Construction of lanthanide coordination polymers based on mixed terpyridyl and dicarboxylate ligands: Syntheses, structures and luminescent properties

Abstract

Reaction of hydrated lanthanide (III) nitrates and 4’-(3-carboxyphenyl)-4,2′:6′,4″-terpyridine (HL) under hydrothermal conditions in the presence of auxiliary ligands afforded four series of lanthanide coordination polymers, [Ln2(L)2(ox)2(H2O)2]n (Ln ​= ​Sm (1), Eu (2)), [Ln(L)(glu)]n (Ln ​= ​Eu (3)), [Ln(L)(adip)(H2O)]n (Ln ​= ​Pr (4), Sm (5)), [Ln2(L)2(1,3-bdc)2]n (Ln ​= ​Pr (6), Nd (7), Sm (8), Eu (9)), where H2ox, H2glu, H2adip and H2(1,3-bdc) denote oxalic acid, glutaric acid, adipic acid and benzene-1,3-dicarboxylic acid, which have been characterized by elemental analysis, IR and single crystal X-ray diffraction. Compounds 1 and 2 possess similar structures and display a two dimensional 6-connected hxl net ground on loop-like binuclear Ln2 units with the (36·46·53) topology. Compound 3 presents a fascinating 3D framework with paddle-wheel units, which exhibits a 2-nodal (3,10)-connected 3,10-T9 net with (418·624·83)(43)2 topology. Isostructural compounds 4 and 5 exhibit a (3,6)-connected kgd net with (43)2(46·66·83) topology. Isomorphous 6–9 feature a 3D (3,10)-connected 3,10-T9 net with (418·624·83)(43)2 topology. The structural diversity adequately demonstrate the abundant coordination chemistry of carboxylate terpyridine derivatives and the coordination geometries of LnIII ions, as well as the effects of introducing auxiliary ligands. Moreover, detailed discussion toward the photoluminescence and thermal stabilities of 1–9 were also conducted.