Metal ion-manipulated afterglow on rhodamine 6G derivative-doped room-temperature phosphorescent PVA films

TL;DR

Scientists created PVA films that glow in different colors when exposed to metal ions, which could be used for encryption.

Contribution

The study introduces a novel method to manipulate phosphorescent afterglow in PVA films using metal ions and rhodamine derivatives.

Findings

TDB@PVA and ATB@PVA films exhibited turquoise and green afterglow at 477 nm and 510 nm, respectively.

Metal ions triggered multicolored afterglow via energy transfer from thiophene boronate to rhodamine dye.

The system enabled reversible write/erase information processes through metal-ligand coordination.

Abstract

The long-lived room-temperature phosphorescence (RTP) originating from thiophene boronate polyvinyl alcohol (PVA) has enabled the creation of metal-ion-responsive RTP films doped with spirolactam ring-containing rhodamine 6G (1). In this study, RTP-active PVA films, namely, TDB@PVA and ATB@PVA, were prepared through boronate esterification of thiophene-2,5-diboronic acid (TDB) and 5-acetylthiophene-2-boronic acid (ATB) with the diol units of PVA. The delayed emission properties were evaluated, revealing an emission band at 477 nm with a turquoise afterglow for TDB@PVA and at 510 nm with a green afterglow for ATB@PVA after UV light irradiation ceased. The photophysical properties were assessed using TD-DFT and DFT calculations at the B3LYP/cc-pVDZ level. N-(rhodamine-6G)lactam dye with a salicylimine unit (1) was doped into the RTP-based PVA films, producing a multicolored afterglow upon the addition of metal ions. This phenomenon is explained by a triplet-to-singlet Förster-type resonance energy transfer process from the cross-linked thiophene boronate in PVA to the metal-ion-activated colored form of 1. This photophysical feature finds applicability in encryption techniques. Notably, the reversible metal-ligand coordination of 1 in the PVA system enabled a write/erase information process.

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