Three Co(II) Coordination Polymers Constructed from 2,5-Di(4 and V-Shaped Dicarboxylic Acids: Syntheses, Characterizations, Structural Diversity and Optical Properties

Abstract

Three novel Co(II) coordination polymers, formulated as {[Co(μ<inf>3</inf>-ipa)(μ-dptztz)]·DMF}<inf>n</inf> (1), {[Co(μ<inf>3</inf>-fdc)(μ-dptztz)(H<inf>2</inf>O)]·DMF}<inf>n</inf> (2) and {[Co(μ<inf>3</inf>-tdc)(μ-dptztz)]·G}<inf>n</inf> (3) (ipa: 1,3-benzenedicarboxylate, fdc: 2,5-furandicarboxylate, tdc: 2,5-thiophenedicarboxylate, dptztz: 2,5-di(4-pyridyl)thiazolo[5,4-d]thiazole, G: Guest solvent molecule) were synthesized with dptztz and V-shaped dicarboxylic acids to investigate the effects of these acids on the structural diversity. Single crystal X-ray results demonstrated that compound 1 has a 2D structure, while compounds 2 and 3 display 3D frameworks, depending on these acids. In 1 and 3, although the coordination modes of the ipa and tdc ligands are the same, different dimensions in the compounds are observed owing to the different angles between the two carboxylate arms of the linkers. Moreover, the dimensionalities of the compounds increased with the angle between two carboxylate arms. 3D networks of compound 3 are interpenetrated with each other to form a 3D + 3D → 3D interpenetrated framework with a pcu topology. Diffuse reflectance spectra showed that the optical band gaps of the compounds decreased in the presence of the dptztz ligand. Furthermore, the thermal properties of compounds 1–3 were also studied. © 2019 Elsevier Ltd