Description The present invention relates to acetylene bridged linkers, metal-organic frameworks produced thereof, processes for producing the linkers and the MOFs and their use.

Metal-organic frameworks are known from the prior art. They are, in particular, distinguished by their porosity and can frequently be employed in applications comparable to those which are known for inorganic zeolites.

Metal-organic frameworks usually comprise an at least bidentate organic compound which is coordinated to a metal ion and joins at least two metal ions in a bridging fashion and thus together with the metal ions represents the skeleton of the metal- organic framework.

A suitable choice of metal and/or organic compound makes it possible to optimize the framework for the desired field of application. Here, for example, the choice of organic compound can have an influence on the pore distribution. Furthermore, the metal can make a contribution in adsorption processes.

A number of MOFs have been reported to exhibit a good adsorption/desorption behavior of economically interesting gases, e.g. methane and hydrogen.

Thus, there is an on-going task to provide porous materials exhibiting high surface area along with high heat of adsorption to pave the way into a sustainable hydrogen economy.

MOFs with magnesium as metal and phenylene based dihydroxy-dicarboxylic acids have been reported in Science 336 (2012) p. 1018 - 1023. The linkers differ in the number of phenylene rings that are attached to each other starting with 2,5-dihydroxyterephthalic acid IRMOF-74-I and ending with dihydroxy-dibenzoic acid groups that are separated by nine eventually substituted phenylene rings (IRMOF-74-XI). The BET surface areas for the series ranging from IRMOF-74-I to IRMOF-74-XI were found to be 1350, 2510, 2440, 2480, 2230, 1600, 1800, 1920, and 1760 m ² /g, respectively. The Mg-MOF structure exhibits a very high affinity towards hydrogen, expressed by means of a heat of adsorption of hydrogen for IR-MOF74-II [Mg2(4-(4-carboxy-3-hydroxy-phenyl)-2-hydroxy- benzoic acid)] at around 10 kJ/mol at 77K, values that are much higher compared to current best in class hydrogen storage material MOF177 (~ 5 kJ/mol). Other dihydroxy-dicarboxylic acids with connecting groups other than phenylene are rarely known. An acetylene bridged compound comprising carboxy-hydroxy-phenyl end groups is known in the literature (CAS Registry Number 1348610-42-3). However, in this compound the carboxylic groups are in meta-position and the hydroxylic groups are in para-position relating to the acetylene group.

Symmetrical diarylacetylenes are disclosed in a generic matter in DE 39 36 297 (US 5,185,454 and EP 425 930, respectively) and WO 91/10634. 4,4'-Ethyne-1 ,2-diyldibenzoate, i.e. a compound without substituents at the aromatic rings, is reported in Inorganic Chemistry 2008, 47, 6329-6335.

The synthesis of another compound without substituents at the aromatic rings, i.e. 4,4'-di- (1 ,4,buta-1 ,3-diynyl) benzoic acid and its use in two-dimensional metal-organic coordination networks is described in J. Am. Chem. Soc. 2012, 134, 6072-6075. Therein, reference is made to syntheses of eventually substituted ethynylarenes: Chem. Lett. 1998, 1099-1 100; J. Mater. Chem. 2005, 15, 690-697.; and J. Org. Chem. 2006, 71 , 4734-4741.

A series of 4,4'-ethynylenedibenzoic acids, their preparation and use as ligands in MOFs are described in Chem. Commun. 2008, 3672-3674.

It was an objective of the present invention to provide metal-organic frameworks with an enhanced ability to adsorb and desorb high amounts of gases, in particular methane or hydrogen. It was a further objective to provide metal-organic frameworks with a high porosity and, thus, a high inner surface.

It was another objective of the present invention to provide compounds that might serve as linkers for said metal-organic frameworks.

The objective is achieved by providing compounds which are derived from the general structure

(GS)

whereas R1 and R2 are independently selected from H, Bn or CH3; and

whereas R

- is chosen from carbons and/or hydrocarbons;

has a Cn symmetry with n > 2; and

comprises at least one acetylene group.

For the purposes of the present invention, the term "derive" means that the benzene rings can be present in protonated form, partially deprotonated or completely deprotonated form. Furthermore, the benzene rings can comprise a substituent or a plurality of independent substituents. Examples of such substituents are OH, NH ₂ , OCH3, linear and/or branched C1 to C10 aikyi, NH(CH.3) , N(CH3)2, CN and halides. However, preferred the benzene rings are present in their protonated form, i.e. each benzene ring comprising three hydrogen atoms directly bound to the ring. For ihe purposes of the preseni invention, the term "carbon" means a biradical rest consisting of carbon atoms. A preferred carbon comprises 1 to 5 acetylene units connected to each other with the structure (G≡C) _a . For the purposes of the present invention, the term "hydrocarbon" means a biradical rest derived from linear or branched or cyclic saturated alkanes; linear or branched or cyclic monoun- saturated aikenes and/or linear or branched polyunsaturated alka-poiy-enes and/or nonsubsti- tuted, partially or totally substituted phenylenes. According to this invention R also comprises combinations of one or more carbons and one or more hydrocarbons.

The C _n symmetry means that group R is symmetrical with regard to an n-fold axis. For the purposes of the present invention, the axis is part of the paper plane and connects the two eventually substituted hydroxy benzoic acid end groups.

Particular preference is given to compounds of the general structure GS wherein R

with a = 1 to 5 having the general formula (GS-a)

and mixtures thereof.

Especially preferred are compounds of the general structure GS-a wherein a = 1 : (GS-1 ) Very particularly preferred are the compounds of the structure GS-1 with R1 = R2 = H, i.e. compounds of the structure I :

I

Also very particularly preferred are the compounds of the structure GS-a with a = 2 and R1 = R2 = H , i.e. compounds of the structure I I :

II

Another aspect of the present invention is a method to produce compounds of the general structure GS. Especially preferred is a method to produce compounds of the general structure GS-a wherein

Very particularly preferred is a method to produce compounds of the structure GS-1 with R1 R2 = H, i.e. compounds of the structure I:

I

A scheme regarding the synthesis of Compound I is depicted in Figure 1.

Also very particularly preferred is a method to produce compounds of the structure GS-a with a = 2 and R1 = R2 = H, i.e. compounds of the structure II:

II

A scheme regarding the synthesis of Compound II is depicted in Figure 2.

Following the schematic synthesis of Compound I and Compound II, respectively, compounds with the following structure might be yielded as intermediates:

wherein R3 = Si(CH ₃ )3 or H.

A further subject of the present invention are metal organic frameworks comprising at least one compound with the general structure GS with R1 = R2 = H as linker.

Particular preference is given to metal organic frameworks comprising at least one compound of the general structure GS with R1 = R2 = H wherein R = -(C≡C) _a - with a = 1 to 5 having the gen- eral formula and mixtures thereof. Especially preferred are metal organic frameworks comprising at least one compound of the

= H wherein a = 1 :

Very particularly preferred are metal organic frameworks comprising at least one compound of the structure GS-1 with R1 = R2 = H, i.e. compounds of the structure I:

I

Also very particularly preferred are metal organic frameworks comprising at least one com pound of the structure GS-a with a = 2 and R1 = R2 = H, i.e. compounds of the structure II

II

The metal component in the framework according to the present invention is preferably selected from groups la, lla, Ilia, iVa to Villa and lb to Vlb. Particular preference is given to Mg, Ca, Sr, Ba, Sc, Y, Ln, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ro, Os, Co, Rh, !r, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Ai, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb and Bi, where Ln represents lanthanides. Lanthanides are La, Ce, Pr, Nd, Pm, Sm, En, Gd, Tb, Dy, Ho, Er, Tm, Yb. The metal organic framework comprises at least one metal. It might comprise only one metal, it might also comprise two or more metals.

As regards the ions of these elements, particular mention may be made of Mg ² *, Ca ² *, Sr ²⁺ , Ba ²⁺ , Sc ³ *, Y ³⁺ +, Ln ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Hf *, V ⁴ *, V ³ *, V ²⁺ , Nb ³ *, Ta ³ *, Cr ³ *, Mo ³⁺ , W ³⁺ , Mn ³⁺ , Mn ² ', Re ³ *, Re ² *, Fe ³ *, Fe ² *, Ru ³ *, Ru ²⁺ , Os ³ *, Os ² ', Co ³ *, Co ² *, Rh ² *, Rh ' , lr ²⁺ , ir*, Ni *, Ni *, Pd ² *, Pel*, Pt ² *, Pt*, Cu ² *, Cu*, Ag ⁺ , Au ⁺ , Zn ²⁺ , Cd ² *, Hg ² *, AI ³ *, Ga ³ *, in ³ *, TI ³ *, Si ⁴ *, Si ² *, Ge ⁴ *, Ge ² *, Sn ⁴ *, Sn ² *, Pb ⁴ *, Pb ² *, As ⁵ *, As ³ *, As*, Sb ⁵ *, Sb ³ *, Sb*, Bi ^5* , Bi ³ * and Bi*.

Particular preference is also given to Mg, AI, Y, Sc, Zr, Ti, V, Cr, Mo, Fe, Co, Cu, Ni, Zn, Ln. Greater preference is given to Ai, Mg, Fe, Cu and Zn. Mg is very particularly pre- ferred.

The inner surfaces of the metal-organic frameworks are determined by methods that are known to the one skilled in the art. In particular, these methods are the multipoint determination of the BET surface area by means of nitrogen adsorption at 77 K according to DIN 66131 and the de- termination of the surface area according to Langmuir.

The inventive metal-organic frameworks exhibit surprisingly high surfaces. The surfaces of the metal-organic frameworks of the present invention are 1000 m ² /g (BET) or above. The surfaces of the metal-organic frameworks are more preferably 2000 m ² /g (BET) or above, even more prefera bly 2500 m ² /g (BET) or above. In particular, the surfaces of the metal-organic frameworks of the present invention are 3000 m ² /g (BET) or above.

Exemplarily, an metal-organic framework according to the present invention (Example 3 in the Examples Section) exhibits a much higher surface when compared to the phenylene based metal-organic frameworks of the state of the art (Comparative Examples 1 and 2): the surfaces of Example 1 are 3482 m ² /g (BET) and 5092 m ² /g (Langmuir), respectively.

The respective areas of the comparative examples are 1 133 m ² /g (BET) and 1535 m ² /g (Langmuir) [Comparative Example 1] and 2469 m ² /g (BET) and 3309 m ² /g (Langmuir) [Comparative Example 2]. Another aspect of the present invention is a method for the production of metal organic frameworks characterized in that that at least one compound with the general structure GS with R1 = R2 = H is used as linker. Particular preference is given to a method for the production of metal organic frameworks characterized in that that at least one compound of the general structure GS with R1 = R2 = H

having the general formula and mixtures thereof is used as linker.

Especially preferred is a method for the production of metal organic frameworks characterized in that that at least one compound of the general structure GS-a with R1 = R2 = H wherein a = 1

is used as linker.

Very particularly preferred is a method for the production of metal organic frameworks characterized in that that at least one compound of the structure GS-1 with R1 = R2 = H, i.e. compounds of the structure I:

is used as a linker.

Also very particularly preferred is a method for the production of metal organic frameworks characterized in that that at least one compound of the structure GS-a with a = 2 and R1 = R2 H, i.e. compounds of the structure II:

II

is used as a linker. The process of the invention for preparing a framework according to the invention comprises, as step (a), reaction of a reaction solution comprising a metal salt corresponding to the at least one metal ion and at least one compound with the general structure (GS) and also a soi- vent at a temperature in the range from 80°C to 180°C for at least 1 hour and (b) isolation of the precipitated solid.

The reaction is preferably carried out with stirring for at least part of the time, in particular at the beginning of the reaction.

A metal salt is used as a starting compound. The initial concentration of this metal salt in the reaction mixture is preferably in the range from 0.05 mo!/i to 1 .5 mo!/1 The initial concentration is more preferably in the range from 0.08 moi/l to 0.8 m oi/l , even more prefera bly i n the ra nge from 0.1 mol/l to 0.5 moi/l. In particular, the initial concentration is in the range from 0.15 mol/l to 0.3 mol/l.

Furthermore, it is preferred that the ratio of the initial molar amount of compounds with the general structure (GS) used to the initial molar amount of metal salt used, based on the metal, is in the range from 1 :5 to 1 :1 . This means that according to the invention the metal is used at least equimolar when compared to the linker, preferredly the metal is used in an excess. The ratio is more preferably in the range from 1 :4 to 1 :2, more preferably in the range from 1 :3.5 to 1 :2.5.

The reaction mixture for step (a) of the process of the invention for preparing the framework of the invention further comprises a solvent.

The solvent has to be suitable for at least partly dissolving the starting materials used, in addition, the solvent has to be selected in such a way that the required temperature range can be adhered to.

The reaction in the process of the invention for preparing the material according to the invention is thus carried out in the presence of a solvent. It is possible here to use soivothermal conditions. For the purposes of the present invention, the term "thermal" refers to a preparative process in which the reaction is carried out in a pressure vessel with the vessel closed during the reaction and elevated temperature being applied so that a pressure is built up within the reaction medium in the pressure vessel as a result of the vapor pressure of the solvent present. The desired reaction temperature can, if appropriate, be achieved in this way.

The reaction is preferably carried out in a water-comprising medium and likewise not under soivothermal conditions.

The reaction is preferably carried out at a pressure of not more than 2 bar (absolute). However, the pressure is preferably not more than 1230 mbar (absolute). The reaction particularly preferably takes place at atmospheric pressure. However, it is possible here for slightly superatmospheric or subatmospheric pressure to occur due to the apparatus. For the purposes of the present invention, the term "atmospheric pressure" therefore refers to a pressure range given by the actual prevailing atmospheric pressure ± 150 mbar.

The reaction takes place in the temperature range from 80°C to 180°C, more preferred in the range f ro m 100°C to 150°C. The temperature is preferably in the range from 105°C to 140°C. The temperature is more preferably in the range from 1 10°C to 125°C. The reaction solution can further comprise a base. This serves, in particular, for making the acid readily soluble when an acid is used. The use of an organic solvent frequently makes it unnecessary to use such a base. Nevertheless, the solvent for the process of the invention can be selected so that it has a basic reaction, but this is not absolutely necessary for carrying out the process of the invention.

It is likewise possible to use a base. However, preference is given to not adding any additional base.

Furthermore, it is advantageaus for the reaction to take place with stirring, which is also ad- vantageaus in the case of a scale-up.

The organic solvent is preferably a d-e-a!kanol, dimethyl sulfoxide (DMSO), N,N- dimethyiformamide (DMF), Ν,Ν-diethy!formamide (DEF), Ν,Ν-dimethylacetamide (DMAc), ace- tonitri!e, toluene, dioxane, benzene, chlorobenzene, methyl ethyl ketone (MEK), pyridine, tet- rahydrofuran {THF), ethyl acetate, halogenated or unhalogenated sulfolane, glycol, N-methylpyrro!idone (N P), gamma- butyroiactone, alicyclic alcohols such as cyclohexanol, ketones such as acetone or acety!acetone, cyclic ketones, such as cyciohexanone, sulfolene or mixtures thereof. A Ci-6-alkanoi is an alcohol having from 1 to 6 carbon atoms. Examples are methanol, ethanol, n-propanoi, i-propanoi, n-butanol, i-butano!, t-butanol, pentanoi, hexanol and mixtures thereof. A halogenated or unhalogenated Ci -200-alkane is an alkane having from 1 to 200 carbon atoms in which one or more up to all hydrogen atoms can or may be replaced by halogen, preferably chlorine or fluorine, in particular chlorine. Examples of this are chloroform, di- chloromethane, tetrachloromethane, dichloroethane, hexane, heptane, octane and mixtures thereof.

The term "solvent" refers to pure solvents and mixtures of different solvents. Preferred solvents are a Ci raikanois. Particular preference is given to ethanol.

Preferred solvents are DMF, DEF, DMAc and NMP. Particular preference is given to DMF. Particular preferred solvents are mixtures of DMF, ethanol and water.

The composition of these DMF - ethanol -water mixtures is a (DMF) : b (ethanol) : c (water) with a, b, and c being the respective volumes of the particular solvent whereas 'a' is in the range of from 220 ml to 330 ml, 'b' is in the range of from 5 ml to 80 ml and 'c' is in the range of from 5 to 40 ml, provided that a + b +c = 340 ml. Other volumes can be calculated accordingly.

Step (a) of this process of the invention for preparing the framework of the invention is carried out for at least 1 hour, preferably for at least 3 hours. The reaction is preferably carried out for at least 6 hours, more preferably at least 12 hours, more preferably at least 18 hours.

Furthermore, the process of the invention comprises the step (b), isolation of the precipitated solid. As a result of step (a) of the preparative process of the invention, the framework precipitates from the reaction mixture as a solid. It can be isolated by methods known in the prior art, e.g. filtration or the like.

The metal-organic framework of the invention can be present in powder form or as ag- glomerate.

The porous metal-organic framework of the invention can be used as such in powder form or is converted into a shaped body. Accordingly, it is a further aspect of the present invention that the porous metal-organic framework of the invention is present as powder.

A further aspect of the present invention is therefore a shaped body comprising the porous metal-organic framework of the invention.

The production of shaped bodies from metal-organic frameworks is described, for example, in WO-A 03/102000.

Preferred processes for producing shaped bodies are extrusion or tableting. In the production of shaped bodies, it is possible to add further materials such as binders, lubricants or other additives which are added during the production process, it is likewise conceivable for the framework to comprise further constituents, for example adsorbents such as activated carbon or the like. The possible geometries of the shaped bodies are essentially not subject to any restrictions. For example, possible shapes are, inter alia, pellets such as disk-shaped pellets, pills, spheres, granules, extrudates such as rods, honeycombs, grids or hollow bodies. To produce the shaped bodies, it is in principle possible to employ all suitable methods. In particular, the following processes are preferred: kneading/pan milling of the framework either alone or tagether with at least one binder and/or at least one pasting agent and/or

at least one template compound to give a mixture; shaping of the resulting mixture by means of at least one suitable method such as extrusion; optionally washing and/or drying and/or calcination of the extrudate; optionally finishing treatment,

tableting tagether with at least one binder and/or other auxiliaries.

- application of the framework to at least one optionally porous support material. The material obtained can then be processed further by the above-described method to give a shaped body.

application of the framework to at least one optionally porous substrate Kneading/pan milling and shaping can be carried out by any suitable method, for example as described in Uilmanns Enzyklopadie der Technischen Chemie, 4th edition, Volume 2, p. 313 ff. (1972).

For example, the kneading/pan milling and/or shaping can be carried out by means of a piston press, roller press in the presence or absence of at least one binder, compounding, peptization, tableting, extrusion, coextrusion, foaming, spinning, coating, granulation, preferably spray granulation, spraying, spray drying or a combination of two or more of these methods. Very particular preference is given to producing pellets and/or tablets.

The kneading and/or shaping can be carried out at elevated temperatures, for example in the range from room temperature to 300°C, and/or under superatmospheric pressure, for exam- pie in the range from atmospheric pressure to a few hundred bar, and/or in a protective gas atmosphere, for example in the presence of at least one noble gas, nitrogen or a mixture of two or more thereof.

The kneading and/or shaping is, in a further embodiment, carried out with addition of at least one binder, with the binder used basically being able to be any chemical compound which en- sures the desired viscosity for the kneading and/or shaping of the composition to be kneaded and/or shaped. Accordingly, binders can, for the purposes of the present invention, be either viscosity-increasing or viscosity-reducing compounds.

Preferred binders are, for example, inter alia aluminum oxide or binders comprising aluminum oxide, as are described, for example, in WO 94/29408, silicon dioxide as described, for example, in EP 0 592 050 A1 , mixtures of silicon dioxide and aluminum oxide as are described, for example, in WO 94/13584, clay minerals as are described, for example, in JP 03-037158 A, for example montmori!ionite, kaolin, bentonite, halloysite, dickite, nacrite and anauxite, alkoxysilanes as are described, for example, in EP 0 102 544 B1 , for example tetraalkoxysilanes such as ietramethoxysilane, tetraethoxysi!ane, tetrapropoxysilane, tet- rabutoxysilane, or for example triaikoxysi!anes such as trimethoxysilane, triethoxysi!ane, tripropoxysiiane, tributoxysilane, aikoxytitanai.es, for example tetraalkoxytitanates such as tet- ramethoxytitanate, tetraethoxytitanate, tetrapropoxytitanate, tetrabutoxytitanate, or for exam- pie trialkoxytitanates such as trimethoxytitanate, triethoxytitanate, tripropoxytitanate, tributoxyti- tanate, alkoxyzirconates, for example tetraalkoxyzirconates such as tetramethoxyzirconate, tetraethoxyzirconate, tetrapropoxyzirconate, tetrabutoxyzirconate, or for example tria!koxyzir- conates such as trimethoxyzirconate, triethoxyzirconate, tripropoxyzirconate, tributoxyzir- conate, silica soles, amphiphilic substances and/or graphites.

As viscosity-increasing compound, it is, for example, also possible to use, if appropriate, in addition to the abovementioned compounds, an organic compound and/or a hydrophilic polymer such as, for example, cellulose or a cellulose derivative such as methylcellulose and/or a poiyacrylate and/or a polymethacrylate and/or a polyvinyl alcohol and/or a polyvinylpyrrolidone and/or a polyisobutene and/or a polytetrahydrofuran and/or a polyethylene oxide.

As pasting agent, it is possible to use, inter alia, preferably water or at least one alcohol such as, for example: a monoalcohol having from 1 to 4 carbon atoms, for example methanol, etha- nol, n-propanol, isopropanol, 1 -butanol, 2-butanol, 2-methy!-1 -propanol or 2-methy!-2-propanol, or a mixture of water and at least one of the alcohols mentioned or a polyhydric alcohol such as a glycol, preferably a water-miscib!e polyhydric alcohol, either alone or as a mixture with water and/or at least one of the monohydric alcohols mentioned, Further additives which can be used for kneading and/or shaping are, inter alia, amines or amine derivatives such as tetraalkylammonium compounds or amino alcohols and carbonate- comprising compounds such as calcium carbonate. Such further additives are described, for instance, in EP 0 389 041 A1 , EP 0 200 260 A1 or WO 95/19222. The order of the additives such as template compound, binder, pasting agent, viscosity- increasing substance during shaping and kneading is in principle not critical.

In a further, preferred embodiment, the shaped body obtained by kneading and/or shaping is subjected to at least one drying step which is generally carried out at a temperature in the range from 25 to 500°C, preferably in the range from 50 to 500°C and particularly preferably in the range from 100 to 350X, it is likewise possible to carry out drying under reduced pressure or under a protective gas atmosphere or by spray drying.

In a particularly preferred embodiment, at least one of the compounds added as additives is at least partly removed from the shaped body during this drying process.

The metal-organic framework of the invention and also the shaped bodies of the invention are suitable for storage of a gas. A further aspeci of ihe present invention is accordingly a method for adsorbing, storing and/or releasing at least one gas by use of the metal-organic framework of the invention.

A preferred gas is a methane-containing mixture or methane. Another preferred gas is hydro- gen. A further preferred gas is carbon dioxide (CO2).

Likewise, a further aspect of the present invention is accordingly a method of storing a gas, which comprises the step of bringing the gas into contact with a framework according to the invention or a shaped body according to the invention.

Methane or methane-containing gases are particularly suitable for this storage.

Hydrogen is particularly suitable for this storage. Carbon dioxide is also particularly suitable for this storage.

In addition, the framework of the invention or the shaped body of the invention is suitable for separating a gas from a gas mixture. A further aspect of the present invention is accordingly the use of a framework according to the invention or a shaped body according to the invention for separating a gas from a gas mixtu e.

Likewise, a further aspect of the present invention is accordingly a method of separating a gas from a gas mixture, which comprises the step: bringing a framework according to the invention or a shaped body according to the invention into contact with the gas mixture.

The gas mixture is, in particular, a gas mixture comprising methane and other gases. Here, methane is preferably removed from the gas mixture.

Furthermore, the gas mixture can be a mixture comprising methane and water. Preference is given to removing gaseous water from the gas mixture. The gas mixture can be, for exam- pie, water-comprising natural gas. Likewise, the gas mixture can be a gas mixture comprising hydrogen.

Likewise, the gas mixture can be a gas mixture comprising carbon dioxide.

The present invention is illustrated by means of the figures and the examples below.

Figure 1 shows a scheme of the synthesis of 4-[2-(4-carboxy-3-hydroxy-phenyl)ethynyl]-2- hydroxy-benzoic acid (Compound I) Figure 2 shows a scheme of the of 4-[4-(4-carboxy-3-hydroxy-phenyl) buta-1 ,3-diinyl]-2- hydroxy-benzoic acid (Compound II)

Figure 3 shows a ¹ H NMR spectrum of Compound 5

Figure 4 shows a ¹ H NMR spectrum of Compound 6

Figure 5 shows a ¹ H NMR spectrum of Compound 7 Figure 6 shows a ¹ H NMR spectrum of Compound 8

Figure 7 shows a ¹ H NMR spectrum of Compound I

Figure 8 shows a ¹³ C NMR spectrum of Compound I

Figure 9 shows a ¹ H NMR spectrum of Compound 7A

Figure 10 shows a GC-MS spectrogram of Compound 7A Figure 1 1 shows a ¹ H NMR spectrum of Compound 8A

Figure 12 shows a GC-MS spectrogram of Compound 8A

Figure 13 shows a ¹ H NMR spectrum of Compound II

Figure 14 shows a ¹³ C NMR spectrum of Compound II

Figure 15 shows a GC-MS spectrogram of Compound II Figure 16 shows the XRD Pattern of the framework (Mg - Compound I) as per Example 3. The respective list of reflexes can be found here (corrected):

Angle d value Intensity Intensity %

2-Theta ° Angstrom Count %

4,099 21 ,54 29432 100

7,099 12,44 24216 82,3

9,779 9,04 5264 17,9

9,922 8,91 1978 6,7

10,815 8,17 5766 19,6

13,153 6,73 195 0,7

14,263 6,2 969 3,3

15,039 5,89 582 2

15,607 5,67 843 2,9 17,963 4,93 1 1 13 3,8

18,861 4,7 959 3,3

19,582 4,53 1054 3,6

21 ,408 4,15 1526 5,2

22,865 3,89 592 2

25,059 3,55 916 3,1

25,969 3,43 576 2

26,592 3,35 380 1 ,3

28,619 3,12 737 2,5

30,232 2,95 394 1 ,3

30,819 2,9 388 1 ,3

31 ,473 2,84 440 1 ,5

33,089 2,71 286 1

33,753 2,65 314 1 ,1

34,661 2,59 314 1 ,1

35,325 2,54 154 0,5

36,312 2,47 200 0,7

37,64 2,39 246 0,8

38,36 2,34 268 0,9

40,24 2,24 845 2,9

40,88 2,21 101 1 3,4

41 ,422 2,18 1005 3,4

Figure 17 shows the adsorption and desorption at ambient temperature for a metal-organic framework (Mg - Compound I) as per Example 3. Here, the amount of adsorbed gas (methane) in mg per gram of framework is shown as a function of the absolute pressure p in bar. The excess methane uptake at ambient temperature and 100 bar is 18.3 wt%.

Figure 18 shows the adsorption and desorption at 77 K for a metal-organic framework (Mg - Compound I) as per Example 3. Here, the amount of adsorbed gas (hydrogen) in mg per gram of framework is shown as a function of the absolute pressure p in bar. The excess hydrogen uptake at 77 K and 100 bar is 5.2 wt%.

Figure 19 shows the adsorption and desorption at ambient temperature for a metal-organic framework (Mg - Compound I) as per Example 3. Here, the amount of adsorbed gas (hydrogen) in mg per gram of framework is shown as a function of the absolute pressure ρ in bar. The excess hydrogen uptake at ambient temperature and 100 bar is 0.82 wt%. Examples: Example 1. Synthesis of 4-[2-(4-carboxy-3-hydroxy-phenyl)ethynyl]-2-hydroxy-benzoic acid (I) Synthesis of Compound 2

1 2

1 1 .0g (72.0mmol) of 4-aminosalicylic acid (1 ) was taken in 1 10.0ml 50% H2SO4 and cooled to - 5°C and stirred for 20 minutes. To this NaNC^ solution (5.5g, 80 mmol of NaN02 in 6.5ml deion- ized water) was added drop wise maintaining temperature below 0°C and stirred for 20 minutes. This diazonium salt solution was added drop wise to the freshly prepared Cul solution ^* at -5°C. After addition, temperature of the reaction mixture was raised to room temperature and then heated to 90°C for 1 h. After completion of reaction, the reaction mixture was cooled to room temperature and filtered to obtain yellow solid which was washed with water and dried. This solid was dissolved in hot ethanol and filtered. The inorganic residue remained was washed with ethanol and the filtrate was evaporated to dryness under vacuum to obtain 16.0g of crude Compound 2 as a brown solid.

^* (Cul solution: 17.95g (72.0mmol) CuS0 ₄ .5H ₂ 0, 5.5g (86.0mmol) Cu-powder and 55.0g (332.0 mmol) Kl were taken in 100.0ml deionized water. To this 100.0 ml 20% hbSC was added with constant stirring. Reaction mixture was allowed to stirred at room temperature for 1 h and then it was cooled to -5°C. Cul gets precipitated out as off-white solid.

The above solution of Cul is directly used for the preparation of Compound 2.

Yield: 84.6%

Analysis: ¹ H NMR (300MHz, MeOD): δ 7.48(d, 1 H); 7.24(d, 1 H); 7.19(dd, 1 H). MS (m/z): 263 (M ⁺ -H)

Synthesis of Compound 3

10. Og (37.8mmol) of Compound 2 was taken in 200.0ml dry methanol. To this 1 1 .5ml

(151 .Ommol) of SOC was added drop wise. Then the reaction mixture was refluxed for 10h.

After completion of reaction, the reaction mixture was cooled to room temperature and methanol was evaporated to dryness under vacuum to obtain 12.0g crude product which was further purified by washing with minimum amount of methanol to obtain 5.2g of Compound 3.

Yield: 50.0% Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 10.8(s, 1 H); 7.49(d, 1 H); 7.40(d, 1 H); 7.24(dd, 1 H); 3.9(s, 3H). MS (m/z): 277 (M ⁺ -H)

Synthesis of Compound 4

3 ⁴

5.2g (18.7mmol) of Compound 3 and 16.0g (37.4mmol) of K2CO3 were taken in 40.0ml acetoni- trile. To this 2.4ml (19.6mmol) of benzyl bromide was added drop wise at RT. Then the reaction mixture was heated to 80°C for 4h. After completion of reaction, the reaction mixture was cooled to room temperature and filtered. The solid residue remained was repeatedly washed with ethyl acetate. Finally the filtrate was evaporated to dryness under vacuum to obtain 7.0g of Compound 4 as dark brown oily liquid which solidifies on standing at room temperature.

Yield: 99.9%

Analysis: ¹ H NMR (300MHz, CDCI3): δ 7.47-7.41 (m, 3H); 7.39-7.31 (m, 5H); 5.1 (s, 2H); 3.9(s, 3H). MS (m/z): 367 (M ⁺ -H)

Synthesis of Compound 5

5

1.0g (2.7mmol) of Compound 4, 0.58 ml (4.1 mmol) of trimethylsilyl acetylene, 0.05g (0.27 mmol) of copper iodide and 0.75ml (5.4mmol) of TEA were taken in 5.0ml dioxane. The reaction system was degassed thoroughly. To this 0.95g (0.135mmol) of (PPh ^PdC was added under inert atmosphere and the reaction was stirred for 1 h at room temperature. After completion of reaction, dioxane was evaporated to dryness. The residue remained was dissolved in chloro- form and filtered through celite. The filtrate was evaporated to dryness to obtain crude product to which methanol was added. On addition of methanol, impurities precipitated out as solid which was filtered and remaining filtrate was evaporated under vacuum to obtain 0.9g of Compound 5 as brown oily liquid.

Yield: 99.0%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 7.6(d, 1 H); 7.33-7.30(dd, 2H); 7.23-7.13(m, 3H); 6.93- 6.89(m, 2H); 4.98(s, 2H); 3.7(s, 3H); 0.06(s, 9H). MS (m/z): 339 (M ⁺ +H) Synthesis of Compound 6

5

0.2g (0.6mmol) of Compound 5 and 0.16g (1.2mmol) of K2CO3 were taken in 5.0ml of methanol. The reaction was stirred at room temperature for 2h. After completion of reaction, methanol was evaporated to dryness. Excess of water was added to the reaction mass and extracted with ethyl acetate. The ethyl acetate layer was evaporated to dryness to obtain 0.15g of Compound 6. Yield: 95.5%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 7.65(d, 1 H); 7.39-7.35(dd, 2H); 7.23-7.13(m, 3H); 6.93- 6.89(m, 2H); 5.09(s, 2H); 3.8(s, 3H); 3.1 (s, 1 H). MS (m/z): 267 (M ⁺ +H)

Synthesis of Compound 7

0.6g (1 .6mmol) of Compound 6, 0.65g (2.4mmol) of Compound 4, 0.031 g (0.16mmol) of copper iodide and 0.45ml (3.2mmol) of TEA were taken in 10.0ml dioxane. The reaction system was degassed thoroughly. To this 0.057g (0.08mmol) of (PPh ^PdC was added under inert atmosphere and the reaction was stirred for 1 h at room temperature. After completion of reaction, dioxane was evaporated to dryness. The residue remained was dissolved in chloroform and filtered through celite. The filtrate was evaporated to dryness to obtain crude product. This was purified by combiflash silica gel column chromatography to get 0.5g of Compound 7 as off-white solid.

Yield: 45.5%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 7.7(d, 2H); 7.45(dd, 4H); 7.38-7.24(m, 6H); 7.16-7.07(m, 4H); 5.1 1 (s, 4H); 3.9(s, 6H). MS (m/z): 507 (M ⁺ +H)

Synthesis of Compound 8

7

8

0.5g of Compound 7 and was taken in 5.0ml toluene. To this 1 .0 ml of TFA was added drop wise till formation of clear solution. Reaction was stirred at room temperature for 16h. After completion of reaction, toluene and TFA was evaporated to dryness to obtain crude oily residue. To this heptane was added and crude mass was stirred vigorously to obtain 0.15g Compound 8 as off white solid. (%Y = 47).

Yield: 46.5%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 10.74(s, 2H); 7.76(d, 2H); 7.08(d, 2H); 6.98-6.93(dd, 2H); 3.8(s, 6H). MS (m/z): 327 (M ⁺ +H)

Synthesis of Compound I

0.15g (0.4mmol) of Compound 8 and 0.18g (4.5mmol) of NaOH were taken in 4.0ml THF and 4.0ml water. Reaction mixture was heated at 80°C for 4 hrs. After completion of reaction, THF layer was evaporated and the remaining aqueous layer was acidified with dilute HCI. The solid precipitated out was filtered, washed with water and dried to obtain 0.1 g of crude Compound I as off white solid. Yield: 76.9%

Analysis: ¹ H NMR (300MHz, DMSO): δ 7.9-7.7(m, 2H); 7.2-6.9(m, 4H). ³ C NMR (300MHz, DMSO): 5 91 .15; 1 14.35; 120.19; 122.76; 131.17; 161 .16; 171 .60. Melting point: >250°C Example 2. Synthesis of 4-[4-(4-carboxy-3-hydroxy-phenyl) buta-1 ,3-diinyl]-2-hydroxy-benzoic acid (II)

Synthesis of Compound 7A

6

5.0g (18.77mmol) of Compound 6, 0.35g (1 .87mmol) of copper iodide and 3.1 ml (22.53mmol) of TEA were taken in 50.0ml THF. The reaction mass was stirred for 16h at room temperature. After completion, water was added to quench the reaction and THF was evaporated. The aque- ous layer was extracted with chloroform (2X50.0ml). The combined organic layers was dried under sodium sulfate and concentrated to give 1 .5g of Compound 7A as yellow solid.

Yield: 15.15%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 7.8(d, 2H); 7.5(dd, 4H); 7.45-7.21 (m, 6H); 7.16-7.07(m, 4H); 5.2(s, 4H); 3.9(s, 6H). GCMS (m/z): 530 (M ⁺ )

Synthesis of Compound 8A

3.5g of Compound 7A and was taken in 35.0ml toluene. To this 7.0 ml of TFA was added drop wise till formation of clear solution. Reaction was stirred at room temperature for 16h. After completion of reaction, toluene and TFA was evaporated to dryness to obtain crude oily residue. To this heptane was added and crude mass was stirred vigorously to obtain 1 .5g Compound 8A as off white solid.

Yield: 71 .4%

Analysis: ¹ H NMR (300MHz, CDCI ₃ ): δ 10.8(s, 2H); 7.8(d, 2H); 7.3(d, 2H); 7.0(dd, 2H); 4.0(s, 6H). GCMS (m/z): 350 (M ⁺ ) Synthesis of Compound II 1.4g (4.00mmol) of Compound 8A and 1.6g (40.00mmol) of NaOH were taken in 14.0ml THF and 14.0ml water. Reaction mixture was heated at 60°C for 4 hrs. After completion of reaction, THF layer was evaporated and the remaining aqueous layer was acidified with dilute HCI. The solid precipitated out was filtered, washed with water and dried to obtain 1 .2g of Compound II as light yellow solid.

Yield: 94%

Analysis: ¹ H NMR (300MHz, DMSO): δ 7.9-7.7(m, 2H); 7.2-7.0(m, 4H). ³ C NMR (300MHz, DMSO): δ 75.70; 82.24; 1 15.18; 121 .12; 123.51 ; 127.03; 131 .25; 161.04; 171 .49. GCMS (m/z): 322 (M ⁺ ). Melting Point >250°C

Example 3. Synthesis of Mg-MOF: [Mg ₂ (Compund I)]

To 225 ml DMF in a 500 ml flask under nitrogen atmosphere 2.4 g Mg(N0 ₃ )2 x 6 H ₂ 0 (9.375 mmol) and 0.85 g 4-[2-(4-carboxy-3-hydroxy-phenyl)ethynyl]-2-hydroxy-benzoic acid (2.85 mmol) were added under stirring. To the obtained slightly yellow solution 15 ml Ethanol was added, followed by drop-wise addition of 15 ml distilled water. After stirring for 30 min at ambient temperature the reaction mixture was heated to 120 °C for 24 h under gentle reflux. After 30 min of heating the precipitation of solid material started. After cooling down to ambient temperature the mother liquor was separated via filtration on a glass frit under nitrogen atmosphere. The precipitate was washed twice with 20 ml DMF, twice with 20 ml dry Methanol and then transferred to a Soxhlett extractor and extracted with Methanol for 16 h. The received solid was dried at 50 mbar for 2 h at ambient temperature and 16 h at 130 °C. After drying 0.78 g of an off-white solid was obtained (yield based on linker 79.6%).

The tamped density was found to be 260 g/L. The surface area was 3482 m ² /g (BET-method) and 5092 m ² /g (Langmuir method). The XRD pattern exhibits reflexes in the area typical for mi- croporous materials (Figure 16).

Example 4. Synthesis of Mg-MOF: [Mg ₂ (Compund II)] To 300 ml DMF under nitrogen atmosphere 3.20 g Mg(N0 ₃ ) ₂ x 6 H ₂ 0 (12.5 mmol) and 1 .22 g 4- [4-(4-carboxy-3-hydroxy-phenyl)buta-1 ,3-diynyl]-2-hydroxy-benzoic acid (3.8 mmol) is added under stirring. To the obtained slightly yellow solution 30.0 ml Ethanol is added, followed by drop-wise addition of 10.0 ml distilled water. After stirring for 30 min at ambient temperature the reaction mixture is heated to 120 °C for 24 h under gentle reflux and stirring (100 RPM). After cooling down to ambient temperature the mother liquor is separated via filtration on a glass frit under nitrogen atmosphere. The precipitate is washed twice with 20 ml DMF, twice with 20 ml of dry Methanol and then transferred to a Soxhlett extractor and extracted with Methanol for 16 h. The received solid is dried at 50 mbar for 2 h at ambient temperature and 16 h at 130 °C.

Comparison Example 1 : Synthesis of Mg-MOF: [Mg2(2,5-dihydroxyterephthalic acid)] (IRMOF- 74-I; commercial name: Basolite M74)

To 300 ml DMF under nitrogen atmosphere 3.20 g Mg(N0 ₃ )2 x 6 H ₂ 0 (12.5 mmol) and 0.76 g 2,5-dihydroxyterephthalic acid (3.8 mmol) were added under stirring. To the obtained slightly yellow solution 20.0 ml Ethanol was added, followed by drop-wise addition of 20.0 ml distilled water. After stirring for 30 min at ambient temperature the reaction mixture was heated to 120 °C for 24 h under gentle reflux and stirring (100 RPM). After cooling down to ambient temperature the mother liquor was separated via filtration on a glass frit under nitrogen atmosphere. The precipitate was washed twice with 20 ml DMF, twice with 20 ml of dry Methanol and then transferred to a Soxhlett extractor and extracted with Methanol for 16 h. The received solid was dried at 50 mbar for 2 h at ambient temperature and 16 h at 130 °C. After drying 1.00 g of an off-white solid was obtained (yield based on linker 107.5%).

The surface area was 1 133 m ² /g (BET-method) and 1535 m ² /g (Langmuir method). The XRD pattern exhibits reflexes in the area typical for microporous materials. Comparison Example 2: Synthesis of Mg-MOF: [Mg2(4-(4-carboxy-3-hydroxy-phenyl)-2- hydroxy-benzoic acid)]; IR-MOF74-II

To 1 186 ml DMF under nitrogen atmosphere 12.67 g Mg(N0 ₃ )2 x 6 H ₂ 0 (49.3 mmol) and 4.12 g 4-(4-carboxy-3-hydroxy-phenyl)-2-hydroxy-benzoic acid (15 mmol) were added under stirring. To the obtained slightly yellow solution 79.3 ml Ethanol was added, followed by drop-wise addition of 79.3 ml distilled water. After stirring for 30 min at ambient temperature the reaction mixture was heated to 120 °C for 12 h under gentle reflux and stirring (130 RPM). After 60 min of heating the precipitation of solid material started. After cooling down to ambient temperature the mother liquor was separated via filtration on a glass frit under nitrogen atmosphere. The precipi- tate was washed twice with 200 ml DMF, twice with 200 ml of dry Methanol and then transferred to a Soxhlett extractor and extracted with Methanol for 16 h. The received solid was dried at 0.2 mbar for 2 h at ambient temperature, 2h at 60 °C and 16 h at 130 °C. Further activation occurred via drying for 16 h at 0.01 bar. After activation 12.08 g of an off-white solid was obtained (yield based on linker 83.6%).

The tamped density was found to be 170 g/L. The surface area was 2469 m ² /g (BET-method) and 3309 m ² /g (Langmuir method). The XRD pattern exhibits reflexes in the area typical for microporous materials. Comparative Examples 1 and 2 are described in Science 336 (2012) p. 1018 - 1023.

Tamped density Surface area Surface area XRD pattern:

(BET) (Langmuir) Microporous

[g/L] [m ² /g] [m ² /g] material?

Example 3 260 3482 5092 Yes

Comp. Ex. 1 480 1 133 1535 Yes

Comp. Ex. 2 170 2469 3309 Yes