Excitonically Coupled Cyclic BF2 Arrays of Calix[8]‐ and Calix[16]phyrin as Near‐IR‐Chromophores. Issue 31 (28th May 2020)

• Record Type: Journal Article
• Authors: Kim, Taeyeon; Duan, Zhiming; Talukdar, Sangita; Lei, Chuanhu; Kim, Dongho; Sessler, Jonathan L.; Sarma, Tridib
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 31(2020)
• Page Start: 13063
• Page End: 13070
• Publication Date: 2020-05-28
• Subjects: calix[n]phyrins -- cyclic BODIPY -- exciton coupling -- NIR dyes -- porphyrinoids; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202004867
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Two giant calix[ n ]phyrin derivatives namely calix[8]‐ (4 ) and calix[16]phyrin (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 4.82×10 5 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. Abstract : Two novel macrocyclic BODIPY derivatives possessing two and four BF2 units, respectively, display very high light‐capturing efficiency due to strong excitonic coupling within the constituent chromophoric units. Detailed photophysical analyses provided insight about their structure–property relationship.