Hybrid materials based on transition metal–BTC–benzimidazole: solvent assisted crystallographic and structural switching
Five transition metal–BTC–BIm based coordination polymers, namely [Zn2(HBTC)2(BIm)2(H2O)2]·(H2O)3, 1; [2-HABI]2[Zn2(BTC)2(2-ABI)(H2O)]·(H2O)5, 2; [Cu3(BTC)2(BIm)6][solvent], 3; [Co4(BTC)3(BIm)6][solvent], 4; and [(CH3CH2)2NH2][Zn(BTC)(BIm)]·(H2O), 5 have been synthesized and characterized using complementary techniques like single crystal X-ray analysis, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) (BTC = 1,3,5-benzene tricarboxylic acid, BIm = benzimidazole and 2-ABI = 2-aminobenzimidazole). Crystal structure analysis of these compounds showed that 1 forms a 1D chain, 2 and 3 have 2D layers while 4 and 5 have three-dimensional architectures. 3 forms a hexagonal bronze sheet, 4 has a three-dimensional network with embedded paddlewheel SBUs and helical assembly, and 5 crystallizes in a polar space group (Pna21) with 3D helical networks with adamantane-type topology. The dielectric properties of 5 showed that the dielectric constant rapidly decreases with an increase in frequency suggesting dipole relaxation at low frequencies.