Electrochemically switchable photoluminescence of an anionic dye in a cationic metallo-supramolecular polymer

Abstract

A fluorescent dye anion (sulforhodamine B, SRB) was successfully introduced into a Fe(II)-based metallo-supramolecular polymer (polyFe) by exchanging the counter anion. The exchange was confirmed by elemental analysis, UV-vis absorption spectroscopy, ¹H-NMR spectroscopy, and FTIR spectroscopy. A solid-state device using the obtained polymer (polyFe–SRB) shows electrochromic properties based on the electrochemical redox of Fe(II) ions by applying ±2.8 V. The device shows electrochemical switching of photoluminescence at 584 nm by applying ±2.8 V. This switching was caused by the appearance and disappearance of the metal-to-ligand charge transfer (MLCT) absorption of polyFe–SRB. It is considered that the MLCT absorbs the excitation light at 560 nm or the emission from SRB.