Five compounds based on [Mo12O40]8− and [β-Mo8O26]4− anions: Electrochemical sensing, photocatalytic and supercapacitor properties

By using two morpholine derivatives five compounds have been synthesized. Compounds 1 – 5 can be used as a catalysts for photodegradation of organic dyes and the reduction of Cr(VI). They also can be used as electrochemical sensors to detect not only NO 2 − anions, but also Cr(VI) cations. Compound 4 have larger capacitance and can be used as a super capacitor. • Compounds 1 and 2 are isomorphic and have a rare [Mo 12 O 40 ] 8- unit. • Compounds 1 – 5 can be used as a catalysts for photodegradation of organic dyes and the reduction of Cr(VI). • Compounds 1 – 5 can be used as electrochemical sensors to detect not only NO 2 − anions, but also Cr(VI) cations. • Compound 4 have larger capacitance and can be used as a super capacitor. In this paper, five compounds were synthesized by hydrothermal method by employing morpholine derivatives with different N sites and numbers. These five compounds are [M II (HL1)(H 2 O) 2 ][(H 2 Mo 12 O 40 ) 0.5 ] (M = Co( 1 ), Ni( 2 )), [M II (HL2) 2 (H 2 O) 2 ]( β -Mo 8 O 26 )] (M = Cu( 3 ), Ni( 4 ), Zn( 5 )), respectively (L1 = 4-[2-(5-Pyridin-2-yl-[1,2,4]triazol-1-yl)-ethyl]-morpholine, L2 = 4-[2-(5-Pyrazin-2-yl-[1,2,4]triazol-1-yl)-ethyl]-morpholine). These compounds were characterized through single crystal X-ray diffraction, FT-IR and PXRD. Compounds 1 and 2 are isomorphic and have a rare [Mo 12 O 40 ] 8- unit. The adjacent [Mo 12 O 40 ] 8- units are connected by bi-nuclear subunits [M 2 II (L1) 2 ] 4+ (M = Co/Ni) to form a 1D structure. Compounds 3 – 5 are isostructural owning 1D metal–organic chains. The [ β -Mo 8 O 26 ] 4- anions are dissociative. Compounds 1 – 5 can be employed as electrochemical sensors to identify NO 2 − anions, Cr(VI) cations. In addition, compound 4 has larger capacitance and can be used as a super capacitor. Compounds 1 – 5 can not only be employed as catalysts for photodegradation of organic dyes, but also as catalysts for photoreduction of Cr(VI), which owns good selectivity.