New macrocyclic Cu(II)-bischelates with paddle wheel Cu2-acetate cage

Two novel bolaamphiphile based dicarboxylic ligands L1H2 and L2H2 are synthesized by desymmetrizing aromatic anhydrides. The corresponding Cu(II) complexes [Cu(L1) · EtOH]2 (1), [Cu(L2) · (CH3CN)]2 (2) are synthesized and characterized. The crystal structure obtained for (1) and (2) indicates that they are new class of tetralactone type macrocyclic Cu(II) chelate complexes with paddle wheel Cu2-acetate cage structure. The 1:1, Cu(II) and ligand ratio leads into formation of a novel binuclear Cu(II) tetracarboxylate complexes. The macrocyclic chelate ring size in compounds 1 and 2 was altered from [15] membered to [19] membered by introducing phthalyl and diphenyl head groups as discussed in detail. The single crystal X-ray structure shows the Cu(II)⋯Cu(II) distance 2.613(13) Å for 1 and 2.626(13) Å for 2, the corresponding room temperature EPR spectra recorded for powdered polycrystalline samples indicate the existence of Cu(II)⋯Cu(II) dimeric system.

Graphical abstractThe novel bolaamphiphile like dicarboxylic ligands obtained by desymmetrizing aromatic anhydrides were shown first time to form new class of tetralactone type macrocyclic Cu(II) chelate complexes which retains the paddle wheel Cu2-acetate cage structure.Figure optionsDownload full-size imageDownload as PowerPoint slide