Aqueous‐Phase Synthesis of Size‐Tunable Copper Nanocubes for Efficient Aryl Alkyne Hydroboration

Abstract

Copper nanocubes with average sizes of 82, 95, and 108 nm have been synthesized in an aqueous mixture of cetyltrimethylammonium chloride (CTAC) surfactant, copper acetate, and sodium ascorbate reductant heated at 100 °C for 40 min. Copper nanowires with an average length of 25 μm can also be prepared this way by simply increasing the volume of sodium ascorbate introduced. Small shifts in the plasmonic absorption band positions with tunable particle sizes have been observed. The copper nanocubes were employed to catalyze hydroboration of phenylacetylene and various substituted aryl alkynes with 100 % (E)-product selectivity and 82-95 % product yields. The copper nanocubes are cheap to make and should catalyze a broad scope of organic coupling reactions.

Unusually Large Lattice Mismatch‐Induced Optical Behaviors of Au@Cu–Cu2O Core–Shell Nanocrystals with Noncentrally Located Cores

“…To extend the examination of optical facet effects of metal‒Cu 2 O systems, use of copper cores to prepare Cu‒Cu 2 O nanocubes, octahedra, and rhombic dodecahedra exposing respectively the {100}, {111}, and {110} surfaces should be a natural extension, because copper nanoparticles also have SPR properties. However, direct aqueous phase synthesis of ultrasmall Cu polyhedra is still difficult . Growing a shell of Cu over very small Au octahedra can provide the needed Cu nanocubes and octahedra, despite the very large lattice mismatch between Au and Cu at 11.4% .…”

Polyhedral Cu2O Crystals for Diverse Aryl Alkyne Hydroboration Reactions

“…Figures S8 and S9 in the Supporting Information show the crude 1 H NMR spectra of the product formed by using Cu 2 O cubes and octahedra as the catalyst. From the appearance of a doublet peak only at around 6.2 ppm for all samples, it was deduced that the E product was exclusively synthesized . The absence of a doublet at around 5.6 ppm indicates that the cis‐ or Z ‐product was not formed .…”

“…From the appearanceo fadoublet peak only at around6 .2 ppm for all samples, it was deduced that the E product wase xclusively synthesized. [17] The absence of a doublet at around5 .6 ppm indicates that the cis-or Z-product was not formed. [26] FigureS10 (Supporting Information) provides the 1 Hand 13 CNMR spectra of the hydroboration product obtained by using Cu 2 Or hombic dodecahedra as the catalyst following purification by silica gel column chromatography.…”

“…[15,16] We have also explored the use of copper nanocubes for aryl alkyne hydroboration reactions in ethanola t5 0 8Cf or 2h giving exclusive E-product selectivity with yields of 82-95 %. [17] Terminal alkyne hydroboration using designed homogeneousc atalysts is an active area of research among the organic chemistry community because of the great utility of the generated products. [18][19][20][21] In this study we used Cu 2 Oc ubes, octahedra, and rhombic dodecahedrat ocatalyze aryl alkyne hydroboration primarily in 1,4-dioxane at 60 8Cf or 5h giving exclusively E-product selectivity.C lear facet-dependent catalytic performancew as observed, with the rhombic dodecahedrap roving to be the best catalyst.…”

“…Cu 2 O particles of undefined shape dispersed on a carbon‐black support and copper nanoparticles have also been employed for the borylation of alkyl bromides . We have also explored the use of copper nanocubes for aryl alkyne hydroboration reactions in ethanol at 50 °C for 2 h giving exclusive E ‐product selectivity with yields of 82–95 % . Terminal alkyne hydroboration using designed homogeneous catalysts is an active area of research among the organic chemistry community because of the great utility of the generated products …”