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Critical review and perspective of macromolecularly imprinted polymers.

Publisher Summary This chapter offers information on homoleptic complexes of 2,2'-bipyridine (bpy). The chapter focuses on the class of complexes that contain only bpy ligands bonded to the metal. The unique metal-binding properties of bpy were recognized from the outset. The third renaissance in bpy chemistry can be traced to the commercial availability of the ligand in the 1950s, when large amounts were required for the preparation of Diquat insecticides. The current interest in complexes of bpy is associated with the extremely interesting electrochemical, photophysical, and photoelectrochemical properties that they exhibit. 2,2'-Bipyridine is a strong field ligand that forms relatively stable complexes, with the inherent M–N bond strength enhanced by the chelate effect. Complexes with main group metal ions, and with lanthanides and actinides, can be prepared in water or organic solvents. The bis complexes are known for a range of metals and oxidation states though they tend to be more common for lower formal oxidation states. The bpy ligand is remarkable for the wide range of formal oxidation states with which it is associated. The chapter discusses the general trends in the reactivity of specific complexes under the appropriate elements. Iron, ruthenium, and osmium have played a crucial role in the development of the chemistry of 2,2'-bipyridine.

Homoleptic Complexes of 2,2′-Bipyridine

Bio‐inspired and single site metal complex catalysts have been discussed to direct towards a rational design of solid heterogeneous catalysts When concepts derived from catalytic antibodies, molecular imprinting and molecular recognition, and site isolation and modification by appropriate ligands are combined, with new techniques to prepare, tailor made solid materials, catalysts can be prepared that improve reaction rate and selectivity by increasing the concentration and activation of reactants in the vicinity of the active sites, and by stabilizing transition states or intermediate products It is also shown that enzymatic, homogeneous and hetergeneous catalysts can be combined to perform “one‐pot” cascade reactions

Attempts to Fill the Gap Between Enzymatic, Homogeneous, and Heterogeneous Catalysis

Homogeneous metal-catalysis in organic photochemistry

Publisher Summary This chapter focuses on the chemistry of excited complexes. The term exciplex (excited complex) is used to describe an electronically excited molecular complex of definite stoichiometry. Complexes falling into this broad classification include excimers (excited dimers) (electronically excited complexes formed between identical atoms or molecules), heteroexcimers (electronically excited complexes formed between two non identical atoms or molecules), and excited charge-transfer complexes (complexes produced by excitation of ground state molecular complexes for which there is conclusive evidence for association in the ground state). The formation of intermolecular complexes in fluid solution requires that after excitation of one of the partners, collision with the other partner must occur within the lifetime of the excited state. The maximum rate constant for the process is determined by the rate constant for diffusion control in the solvent employed.

The Chemistry of Excited Complexes: a Survey of Reactions

Irradiation of an acetonitrile solution of phenyl vinyl ether in the presence of various metal complexes[Fe(III) and Mn(II) complexes] gave two cyclodimers. Similar irradiation of 1,1-dimethylindene and 1,1-diphenylethylene afforded the corresponding cyclodimers. In these photodimerization, the metal complexes with ligands such as 2,2′-bipyridine and 1,10-phenanthroline served as catalysts for electron-transfer reaction.

Photo-induced cyclodimerization of electron-rich aromatic olefins in the presence of transition metal complexes

The cyclopropane ring of arylcyclopropanes is oxidatively cleaved by irradiation in polar solvents containing nucleophiles such as alcohols, water, and sodium cyanide in the presence of electron-acceptor such as 1,4-dicyanobenzene and 1-cyanonaphthalene, giving nucleophile-incorporated products. This photoreaction proceeds via an electron-transfer from the cyclopropanes to the excited electron-acceptors, and the cation radicals of arylcyclopropanes are involved as key intermediates.

Photoinduced oxidative cleavage of arylcyclopropanes in the presence of organic electron-acceptor

Irradiation of a methanolic solution of phenylcyclopropane in the presence of copper(II) ions affords 1,3-dimethoxy-1-phenylpropane and meso- and dl-1,6-dimethoxy-3,4-diphenylhexanes in good yields through the electron-transfer from the excited cyclopropane to Cu(II) ions.

Cleavage of cyclopropane ring via photoinduced electron-transfer by the use of copper(ii) ions

Photo-induced redox reactions of di-μ-oxo-binuclear manganese complex [Mn2IV,IIIO2(bpy)4]3+(ClO4)3[1] were studied in the presence of organic compounds. Irradiation of a CH3CN-1.0 M H2SO4(3:1) solution of [1] in the presence of anthracene gave anthraquinone with the reduction of [1]. On the other hand, similar irradiation of [1] in the presence of 9,10-dicyanoanthracene promoted the photochemical oxidation of water.

Jun Ogawa

Papers

Photo-induced cyclodimerization of electron-rich aromatic olefins in the presence of transition metal complexes

Photoinduced oxidative cleavage of arylcyclopropanes in the presence of organic electron-acceptor

Cleavage of cyclopropane ring via photoinduced electron-transfer by the use of copper(ii) ions

PHOTO-INDUCED ELECTRON-TRANSFER REACTIONS OF DI-μ-OXO-BINUCLEAR MANGANESE COMPLEXES

Photoinduced oxidative cleavage of arylcyclopropanes in the presence of organic electron acceptors