Water-soluble luminescent hybrid aminoclay grafted with lanthanide complexes synthesized by a Michael-like addition reaction and its gas sensing application in PVP nanofiber

Abstract

Aminoclay was used as a scaffold for lanthanide complexes and dye molecules for light harvesting applications. However, these syntheses are mainly based on a non-covalent electrostatic attraction between aminoclay and guest molecules. Herein, we develop a strategy to synthesize luminescent aminoclay by a Michael-like addition reaction between an amino-group of aminoclay and a Michael acceptor group. UV absorbance, photoluminescence, and phosphorescence spectra studies confirmed that luminescent lanthanide complexes were covalently grafted onto the amionclay. We found that the hybrid aminoclays (AC-Ln(DPA)_n) exhibit favorable luminescent properties coupled with good water-solubility. Furthermore, the luminescent aminoclay can be incorporated into water-soluble polyvinylpyrrolidone (PVP) to obtain a highly luminescent, physically crosslinked nanofiber by electrospinning technology. Interestingly, an exposure of the nanofiber to HCl vapors can cause a significant quenching of Eu³⁺ luminescence, while a remarkable luminescence enhancement occurred upon exposure of the acid-treated nanofiber to Et₃N vapors. Further studies indicated that this reversible luminescence change is due to the dissociation and recovery of Eu³⁺ complexes by HCl and Et₃N vapors. The results present a promising gas sensing application based on developed hybrid luminescent materials.