Development of Metal Nanoparticle Catalysis toward Drug Discovery

Abstract

Transition-metal nanoparticles (NPs) catalysts supported on solid material represent one of the most important subjects in organic synthesis due to their reliable carbon-carbon or carbon-heteroatom bondforming cross-coupling reactions. Therefore methodologically and conceptually novel immobilization methods for nonprecious transition-metal NPs are currently required for the development of organic, inorganic, green, materials, and medicinal chemistry. We discovered a self-assembled Au-supported Pd NPs catalyst (SAPd(0)) and applied it as a catalyst to Suzuki-Miyaura coupling, Buchwald-Hartwig reaction, Carbon(sp 2 and sp 3 )-Hydrogen bond functionalization, double carbonylation, removal of the allyl protecting groups of allyl esters, and redox switching. SAPd(0) comprises approximately 10 layers of self-assembled Pd(0) NPs, whose size is less than 5 nm on the surface of a sulfur-modified Au. The Pd NPs are wrapped in a sulfated p-xylene polymer matrix. We thought that the self-assembled Au-supported Pd NPs could be made by in situ metal NP and nanospace simultaneous organization (PSSO). This methodology involves 4 kinds of simultaneous procedures: i) reduction of a higher valence metal salt, ii) growth of metal NPs with appropriate size, iii) growth of a matrix with appropriate pores, and iv) wrapping of the metal NPs by matrix nanopores. This methodology is different from previously reported metal NPs-immobilizing methods, which use solid supports with preformed pores or coordination sites. We also applied the in situ PSSO method to prepare various immobilized transition-metal NPs, including base metals. For example, the in situ PSSO method can be applicable to easily prepare Ni, Ru, and Fe NPs with good recyclability and low metal leaching for use in organic synthesis. . His current research interest is in organic chemistry toward the development of medicinal chemistry. 735 Chem. Pharm. Bull. indicate that the sulfur on Au was reduced and had chemically bonded with Pd during Pd adsorption. In Pd 2p core-level photoemission spectra, the peaks from A appear close to the metallic Pd peak. These results suggest that, in the case of A, Pd(dba) 2 molecules were changed to zerovalent molecules or metallic Pd, as summarized in Fig. 4.Single crystal Au(111)/mica is not versatile. Eventually, instead of Au(111)/mica, we used Au foil and mesh to prepare B and C according to the Pd-adsorption procedure for A. When A, B, or C was subjected to the Suzuki-Miyaura coupling of 1a and 2a, the yields of the product 3a for runs 1 to 10 were excellent to quantitative in all cases, as shown in Table 1, entries 1-3. Entry 4 indicates that Material D, which was prepared from Au(mesh) with Pd(OAc) 2 as a Pd-source, was also highly active for the Suzuki-Miyaura coupling. These results show that the Pd materials A, B, C, and D are highly reactive and recyclable in this reaction.Next, we measured the amount of Pd on the Pd materials B-D using inductively coupled plasma mass spectrometry (ICP-MS) analysis. These analyses showed that in ...

Goethite and Hematite Nanoparticles Show Promising Anti-Toxoplasma Properties

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“…The small size of NPs also allows them to penetrate cell membranes, making them highly reactive. Metal NPs are already being used for biomedical applications [16][17][18].…”

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