Indexed by:期刊论文

Date of Publication:2014-11-07

Journal:JOURNAL OF ORGANIC CHEMISTRY

Included Journals:SCIE、EI、PubMed、Scopus

Volume:79

Issue:21

Page Number:10240-10255

ISSN No.:0022-3263

Abstract:IodoBodipy-styrylBodipy dyads triplet photosensitizers were prepared (B-1 and B-2) which contain acid-responsive moiety. Both compounds show broadband visible light absorption, due to the resonance energy transfer (RET) between the two different visible light-harvesting Bodipy units. The photophysical properties of the dyads were studied with steady-state and nanosecond time-resolved transient absorption spectroscopy. The production of triplet excited state is switched ON or OFF by protonation/deprotonation of the amino group in the dyads. In the neutral form, the excited state is short-lived (<10 ns) and no singlet oxygen (O-1(2)) photosensitizing was observed. Upon protonation, a long-lived triplet excited state was observed (tau(T) = 3.1 mu s) and the O-1(2) quantum yield (Phi(triangle)) is up to 73.8%. The energy levels of the components of the dyads were changed upon protonation and this energy level tuning exerts significant influence on the triplet state property of the dyad. Acid-activated shuffling of the localization of the triplet excited state between two components of a dyad was observed. Furthermore, we observed a rare example that a chromophore giving shorter absorption wavelength is acting as the singlet energy acceptor in RET. The experimental results were rationalized by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations.