In situ ligand and complex transformation of an iron(III) Schiff base complex: structural evidence and theoretical calculations.
ABSTRACT A C-C coupling reaction has been achieved at room temperature by in situ ligand transformation. The iron(III) complexes before and after the in situ transformation, [FeNaL(1)(2)(H(2)O)(4)](2)·2H(2)O (1) (H(2)L(1) = (Z)-2-(2-hydroxyl)benzylideneamino) and [FeL(2)](2)·7.5H(2)O (2) (H(3)L(2) = (E)-2-(2-hydroxyl-benzylideneamino)-3-hydroxyl-3-(2-hydroxyphenyl), have been studied by elemental analyses, FT-IR, UV-vis, TGA and X-ray single crystal diffraction analysis. The proposed mechanism of this in situ transformation has been determined based on structural evidence and theoretical calculations using the density functional theory (DFT) M06 method.
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ABSTRACT: We describe how reactivity can be controlled in the solid state using molecules and self-assembled metal-organic complexes as templates. Being able to control reactivity in the solid state bears relevance to synthetic chemistry and materials science. The former offers a promise to synthesize molecules that may be impossible to realize from the liquid phase while also taking advantage of the benefits of conducting highly stereocontrolled reactions in a solvent-free environment (i.e., green chemistry). The latter provides an opportunity to modify bulk physical properties of solids (e.g., optical properties) through changes to molecular structure that result from a solid-state reaction. Reactions in the solid state have been difficult to control owing to frustrating effects of molecular close packing. The high degree of order provided by the solid state also means that the templates can be developed to determine how principles of supramolecular chemistry can be generally employed to form covalent bonds. The paradigm of synthetic chemistry employed by Nature is based on integrating noncovalent and covalent bonds. The templates assemble olefins via either hydrogen bond or coordination-driven self-assembly for intermolecular [2 + 2] photodimerizations. The olefins are assembled within discrete, or finite, self-assembled complexes, which effectively decouples chemical reactivity from effects of crystal packing. The control of the solid-state assembly process affords the supramolecular construction of targets in the form of cyclophanes and ladderanes. The targets form stereospecifically, in quantitative yield, and in gram amounts. Both - and -ladderanes have been synthesized. The ladderanes are comparable to natural ladderane lipids, which are a new and exciting class of natural products recently discovered in anaerobic marine bacteria. The organic templates function as either hydrogen bond donors or hydrogen bond acceptors. The donors and acceptors generate cyclobutanes lined with pyridyl and carboxylic acid groups, respectively. The metal-organic templates are based on Zn(II) and Ag(I) ions. The reactivity involving Zn(II) ions is shown to affect optical properties in the form of solid-state fluorescence. The solids based on both the organic and metal-organic templates undergo rare single-crystal-to-single-crystal reactions. We also demonstrate how the cyclobutanes obtained from this method can be applied as novel polytopic ligands of metallosupramolecular assemblies (e.g., self-assembled capsules) and materials (e.g., metal-organic frameworks). Sonochemistry is also used to generate nanostructured single crystals of the multicomponent solids or cocrystals based on the organic templates. Collectively, our observations suggest that the organic solid state can be integrated into more mainstream settings of synthetic organic chemistry and be developed to construct functional crystalline solids.Accounts of Chemical Research 03/2008; 41(2):280-91. · 20.83 Impact Factor
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ABSTRACT: The use of organic multidentate ligands to organize inorganic species is an effective method to prepare porous solids with tunable pore sizes. However, thus far, inorganic building units are generally limited to individual metal ions (e.g., Zn2+) or their oxide clusters (e.g., Zn4O6+). To expand applications of porous materials to electronic, electrooptic, or optical areas, the organization of semiconducting chalcogenide nanoclusters is desirable. Here we report the organization of cubic [Cd8(SPh)12]4+ clusters by in-situ-generated tetradentate 1,2,4,5-tetra(4-pyridyl)benzene molecules. The structure consists of three-dimensional inorganic-organic open framework with large unidimensional channels. The combination of dye molecules and inorganic cluster units in the same material creates a synergetic effect that enhances the emission of the inorganic cluster at 580 nm. Such an emission can be excited by a broad spectral range down to the UV, which is believed to result from the absorption of dye molecules and the subsequent energy transfer. The inorganic double four-ring cluster, [Cd8(SPh)12]4+, is formed from conversion of supertetrahedral clusters, while the novel tetradentate dye molecule is formed by oxidative coupling of two diamines.Journal of the American Chemical Society 09/2002; 124(33):9688-9. · 10.68 Impact Factor
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ABSTRACT: Two novel coordination polymers, Cu3(4-pyt)3 (1) and Co(4-pyt)2 (2) (4-pyt = pyridine-4-thiolate), have been synthesized by in situ generation of a 4-pyt ligand from a 4,4'-dithiodipyridine precursor through reductive cleavage of the disulfide bond under solvothermal conditions. 1 and 2 exhibit a three-dimensional (3,4)-connected network and a two-dimensional square-grid-type structure, respectively.Inorganic Chemistry 08/2006; 45(15):5736-8. · 4.59 Impact Factor