A series of polyoxometalate-based hybrid complexes constructed by a tripodal ligand containing mixed N/O donors

• Published in: CrystEngComm 2021-11, Vol.23 (44), p.7846-7854
• Main Authors: Ying, Jun, Jin, Liang, Yu, Hai-Yan, Tian, Ai-Xiang, Wang, Xiu-Li
• Format: Article
• Language: English
• Subjects: Anions; Benzoic acid; Carboxylic acids; Chains; Electrical measurement; Electrochemical analysis; Fluorescence; Hydrogen peroxide; Imidazole; Ligands; Nickel; Polyelectrolytes; Polyoxometallates; Transition metals
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d1ce01195b

By changing the transition metals (TMs) and polyanions, six polyoxometalate (POM)-based complexes 1-6 were synthesized by the hydrothermal method, namely [Cd II (L 1 ) 2 (HPMo 12 O 40 )]·2H 2 O ( 1 ), {M II 2 (H 2 O) 4 (L 1 ) 2 [H 2 (β-Mo 8 O 26 )]} n · x H 2 O ( n = 1, x = 1, M = Co ( 2 ), Cu ( 3 ), Fe ( 4 ); n = 0.5, x = 0, M = Ni ( 5 ), Zn ( 6 )). The organic component 3,5-bis-(2,5-dihydro-imidazole-1-yl)benzoic acid (L 1 ) is a tripodal ligand containing two imidazole and one carboxylic acid group. The N donors in the imidazole groups and the O donors in the carboxylic acid group of L 1 can coordinate with different transition metal atoms to construct POM-based complexes. In complex 1 , the Keggin anions are linked by [Cd(L 1 ) 2 ] 2+ subunits to construct a chain. Complexes 2-6 are isostructural with [β-Mo 8 O 26 ] 4− anions linked by double metal-organic chains to build a 2D layer. The electrochemical behaviour and photocatalytic properties of these complexes were studied. These complexes can be used as amperometric sensors for the amperometric detection of Cr( vi ), Fe( iii ) and H 2 O 2 . Moreover, these complexes can be used for fluorescence selective sensing of Cr 3+ . We designed two synthetic strategies using identical ligands to construct six POM-based complexes. These complexes can act as amperometric sensors for the detection of Cr( vi ), Fe( iii ) and H 2 O 2 and fluorescence sensors for sensing Cr 3+ .