Syntheses, characterization and properties of silver, copper and palladium complexes from bis(oxazoline)-containing ligands

The reactions of 2,6-di(2-oxazolyl)pyridine (L{sup 1}) and 2,6-bis[(S)-4-phenyl-2-oxazolyl]pyridine (L{sup 2}) with silver, copper and palladium salts to yield six new complexes: ([Ag{sub 5}(L{sup 1}){sub 5}](BF{sub 4}){sub 5}){sub n} (1), ([Ag(L{sup 1})](SbF{sub 6})){sub n} (2), [Cu{sub 4}I{sub 4}(L{sup 1}){sub 2}] (3), [Cu{sub 6}I{sub 6}(L{sup 1}){sub 2}] (4), [Pd(L′{sup 1})(OAc)] (5), [Pd(L′{sup 2})Cl] (6), which were fully characterized by single-crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. 1 and 2 are a pair of Ag-oxazoline helical chain structure complexes. The spiral directions of chains are opposite in 1, while identical in 2; the measurement of CD spectra can further confirm their meso and chiral structures. Complexes 3 and 4 show eight-nuclear and twelve-nuclear iodine–cuprous cluster structure. Their structural diversity is induced by different molar ratios of CuI:L{sup 1}. Complexes 5 and 6 are discrete mononuclear palladium complexes. In situ oxazolyl-ring-opening reactions take place in the syntheses of them and the L{sup 1} and the L{sup 2} were transformed to their oxazolyl-ring opened derivatives L′{sup 1} and L′{sup 2}. Moreover, fluorescence, non-linear optical properties, and ferroelectric properties have been investigated. - Graphical abstract: 2,6-di(2-oxazolyl)pyridine (L{sup 1}) reacts with silver and copper salts to yield helical and cluster structure complexes. - Highlights:more » • Helical and cluster structure complexes. • In situ oxazolyl-ring-opening reactions. • Fluorescence, non-linear optical properties, and ferroelectric properties.« less