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Multistep Energy and Electron Transfer in a “V‐Configured” Supramolecular BODIPY–azaBODIPY–Fullerene Triad: Mimicry of Photosynthetic Antenna Reaction‐Center Events
Author(s) -
Bandi Venugopal,
D'Souza Fiona P.,
Gobeze Habtom B.,
D'Souza Francis
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405663
Subject(s) - bodipy , photochemistry , photosynthetic reaction centre , chemistry , triad (sociology) , electron transfer , supramolecular chemistry , materials science , fluorescence , molecule , organic chemistry , physics , psychology , quantum mechanics , psychoanalysis
A new photosynthetic antenna‐reaction‐center model compound composed of covalently linked BF 2 ‐chelated dipyrromethene (BODIPY), BF 2 ‐chelated azadipyrromethene (azaBODIPY), and fullerene (C 60 ), in a “V‐configuration”, has been newly synthesized and characterized by using a multistep synthetic procedure. Optical absorbance and steady‐state fluorescence, computational, and electrochemical studies were systematically performed in nonpolar, toluene, and polar, benzonitrile, solvents to establish the molecular integrity of the triad and to construct an energy‐level diagram revealing different photochemical events. The geometry obtained by B3LYP/6‐31G* calculations revealed the anticipated V‐configuration of the BODIPY‐azaBODIPY‐C 60 triad. The location of the frontier orbitals in the triad tracked the site of electron transfer determined from electrochemical studies. The different photochemical events originated from 1 BODIPY* were realized from the energy‐level diagram. Accordingly, 1 BODIPY* resulted in competitive ultrafast energy transfer to produce BODIPY– 1 azaBODIPY*–C 60 and electron transfer to produce BODIPY . + –azaBODIPY–C 60 . − as major photochemical events. The charge‐separated state persisted for few nanoseconds prior populating 3 C 60 *, which in turn revealed an unusual triplet–triplet energy transfer to produce 3 azaBODIPY* prior returning to the ground state. These findings delineate the importance of multimodular systems in energy harvesting, and more importantly, their utility in building multifunction performing optoelectronic devices.