Spectroscopy study of 5-amino-1,10-phenanthroline

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 60; no. 4; pp. 781 - 789
• Main Authors: Ramı́rez-Silva, Ma.Teresa, Gómez-Hernández, Martı́n, Pacheco-Hernández, Ma de Lourdes, Rojas-Hernández, Alberto, Galicia, Laura
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.03.2004
• Subjects: 5 Amino-1,10 phenanthroline; Acidity constants; Electrochemistry; Hydrogen-Ion Concentration; Models, Chemical; Nitrogen - chemistry; Phenanthrolines - analysis; Potentiometry; Protons; Software; Spectrophotometry - methods; Spectroscopic study; Ultraviolet Rays; 5 Amino-1,10 phenanthroline; Spectroscopic study; Acidity constants
• ISSN: 1386-1425
• DOI: 10.1016/S1386-1425(03)00301-9

Acidity constants for the 5-amino-1,10-phenanthroline (5-Aphen) were determined in aqueous media, using SQUAD and SUPERQUAD programs. Spectrophotometry and potentiometry data were fitted to the best model to enable correlation of the following acidity equilibria: 5-AphenH=5-Aphen+H + (− log K=5.78±0.03 ) and 5-AphenH 2=5-Aphen+2H + (− log K=6.89±0.07 ). UV absorptivity coefficients obtained suggest that the first protonation takes place on the nitrogens of the heterocycle ring and the second protonation could take place on the amino group. As expected, the electrochemical evidence of the 5-Aphen species depends on the degree of protonation.