We present symmetry-breaking charge transfer (SBCT) in the excited state with directly linked porphyrin triad (ADA) by spectroscopic results which are of steady-state absorption and fluorescence, time-resolved fluorescence (TRF), femtosecond transient absorption (fs-TA) and time-resolved infrared (TRIR) measurements. Unprecedented broad fluorescence spectra in porphyrin arrays were observed in polar solvents which were attributed to existence of a strong charge transfer state shown via TRF measurement. TA results of triad (ADA) and dyad (AD) showed rising features in excited state absorption (ESA) in polar solvents indicating the formation of a strong CT state which has dipolar sym-metry. This dynamics was also confirmed by TRIR measurement as kinetics was in line with above results providing further information such as solvation and structural relaxation hence those together finally contribute to a relaxed SBCT state. Since this is the first observation of SBCT process among porphyrin arrays, it will provide a fundamental understanding in systems composed of porphyrins, especially for systems composed of strongly coupled moieties. New opportunities for porphyrin arrays will come forward to be used in relevant applications where SBCT is needed. |
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