An investigation into luminescent phenoxo-bridged heterobimetallic copper(II)-calcium(II)/strontium(II)-based bis(salamo)-like complexes

Two luminescent hetero-trinuclear complexes [Cu2Ca(L)(mu(2)-NO3)(2)] (1) and [{Cu2Sr(L)(mu(2)-NO3 )(eta(2)-NO3)}(2)]center dot 2EtOH center dot H2O (2) have been prepared by a flexible bis(salamo)-based ligand (H4L) with Cu(NO3)center dot 3H(2)O and M(OAc)(2)center dot nH(2)O (M(II) = Sr, n= 2; Ca, n= 1), respectively. The structural characterizations were performed by physicochemical and spectroscopic methods. Two penta-coordinate Cu(II) atoms of complex 1 are sited at the N2O2-donor coordination environments of the (L)(4-) moiety, while tetra- and penta-coordinate Cu(II) atoms in complex 2 are also located in the N2O2 cavities of the (L)(4-) unit. Ca(II) and Sr(II) atoms are located in various O-8 and O-9 cavities, respectively. In the solid state, infinite 3D supra-molecular structures are formed in complexes 1 and 2 through the abundant intermolecular hydrogen bonds and pi...pi interactions. These interactions were quantitatively analyzed by Hirshfeld surface analyses. DFT calculations and fluorescence properties showed that complexes 1 and 2 have stable chemical properties and good luminescence properties.