title: Experimental and quantum mechanical studies on the ion-pair of levocetirizine and bromocresol green in aqueous solutions.
abstract: In the present work, levocetirizine dihydrochloride (LEV) was found to interact with bromocresol green (BCG) via ion-pair formation. UV-vis and FTIR spectroscopy were used to validate the data obtained from quantum mechanical calculations (QMC). The electrostatic potential maps show that the reaction is preferred through the interaction of the sulfonic acid group of BCG and the quaternary ammonium group of LEV. The optimized geometry of the product shows that there are six different intermolecular hydrogen bonds between the studied molecules resulting from the ionic attraction between the oppositely charged groups. The UV-vis spectra suggest the formation of an ion-pair. This finding is contradicting with the previous charge-transfer hypothesis.
authors.affiliation: National Organization for Drug Control and Research (NODCAR), P.O. Box 29, Giza, Egypt; Faculty of Oral and Dental Medicine, Future University in Egypt (FUE), New Cairo, Egypt. Electronic address: ahmed_said5899@yahoo.com.
authors.forename: Ahmed S Abo
authors.initials: AS
authors.lastname: Dena
authors.affiliation: Chemistry Department, Faculty of Science, King Abdulaziz University, B.O. 80203, Jeddah 21589, Saudi Arabia; Chemistry Department, Faculty of Science, Cairo University, Giza 12613, Egypt.
authors.forename: Walid M I
authors.initials: WM
authors.lastname: Hassan
mesh_terms: D001961:Bromcresol Green / Q000032:analysis* / Q000737:chemistry; D017332:Cetirizine / Q000032:analysis* / Q000737:chemistry; D004583:Electrons; D006860:Hydrogen Bonding; D007477:Ions; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
chemical_list: D007477:Ions; D012996:Solutions; C472067:levocetirizine; D001961:Bromcresol Green; D017332:Cetirizine
keywords: Hydrogen bond; Ion–pair; Proton–transfer; Spectroscopy; Triphenylmethane