Three Proton‐Conductors Based on Keggin‐Type Polyoxometalates Well‐Arranged in the Networks of Dinuclear‐Cu(II)‐Mixed‐Organic‐Ligand Clusters

• Published in: European journal of inorganic chemistry Vol. 2022; no. 30
• Main Authors: Zhang, Guang‐Guang, Duan, Xian‐Ying, Zhao, Yan, Wei, Mei‐Lin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 26.10.2022
• Subjects: Anions; Clusters; Conductors; Copper; Hybrid materials; Impedance measurement; Inorganic chemistry; Ligands; Polyoxometalates; Polyoxometallates; Proton conductivity; Protons; Relative humidity; Room temperature; Structure elucidation; Synthesis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202200382

Three proton‐conductors, [Cu(5‐H2L)(IN)(H2O)]2H2[SiW12O40] ⋅ 2CH3CN ⋅ 2.5H2O (1), [Cu(4‐HL)(HIN)(H2O)]2H2[SiW12O40] ⋅ 7H2O (2) and [Cu(4‐HL)(HIN)(CH3CN)]2[HIN]2H4[PMo12O40]2 ⋅ 2CH3CN ⋅ 12H2O (3) (where 5‐H2L/4‐H2L is 5,5’/4,4’‐bis(hydroxymethyl)‐2,2’‐bipyridine and HIN is isonicotinic acid), were synthesized at room temperature. Interestingly, three dinuclear‐Cu(II)‐mixed‐organic‐ligand clusters, [Cu(5‐H2L)(IN)(H2O)]22+ cluster for 1, [Cu(4‐HL)(HIN)(H2O)]22+ for 2 and [Cu(4‐HL)(HIN)(CH3CN)]22+ for 3, are in situ synthesized under the coexistence of Keggin‐type polyoxometalates. More interestingly, in 1–3, the global Keggin‐type anions are well‐arranged in the hydrogen‐bonding networks of double‐Cu(II)‐mixed‐organic‐ligand clusters to give different spatial arrangement patterns. The [SiW12O40]4− anions in 1 display two dimensional layer pattern. The [SiW12O40]4− anions in 2 act as single bidentate O,O bridge ligands. The [PMo12O40]3− anions in 3 form the pair pattern. The AC impedance measurement results reveal 3 gives a high conductivity value over 10−3∼10−2 S ⋅ cm−1 in a wide temperature range from 25 to 100 °C under a wide relative humidity range from 35 to 98 %, while 1 and 2 give a middle conductivity value over 10−5∼10−4 S ⋅ cm−1 under the same conditions. Three proton‐conductive multicomponent crystalline materials have been designed and synthesized using a conventional solvent method. In them, Keggin‐type POMs with different spatial arrangement patterns and HIN molecules are well‐arranged in the hydrogen‐bonding networks of dinuclear‐Cu(II)‐mixed‐organic‐ligand clusters, realizing the cooperative functional multicomponent combination for good proton‐conductors.