Highly-efficient upconversion via direct one-photon absorption of xanthene-based chromophores

Abstract A series of xanthene-based chromophores, including rhodamines (Rh6G, RhA, RhB and RhBS) and luciferin derivatives (fluorescein, eosin and rose bengal), were firstly reported to obtain the structure-performance correlations in the upconversion via one-photon absorption (OPA-UC). These xanthene derivatives capped with different aryl groups contain the varying tautomeric donor-acceptor pairs at both ends. Electron cloud density calculations show that attaching different tautomeric donor-acceptor pairs and aryl group can change the intramolecular charge-transfer (ICT) strength and the restricted intramolecular rotation (RIR) degree. Under the excitation of CW diode laser (655 nm,