Three Lindqvist-type POM-based compounds constructed by a conjugate ring-riched quinoxaline derivative through controlling the hydrothermal conditions

Abstract

Using a conjugate ring-riched quinoxaline derivative 2,3-diphenyl-quinoxaline ( L ), three new Lindqvist polymolybdate based compounds, [Cu I 2 L 3 (Mo 6 O 19 )] ( 1 ), [Cu I 2 L 2 (C 16 H 36 N) 2 (Mo 6 O 19 ) 2 ] ( 2 ) and [Cu I 4 L 4 Cl 2 (Mo 6 O 19 )] ( 3 ) (C 16 H 36 N=tetrabutyl ammonium), were synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction. In compound 1 , the Cu + ions as connecting bodies are linked by L molecules to form a [Cu L ] n n + metal-organic line, and these lines link the Mo 6 anions to construct 1D chains. Then these 1D chains connect each other by sharing the same Mo 6 anions and a 2D grid-like layer is built. In compound 2 , there is also a [Cu L ] n n + line. The Mo 6 anions offering one terminal O atom covalently hang this metal-organic line to construct a wave-like 1D chain of compound 2 . There exist two types of L ligands (type-a and type-b) in compound 3 . The type-a L molecules and Cl-bridging are linked by Cu + ions to form a metal-organic line, with the type-b L and Mo 6 anions covalently hanging it up and down. Additionally, the electrochemical and photocatalytic properties of the three compounds were also studied.