Syntheses, structures and photoluminescence of five zinc(ii) coordination polymers based on 5-methoxyisophthalate and flexible N-donor ancillary ligands

Abstract

A series of zinc(II) coordination polymers with 5-methoxyisophthalate (CH₃O–H₂ip) and five related flexible N-donor ancillary ligands, [Zn(CH₃O-ip)(bime)_0.5] (1), [Zn(CH₃O-ip)(btx)]₂·H₂O (2), [Zn(CH₃O-ip)(bix)]₂ (3), Zn(CH₃O-ip)(bib) (4), [Zn₂(CH₃O-ip)₂(bbim)]₂ (5) [bime = 1,2-bis(imidazol-1′-yl)ethane, btx = 1,4-bis(triazol-1-ylmethyl)benzene), bix = 1,4-bis(imidazol-1-ylmethyl)benzene, bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, bbim = 1,1′-(1,4-butanediyl)bis(benzimidazole)], have been synthesized under hydrothermal conditions. Complexes 1–5 were structurally characterized by elemental analysis, infrared spectra and X-ray single-crystal diffraction. These complexes display different types of entanglements. Complex 1 features an extended 3D polythreaded network based on 2D coordination frameworks with a (3,4)-connected (4².6)(4².6³.8) topology. Complex 2 shows a rare example of entangled coordination polymer containing both interpenetrating and polythreading features. Complex 3 manifests a highly corrugated 2D (4,4) layer. The layers are penetrated by each other to give rise to 3D polycatenations. While 4 and 5 exhibit three-fold interpenetrated 3D 4-connected (6⁵.8) and (3,4)-connected (4².6)(4².6.10².12) topologies, respectively. These results suggest that both 5-methoxyisophthalate and N-donor ancillary ligands influence on the final resulting structures. Furthermore, luminescent properties and thermogravimetric properties of these complexes were investigated.