Two giant calix[n]phyrin derivatives namely calix- (4) and calixphyrin (5), involving two and four BF2 units, respectively, were prepared through the condensation of the bis-naphthobipyrrolylmethene-BF2 complex (3) with pentafluorobenzaldehyde. Calix[n]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 calix[n]phyrin structure, not just its size.
Bibliographical noteFunding Information:
The work in Shanghai was supported by Shanghai University, the National Natural Science Foundation of China (no. 21901155 to C. L.), and the Eastern Scholars program from the Shanghai Municipal Education Committee (to C.L.). The work at Yonsei University was supported by the National Research Foundation of Korea (NRF) through a grant funded by the South Korean government (MEST) (No. 2016R1E1A1A01943379 to D.K.). The quantum mechanical calculations were supported by the National Institute of Supercomputing and Network (NISN)/Korea Institute of Science and Technology Information (KISTI) with needed supercomputing resources, including technical support (KSC‐2019‐CRE‐0201). The work in Austin was supported by the U.S. National Science Foundation (CHE‐1807152 to J.L.S.) and the Robert A. Welch Foundation (F‐0018 to J.L.S.). We thank the staff of Beamline BL17B1 at the National Facility for Protein Science Shanghai and the Shanghai Synchrotron Radiation Facility for assistance during the single crystal X‐ray data collection. We thank Ms. Yanfei Niu and Prof. Xiaoli Zhao at East China Normal University for collecting the X‐ray data for compound . 3
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