title: Synthesis of a NbO Type Homochiral Cu(II) Metal-Organic Framework: Ferroelectric Behavior and Heterogeneous Catalysis of Three-Component Coupling and Pechmann Reactions.
abstract: A chiral tetracarboxylic acid ligand, H4L, incorporating the (S)-(+)-2-methylpiperazine moiety in its middle, solvothermally forms a homochiral Cu(II) framework, {[Cu2(L)(H2O)2]·(4DMF)(4H2O)}n(LCu). It forms a non-interpenetrated structure consisting of [Cu2(COO)4] paddle-wheel secondary bonding units (SBUs) with NbO topology. Interestingly, the framework LCu exhibits excellent ferroelectric properties. It shows a remnant polarization (Pr) of ∼3.5 μC cm-2and a coercive field (Ec) of ∼12 kV cm-1with a distinct electric hysteresis loop. Dielectric studies of LCu reveal almost frequency-independent behavior with a dielectric constant (εr) of ∼42 and a low dielectric loss (tan δ) of ∼0.04 up to 106Hz, for potential use in high-frequency applications. In addition, activated framework LCu' having uncoordinated metal sites acts as an efficient heterogeneous catalyst in the three-component coupling of amines, aldehydes, and alkynes, as well as in Pechmann reactions of phenols with β-ketoesters.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur, UP 208016, India.
authors.forename: Anoop K
authors.initials: AK
authors.lastname: Gupta
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur, UP 208016, India.
authors.forename: Dinesh
authors.initials: D
authors.lastname: De
authors.affiliation: Department of Materials Science and Engineering, Indian Institute of Technology Kanpur , Kanpur, UP 208016, India.
authors.forename: Rajesh
authors.identifier: http://orcid.org/0000-0003-2732-1309
authors.initials: R
authors.lastname: Katoch
authors.affiliation: Department of Materials Science and Engineering, Indian Institute of Technology Kanpur , Kanpur, UP 208016, India.
authors.forename: Ashish
authors.initials: A
authors.lastname: Garg
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur, UP 208016, India.
authors.forename: Parimal K
authors.identifier: http://orcid.org/0000-0003-3347-8791
authors.initials: PK
authors.lastname: Bharadwaj