265114-75-8Relevant academic research and scientific papers
Structure and thermal reactivity of a novel Pd(0) metalloenediyne
Coalter, Nicole L.,Concolino, Thomas E.,Streib, William E.,Hughes, Chris G.,Rheingold, Arnold L.,Zaleski, Jeffrey M.
, p. 3112 - 3117 (2000)
We report the X-ray diffraction structure and thermal reactivity of the metalloenediyne compound bis(1,2- bis(diphenylphosphinoethynyl)benzene)palladium(0) (Pd(dppeb)2, 1). The structure of 1 features a tetrahedral Pd(0) center with four phosphorus atoms from two chelating ligands. The P - Pd - P bond angles nearly match the idealized 109.5°geometry expected for a d10 metal center in a tetrahedral ligand field. The tetrahedral geometry of the metal center forces the alkyne termini separation of the enediyne ligand to a distance of 3.47 A, which results in a thermally stable compound at room temperature. However, at 115 °C 1 exhibits solvent-dependent reactivity. In o-fluorotoluene, 1 decomposes via ligand dissociation, while in o-dichlorobenzene, carbon-halide bond activation of solvent occurs leading to the oxidative addition product trans- Pd((2-chlorophenyl)diphenylphosphine)2Cl2 and free (2- chlorophenyl)diphenylphosphine. The thermal reactivity of 1 is markedly more endothermic (44 kcal/mol) than that of the known Pd(dppeb)Cl2 analogue (12.3 kcal/mol). The diminished reactivity can be attributed to two factors: the increased alkyne termini separation in 1 (3.47 vs 3.3 A) due to the metal- mandated tetrahedral geometry of the Pd(0) center, and the resistance of the Pd(0) to adopting a planar transition state geometry to promote Bergman cyclization. Overall this study demonstrates that metal binding can impose structural consequences upon the enediyne ligand governed by the oxidation state and corresponding ligand field geometry of the metal center.
Compounds, composition, and methods for photodynamic therapy
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Page column 29-30, (2008/06/13)
Disclosed are novel compounds, compositions, and methods that are particularly useful in photodynamic therapy. In particular, the inventive compounds, compositions, and methods relate to the formation of cytotoxic radical species in the presence of light. Significantly, the compounds, compositions, and methods of the present invention do not require the presence of oxygen in the photodynamic therapy and, as such, rely on a unimolecular mechanism for producing the radicals. The inventive compounds, compositions, and methods can be used, for example, in the treatment of cancers as well as infections caused by microorganisms such as protozoa, fungi, bacteria, and viruses.
