A crystalline metal organic framework which comprises repeating units of formula, or alternatively a crystalline metal organic framework which comprises repeating units of formula, comprising a metal M 2+ and two ligands L 1 - wherein: the two ligands L 1 - can be the same or different, M 2+ is a divalent metal cation, each L 1 - is an anion independently selected from the group consisting of -(imidazole-5-ylmethyl)-(1,2,4-triazol-4-yl)acetate of formula - and -(imidazole-5-ylmethyl)-(1,2,4-triazol-4-yl)acetate of formula -; in the repeating unit of formula, the metal M is coordinated to two solvent molecules S, both S are equal and are a solvent molecule selected from the group consisting of water, methanol, ethanol, isopropanol, tert-butanol, diethyl ether, 1,4-dioxane, tetrahydrofurane, N,N-dimethylformamide, acetonitrile, acetone, 1,2-ethyleneglycol, dimethylsulfoxide and pyridine, → represents a coordination bond between the metal M 2+ and a nitrogen atom of each ligand L 1 -; wherein one of the coordination bonds is between the metal M 2+ and the nitrogen atom N 1 of one L 1 -; and the other coordination bond is between the metal M 2+ and the nitrogen atom N 2 of the other L 1 -; and between the metal M 2+ and the solvent molecules S; thereby the repeating unit has the formula -, or alternatively, the formula (S S)- or alternatively, the formula -, or alternatively, the formula - or alternatively, the formula -, or alternatively, the formula - or alternatively, the formula -, or alternatively, the formula - wherein each repeating unit in the metal organic framework is connected to other repeating units in such a way that the metal M 2+ of one repeating unit is connected to two additional repeating units of formula, or alternatively of formula, through coordination bonds represented by between the metal M 2+ of the first repeating unit and the nitrogen atoms of the ligands L 1 - of the additional repeating units, wherein one of the additional coordination bonds is between the metal M 2+ of the first repeating unit and the nitrogen atom N 1 of an L 1 - of an additional repeating unit; and the other additional coordination bond is between the metal M 2+ of the first repeating unit and the nitrogen atom N 2 of an L 1 - of another additional repeating unit. the two ligands L 1 - can be the same or different, M 2+ is a divalent metal cation, each L 1 - is an anion independently selected from the group consisting of -(imidazole-5-ylmethyl)-(1,2,4-triazol-4-yl)acetate of formula - and -(imidazole-5-ylmethyl)-(1,2,4-triazol-4-yl)acetate of formula -; in the repeating unit of formula, the metal M is coordinated to two solvent molecules S, both S are equal and are a solvent molecule selected from the group consisting of water, methanol, ethanol, isopropanol, tert-butanol, diethyl ether, 1,4-dioxane, tetrahydrofurane, N,N-dimethylformamide, acetonitrile, acetone, 1,2-ethyleneglycol, dimethylsulfoxide and pyridine, → represents a coordination bond between the metal M 2+ and a nitrogen atom of each ligand L 1 -; wherein one of the coordination bonds is between the metal M 2+ and the nitrogen atom N 1 of one L 1 -; and the other coordination bond is between the metal M 2+ and the nitrogen atom N 2 of the other L 1 -; and between the metal M 2+ and the solvent molecules S; thereby the repeating unit has the formula -, or alternatively, the formula (S S)- or alternatively, the formula -, or alternatively, the formula - or alternatively, the formula -, or alternatively, the formula - or alternatively, the formula -, or alternatively, the formula - wherein each repeating unit in the metal organic framework is connected to other repeating units in such a way that the metal M 2+ of one repeating unit is connected to two additional repeating units of formula, or alternatively of formula, through coordination bonds represented by between the metal M 2+ of the first repeating unit and the nitrogen atoms of the ligands L 1 - of the additional repeating units, wherein one of the additional coordination bonds is between the metal M 2+ of the first repeating unit and the nitrogen atom N 1 of an L 1 - of an additional repeating unit; and the other additional coordination bond is between the metal M 2+ of the first repeating unit and the nitrogen atom N 2 of an L 1 - of another additional repeating unit.