Synthesis and Physical Properties of Two Chiral Terpyridyl Europium(III) Complexes with Distinct Crystal Polarity

By utilizing the chiral terpyridyl-type ligand L(-) [L = dipmeno-(4,5:4 '',5 ''')-fused 2,2':6',2 ''-terpyridine or 2,6-bis(7,7-dimethyl-5,6,7,8-tetrahydro-6,8-methanoisoquinolin-3-yl)pyridine], two novel Eu-III complexes with the formula [Eu(tta)(3)L](C3H6O)center dot 0.5(H2O) (1) and [Eu(bta)(3)(L)](C3H6O)(2) (tta = 2-thenoyltrifluoroacetonate, bta = benzoyltrifluoroacetonate) were synthesized and characterized by X-ray crystallography and spectroscopic methods. The Eu-III atoms in I and 2 are nine-coordinate in a geometrical environment of a distorted, monocapped square antiprism. Complex 1 crystallizes in the polar space group P2(1), while complex 2 crystallizes in the nonpolar space group P2(1)2(1)2(1). The chirality of both complexes is evidenced by the circular dichroism (CD) spectra. Both complexes show the characteristic photoluminescence of the Eu-III ion. In contrast to complex 2, complex I exhibits brilliant triboluminescence, an intense NLO property and ferroelectric behaviour at room temperature. The distinct chiral optical properties of complexes 1 and 2 originate from the differing crystal polarities. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)