Four distinctive 1-D lanthanide carboxylate coordination polymers: Synthesis, crystal structures and spectral properties

Abstract

Four novel lanthanide coordination polymers [Pr(mal)(OH)(bipy) · 2H 2O] n ( 1), {[Dy 1(SBA) 3(H 2O) 2][Dy 2(SBA) 3(H 2O) 2] · 4H 2O} n ( 2), {[Tb(OHnic)(Onic)(H 2O) 5 · (OHnicH)] · H 2O} n ( 3) and {[Sm(OHnic)(Onic)(H 2O) 5 · (OHnicH)] · H 2O} n ( 4) (Hmal = maleic acid, HSBA = 4-sulfobenzoic acid, OHnicH = 6-hydroxynicotinic acid and bipy = 2,2′-bipyridine) have been synthesized and determined by single crystal X-ray diffraction. Complex 1 is a 1-D helical chain with seven-coordinated praseodymium centers. Complex 2 forms 1-D chain-like molecular structure containing two crystallographically unique dysprosium centers, the Dy 1 center is seven-coordinated while Dy 2 is eight-coordinated. The isomorphous complexes 3 and 4 exhibit an unprecedented 1-D chain-like polymeric structure through hydroxyl oxygen atoms of bridging Onic 2− anions linking up the neighboring central ions, and there exist three types of 6-OHnicH ligands in the structural unit which is rare for lanthanide carboxylate complexes. The photophysical properties of these complexes were studied using ultraviolet absorption spectra, fluorescence excitation and emission spectra.