Synthesis, Structure Determination, and Hydrogen Sorption Studies of New Metal−Organic Frameworks Using Triazole and Naphthalenedicarboxylic Acid

Two new metal−organic framework compounds were synthesized under solvothermal conditions using Zn 2+ ion, 1,2,4-triazole (TRZ), and 1,4- and 2,6-naphthalenedicarboxylic acids (NDC): Zn 4 (TRZ) 4 (1,4-NDC) 2 ·2DMF·2H 2 O ( 1 ) and Zn 4 (TRZ) 4 (2,6-NDC) 2 ·2DMF·4H 2 O ( 2 ). Their crystal structures were characterized by single-crystal X-ray diffraction. Structure 1 crystallizes in the P 2 1 / n space group with a = 13.609(2) Å, b = 27.181(5) Å, c = 13.617(3) Å, β = 92.46(1) °, V = 5032.4(16) Å 3, and Z = 4. Structure 2 crystallizes in orthorhombic Pna 2 1 space group with a = 30.978(6) Å, b = 12.620(3) Å, c = 13.339(3) Å, V = 5215(2) Å 3, and Z = 4. Both structures are analogues of the previously reported Zn 4 (TRZ) 4 (1,4-BDC) 2 ·16H 2 O where the layers of Zn−triazole moieties are pillared by aromatic dicarboxylates to create 3-D open frameworks. Nitrogen sorption studies revealed that these structures have Brunaer−Emmett−Teller (BET) surface areas of 362.1−584.1 m 2 /g. Hydrogen sorption experiments showed they can store 0.84−1.09 wt % of H 2 at 77 K and 1 atm. Although they do not contain large pores or surface areas, they possess the hydrogen sorption capacities comparable to those of highly porous metal−organic frameworks.