Systematic measurements of charge transfer complexes caused from 1-phenyl-1,2,3,4-tetrahydroisoquinoline and 4-aminoacetanilide with series of π-acceptors (BQ, DDQ, TCNQ)

Molecular charge-transfer interaction of a series of electron pi-acceptors of 1,4-benzoquinone (BQ), 2,3-dichloro5,6-dicyano-1,4-benzoquinone (DDQ) and Tetracyanoquinodimethane (TCNQ) with selected donors of 1-phenyl-1,2,3,4-tetrahydroisoquinoline (PTHIQ) and 4-aminoacetanilide (ACE) have been studied in methanol at room temperature. The stoichiometry of the complexes was determined by photometric titration method and was found to be 1:1, in all the cases. Spectro-kinetic interaction studies along with rate constants and observed formation constants (K) indicated that the strength of the complex formations is PTHIQ-BQ < PTHIQ-DDQ < PTHIQ-TCNQ. Also, Similar observations happened in ACE-BQ and < ACE-DDQ < ACE-TCNQ systems. FT-IR results indicated that the point of interaction was identifying in NH moiety of PTHIQ and NH2 moiety of ACE with series of pi-acceptor complexes. The experimental results were compared with Ab initio DFT calculations at the B3LYP/6-31 + G(d) level of theory. The increasing order of the experimentally measured formation constant of CT-complexes (PTHIQ and ACE with series of acceptors) was well supported by theoretical HOMO-LUMO energy gap and drastically changes in Mulliken charges of NH moiety of PTHIQ, NH2 moiety of ACE with complexation with acceptors. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

A study on the molecular charge-transfer interaction between a series of electron pi-acceptors and selected donors reveals consistent results between experimental and theoretical analyses. The order of complex formation strengths between donors and acceptors is observed, along with the identification of interaction sites on the donor molecules complexed with acceptors.