An efficient dual-response luminescent metal-organic framework sensor constructed by new photochromic ligand

Abstract

Photochromic materials have shown very promising applications. However, developing new photochromic materials remains a huge challenge. In this work, a new photochromic organic molecule, namely 6,13-bis(di(pyridin-4-yl)methylene)-6,13-dihydropentacene (L), has been successfully synthesized. Its photochromic mechanism has been elucidated. The dihydropentacene-based photochromic organic molecule was firstly applied as functional ligands to construct LMOF-based sensor {Zn(L)(TPA)·H2O}n (1; LMOF = luminescent metal-organic framework; H2TPA = terephthalic acid). 1 exhibits a three-dimensional (3-D) two-fold interpenetrated architecture, excellent stabilities, luminescent and photochromic properties. 1 can highly sensitively detect Cu2+ and MnO4− in aqueous medium by luminescent quenching effect. Notably, the quenching constants of 1′ (1 after photochromism) towards Cu2+ and MnO4− are 6.4 and 6.5 times higher than those of 1, respectively, which demonstrates significantly enhanced sensing sensitivities for 1′. Furthermore, 1′ can effectively identify MnO4− from similar strong oxidizing anions CrO42− and Cr2O72−. This dual-response luminescent sensor exhibits good recyclability, and its quenching sensing mechanisms have been discussed in detail. This work will contribute to the development of efficient photochromic luminescent sensors.