CONFORMATIONAL ANALYSIS OF THIAZOLE-5-CARBOXYLIC ACID USING DFT/TD-DFT METHODS

Year 2020, Volume: 21 , 63 - 73, 27.11.2020

Nihal Kuş

https://doi.org/10.18038/estubtda.820152

Abstract

In this work, structures of the conformations of the thiazole-5-carboxylic acid (T5CA) were studied using density functional theory (DFT) with B3LYP/6-311++G(d,p) level of approximation. From calculations of the potential energy distribution depending on the orientation of the carboxylic group (C-C-OH and O=C-OH) attached to the five-membered heterocyclic ring, four conformers were found at minimum energy. Considering that the relative energy in the most stable structure is zero. The relative energies of the other conformations were found to be about 0.14, 27.11, 29.84 kJ mol-1, respectively. It was found that the carboxylic acid group of the T5CA_3 and 4 were not planar, while T5CA_1 and T5CA_2 were planar. Stabilization and donor-acceptor orbital interaction energies were calculated for all conformations and orbitals were plotted using natural bond orbital analysis (NBO) method. The excited state energies were calculated and graphed using Time-Dependent Density Functional Theory (TD-DFT) calculations. The singlet state energies were tabulated for all conformations and it was seen that the most stable form with the highest oscillator strength was at the second singlet state (S2). In addition, HOMO-LUMO energy gaps were calculated and electrostatic potential surface maps were drawn for all conformations.

Keywords

Thiazole-5-carboxylic acid, DFT/ TD-DFT, NBO, HOMO-LUMO energy

References

• Kaur G, Singh JV, Gupta MK, Bhagat K, Gulati HK, SinghA, Bedi PMS, Singh H and Sharma S. Thiazole-5-carboxylic acid derivatives as potent xanthine oxidase inhibitors: design, synthesis, in vitro evaluation, and molecular modeling studies. Medicinal Chemistry Research 2020, 29, 83–93.
• Halasa A, Reva I, Lapinski L, Nowak MJ and Fausto R. Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light. J. Phys. Chem. A 2016; 120, 13, 2078–2088.
• Schneider JMFM., Sales ES, Livotto PR, Schneider PH, Merlo AA. Synthesis of new family of thiazoline and thiazole esters and investigation of their thermal properties. . J. Braz. Chem. Soc. 2014; 25, 8, 1493–1503. Meundaeng N, Rujiwatra A, Prior JT. Polymorphism in metal complexes of thiazole-4-carboxylic acid. Transition Metal Chemistry 2016; 41, 783–793.
• Li H, Kennedy SD, Goldstein BM. Solid-state and solution conformations of isotiazofurin: crystallographic, computational and 1H NMR studies. Acta Crystallogr B. 1993; 1;49 (Pt 4):729–38.
• Bonnel C, Legrand B, Bantignies J-L., Petitjean H, Martinez J, Masurier N and Maillard LT. FT-IR and NMR structural markers for thiazole-based γ-peptide foldamers. Organic & Biomolecular Chemistry 2016; 14, 8664–8669.
• Frisch MJ et al. Gaussian 09, Revision A.0.2, Gaussian, Inc., Wallingford CT, 2009.
• Reed AE, Curtiss LA, Weinhold F. Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint. Chem. Rev. 1988; 88, 899–926.
• Bauernschmitt R, Ahlrichs R. Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory. Chem. Phys. Lett. 1996; 256, 454–464.
• Stratmann RE, Scuseria GE, Frisch MJ. An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules. J. Chem. Phys. 1998; 109, 8218–8224.
• Miyagawa M, Akai N, Nakata M. UV-Light Induced Conformational Changes of 2-Pyridinecarboxylic Acid Isolated in Low-Temperature Argon Matrices. J. Mol. Struct. 2015; 1086, 1−7.
• Weinhold F, Landis CR. Valency and Bonding. A Natural Bond Orbital Donor-Acceptor Perspective. Cambridge University Press: New York, 2005.
• Alcamí M, Mó O, Yáñez M. Modelling Intrinsic Basicities: The Use of the Electrostatic Potentials and the Atoms-in-Molecules Theory. Theoretical and Computational Chemistry 1996; 3, 407−456.