350021-81-7Relevant articles and documents
A Bioinspired Multicomponent Catalytic System for Converting Carbon Dioxide into Methanol Autocatalytically
Rayder, Thomas M.,Adillon, Enric H.,Byers, Jeffery A.,Tsung, Chia-Kuang
supporting information, p. 1742 - 1754 (2020/05/25)
Nature utilizes multicomponent catalyst systems to convert simple, abundant starting materials into complex molecules that are essential for life. In contrast, synthetic chemical transformations rarely adopt this strategy because it is difficult to replicate the sophisticated supramolecular assemblies used by biology for active-site separation and substrate trafficking. Here, we describe a method for multicomponent catalyst separation that involves encapsulating transition-metal complexes in nanoporous materials called metal-organic frameworks. The multicomponent catalyst system was highly active for converting hydrogen and carbon dioxide to methanol, and it could be formulated to be readily recyclable. Moreover, we uncovered an autocatalytic feature that was possible only when we utilized the multicomponent catalyst strategy. These results open avenues for obtaining fuel from abundant and renewable resources. Methanol is a promising renewable fuel that can be adapted to the current liquid fuel infrastructure. It can be produced from hydrogen and carbon dioxide, mitigating greenhouse gas emissions and storing hydrogen in the process. However, the industrial production of methanol through this hydrogenation reaction currently requires elevated temperatures and pressures and can produce significant amounts of unwanted byproducts. Here, we employ a bioinspired tandem catalytic system to efficiently hydrogenate carbon dioxide to methanol selectively at low temperatures. We achieved superior performance by eliminating catalyst incompatibility through encapsulating at least one of the catalysts involved in the tandem process in nanoporous materials called metal-organic frameworks. In the long term, this method could be applied to other tandem catalytic processes, allowing more efficient access to alternative fuels, commodity chemicals, and valuable pharmaceutical products. Tsung and co-workers describe a three-component tandem catalytic process for the hydrogenation of carbon dioxide to methanol. The bioinspired process is enabled by encapsulation of at least one of the two ruthenium-based catalysts required in the metal-organic framework (MOF) UiO-66. The reaction was found to have an autocatalytic feature that enables the reaction to be carried out without superstoichiometric additives. Encapsulating both ruthenium-based catalysts in the MOF allowed the catalyst to be recycled.
Control of aminophosphine chelate ring-opening in Pt(II) and Pd(II) complexes: Potential dual-mode anticancer agents
Habtemanam, Abraha,Watchman, Beth,Potter, Brian S.,Palmer, Rex,Parsons, Simon,Parkin, Andrew,Sadler, Peter J.
, p. 1306 - 1318 (2007/10/03)
We show that bis(aminophosphine) complexes of the type [M(R1R2N(CH2)nPPh2)2 ]2+, M = Pt(II) or Pd(II), can exist in chelate ring-closed and ring-opened forms both in the solid state and in aqueous solution. The equilibrium between them in solution can be controlled by the nature of the groups R1 and R2 (H, Me, Bz, cyclohexyl), by the bridge length n, and by the pH and Cl- concentration. X-Ray crystal structures are reported for the ring-closed complexes cis-[Pt(H2N(CH2)2PPh2-P,N)2 ]Cl2, cis-[Pt(H2N(CH2)3PPh2-P,N)2 ]Cl2, and cis-[Pt(Me(H)N(CH2)2PPh2-P,N)2][HCl 2]2, the mono-ring-opened complex cis-[Pd(Me2N(CH2)2PPh2-N,P)Cl(Me 2NH(CH2)2PPh2-P)](NO3) 2, the di-ring-opened complex cis-[Pt(Me2N(CH2)3PPh2-P)2 CL2], and, for comparison, the monochelate cis-[Pd(Me2N(CH2)3PPh2-N,P)CL2 ]. These square-planar complexes exhibit varying degrees of distortion and variable M-N bond lengths dependent not only on the trans influence of P but also on steric effects within the complex, pH-induced chelate ring-opening of cis-[Pt(Me2N(CH2)2PPh2-P,N)2 ]CL2 had an associated pK value of 6.9. In contrast, complexes with R1 and R2 = H, n = 2 or 3 or R1 = H and R2 = Me, n = 2, are more difficult to ring-open. Thus the complexes cis-[Pt(Me(H)N(CH2)2-PPh2-P,N)2]CL 2 and cis-[Pt(H2N(CH2)3PPh2-P,N)2 ]CL2, had associated pK values of 2.1 and 2.9, respectively. These aminophosphine complexes may exhibit anticancer activity by two mechanisms: by disrupting mitochondrial membrane potentials as bis-chelated (ring-closed) lipophilic cations, or by direct binding to DNA bases as ring-opened complexes.
