Luminescent Study on Nd3+ Complexes Containing Carboxylate-Dithiolene and Alkoxide-Dithiolene Ligands

Reaction of ligand LH2 (4,5‐bis[carboxymethylthio]‐1,3‐dithiol‐2‐thione) with neodymium silyl‐amide (Nd[N(TMS)2]3; TMS= ‐SiMe3), in a ratio 2:1, yields a neodymium‐dithiolene‐carboxylato complex (1) (Nd(LH)L). Similarly, reaction of 2 equivalents of L′H2 (4,5‐bis[2′‐hydroxyethyl)thio]‐1,3‐dithiol‐2‐thione) and one equivalent of neodymium silyl‐amide (Nd[N(TMS)2]3) allowed the isolation of complex 2, with a ligand:metal ratio of 3:2. ATR‐IR spectrum of 1 displays a broad band characteristic of an OH group showing that one carboxylate group remains protonated. Emission spectrum of complex 1 under excitation in the visible region (at 360 nm i.e. on the ligand) displayed typical emission bands of the Nd3+, showing that energy transfer from the ligand to the lanthanide was achieved (i.e. “antenna effect”). No significant quenching from the remaining –OH group was detected. In the case of complex 2, the main emission bands characteristic of the Nd3+ ion have been observed, by excitation at 495 nm.