NOVELTY - Microporous transition metal organic framework material is claimed. The metal organic framework material is a three-dimensional crystalline material obtained by self-assembly of transition metal ion with polycarboxylic acid ligand through co-ordination bond, where metal ion is copper(II), zinc(II), nickel(II), magnesium(II) or cobalt(II) ion, and the polycarboxylic acid ligand is 5,5',5''-(9H-carbazole-3,6,9-triyl)triisophthalic acid (I).    USE - The metal-organic framework material is useful for adsorption and storage of methane and acetylene.    ADVANTAGE - The metal-organic framework material: has high specific surface area and pore volume, good thermal stability and simple preparation process; and has high density open metal sites, and thus it improves adsorption and storage of methane and acetylene at 273K and 298K.    DETAILED DESCRIPTION - Microporous transition metal organic framework material is claimed. The metal organic framework material is a three-dimensional crystalline material obtained by self-assembly of transition metal ion with polycarboxylic acid ligand through co-ordination bond, where metal ion is copper(II), zinc(II), nickel(II), magnesium(II) or cobalt(II) ion, and the polycarboxylic acid ligand is 5,5',5''-(9H-carbazole-3,6,9-triyl)triisophthalic acid of formula (I). An INDEPENDENT CLAIM is also included for preparation of (I) comprising (i) dissolving dimethyl 5-aminoisophthalate in 15% hydrobromic acid solution, stirring and cooling to 0 degrees C, adding 2.5 mol/l aqueous sodium nitrite solution dropwise, performing diazotization reaction to obtain diazonium salt solution, where molar ratio between dimethyl 5-aminoisophthalate and hydrobromic acid is 1:13, and volume ratio between hydrobromic acid solution and sodium nitrite solution is 10:1, (ii) dissolving copper bromide in 15% hydrobromic acid solution, stirring and cooling to 0 degrees C, adding diazonium salt solution, reacting first at 0 degrees C for 20-30 minutes and then reacting at room temperature for 12 hours, then filtering, separating to obtain organic layer, washing organic layer repeatedly with water, dissolving the organic layer in dichloromethane, and drying over anhydrous magnesium sulfate, again filtering and purifying to obtain dimethyl 5-bromoisophthalate (II), where molar ratio between copper bromide and hydrobromic acid is 1:4, (iii) dissolving (II) and boronic acid pinacol ester in dry dioxane, adding potassium acetate and bis(triphenylphosphine)palladium dichloride, reacting at 65-70 degrees C for 12 hours, then extracting with ethyl acetate, drying organic layer over anhydrous magnesium sulfate, removing the organic solvent under reduced pressure, and purifying by column chromatography to obtain dimethyl 5-(4,4,5,5,-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalate (III), where molar ratio between (II) and boronic acid pinacol ester is 1:1.2, molar ratio between (II) and potassium acetate is 1:2.9, and molar ratio between (II) and bis(triphenylphosphine)palladium dichloride is 70:1, (iv) dissolving dimethyl 5-aminoisophthalate in 15% hydrobromic acid solution, stirring and cooling to 0 degrees C, adding 2.5 mol/l sodium nitrite aqueous solution dropwise, performing diazotization reaction to obtain a diazonium salt solution, where molar ratio between dimethyl 5-aminoisophthalate and hydrobromic acid is 1:13, volume ratio between hydrobromic acid solution and sodium nitrite solution is 10:1, (v) dissolving potassium iodide in an aqueous solution, adding diazonium salt solution while stirring, then adding dichloromethane solution dropwise, reacting first at 0 degrees C for 20-30 minutes and then reacting at room temperature for 12 hours, separating the organic layer, washing repeatedly with water and drying over anhydrous magnesium sulfate, filtering, and purifying by column chromatography to obtain dimethyl 5-iodoisophthalate (IV), where molar ratio between potassium iodide and water is 1:4, (vi) reacting (IV), 3,6-dibromocarbazole (V), potassium carbonate and copper powder at 175 degrees C for 24 hours, then extracting with dichloromethane, drying the organic layer over anhydrous magnesium sulfate, removing the organic solvent under reduced pressure, and then purifying by column chromatography to obtain dimethyl 5-(3,6-dibromo -carbazol-9-yl)isophthalate (VI), where molar ratio between (IV) and (V) is 1.5:1, molar ratio between (V) and potassium carbonate is 1:12, and molar ratio between (V) and copper powder is 1:12, (vii) dissolving (III) and (VI) in 100 ml dry dioxane, adding potassium carbonate, passing argon gas for 15 minutes, then adding tetrakis(triphenylphosphine)palladium, reacting at 80 degrees C, extracting with chloroform, drying organic layer over anhydrous magnesium sulfate, and purifying by column chromatography to obtain hexamethyl 5,5',5''-(9H-carbazole-3,6,9-triyl)triisophthalate (VII), where molar ratio between (III) and (VI) is 3:1, molar ratio between (VI) and potassium carbonate is 1:10, molar ratio between (VI) and tetrakis(triphenylphosphine)palladium is 2:1, then(viii) adding (VII) into 10 mol/l aqueous sodium hydroxide solution in a molar ratio 1:60, refluxing at 100 degrees C for 12 hours, adjusting pH to 2 at room temperature, filtering, washing with water until pH of the filtrate is neutral, and drying to obtain (I), and (ix) dissolving copper, zinc, nickel, magnesium, cobalt nitrate or chloride salt and (I) in a molar ratio of 4:1 in an organic solvent and/or water, adding concentrated nitric acid or hydrochloric acid or acetic acid, and reacting at 80-120 degrees C to obtain final product.