ABSTRACT
The water-soluble cage-like phosphine PTA (1,3,5-triaza-7-phosphaadamantane) and its phosphine oxide derivative [PTA(O)] (1,3,5-triaza-7-phosphaadamantane-7-oxide) were used to explore their reactivity towards two gallium(iii)-halide precursors, namely GaCl3 and GaI3, for the first time. By using various reaction conditions, a series of N-mono-protonated phosphine salts with [GaCl4]- or [I]- as counterions were obtained in all cases, while the formation of coordinated Ga-PTA and Ga-[PTA(O)] complexes was not observed. All compounds were characterized in solution using multinuclear NMR spectroscopy (1H, 13C{1H}, 31P{1H} and 71Ga) and in the solid state using FT-IR spectroscopy and X-ray crystal diffraction. The new Ga-phosphine salts resulted stable and highly soluble in aqueous solution at room temperature. Density functional theory (DFT) calculations were also performed to further rationalize the coordination features of PTA with Ga3+ metal ion, highlighting that the phosphorus-gallium bond is about twice weaker than the phosphorus-metal bond commonly established by PTA with transition metals such as gold. Furthermore, the mono-protonation of PTA (or [PTA(O)]) makes the formation of ionic gallium-PTA coordination complexes thermodynamically unstable, as confirmed experimentally by the formation of Ga-phosphine salts reported herein.
ABSTRACT
This paper describes the preparation and comprehensive characterization of a series of water-soluble cationic silver(I)-centered complexes featuring the hemilabile P, N-ligand known as 3,7-dimethyl-1,3,5-triaza-7-phosphabicyclo[3.3.1]nonane (herein abbreviated as PTN(Me)) and differing types of monoanionic counterions including known biologically active sulfadiazine and triclosan. The complexes primarily differed though the number of coordinating PTN(Me) ligands. The bis-substituted Ag(I) complexes revealed P, N bidentate coordination, while the only P-monocoordination of the metal center was observed for the tris-substituted systems. The bis-ligated silver compounds were observed to quickly degrade upon photoexposure or in contact with air. In contrast, the tris-ligated complexes demonstrated greater stability, in particular, a high resistance to photo-decomposition. Calculated geometry optimized models using the density functional theory method (BP86) revealed for the bis-substituted PTN(Me) Ag(I) species that the total enthalpy of the tetrahedral C2-symmetric structure is marginally lower by -0.6 kcal mol-1 compared to the planar C2 h structure, which is analogous for the corresponding [Au(PTN(Me))2]+ complex with Δ H = -0.5 kcal mol-1. Hence both types of complexes feature free rotation of the PTN ligand about the M-P bond axis. This series of Ag(I) and bis-PTN(Me) Au(I) complexes were evaluated using the agar well diffusion test for potential antimicrobial and antifungal activity. The nature of the counterion was found to have a strong correlation with the area of microbiological growth inhibition. Silver(I) complexes bearing the deprotonated triclosan as the counterion demonstrated the greatest activity, with large zones of growth inhibition, with the tris-ligated triclosan complex obtaining of a high clearance of 42 mm against the Gram-negative Escherichia coli. In contrast, the previously reported [Au(PTN(Me))2]Cl complex demonstrated activity only against E. coli, which is lower than that observed for the silver(I) PTN(Me) species.
Subject(s)
Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Azabicyclo Compounds/pharmacology , Coordination Complexes/pharmacology , Organophosphorus Compounds/pharmacology , Silver/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Azabicyclo Compounds/chemical synthesis , Azabicyclo Compounds/chemistry , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Crystallography, X-Ray , Drug Stability , Escherichia coli/drug effects , Ligands , Light , Microbial Sensitivity Tests , Mitosporic Fungi/drug effects , Models, Chemical , Molecular Structure , Organophosphorus Compounds/chemical synthesis , Organophosphorus Compounds/chemistry , Proton Magnetic Resonance Spectroscopy , Quantum Theory , Solubility , Staphylococcus aureus/drug effects , Triclosan/pharmacology , Water/chemistryABSTRACT
Ruthenium(II) arene complexes of 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) were obtained. Cytotoxicity studies against cancer cell lines reveal higher activity than the corresponding PTA analogues and, in comparison to the effects on noncancerous cells, the complexes are endowed with a reasonable degree of cancer cell selectivity.
Subject(s)
Antineoplastic Agents/pharmacology , Coordination Complexes/pharmacology , Ruthenium/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , HEK293 Cells , Humans , Ligands , Molecular Structure , Ruthenium/chemistry , Solubility , Structure-Activity Relationship , Water/chemistryABSTRACT
Recent developments in the coordination chemistry and applications of Ru-triphos [triphos = 1,1,1-tris-(diphenylphosphinomethyl)ethane] systems are reviewed, highlighting their role as active and selective homogenous catalysts for small molecule activation, biomass conversions and in carbon dioxide utilization-related processes.
Subject(s)
Biphenyl Compounds/chemistry , Coordination Complexes/chemistry , Ethanol/chemical synthesis , Formates/chemical synthesis , Phosphines/chemistry , Ruthenium/chemistry , Small Molecule Libraries/chemical synthesis , Biomass , Carbon Dioxide/chemistry , Catalysis , Hydrogen/chemistry , HydrogenationABSTRACT
In this chapter the effect of transition metals and of ancillary stabilizing ligands on the activity, regioselectivity, and chemoselectivity in hydroformylation reactions applied to organic synthesis will be reviewed, highlighting recent cases of particular interest, including examples of both homogeneous and heterogeneous catalytic reactions.
