Ionic photodissociation of some polymers quenched with electron donor or acceptor in solution

Ionic photodissociation processes of vinyl polymers with pendant carbazolyl groups in solution have been studied by nonsecond laser photolysis. The ionic dissociation yield decreases in the order of monomer, oligomers, and polymers.     

Density-functional calculations of icosahedral M13 (M = Pt and Au) clusters on graphene sheets and flakes

Density-functional calculations were done to examine the interface between graphene and a Pt₁₃ or Au₁₃ cluster. Introducing a carbon vacancy into a graphene sheet enhanced the interaction between graphene and the metal clusters. Five- or seven-member rings introduced into the graphene also increased the stability of the interface. The CO and H chemisorption energies on the metal clusters on graphene were calculated to clarify support-dependent reactivity.     

Chiral Iodotriptycenes: Synthesis and Catalytic Applications

New iodotriptycenes, including some chiral derivatives, have been synthesised, and their catalytic potential towards oxidative transformations has been investigated. The enantioselectivities observed in the products using chiral iodotriptycene catalysts are low, probably owing to the large distances between the coordinating groups and the iodine moieties in these compounds.     

In situ scanning tunneling microscopy imaging of mercury film electrodeposited on Ir(1 1 1)

In situ scanning tunneling microscopy (STM) was used to examine multilayer Hg film electrodeposited on a well-ordered Ir(1 1 1) single crystal electrode in 0.1 M HClO₄ + 1 mM Hg(ClO₄)₂. Topography STM scans showed that the Ir(1 1 1) – supported Hg film electrode contained well-defined terraces separated by monatomic steps (Δz = 2.3 Å). The STM’s tip could be used to induce local dissolution of the Hg deposit under proper operating conditions and the depth of the etched pit informed directly the thickness of Hg deposit. Although in situ STM imaging with a tungsten tip could not result in atomic structure of bare Hg film in 0.1 M HClO₄, it discerned highly ordered iodine adlayers, represented by a (2 × 8√3)rect – I structure, on the Hg film in solution containing potassium iodide. These STM results suggested that the Hg substrate could have an ordered atomic structure.     

Redox-photosensitized reaction of indene using photosensitive surfactant in emulsion: dependence on oil droplet size and surfactant charge

A redox-photosensitized reaction of indene 2 using a photosensitive surfactant 1a in an oil-in-water emulsion proceeded efficiently to give alcohol 3 as a major product and is strongly influenced by the oil droplet size and surfactant charge.     

Electrochemical control of the structure of two-dimensional supramolecular organization consisting of phthalocyanine and porphyrin on a gold single-crystal surface

Two-component adlayers consisting of cobalt(II) phthalocyanine (CoPc) and a metalloporphyrin such as 5,10,15,20-tetraphenyl-21H,23H-porphine copper(II) (CuTPP), 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine copper(II) (CuOEP), or 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (CoTPP) were prepared by immersing either an Au(111) or Au(100) substrate in a benzene solution containing those molecules. The mixed adlayers thus prepared were investigated in 0.1 M HClO4 by cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM). The composition of the mixed adlayer consisting of CoPc and CuTPP molecules was found to vary with immersion time. CoPc molecules displaced CuTPP molecules during the modification process with increasing immersion time, and the CuTPP molecules were completely displaced by CoPc molecules in the mixed solution after a prolonged modification time, during which the underlying Au(100) substrate underwent phase transition from the reconstructed (hex) lattice to the unreconstructed (1 x 1) lattice. The two-component adlayer of CoPc and CuTPP was found to form a supramolecular adlayer with the constituent molecules arranged alternately on Au(100)-(hex). The striped structure was stable on Au(100)-(hex) at or near the open circuit potential (OCP), whereas the mixed adlayer was disordered on Au(100)-(1 x 1) at potentials more positive than OCP, where the phase transition of the arrangement of underlying Au atoms (i.e., the lifting of reconstruction) was induced electrochemically. A similar two-component supramolecular adlayer consisting of CoPc and CuTPP was formed on Au(111). A highly ordered, compositionally disordered adlayer of CoTPP and CuTPP was formed on Au(100)-(hex), suggesting that the adlayer structure is independent of the coordinated central metal ion for the formation of supramolecular nanostructures composed of those molecules. A supramolecular organization of CoPc and CuOEP was also found on Au(111). The surface mobility and the molecular reorganization of CoPc and CuOEP on Au(111) were tuned by modulation of the electrode potential. It is concluded that molecular assemblies of the two-component structure consisting of phthalocyanine and porphyrin were controlled not only by the crystallographic orientation of Au but also by the modulation of electrochemical potential.     

Ordered molecular assemblies of substituted bis(phthalocyaninato) rare earth complexes on Au(111): in situ scanning tunneling microscopy and electrochemical studies

Substituted bis(phthalocyaninato) rare earth complexes ML2 (M = Y and Ce; L = [Pc(OC8H17)8]2, where Pc = phthalocyaninato) were adsorbed onto single crystalline Au(111) electrodes from benzene saturated with either YL2 or CeL2 complex at room temperature. In situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) were used to examine the structures and the redox reactions of these admolecules on Au(111) electrodes in 0.1 mol dm(-3) HClO4. The CVs obtained with YL2- and CeL2-coated Au(111) electrodes respectively contained two and three pairs of redox peaks between 0 and 1.0 V (versus reversible hydrogen electrode). STM molecular resolution revealed that YL2 and CeL2 admolecules were imaged as spherical protrusions separated by 2.3 nm, which suggests that they were oriented with their molecular planes parallel to the unreconstructed Au(111)-(1 x 1). Both molecules when adsorbing from approximately micromolar benzene dosing solutions produced mainly ordered arrays characterized as (8 x 5 radical3)rect (theta = 0.0125). The redox reactions occurring between 0.2 and 1.0 V caused no change in the adlayer, but they were desorbed or oxidized at the negative and positive potential limits. The processes of adsorption and desorption at the negative potentials were reversible to the modulation of potential. Electrochemical impedance spectroscopy (EIS) and CV measurements showed that YL2 and CeL2 adlayers could block the adsorption of perchlorate anions and mediating electron transfer at the Au(111) electrode, leading to the enhancement of charge transfer for the ferro/ferricyanide redox couple.     

Formation of highly ordered porphyrin adlayers induced by electrochemical potential modulation

Molecular self-assembly of porphyrin derivatives formed with intermolecular hydrogen bonding on the surface of Au(111) electrode in acidic solution can be controlled by varying the number of peripheral carboxy groups and the applied electrochemical potential.     

Production ofl-aspartic acid byE. coli aspartase immobilized on phenol-formaldehyde resin

Aspartase was extracted from E. coli cells by autolysis in the presence of the substrate. The enzyme could be conveniently immobilized to a weakly basic anion exchange resin Duolite A7 by adsorption. Enzymatic properties of the immobilized aspartase were found to be fit for industrial purposes. Consequently,l-aspartic acid has been industrially produced by this immobilized-enzyme process since 1974.