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Photoinduced Charge Separation Prompted Intervalence Charge Transfer in a Bis(thienyl)diketopyrrolopyrrole Bridged Donor‐TCBD Push‐Pull System
Author(s) -
Khan Faizal,
Jang Youngwoo,
Patil Yuvraj,
Misra Rajneesh,
D'Souza Francis
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202108293
Subject(s) - comproportionation , ultrafast laser spectroscopy , chemistry , electron donor , redox , photochemistry , electron transfer , acceptor , electron acceptor , spectroscopy , electrochemistry , catalysis , inorganic chemistry , organic chemistry , physics , electrode , quantum mechanics , condensed matter physics
Intervalence charge transfer (IVCT), a phenomenon observed in molecular systems comprised of two redox centers differing in oxidation states by one unit, is reported in a novel, newly synthesized, multi‐modular donor‐acceptor system comprised of central bis(thienyl)diketopyrrolopyrrole (TDPP) hosting two phenothiazine‐tetracyanobutadiene (PTZ‐TCBD) entities on the opposite sides. One‐electron reduction of TCBD promoted electron exchange between the two TCBD resulting in IVCT transition in the near‐infrared region. The stabilization energy, −Δ G com and comproportionation equilibrium constant, K com calculated from peak potentials of the split reduction waves were found to be 1.06×10 4 J mol −1 , and 72.3 M −1 , respectively. Further, the IVCT transition was also witnessed during the process of thermodynamically feasible electron transfer upon excitation of the TDPP entity in the system, and served as a diagnostic marker to characterize the electron transfer product. Subsequent transient absorption spectral studies and data analysis by Global and Target analyses revealed occurrence of ultrafast charge separation ( k cs ≈10 10 s −1 ) owing to the close proximity and good communication between the entities of the multi‐modular donor‐acceptor system. The role of central TDPP in promoting IVCT is borne out from the present investigation.