An unusual double T5(2) water tape trapped in silver(i) coordination polymer hosts: influence of the solvent on the assembly of Ag(i)-4,4′-bipyridine chains with trans-cyclohexanedicarboxylate and their luminescent properties

Abstract

In this paper, four silver(I) compounds, namely, {[Ag₄(bipy)₄(chda)]·2NO₃·10H₂O}_n (1), {[Ag₂(bipy)₂(chda)]·14H₂O}_n (2), {[Ag₂(bipy)₂(chda)]·3EG·2H₂O}_n (3) and {[Ag₂(bipy)₂(chda)]·H₂chda}_n (4) (where bipy = 4,4′-bipyridine, H₂chda = trans-cyclohexane-dicarboxylate and EG = ethylene glycol), have been synthesized and characterized by single-crystal X-ray diffraction analyses. In all of these compounds, the Ag(I) centers are linked by bipy ligands to form 1D Ag(I)-bipy chain structures. The chda²⁻ anions of compound 1 adopt a μ₄-coordination mode to connect the Ag(I)-bipy chains, forming a H-beam-like chain. In 2, the chda²⁻ anions adopt a μ₂-coordination mode to connect the Ag(I)-bipy chains resulting in two distinct 2D brick wall-like layers. These layers are further stacked in an ⋯ABAB⋯ fashion through interlayer π⋯π stacking interactions giving rise to a 3D framework consisting of quasi-rectangular channels, in which an unusual double T5(2) water tape is trapped. For 3 and 4, the chda²⁻ anions show a similar μ₄-coordination mode to that of 1 and connect the Ag(I)-bipy chains to form 2D grid layers with identical compositions and connective topologies. The experimental studies show that the final structures are greatly influenced by the molar ratio of the components and the solvents, which can be rationally interpreted by the existence of various supramolecular interactions between the host and guest molecules within these compounds through a systematic structural comparison. Additionally, the thermal stability and luminescent properties of these compounds were also studied.