Proton transfer and Cu(II) binuclear complexes of 1,4 bis-(p-sulfonylazo)-2,3 dihydroxynaphtalene: a spectroscopic and potenciometric study in aqueous solution

GABRIELA IBAÑEZ; ALEJANDRO OLIVIERI; GRACIELA ESCANDAR

JOURNAL OF MOLECULAR STRUCTURE

Elsevier

Lugar: Asterdam; Año: 1997 vol. 435 p. 199 - 206

0022-2860

Abstract A proton‑transferring aromatic bis‑azo compound, 1,4‑bis‑p‑sulfonylazo‑2,3‑dihydroxy naphthalene (SADN), and its possible binuclear copper(II) complexes have been studied in aqueous solution. Both ground‑ and excited‑state prototropism of this compound is investigated by means of carbon‑13 nuclear magnetic resonance, electronic absorption and fluorescence emission spectroscopies, and semi‑empirical molecular orbital methods. By using fluorescence measurements evidence for both single and double ESIPT phenomena have been established in SADN. The formation constants of both mono‑ and binuclear CuII complexes have been evaluated from potentiometric and spectrophotometric results. The possible structures of both free SADN and its complexes are discussed.