Excitonically Coupled Cyclic BF2 Arrays of Calix[8]- and Calix[16]phyrin as Near-IR-Chromophores |
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| Authors: | Taeyeon Kim Dr Zhiming Duan Dr Sangita Talukdar Dr Chuanhu Lei Prof?Dr Dongho Kim Prof?Dr Jonathan L Sessler Dr Tridib Sarma |
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| Institution: | 1. Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722 Korea;2. Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, College of Science, Shanghai University, Shanghai, 200444 P. R. China |
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| Abstract: | Two giant calixn]phyrin derivatives namely calix8]- ( 4 ) and calix16]phyrin ( 5 ), involving two and four BF2 units, respectively, were prepared through the condensation of the bis-naphthobipyrrolylmethene-BF2 complex ( 3 ) with pentafluorobenzaldehyde. Calixn]phyrins 4 and 5 display extremely high extinction coefficients (3.67 and 4.82×105 m ?1 cm?1, respectively) in the near-IR region, which was taken as initial evidence for strong excitonic coupling within these cyclic multi-chromophoric systems. Detailed insights into the effect of excitonic coupling dynamics on the electronic structure and photophysical properties of the macrocycles came from fluorescence, time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements. Support for these experimental findings came from theoretical studies. Theory and experiment confirmed that the coupling between the excitons depends on the specifics of the calixn]phyrin structure, not just its size. |
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| Keywords: | calix[n]phyrins cyclic BODIPY exciton coupling NIR dyes porphyrinoids |
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