Luminescent study on Nd3+ complexes containing carboxylate-dithiolene and akoxide-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.