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1.
ChemSusChem ; 13(24): 6574-6581, 2020 Dec 17.
Article in English | MEDLINE | ID: mdl-32881393

ABSTRACT

It has been suggested in the literature that keto-to-enol tautomerization plays a vital role for lignin fragmentation under mild conditions. On the other hand, previous modelling has shown that the adsorbed keto form is more stable than enol on the Pd(111) catalyst. The current density functional theory study of lignin model molecules shows that, in the gas-phase, keto is more stable than enol, but on the Pd surface, we find enol conformers that are at least as stable as keto. This supports the experimental result that the favourable reaction pathway for lignin depolymerization involves keto-enol tautomerization. An energy decomposition analysis gives insights concerning the origin of the fine energy balance between the keto and enol forms, where the molecule-surface interaction (-7 eV) and the molecular strain energy (+3 eV) are the main contributors to the adsorption energy.

2.
Eur J Med Chem ; 123: 508-513, 2016 Nov 10.
Article in English | MEDLINE | ID: mdl-27494167

ABSTRACT

Trisubstituted thiazoles were synthesized and studied for their antimicrobial activity and supported by theoretical calculations. In addition, MIC, MBC and MFC were also tested. Moreover, the present study was analyzed to scrutinize comprehensive structure-activity relationships. In fact, LUMO orbital energy and orbital orientation was reliable to explain their antibacterial and antifungal assay. Amongst the tested compounds, tri-methyl-substituted thiazole compound showed higher antimicrobial activity and low MIC value due to highest LUMO energy.


Subject(s)
Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Antifungal Agents/chemical synthesis , Antifungal Agents/pharmacology , Drug Design , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Anti-Bacterial Agents/chemistry , Antifungal Agents/chemistry , Aspergillus flavus/drug effects , Aspergillus niger/drug effects , Bacteria/drug effects , Chemistry Techniques, Synthetic , Models, Molecular , Molecular Conformation , Static Electricity , Structure-Activity Relationship , Thiazoles/chemistry
3.
J Chem Phys ; 143(24): 244906, 2015 Dec 28.
Article in English | MEDLINE | ID: mdl-26723710

ABSTRACT

The development of new conductive polymers nowadays is one of the most important technological areas in materials design. Computational investigation of desired properties in conductive polymers could save financial resources and time, but it is important to choose the methodology that produces good results comparing to experimental results. To verify the prediction of second hyperpolarizability (γ) in oligomers of Trans-Polyacetylene (TPA) by theoretical calculations, a series of semi-empirical, Hartree-Fock (HF), and Density Functional Theory (DFT) calculations were performed and analysed through linear fitting statistical analysis to investigate the accuracy of such theoretical predictions in comparison to the experimental ones. The results showed that HF and DFT methodologies do not describe γ with good accuracy, but the use of diffuse and polarizability functions in HF methodology provided better results than 3-21G and 6-31G functions. It was concluded that RM1 methodology better agrees with γ experimental results for TPA oligomers, and linear fitting statistical analysis is a useful tool to compare experimental and theoretical results.

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