International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2533

Full Length Research Paper

Quantum chemical calculations on molecular structures and solvents effect on 4-nitropicolinic and 4-methoxypicolinic acid

Semire Banjo* and Adeoye Idowu Olatunbosun
Department of Pure and Applied Chemistry, Faculty of Pure and Applied Sciences, Ladoke Akintola University of Technology, P. M. B. 4000, Ogbomoso, Oyo State, Nigeria
Email: [email protected]

  •  Accepted: 08 July 2013
  •  Published: 16 July 2013

Abstract

The density functional theory (DFT) (B3LYP) was used to study the solvents effect on electronic properties of 4-methoxypicolinic acid (4MOPIC) and 4-nitropicolinic acid (4NPIC). The calculated vibration frequencies at DFT/6-311++G** were compared to that of un-substituted picolinic acid to know the effect of donor/acceptor substituent on the molecules. Five solvents namely acetone, ethanol, diethyl ether, N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) were used to study solvents effect. The methoxyl (OCH3) group in 4MPIC pushed electrons into the picolinic acid ring thereby resulted in upfield resonance as compared to 4NPIC in which nitro (NO2) group brought about downfield in1HNMR. The solvents increased the minimum energy required to remove an electron for 4MOPIC whereas it was lower in 4NPIC. The HOMO and LUMO energies calculated in the solvents revealed that both HOMOs and LUMOs experienced stabilization in 4NPIC but LUMOs were destabilized in 4MOPIC as compared to gas phase.

 

Key words: 4-methoxypicolinic acid, 4-nitropicolinic acid, solvents effect, density functional theory (DFT).