RESUMEN
The cluster series Ag4M2(DMSA)4 (M = Ni, Pd, Pt) has been synthesized and the optical spectra and stability have been examined as a function of the metal, M. We have also obtained the structure of Ag4Ni2(DMSA)4 using X-ray crystallography, confirming the previously calculated structure. In the optical spectrum, there is a significant blue shift as the substituted metal M progresses down the periodic table. Theoretical calculations suggest that the blue shift is due to the lowering in energy of the d orbitals of the transition metal, M; however the expected metal-metal excitations are optically weak, and the spectra are dominated by metal-ligand excitations. The Ag4Pd2(DMSA)4 species has exceptionally high stability relative to the previously reported Ni and Pt analogues.
RESUMEN
Ligand stabilized water soluble Pt nanoclusters were synthesized and characterized through electrospray ionization mass spectrometry. Glutathione was used as the ligand, and Pt5(SG)10, and Pt6(SG)12 clusters were synthesized. Theoretical investigations found that these clusters do not possess a metal core, but rather are most stable in a ring structure. The clusters are stabilized through the thiol ligands forming a square planar structure around each Pt atom to form a ring. The structural elucidation was confirmed through UV/Vis and IR spectroscopy.
RESUMEN
Mechanochemical approaches to chemical synthesis offer the promise of improved yields, new reaction pathways and greener syntheses. Scaling these syntheses is a crucial step toward realizing a commercially viable process. Although much work has been performed on laboratory-scale investigations little has been done to move these approaches toward industrially relevant scales. Moving reactions from shaker-type mills and planetary-type mills to scalable solutions can present a challenge. We have investigated scalability through discrete element models, thermal monitoring and reactor design. We have found that impact forces and macroscopic mixing are important factors in implementing a truly scalable process. These observations have allowed us to scale reactions from a few grams to several hundred grams and we have successfully implemented scalable solutions for the mechanocatalytic conversion of cellulose to value-added compounds and the synthesis of edge functionalized graphene.
Asunto(s)
Grafito/síntesis química , Biomasa , Catálisis , Celulosa/química , HidrólisisRESUMEN
We report the synthesis, isolation, and characterization of the ligand-protected bimetallic cluster, Ag4Pt2(DMSA)4 (DMSA = meso-2,3,-dimercaptosuccinic acid). The procedure is similar to the one employed for the synthesis of Ag4Ni2(DMSA)4. Theoretical studies suggest that the Pt and Ni atoms have square planar configurations. Because the crystal field splitting of 5d orbitals is typically larger than that for 3d orbitals, the Pt-based cluster has an optical spectrum that is significantly blue-shifted as compared to the Ni-based cluster.
RESUMEN
A bimetallic ligand-protected cluster, Ag(4)Ni(2)(DMSA)(4) (DMSA = meso-2,3-dimercaptosuccinic acid) was synthesized and characterized through electrospray ionization mass spectroscopy. Such bimetallic clusters involving a noble metal and a first-row transition metal have not been previously reported. Theoretical calculations revealed an octahedral structure with silver atoms occupying the corners of the square plane and the nickel atoms at the apexes. Close agreement between the predicted and observed spectroscopic features was found.