Investigation of acid-base behaviour of some 2-pyridylbenzimidazoles using semi-empirical methods

Kaniskan N., Ogretir C.

JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, cilt.584, ss.45-52, 2002 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 584
  • Basım Tarihi: 2002
  • Doi Numarası: 10.1016/s0166-1280(02)00018-0
  • Dergi Adı: JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.45-52
  • Anahtar Kelimeler: 2-pyridylbenzimidazoles, acidity, basicity, proton affinity, semi-empirical calculations, acidity constants, AQUEOUS-SOLUTION, AM1
  • Anadolu Üniversitesi Adresli: Hayır

Özet

Acid-base behaviour of some 2-(n'-pyridyl) benzimidazoles (n' = 2,3,4) have been studied in order to search the protonation site and to predict pK(a) values of these molecules both in gas and aqueous phases using semi-empirical quantum chemical calculation methods. The best correlation between the experimental acidity constants, pK(a), and proton affinities was detected with PM3 method in aqueous phase. Furthermore, acceptable correlations were observed between the experimental acidity constants, pK(a) (exp.) and calculated acidity constant, pK(a) (calc.) by AM1 and PM3 methods. A change-over in the protonation mechanism for the second proton-gain process for all compounds was observed. (C) 2002 Elsevier Science B.V. All rights reserved.