title: Spectrophotometric determination of acidity and tautomeric constants and hydrogen bonding strength for a new Schiff base using hard modeling and multivariate curve resolution alternative least squares methods.
abstract: The equilibria of a new Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were studied spectrophotometrically with the aid of factor-analytical methods. Hard modeling program was used for determination of the acidity constants of the Schiff base in dimethylformamide (DMF)/water mixture (30:70 v/v). In this method acidity constant equations act as hard models and the score vectors obtained by decomposing of absorbance data matrix will be linear combinations of equilibrium concentrations of species that exist in the absorption matrix. Two rank annihilation factor analysis (TRAFA) was used as a standard method to investigate the accuracy of the method. The tautomerization constant, K(t), of the Schiff base solution in various DMF/water mixtures has also been determined using spectral variations of the Schiff base solutions in various volume ratios of water with the aid of evolving factor analysis (EFA) and multivariate curve resolution alternative least squares (MCR-ALS) methods. In addition the intramolecular hydrogen bonding strength and its related thermodynamic parameters have been determined using MCR-ALS and spectral variation of the Schiff base solutions in different temperatures.
authors.affiliation: Faculty of Chemistry, Bu-Ali-Sina University, Hamadan, Iran. afkhami@basu.ac.ir
authors.forename: Abbas
authors.initials: A
authors.lastname: Afkhami
authors.forename: Farzad
authors.initials: F
authors.lastname: Khajavi
authors.forename: Hamid
authors.initials: H
authors.lastname: Khanmohammadi
mesh_terms: D004126:Dimethylformamide / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D016018:Least-Squares Analysis; D008956:Models, Chemical; D015394:Molecular Structure; D015999:Multivariate Analysis; D011724:Pyridazines / Q000032:analysis*; D012545:Schiff Bases / Q000737:chemistry*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
chemical_list: D011724:Pyridazines; D012545:Schiff Bases; D014867:Water; D004126:Dimethylformamide