Solutions of two nitrilotriacetamide (NTA) ligands, viz., N,N,N',N',N", N"-hexa-n-butylnitrilotriacetamide (HBNTA) and N,N,N',N',N",N"hexa-n-hexylnitrilotriacetamide (HHNTA) in 20% isodecanol-80% n-dodecane were employed for the extraction of U(VI), Np(IV), Pu(IV), and Am(III) from nitric acid feed solutions. Limitations of ligand solubility and third-phase formation when contacted with nitric acid solutions led to the choice of the diluent composition of 20% isodecanol and 80% n-dodecane. The results of the solvent extraction studies indicated poor extraction of the metal ions with HBNTA as compared to that with HHNTA as the extractant and hence, major part of this work involved HHNTA. Slope analysis suggested extraction of 1:1 (ML) species with Np(IV) and Pu(IV) at 3 M HNO 3 and mixed 1:2 (ML 2 ) and 1:3 (ML 3 ) species with U(VI) at pH 2. At 0.5 M HNO 3 , the observed trend for extraction was Pu(IV) > Np(IV) >> Am(III) > U(VI).

Photophysical characteristics of 2-(4'-amino-2'-hydroxyphenyl)-1H-imidazo-[4,5-c]pyridine (AHPIP-c) have been studied in various aprotic and protic solvents using UV-visible, steady state fluorescence and time-resolved fluorescence spectroscopic techniques. To comprehend the competition between the intramolecular charge transfer (ICT) and the excited state intramolecular proton transfer (ESIPT) processes, the photophysical properties of 2-(4'-amino-2'-methoxyphenyl)-1H-imidazo-[4,5-c]pyridine (AMPIP-c) and 2-(4'-aminophenyl)-1H-imidazo-[4,5-c]pyridine (APIP-c) were also investigated. Though APIP-c displays twisted ICT (TICT) emission in protic solvents, AHPIP-c exhibits normal and tautomer emissions in aprotic as well as in protic solvents due to ESIPT. However, the methoxy derivative, AMPIP-c, emits weak TICT fluorescence in methanol.

No abstract