Photochromism and photoresponsive luminescence in naphthalenediimide coordination polymers with high thermostability

Abstract

Two novel photochromic complexes [Zn₂(bpdc)₂(m-DPNDI)₂]·H₂O (1) and [Cd(bpdc)(m-DPNDI)]·H₂O (2) (H₂bpdc = 4,4′-diphenic acid, m-DPNDI = N,N′-bis(3-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide) were prepared through a solvothermal method. In complexes 1 and 2, the selection of electron-deficient ligand m-DPNDI and electron-rich ligand bpdc²⁻ is aimed at forming a complete donor–acceptor pair and establishing a suitable electron transfer pathway to realize photoinduced electron transfer. Both complexes exhibited interesting photochromic and photoresponsive luminescence behaviours, which was verified by EPR, XRD and IR measurements. Furthermore, the existence of interpenetrating networks and abundant π⋯π interactions in 1 makes the framework intact at below 460 °C.