A Significant Two‐Dimensional Structural Transformation in a Coordination Polymer that Changes Its Electronic and Protonic Behavior

Abstract

AbstractA 2D‐to‐2D (2D: two‐dimensional) structural transformation accompanying significant bond rearrangement and coordination environment change is demonstrated in a coordination polymer (CP) comprised of copper(II) ions and terephthalate (BDC2−) ligands for the first time. When immersed in water, a free‐standing membrane of 2D Cu(BDC)(DMF) (Cu‐1; DMF: N,N‐dimethylformamide) transforms into 2D Cu(BDC)(H2O)2 (Cu‐2) while maintaining its highly oriented layered structure. In the 2D sheet, paddlewheel‐type CuII dimers coordinated with four bidentate BDC ligands in a square‐planar array in Cu‐1 were released to form uniform aqua‐bridged CuII chains, which are cross‐linked with each other by unidentate BDC ligands, in Cu‐2. The present facile approach to implement the 2D‐to‐2D transformation accompanied by bond rearrangement, which is characteristic of CPs, leads to a marked increase in in‐plane magnetic susceptibility and proton conductivity. In situ experiments in support of theoretical calculations unveiled the energy diagram that governs the unique structural transformation.