A photochromic Cd(ii)-organic framework showing highly efficient dual-response sensing properties

Photochromic materials have been found to be promising for a broad range of applications. However, it remains a great challenge to develop new photochromic materials. In this work, a dihydroanthracene-based photochromic organic molecule 9,10-bis(di(pyridine-4-yl)methylene)-9,10-dihydroanthracene (L) was developed as a functional ligand to construct a LMOF-based sensor material [Cd-2L(HBTC)(2)2H(2)O2i-PrOH](n) (1) (LMOF = luminescent metal-organic framework; H3BTC = benzene-1,3,5-tricarboxylic acid; i-PrOH = isopropanol). 1 is constructed using a 6-connected [Cd-2(COO)(2)](2+) cluster, a 4-connected L unit and a HBTC double-bridge and exhibits a two-dimensional (2-D) (4,6)-connected architecture. 1 has good water and thermal stability. Before and after photochromism, this LMOF exhibits different luminescence properties, which results in dual-response and highly selective sensing properties. 1 can detect TNP with high sensitivity and selectivity in aqueous media by luminescence quenching effects. More importantly, 1 ' (1 after photochromism) shows ultrahigh sensing sensitivity and selectivity towards MnO4- (the second highest K-sv of 4.08 x 10(5) M-1). Furthermore, 1 ' can identify MnO4- in the presence of a similar strong oxidizing anion Cr2O72-. In addition, quenching sensing mechanisms are discussed in detail. This work will contribute to the development of highly efficient dual-response sensors.

Automated summary

This work developed a photochromic organic molecule as a sensor material and achieved high sensitivity and selectivity detection of specific ions through fluorescence quenching effects.