A new stepped tetranuclear copper(II) complex: synthesis, crystal structure and photoluminescence properties

Binuclear and tetranuclear copper(II) complexes are of interest because of their structural, magnetic and photoluminescence properties. Of the several important configurations of tetranuclear copper(II) complexes, there are limited reports on the crystal structures and solid-state photoluminescence properties of 'stepped' tetranuclear copper(II) complexes. A new Cu-II complex, namely bis{mu(3)-3-[(4-methoxy- 2-oxidobenzylidene) amino] propanolato} bis{mu(2)-3-[(4-methoxy-2-oxidobenzylidene) amino] propanolato} tetracopper(II), [Cu-4(C11H13NO3)(4)], has been synthesized and characterized using elemental analysis, FT-IR, solid-state UVVis spectroscopy and single-crystal X-ray diffraction. The crystal structure determination shows that the complex is a stepped tetranuclear structure consisting of two dinuclear [Cu-2(L)(2)] units {L is 3-[(4-methoxy-2-oxidobenzylidene) amino] propanolate}. The two terminal Cu II atoms are four-coordinated in square-planar environments, while the two central Cu-II atoms are fivecoordinated in square-pyramidal environments. The solid-state photoluminescence properties of both the complex and 3-[(2-hydroxy-4-methoxybenzylidene) amino] propanol (H2L) have been investigated at room temperature in the visible region. When the complex and H2L are excited under UV light at 349 nm, the complex displays a strong blue emission at 469 nm and H2L displays a green emission at 515 nm.