title: N-annulated perylene-substituted and fused porphyrin dimers with intense near-infrared one-photon and two-photon absorption.
abstract: 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 1 a/1 b with very intense absorption (ε>1.3×10(5) M(-1) cm(-1)) beyond 1250 nm. Both compounds displayed moderate NIR fluorescence with fluorescence quantum yields of 4.4×10(-6) and 6.0×10(-6) for 1 a and 1 b, respectively. The NP-substituted porphyrin dimers 2 a/2 b 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.
authors.affiliation: Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore), Fax: (+65) 67791691.
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.forename: Sangsu
authors.initials: S
authors.lastname: Lee
authors.forename: Minjung
authors.initials: M
authors.lastname: Son
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Huang
authors.forename: Qingbiao
authors.initials: Q
authors.lastname: Qi
authors.forename: Wangdong
authors.initials: W
authors.lastname: Zeng
authors.forename: Gongqiang
authors.initials: G
authors.lastname: Li
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.forename: Jishan
authors.initials: J
authors.lastname: Wu
keywords: near-infrared dye; nonlinear optics; porphyrinoids; rylene; transient absorption; two-photon absorption