Electronic Structure, Spectra and Chemical Reactivity Descriptors of Some Novel Rhodanine Derivatives. Density Functional Theory Approach | ||
| Egyptian Journal of Chemistry | ||
| Volume 66, Issue 13, December 2023, Pages 483-497 PDF (1.79 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejchem.2023.196920.7651 | ||
| Authors | ||
| Mahmoud Sharaf; hussein moustafa* ; Rifaat H Hilal | ||
| Chemistry Department, Faculty of Science, Cairo University, University Ave., Dokki, Cairo 12613, Egypt | ||
| Abstract | ||
| The ground state optimized structure of the newly synthesized and characterized 2-4 rhodanines derivatives were investigated theoretically at the B3LYP/6-311++G** level of theory. The optimized structure is planar with the N-ph. moiety out of the molecular plane by 900. The correspondence between the theoretically computed and x-ray experimentally measured geometric parameters is excellent. The electronic absorption spectra of the rhodanines 1-5 are measured in both polar and nonpolar solvents. Assignments of the experimentally recorded transitions are facilitated via computation of the spectra at the TD-DFT/B3LYP/6-311++G** level of theory. Natural transition orbitals (NTO) enable deep insight into the nature of the observed electronic transitions. Gross Solvents effects are cogitated by applying Polarizable Continuum Model (PCM) in the TD-DFT computations. Compounds 2-5 displayed the two π-π* rhodanine ring transitions at 294 nm and 252 nm besides a new band due to 5-arylmethylidene group in position 5 for Rh ring. The computed HOMO - LUMO energies of the investigated compounds could be utilized to determine the overall characteristics parameters. The order of increasing EHOMO is 3 < 1 < 5 < 2 < 4 while the order of decreasing ELUMO is 3 < 5 < 2 < 4 < 1. From these results it is obvious that derivative 4 holds the uppermost nucleophilicity while compound 3 has the highest electrophilicity. Analyzing the computed hardness (η) values and softness (S) values for the studied compounds revealed their donor-acceptor behavior, Results of the present work indicate that compound 4 is the most polarizable, of the highest chemical reactivity and easier charge transfer with S=0.3117 eV, while the least is compound 1 with η=2.1722 eV. The molecular electrostatic potential (MEP) maps are correlated to the electronic density and are a highly useful signifier for elucidating electrophilic and nucleophilic reaction sites, as well as hydrogen bonding interactions and chemical activity. Negative areas are mostly gone over O7 atom of CO group for compounds (1-5) and the nitrogen atoms of pyridine group for compound 3, while S6 atom in compound 4 is slightly red. These are the molecular residues that are most frequently targeted by electrophilic attacks. | ||
| Keywords | ||
| Rhodanine derivatives; Density Functional Theory (DFT); UV spectra; NTO analysis; Global descriptors | ||
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