Fusion of two N-annulated perylene (NP) units with a fused porphyrin dimer along the S0-S1 electronic transition moment axis has resulted in new near-infrared (NIR) dyes 1a/1b with very intense absorption (ε>1.3×105M-1cm-1) beyond 1250nm. Both compounds displayed moderate NIR fluorescence with fluorescence quantum yields of 4.4×10-6 and 6.0×10-6 for 1a and 1b, respectively. The NP-substituted porphyrin dimers 2a/2b have also been obtained by controlled oxidative coupling and cyclodehydrogenation, and they showed superimposed absorptions of the fused porphyrin dimer and the NP chromophore. The excited-state dynamics of all of these compounds have been studied by femtosecond transient absorption measurements, which revealed porphyrin dimer-like behaviour. These new chromophores also exhibited good nonlinear optical susceptibility with large two-photon absorption cross-sections in the NIR region due to extended π-conjugation. Time-dependent density functional theory calculations have been performed to aid our understanding of their electronic structures and absorption spectra.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: J.W. acknowledges financial support from MOE Tier 2 grants (MOE2011-T2-2-130, MOE2014-T2-1-080) and an A*STAR JCO grant (1431AFG100). The work at Yonsei University was financially supported by the Mid-career Researcher Program (2005-0093839) and Global Research Laboratory (2013K1A1A2A02050183) administered through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST). K.-W.H. is grateful for financial support from KAUST.
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