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7621886 
Journal Article 
Near-IR-Absorbing BODIPY-5,10-Dihydrophenazine Compact Electron Donor/Acceptor Dyads and Triads: Spin-Orbit Charge Transfer Intersystem Crossing and Charge-Transfer State 
Chen, K; Taddei, M; Bussotti, L; Foggi, P; Zhao, J; Di Donato, M; , 
2020 
WILEY-V C H VERLAG GMBH 
WEINHEIM 
487-501 
WOS:000547491300006 
5,10-dihydro-5,10-dimethylphenazine (PZ) and boron dipyrromethene (Bodipy) were linked to prepare compact electron donor/acceptor dyads and triads. The effect of the molecular geometry on the UV-Vis absorption, fluorescence and the spinorbit charge transfer intersystem crossing (SOCT-ISC) efficiency were studied. Interestingly, a broad near-IR charge transfer (CT) absorption band (centred at 670 nm) was observed for the dyad/triad showing more coplanar geometry. Triplet state formation was observed in low polar solvents for the triad with orthogonal geometry (triplet state quantum yield is 30% and lifetime is tT= 210 mu s). Femtosecond transient absorption spectra indicated fast charge separation (CS, 2 ps) and slow charge recombination (CR, > 1.5 ns). The low-lying (CT)-C-3 state of the dyads/triads in polar solvent (1.23 eV vs. the 1.65 similar to 1.69 eV of the 3LE state) was confirmed by intermolecular triplet photosensitizing experiments and the spin density surface analysis. These results are useful for design of new broadband, near-IR absorbing heavy atom-free triplet photosensitizers.