Synthesis, crystal structure and luminescence properties of "paddle wheel" and "butterfly" shaped polynuclear complexes

A series of metal cluster-based complexes were constructed from the reaction of metal ions (Fe-III, Cu-II, Zn-II) and ligand (2({2-[2-carbosybenzoy])oxy]-ethoxy}carbonyal)benzoic acid) (H2L) in CH3CH2OH, CH3OH, (C2H5)(3)N and C2H3N. Two paddle wheel trinuclear clusters [Fe-3(mu(3)-O)(mu(2)-eta(2)-L)(3)(CH3OH)(3)] NO3 center dot C2H5OH center dot CH3OH (1) and [Fe-3(mu(3)-O)(mu(2)-eta(2)-L)(3)(H2O)(3)NO3 center dot 5CH(3)OH center dot H2O (2), one tetranuclear cluster [Cu-2(mu(2)-L)(2)(C2H3N)(2)center dot 2C(2)H(3)N](2) (3) and one butterfly shaped dinuclear cluster [Zn-2(mu(2)-L)(2)(C2H5OH)(2)]center dot 2CH(3)OH (4) were obtained. Complexes 1, 2, and 4 are further assembled by intermolecular hydrogen bonds to form supramolecular frameworks. In complex 3, the flexible benzoic acid ligand chelates with two Cu-II, which induces a decrease of Cu-Cu intermetallic separation (rang from 2.644 to 2.657 angstrom). The structures of the complexes are characterized by elemental analyses, Infrared spectroscopy (IR spectroscopy), thermal gravimetry (TG) analyses, single crystal X-ray diffraction and powder X-ray diffraction techniques (PXRD), and high resolution mass spectra (HRMS). The luminescent properties of the clusters 1-4 are also studied, the results show that the cluster 4 exhibits blue fluorescence at room temperature. (C) 2016 Elsevier B.V. All rights reserved.