Copper(II)-phenanthroline hybrid material as efficient catalyst for the multicomponent synthesis of 1,2,3-triazoles via sequential azide formation/1,3-dipolar cycloaddition

Abstract

A copper(II)-phenanthroline hybrid material based on the SBA-15 architecture was prepared using a two-step synthesis through co-condensation of 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline with tetraethoxysilane, followed by coordination of Cu(OAc)2. The obtained hybrid material, Cu(II)phen@SBA-15, was fully characterized, at each stage of the preparation, by means of bulk and molecular techniques to assess both textural and structural catalyst features using XRD, XPS, EPR, HRTEM, SEM, solid-state NMR UV–vis and IR analytical tools. The characterization results altogether confirmed the structural integrity of the mesoporous host and the successful anchoring of the copper-phenanthroline complex as discrete mononuclear Cu(II)L species. The catalytic performances of Cu(II)phen@SBA-15 were evaluated in the aqueous 1,3-dipolar cycloaddition of azides with alkynes using a multicomponent one-pot synthesis where organic azides were produced in situ from organic bromide (or aryl diazonium salts or epoxides), providing for safer synthetic technologies. The catalyst proved to be highly active under mild reaction conditions (0.5mol%, 70°C) over a broad range of substrates, providing 1,4-disubstituted-1,2,3-triazoles in high yields.