Three Keggin POMs-based coordination polymers constructed by linear N-heterocyclic ligand for proton conduction, photocatalytic activity and magnetic property

POMs-based coordination polymers are promising materials for their potential application in the fields of proton conduction, catalysis and magnetism. Three new coordination polymers namely, {[Co 2 (bib) 3 (H 2 O) 2 (H 4 W 12 O 40 )]·7H 2 O} n ( 1 ), {[Zn 3 (bib) 8 (H 3 ZnW 12 O 40 ) 2 ]·12H 2 O} n ( 2 ) and {[Ag 5 (bib) 5 (H 3 W 12 O 40 )]·5H 2 O} n ( 3 ) were synthesized under hydrothermal conditions based on linear nitrogen heterocyclic ligand 1,4-bis(1-imidazolyl)benzene (bib). In compound 1 , Co II ions are linked with [H 4 W 12 O 40 ] 4– anions to form a planar network and can be simplified as kgd topology, which are further linked with bib ligands to form a 3D framework. Zn2 ions of compound 2 alternately connect with bib ligands and [H 3 ZnW 12 O 40 ] 3– anions to form 1D chain structure, while Zn1 ion forms isolated unit with three bib ligands and one [H 3 ZnW 12 O 40 ] 3– anion, and a 3D framework is finally constructed through π … π stacking interactions. In compound 3 , the 3D structure is constructed from a number of 1D chains formed by Ag I ions and bib ligands in different directions through π … π stacking interaction and Ag⋯O weak connection. The proton conductivity of 1 – 3 are 2.03 ​× ​10 −5 , 1.04 ​× ​10 −6 and 1.87 ​× ​10 −4 ​S ​cm −1 at 98% RH and 358 ​K, respectively. In addition, compounds 1 – 3 exhibit photocatalytic degradation capacity towards RhB and compound 1 displays antiferromagnetic behavior. Three Keggin POM-based coordination polymers have been prepared under hydrothermal condition and characterized by single-crystal X-ray diffraction, IR, XRD and TGA. The highest proton conductivity of 3 is up to 1.87 ​× ​10 −4 ​S ​cm −1 at 358 ​K and 98% RH. • Three Keggin POM-based coordination polymers have been prepared under hydrothermal condition. • Their structures were characterized by single-crystal X-ray diffraction, IR, XRD and TGA. • The highest proton conductivity of 3 is up to 1.87 ​× ​10 −4 ​S ​cm −1 at 358 ​K and relative humidity of 98% RH.