The Photophysics of Dibenzo[a,j]phenazine

• Published in: ChemPhotoChem Vol. 5; no. 4; pp. 335 - 347
• Main Authors: Thom, Kristoffer A., Förster, Tom, Weingart, Oliver, Goto, Shimpei, Takeda, Youhei, Minakata, Satoshi, Gilch, Peter
• Format: Journal Article
• Language: English
• Published: 01.04.2021
• Subjects: dibenzophenazine; excited states; quantum chemistry; time-resolved spectroscopy; transient absorption
• ISSN: 2367-0932; 2367-0932
• DOI: 10.1002/cptc.202000250

The photophysics of dibenzo[a,j]phenazine (DBPHZ) in solution was investigated by steady‐state and time‐resolved spectroscopy. The nature of the solvent (methanol, acetonitrile, dichloromethane and cyclohexane were considered) only weakly affects the photophysical properties. The first excited singlet state features a lifetime of the order of 1 ns. Its fluorescence emission is centered around 420 nm and occurs with moderate yields of ≈0.1. The lowest triplet state is populated with yields of ≈0.3. Quantum chemical computations suggest that a 3nπ* state energetically close to the primarily excited singlet state is responsible for the efficient intersystem crossing towards the triplet manifold. Synthesis meets spectroscopy meets quantum chemistry: The photophysics of the N‐heterocyclic azaacence dibenzo[a,j]phenazine (DBPHZ) is investigated. Time‐resolved spectroscopy and quantum chemistry give insights into the processes after photo‐excitation of this promising chromophore.