Temperature and concentration dependence towards physicochemical and FTIR spectral studies of glycine, L-alanine and L-valine in aqueous solutions of nortriptyline hydrochloride

Abstract

Apparent and partial molar properties for glycine, L-alanine and L-valine in aqueous solutions (0.025–0.075) mol·kg−1 of drug NTPH (nortriptyline hydrochloride) have been reported in the present study at intervals of 5 K from temperature 288.15 K to 308.15 K and at experimental pressure of p=0.1 MPa. Different parameters viz. transfer partial molar properties, hydration numbers (nH), partial molar expansibility (E∅0), isobaric thermal expansion coefficient (α) and Hepler’s constant, calculated by using the experimental data of density (ρ) and ultrasonic speeds (u) predict that the solute-solvent interactions are dominating in these ternary systems. The linear variation of V∅0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups NH3+,COO-, (CH2) group and other alkyl chains of the amino acids to V∅0. Pair and triplet interaction coefficients determined from ΔV∅0 and ΔK∅,s0 values using McMillan-Mayer theory indicate the dominance of pairwise interactions in the studied ternary mixtures. The hydration number (nH) comes out to be positive suggesting strong dehydration effect of NTPH. FTIR spectra have been recorded for the mixtures of amino acids in aqueous solutions of NTPH. The decrease in wave number of N–H stretching band also suggests the structural changes in these systems.