Two Series of Lanthanide Coordination Polymers and Complexes with 4′-Phenylterpyridine and their Luminescence Properties

Two series of trivalent lanthanide and group 3 metal coordination polymers with 4 '-phenyl-2,2 ':6 ',2 ''-terpyridine (ptpy) of the composition (1)(infinity)[MCl3(ptpy)] (1, M = La, Ce, Pr, Nd) and the complexes [MCl3(ptpy)(py)] (2, M = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) have been synthesized and characterized. For europium, the complex [Eu2Cl6(ptpy)(2)] (3) was obtained as single crystals, its dimeric structure providing potential insight into the coordination polymer formation from monomeric entities. Product series 1 and 2 were photophysically investigated in the solid state at room temperature and 77 K. Alongside with standard ion-specific 4f-4f trivalent lanthanide luminescence in the visible and NIR (of emitters such as europium, terbium, dysprosium, neodymium, etc.), visible range emission of praseodymium, holmium, erbium, and thulium was observed, which is rarely reported for coordination compounds. It occurs in addition to their characteristic NIR emission. For complexes of series 1, an exciplex based luminescence was observed originating from ligand pi-stacking in the crystal packing.