Synthesis and structures of a series of d¹⁰ coordination compounds based on flexible bis(imidazole) ligand and dicarboxylates

ABSTRACT

A series of new coordination compounds based on 1,6-bis(2-methyl-imidazole-yl)-hexane (bimh), namely [Zn(bimh)_0.5(chda)]_n (1), {[Cd(bimh)_0.5(bda)]·H₂O}_n (2), [Cd(bimh)(oba)]_n (3), [Zn(bimh)(oba)]_n (4), [Cd(bimh)(ipa)]_n (5), {[Zn(bimh)_0.5(ipa)]·H₂O}_n (6), (bimh  =  1,6-bis(2-methyl-imidazole-1-yl)hexane, H₂chda  =  1,4-cyclohexanedicarboxylic acid, H₂bda  =  2,2′-biphenyldicarboxylic acid, H₂oba  =  4,4′-oxybis(benzoic acid), and H₂ipa  =  isophthalic acid) have been synthesized by solvothermal route and diffusion method and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction technology. Compound 1 affords a two-dimensional (2D) wave-like framework with dinuclear paddle-wheel units, where the structures are further assembled via aromatic π–π stacking to generate a 3D network. Compound 2 exhibits a 1D ladder chain, which is further linked by hydrogen bonds to form a 2D architecture. Compounds 3 and 4 are isostructural, possessing a 2D layer network based on hydrogen bonds. Compound 5 displays a 2D wave-like layer structure. Compound 6 has a 1D line chain structure, which is packed into a 3D supermolecule network by two types of hydrogen bonds. Furthermore, the thermal stabilities and photoluminescent properties for compounds 1–6 were investigated.

KEYWORDS:

• Coordination compound
• crystal structure
• flexible bis(imidazole)
• paddle-wheel unit

Funding

This work was supported by the Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources (2014SKYWK002), the NSF of China (21543001, 21273137), the NSF for Fostering Talents in Basic Science (No. J1210057), and the Open Foundation of Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education (338080041).