Melting Behaviour of Shell-symmetric Aluminum Nanoparticles： Molecular Dynamics Simulation

Molecular dynamics simulations with embedded atom method potential were carried out for A1 nanoparticles of 561 atoms in three structures： icosahedron, decahedron, and truncated octahedron. The total potential energy and specific heat capacity were calculated to estimate the melting temperatures. The melting point is 540＋10 K for the icosahedral structure, 500±10 K for the decahedral structure, and 520±10 K for the truncated octahedral structure. With the results of mean square displacement, the bond order parameters and radius of gyration are consistent with the variation of total potential energy and specific heat capacity. The relaxation time and stretching parameters in the Kohlraush-William-Watts relaxation law were obtained by fitting the mean square displacement. The results show that the relationship between the relaxation time and the temperatures is in agreement with standard Arrhenius relation in the high temperature range.

Easily fabricated and recyclable Pd&Cu@Al catalyst for gram-scale phosphine-free Heck reactions with high TON

A unique Pd＆Cu@Al catalyst was easily fabricated just by immersing commercial aluminum foil in a mixed xylene solution of PdC12 and CuCl2. The catalyst fabrication process led to aluminum oxide coatings in situ, which supported the metal nanoparticles and enhanced their catalytic activities for the phosphine-free Heck reaction of awl halides and styrenes with high turnover number （TON） up to 3.9×10^5. The reaction can be scaled up to at least 100 mmol and has been applied in modification of drug Lapatinib＇s intermediate with low metal residue. This novel catalyst is of good application potential in industrial production because it was extremely easy to be recycled, in regardless of the generation of the insoluble impurities or tars during the reaction processes.