title: [Synthesis of 2-(4-dimethylaminophenyl)-5-fluoro-6-(morpholin-4-yl)-1H-benzimidazole and its spectroscopic research].
abstract: A new potential pharmaceutical compound, 2-(4-dimethylaminophenyl)-5-fluoro-6-(morpholin-4-yl)-1H-benzimidazole (4) was synthesized. The effect of the pH value of aqueous solution on the absorption spectrum of compound 4 and its interaction with beta-cyclodextrin (beta-CD) were investigated by UV-Vis spectrum, steady-state fluorescence and time-resolved spectroscopic measurements. The results indicate that compound 4 mainly exists in neutral molecular state when pH value of the aqueous phase is above 7.0. In the pH range from 7.0 to 3.8 the neutral molecular state and protonated univalent cationic form coexist. As the pH value decreases, the content of univalent cationic form increases. When 2.76 < pH < 3.8, the protonated univalent cationic form is the predominant species. With further decrease of the pH value, the univalent cation is protonated by another H+ to form a bivalent cation, and both univalent and bivalent cations coexist in the solution. The steady-state fluorescence and time-resolved spectroscopic measurements revealed that compound 4 is a sensitive molecular probe. The interaction of compound 4 and beta-CD is very strong. The guest:host ratio of inclusion complex between compound 4 and beta-CD formed in the aqueous solution (pH = 9.50) is 1:1, and the association constant was determined to be (1.02 +/- 0.04) x 10(3) mol x L(-1).
authors.affiliation: College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
authors.forename: Ling-tian
authors.initials: LT
authors.lastname: Tang
authors.forename: Xiang-yun
authors.initials: XY
authors.lastname: Wang
authors.forename: Xin-qi
authors.initials: XQ
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000042:Absorption; D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D004364:Pharmaceutical Preparations / Q000138:chemical synthesis* / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013057:Spectrum Analysis; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D001562:Benzimidazoles; D004364:Pharmaceutical Preparations