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Assessing the potential of para-donor and para-acceptor substituted 5-benzylidenebarbituric acid derivatives as push–pull electronic systems: Experimental and quantum chemical study
Ist Teil von
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2021-05, Vol.253, p.119576, Article 119576
Ort / Verlag
Elsevier B.V
Erscheinungsjahr
2021
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
[Display omitted]
•5-benyzlidenebarbiturates were investigated spectroscopically and theoretically.•LFER analysis of spectral data and optimized geometry parameters are performed.•ICT analysis for quantification of the efficiency of charge transfer is used.•The best candidate for the push–pull system is para–N(CH3)2 substituted derivative.•The weak electron-donating properties of barbituric acid are reported.
Electronic interactions in donor-π-linker-acceptor systems with barbituric acid as an electron acceptor and possible electron donor were investigated to screen promising candidates with a push–pull character based on experimental and quantum chemical studies. The tautomeric properties of 5-benzylidenebarbituric acid derivatives were studied with NMR spectra, spectrophotometric determination of the pKa values, and quantum chemical calculations. Linear solvation energy relationships (LSER) and linear free energy relationships (LFER) were applied to the spectral data - UV frequencies and 13C NMR chemical shifts. The experimental studies of the nature of the ground and excited state of investigated compounds were successfully interpreted using a computational chemistry approach including ab initio MP2 geometry optimization and time-dependent DFT calculations of excited states. Quantification of the push–pull character of barbituric acid derivatives was performed by the 13CNMR chemical shift differences, Mayer π bond order analysis, hole-electron distribution analysis, and calculations of intramolecular charge transfer (ICT) indices. The results obtained show, that when coupled with a strong electron-donor, barbituric acid can act as the electron-acceptor in push–pull systems, and when coupled with a strong electron-acceptor, barbituric acid can act as the weak electron-donor.