to yield a bright white powder in 56.7% yield, the powder being stable for a minimum of 30 seconds under germicidal ultraviolet (UV) light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 2: Scaled-up formation of a diacetylene Compound of formula (I) (Compound 1 )

Compound 1 was formed according to the scheme above. The reaction takes place at room temperature (around 25 °C).

49.99 g of DCDA was dissolved in 1.5 L of chloroform in a beaker. The solution was stirred for 30 minutes with gentle heating to produce a clear solution with a small amount of red insoluble solids.

56.41 g of EDAC was added to a beaker, followed by 1.68 g of DMAP, and 55.79 g of dodecylamine, and finally 0.5 L of chloroform. Following dissolution/suspension the mixture was added to a 5 L Radley’s reactor fitted with an overhead stirrer; an additional 0.5 L chloroform was used to wash out the beaker and the sides of the reactor. The solution of DCDA in chloroform was filtered into the Radley’s reactor using filter paper, which was washed with an additional 0.5 L of chloroform. An additional 100 ml_ of chloroform was then used to wash the filter paper and ensure all of the DCDA was transferred to the round bottomed flask. The reaction was stirred for a period of 20 hours. The resulting solids were then vacuum filtered onto paper, transferred to a beaker and slurried for 1 hour in 2 L of water. The resulting solids were again vacuum filtered onto paper, returned to the beaker and slurried in 2 L of acetone. The resulting solids were again vacuum filtered onto paper, and then transferred to a dish to be dried. The solids were dried overnight in a vacuum oven at 20 °C to yield a bright white powder in 85% yield, the powder being stable for a minimum of 30 seconds under germicidal ultraviolet (UV) light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 3: Variation of the coupling reagent & catalyst in the formation of a diacetylene compound of formula (I) (Compound 1 )

Compound 1 was formed according to the scheme above but with the [ii] coupling reagent and [iii] catalyst replaced with different coupling reagents and catalysts or bases as detailed in the following Table 1. It will be appreciated that the [vi] by-product will thus be different from that detailed in the scheme above.

Table 1

¹ The salt 1 -ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was used.

The reaction takes place at room temperature (around 25 °C).

10g of DCDA was dissolved in 100 ml_ of chloroform in a beaker. The solution was stirred for 30 minutes with gentle heating to produce a clear solution with a small amount of red insoluble solids.

The solution of DCDA in chloroform was filtered into a second beaker fitted with a stirrer bar using filter paper.

The coupling reagent (molar equivalents in Table 1 ) was added to the second beaker, followed by the catalyst or base as appropriate (molar equivalents in Table 1 ).

Dodecylamine (molar equivalents in Table 1 ) was added to the second beaker and an additional 50 ml_ of chloroform was used to ensure all reagents were washed into the reaction mixture. The beaker was covered and the reaction mixture stirred for a period of 20 hours. The resulting solids were vacuum filtered onto paper and washed with 100 ml_ of chloroform, followed by 100 ml_ of acetone on the filter paper. The resulting solids were then transferred to a dish and dried overnight in a vacuum oven at 20 °C to yield a bright white powder, the powder being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 4: No catalyst in the formation of a diacetylene compound of formula (I) (Compound 1 )

Compound 1 was formed according to the scheme above, but without catalyst [iii].

The reaction takes place at room temperature (around 25 °C).

10 g of DCDA (diacetylene compound of formula (II)) was weighed into a beaker and dissolved in 100 ml_ of chloroform. The solution was stirred with gentle heating to produce a clear solution with a small amount of red insoluble solids. 11.1 g of EDAC (coupling reagent) was weighed into a second beaker, and the DCDA solution gravity filtered through paper into the second beaker forming a pale-yellow solution with the EDAC.

10.7 g of dodecylamine (compound of formula (III)) was weighed and added to the beaker with the other reactants. An additional 50 ml_ of chloroform was used to ensure all the reagents were washed into the reaction mixture. The beaker was covered and the reaction mixture stirred for 4 days. The resulting solids were vacuum filtered onto paper and washed with 100 ml_ of chloroform on the filter paper. The solids were then transferred to a beaker and slurried in 100 ml_ of acetone for 1 hour. The solids were then vacuum filtered onto paper and dried by suction on the filter paper for around 1 hour. The solids were transferred to a drying dish and dried overnight in a vacuum oven at 20 °C to yield a bright white powder (16.25 g, 84.5 %), the powder being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 5: Variation of the solvent in the formation of a diacetylene compound of formula (I) (Compound 1 )

Compound 1 was formed according to the scheme above, but using different solvents as detailed in the following Table 2.

Table 2

The reaction takes place at room temperature (around 25 °C).

5 g of DCDA was dissolved in 250 ml_ of solvent in a beaker. The solution was stirred for 30 minutes with gentle heating to produce a clear solution with a small amount of red insoluble solids.

The solution of DCDA in solvent was filtered into a second beaker fitted with a stirrer bar using filter paper.

EDAC (molar equivalents in Table 2) was added to a second beaker, followed by DMAP (molar equivalents in Table 2).

Dodecylamine (molar equivalents in Table 2) was added to the second beaker and an additional 50 ml_ of solvent was used to ensure all the reagents were washed into the reaction mixture. The beaker was covered, and the reaction mixture stirred for 20 hours.

The resulting solids were then vacuum filtered onto paper, transferred to a beaker and slurried for 2 hours in 200 ml_ of water. The resulting solids were again vacuum filtered onto paper, returned to the beaker, and slurried in 200 ml_ of acetone. The resulting solids were again vacuum filtered onto paper, and then transferred to a dish to be dried. The solids were dried overnight in a vacuum oven at 20 °C to yield a bright white powder, the powder being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non- active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 6: Formation of different diacetylene compounds of Formula (I) (Variation of the compounds of formula (III))

Different diacetylene compounds of formula (I) were formed according to the following scheme, using different compounds of formula (III) as detailed in the following Table 3.

[i] 10,12-docosadiynedioic acid (DCDA) (diacetylene compound of formula (II));

[ii] 1 -ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC) (coupling reagent); [iii] 4-dimethylaminopyridine (DMAP) (catalyst); and [iv]

[v] diacetylene compound of formula (I); and [vi] 1-(3-(dimethylamino)propyl)-3- ethylurea (by-product). Table 3

The reaction takes place at room temperature (around 25 °C).

15g of DCDA was dissolved in 250 ml_ of solvent in a beaker. The solution was stirred for 30 minutes with gentle heating to produce a clear solution with a small amount of red insoluble solids.

The solution of DCDA in solvent was filtered into a second beaker fitted with a stirrer bar using filter paper.

EDAC was added to a second beaker, followed by DMAP (0.1 molar equivalents). The compound of formula (III) (molar equivalents in Table 3) was added to the second beaker and an additional 50 ml_ of solvent was used to ensure all of the reagents were washed into the reaction mixture. The beaker was covered and the reaction mixture stirred for 20 hours.

The resulting solids were then vacuum filtered onto paper, transferred to a beaker and slurried for 2 hours in 200 ml_ of water. The resulting solids were again vacuum filtered onto paper, returned to the beaker and slurried in 200 ml_ of acetone. The resulting solids were again vacuum filtered onto paper, and then transferred to a dish to be dried. The solids were dried overnight in a vacuum oven at 20 °C to yield a bright white powder, the powder being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non- active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 7: Formation of different diacetylene compounds of formula (I) (Variation of the diacetylene compounds of formula (ID)

A diacetylene compound of formula (I) was formed according to the following scheme.

[i] dodec-6-ynedioic acid (diacetylene compound of formula (II)); [ii] 1 -ethyl-3-(3- dimethylaminopropyl)carbodiimide hydrochloride (EDAC) (coupling reagent); [iii] 4-dimethylaminopyridine (DMAP) (catalyst); and [iv] tert- butyl carbazate (compound of formula (III));

[v] diacetylene compound of formula (I); and [vi] 1-(3-(dimethylamino)propyl)-3- ethylurea (by-product). The reaction takes place at room temperature (around 25 °C).

Dodec-6-ynedioic acid (compound of formula (II)) (10 g, 40 mmol) was weighed into a beaker and dissolved in THF.

EDAC (coupling reagent) (16.08 g, 84 mmol, 2.1 molar equivalent) was weighed into a round bottom flask fitted with a stirrer bar. 200 mL of THF was added to the beaker. DMAP (catalyst) (488 mg, 4 mmol, 0.1 molar equivalent) was added to the round bottomed flask. Tertbutyl carbazate (compound of formula (III)) (11.09 g, 84 mmol, 2.1 molar equivalent) was added to the round bottomed flask. The dodec-6-ynedioic acid solution was transferred to the round bottom flask.

The reaction mixture was stirred overnight, and then concentrated using a rotary evaporator under reduced pressure to obtain a brown oil. The brown oil was dissolved in 300 mL of acetone and precipitated with 1 L of de-ionised water. The off-white precipitate was stirred for 1 hour at room temperature. The solids were isolated by vacuum filtration on paper. The solids were stirred with 500 mL of de-ionised water for an hour. The mixture was separated via vacuum filtration on paper to obtain an off-white pasty solid. The solid product was allowed to air dry at room temperature for 2 hours. The solids were transferred to a vacuum oven for further drying at 20 °C overnight to produce an off-white solid (14.65 g, 76%), the off-white solid being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 8: Formation of different diacetylene compounds of formula (I) (Variation of the diacetylene compounds of formula (ID) A diacetylene compound of formula (I) was formed according to the following scheme.

[i] pentacosa-10,12-diynoic acid (diacetylene compound of formula (II)); [ii] 1 - ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC) (coupling reagent); [iii] 4-dimethylaminopyridine (DMAP) (catalyst); and [iv] tetradecylamine (compound of formula (III));

[v] diacetylene compound of formula (I); and [vi] 1-(3-(dimethylamino)propyl)-3- ethylurea (by-product).

The reaction takes place at room temperature (around 25 °C). EDAC (coupling reagent) (5.63 g, 29 mmol, 1.1 molar equivalent) was weighed into a 500 ml_ round bottom flask containing chloroform (100 ml_) with a stirrer bar. DMAP (catalyst) (326 mg, 2.7 mmol, 0.1 molar equivalents) was added to the round bottom flask. Tetradecylamine (compound of formula (III)) (6.27 g, 29 mmol, 1.1 molar equivalents) and 120 ml_ of chloroform were added to a beaker and heated gently to form a solution.

Pentacosa-10,12-diynoic acid (diacetylene compound of formula (II)) (10 g, 27 mmol) was added as a dry solid to the round bottom flask. The tetradecylamine solution was transferred to the round bottom flask and the reaction mixture stirred overnight. A precipitate was observed. The precipitate was vacuum filtered on paper to obtain a white solid cake. The solids were stirred in a mixture of 500 ml_ of Dl water and 100 ml_ acetone for an hour. The solids were vacuum filtered on paper. The solids were allowed to dry for 2 hours. The solids were dried in a vacuum oven at 20 °C overnight to obtain a light pink powder (11.4g, 72.9%), the powder being stable for a minimum of 30 seconds under germicidal UV light, i.e. remained in a non-active form for a minimum of 30 seconds upon exposure to UV radiation.

Example 9: Comparative purity analysis The following reaction product (diacetylene compound of formula (I)) was prepared according to the method of the invention:

The reaction product was prepared using 1.0 molar equivalent of DCDA (diacetylene compound of formula (II)), 2.1 molar equivalent of EDAC (coupling reagent), 2.1 molar equivalent of dodecylamine (compound of formula (III)), and 0.1 molar equivalent of DMAP (catalyst).

The same reaction product (diacetylene compound of formula (I)) was prepared according to a prior art methodology (the formation of a highly reactive acyl chloride, followed by subsequent addition of amine). 1.0 molar equivalent of DCDA, 0.1 molar equivalent of dimethylformamide (DMF) and 4.6 molar equivalent of oxalyl chloride were combined and vacuumed dried to form and isolate an acyl chloride intermediate (DCDA-CI). 1.0 molar equivalent of the acyl chloride intermediate was then combined with 0.1 molar equivalent of DMAP, 2.4 molar equivalent of NMM and 2.2 molar equivalent of dodecylamine, and the reaction product isolated.

The purity of the two reaction products was analysed and compared using MALDI-TOF mass spectrometry. Analysis of these two products is shown in Figure 1 a (according to the invention) and Figure 1 b (according to a prior art methodology). MALDI-TOF mass spectrometry represents an empirical method for measuring purity. The target peak shown in the figures represents the reaction product, the diacetylene compound of formula (I). This target peak is allocated an intensity of 100%. The non-target peaks represent any impurities present in the reaction product, the intensity of each non-target peak being defined as a percentage of the intensity of the target peak. For example, a non-target peak having half the intensity of the target peak has an intensity of 50%.

In order to determine the purity of the reaction product, a pass/fail criterion is defined for the summed total intensity of all non-target peaks. For the analysis shown in Figures 1 a and 1 b, the pass/fail criterion was set at 200%.