Polymer-Assisted Chain-like Organization of CuNi Alloy Nanoparticles: Solvent-Adoptable Pseudohomogeneous Catalysts for Alkyne-Azide Click Reactions with Magnetic Recyclability

A solution-phase reduction method is undertaken to produce polymer magnetic bimetallic CuNi nanoalloy with chain-like structures, which are formed by the magnetic dipole-directed assembly of spherical alloy nanoparticles as confirmed from TEM analysis. Magnetic property measurement reveals paramagnetic nature of the alloy nanochain. These polymer-capped chain-like alloy nanoparticles are dispersible in water as well as in organic solvents that increase their ease of application as catalyst in both of these environments. The XPS and zeta potential analysis demonstrates the presence of Cu(I) on the alloy particle surface and justifies their catalytic activity toward alkyne-azide click reactions. Consequently, the catalytic activity of the as-synthesized polymer CuNi alloy nanochain is investigated toward a wide variety of alkyne-azide click reactions at room temperature in water and in DMF. Depending upon the nature of the substrate and the surface stabilizing polymer on the nanocatalyst, a moderate to quantitative yield of the click-conjugated product is obtained. Additionally, the advantage of pseudohomogeneity of CuNi nanoalloy suspension is utilized to modify polymer end group with amino acid and peptide with ionic liquid via click reaction to create new bioconjugates. Moreover, the nanoalloy catalyst is magnetically recoverable and reusable up to three cycles of click reactions without losing much of its original activity.