Encapsulation of a novel D-A phenothiazine derivative in ZIF-8 for luminescent response to organic solvents vapor

Abstract

A donor-acceptor (D-A) phenothiazine derivative(PZQ) was designed and synthesized. The PZQ was characterized utilizing infrared (FTIR) and 1H/13C nuclear magnetic resonance. The fluorescence spectra of PZQ were investigated in various solvents with differing polarities to demonstrate the presence of positive solvatochromism was attributed to the intramolecular charge transfer. It was observed that the Stokes’ shifts increased proportionally with the polarity of the solvents, exhibiting a maximum value of 11420 cm−1 in the highly polar solvent (ACN). Moreover, a porous composite (PZQ@ZIF-8) was fabricated by encapsulating PZQ into the metal-organic framework (ZIF-8) to respond to the organic solvent vapors. The PZQ@ZIF-8 was characterized using infrared, X-ray diffraction (XRD). The fluorescence spectra of the PZQ@ZIF-8 displayed significant solvent-dependent emission. Most importantly, the PZQ@ZIF-8 exhibited high reusability, and a specific response to methanol vapor. The emission intensity of the PZQ@ZIF-8 was correlated with methanol vapor concentration negatively, which was essential for the practical sensing application.