Effects of crosslinking density on the in situ formation of gold-polymer composite particles and their catalytic properties

Experimental Selection of Bases for Colloidal Gold‐Polymer Composite Catalyst in Homocoupling Reactions

“…It is also important to remember that the influence of crosslinking density of PNIPAM particles during the in situ formation of AuNPs and their dispersity in reaction media was investigated to understand the overall catalytic properties associated with the free volume and diffusion of organic molecules. [7] Thus, the last factor to consider is the necessity of bases to improve the yields of homocoupling reactions.…”

“…It is also noted that the overall reaction yields were comparably higher with these composite particles (i. e., loosely crosslinked polymer network as the AuNPs were incorporated into the PNIPAM particles formed with 5.0 wt% BIS crosslinker) than our previous composite particles utilizing the PNIPAM particles formed with 10 wt% BIS crosslinker. [7,28] Although the weak inorganic bases at 3.0 eq. were examined to be most suitable for the reaction, their limited solubility in EtOH prompted us to figure out the required minimum amounts of these bases to maintain high reaction yields (Table 1).…”

“…The reactivity of the catalysts is then presented as tabulated lists of bases, solvents, reaction yields, and additives. Although this type of work could fulfill the validation of newly designed catalysts, attempting to additionally regulate the reaction parameters and understanding the influence of each factor could provide a much better view for the development of ideal chemical reaction systems [7–10] . Recently, relatively non‐toxic gold nanoparticles (AuNPs) have drawn much attention due to their tunable reactivity, selectivity, and recyclability in challenging homo‐ and cross‐coupling reactions, which could serve as an alternative for potentially toxic metal‐based (e. g., Pd) catalysts [2,9,11–14] .…”

“…Although this type of work could fulfill the validation of newly designed catalysts, attempting to additionally regulate the reaction parameters and understanding the influence of each factor could provide a much better view for the development of ideal chemical reaction systems. [7][8][9][10] Recently, relatively non-toxic gold nanoparticles (AuNPs) have drawn much attention due to their tunable reactivity, selectivity, and recyclability in challenging homo-and cross-coupling reactions, which could serve as an alternative for potentially toxic metalbased (e. g., Pd) catalysts. [2,9,[11][12][13][14] Even after developing these catalytically active AuNPs, finding reaction condition parame-ters that can provide the enhanced reactivity and selectivity of target molecules in mild and green environments can help to establish practical synthetic systems for the preparation of nontoxic products including food preservatives, medicines, and pharmaceutical intermediates.…”

“…[28][29] In addition, the influence of crosslinking density of host PNIPAM particle networks has been examined to understand the formation of guest AuNPs and their catalytic properties associated with the diffusion of reactant and product molecules. [7,[30][31][32] Similarly, a reactive reaction medium was also screened to determine the dispersion degree of the composite particles and the effect of their catalytic functions related to the solubility of reactants and products. [28] As such, the last contributing parameter in the homocoupling reaction is the inevitable necessity of bases when the AuNP-PNIPAM composite particles are employed as a catalyst.…”