Polymorphic layered copper phosphonates: exfoliation and proton conductivity studies. Issue 19 (23rd April 2019)

• Record Type: Journal Article
• Authors: Liu, Bei; Liu, Jing-Cui; Shen, Yang; Feng, Jian-Shen; Bao, Song-Song; Zheng, Li-Min
• Is Part Of: Dalton transactions. Volume 48:Issue 19(2019)
• Page Start: 6539
• Page End: 6545
• Publication Date: 2019-04-23
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt00970a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : α-Cu(4-cnappH)(H2 O) (α-Cu-1 ), α-Cu(4-cnappH)(H2 O)·0.5H2 O (α-Cu-2 ) and β-Cu(4-cnappH)(H2 O) (β-Cu ) [4-cnappH3 = (4-carboxynaphthalen-1-yl)phosphonic acid] are polymorphic layered compounds. Proton conduction is more favorable inα-Cu-2 than inα-Cu-1, but exfoliation into nanosheets decreases the conductivity. Abstract : Three polymorphic copper carboxylate-phosphonates are reported, namely, α-Cu(4-cnappH)(H2 O) (α-Cu-1 ), α-Cu(4-cnappH)(H2 O)·0.5H2 O (α-Cu-2 ) and β-Cu(4-cnappH)(H2 O) (β-Cu ), where 4-cnappH3 is (4-carboxynaphthalen-1-yl)phosphonic acid. All show layer structures but with different layer topologies. The layer topologies of the α-phases are similar, where the distorted {CuO4 } planes and {PO3 C} tetrahedra are corner-shared forming an inorganic layer containing 8- and 16-member rings. Inβ-Cu, double chains made up of corner-sharing {CuO5 } and {PO3 C} are crossed-linked through edge-sharing of the {CuO5 } square pyramids to form an inorganic layer containing 4- and 8-member rings. The uncoordinated carboxylate groups are protonated and are involved in the interlayer hydrogen bonds in all cases. Antiferromagnetic interactions are dominant in all cases. Compoundsα-Cu-1, α-Cu-2 andβ-Cu can be exfoliated in THF resulting in 2D nanosheets of mainly two-layer thickness. Proton conductivity measurements reveal that the proton conduction is more favorable inα-Cu-2 than inα-Cu-1, but exfoliation into nanosheets decreases the conductivity.