Switchable luminescent properties in two photochromic naphthalene diimide coordination networks.

Photochromic materials as a new class of multifunctional materials have received much attention owing to their potential applications in many fields. In order to investigate the electron-transfer photochromic behaviour of coordination polymers, two new coordination polymers based on the electron-deficient naphthalene diimide (NDI) and dicarboxylate ligand, namely [Zn 2 (DPNDI)(TPDC) 2 ] (1) [Cd 6 (DPNDI)(TPDC) 6 (DMF) 6 ] (2) (DPNDI = N,N ′-di(3-pyridyl)-1,4,5,8-naphthalene tetracarboxydiimide, H 2 TPDC = thiophene-2,5-dicarboxylic acid, DMF = N,N′-dimethylformamide), were synthesized under solvothermal condition and were characterized by elemental analysis, IR spectroscopy, thermogravimetric analyses, and single-crystal X-ray diffraction. Complex 1 is a three-dimensional coordination with rhombus channels, whereas complex 2 shows a sandwiched layer structure. Because of the presence of electron-deficient NDI moieties, complexes 1 and 2 can easily undergo photoinduced electron transfer and eye-detectable photochromic behaviour. Moreover, their luminescence can be switched by UV–Vis light irradiation and standing in the air. Two naphthalene diimide based coordination complexes exhibit the rare discoloured function of reversible photochromism. Interestingly, their luminescence performance can be switched by UV–Vis light irradiation and standing in the air. Image 1 • Two electron-transfer coordination polymer based on electron-deficient naphthalene diimide. • 3D structure with 1D channel. • Complexes 1 and 2 exhibit the eye-detectable photochromic phenomenon. • Their luminescence performance can be switched by UV–Vis light irradiation and standing in air. [ABSTRACT FROM AUTHOR]