Syntheses and Structures of Four Pairs of Coordination Polymers Based on 2,2'-((5-(Methoxycarbony1)-1,3-phenylene)bis(oxy))dipropanoic Acid

Hydrothermal reactions of rare earth (Nd, Sm, Eu, and Tb) and D-. or D-lactic acid are used to construct four pairs of homochiral metal organic frameworks (HMOFs) with polymetallic building blocks, namely, {[Nd-2(L)(2)(H2O)(3)]center dot 4H(2)O}(n) (1-r)/(1-s) and {[Ln(2)(L)(2)(H2O)(2)]center dot 4H(2)O}(n), {Ln = Sm (2), Eu (3), Tb (4)} (n-r)/(n-s). The eight complexes were characterized by single-crystal X-ray diffraction, infrared spectra, elemental analysis, thermogravimetric analysis, electronic circular dichroism (ECD) spectra, and powder X-ray diffraction measurements. The complexes 1-4 featuring a 3D porous metal organic framework crystallize in chiral space groups, and their chirality is proven by the solid-state ECD spectra. Moreover, the second-harmonic generation (SHG) investigation reveals that the complexes 1-r, 2-r, 3-r, and 4-r have medium SHG eficiencies. The complexes 2, 3, and 4 exhibit relatively high luminescence properties, which could be ascribed to ligandcentered emission. The luminescence of complex 4-r could be quenched by nitrobenzaldehyde, which may be used for molecular sensing and recognition.