Synthesis and Photophysical Properties of Hetero‐Bischelated Complexes of Rhodium(III) Containing Phenyl‐Pyridin‐2‐Ylmethylene‐Amine

Three new hetero‐bischelated rhodium (III) complexes of cis‐[Rh(PA)(L)Cl₂]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence.     

A Study of the Sydnone Compounds: Bromination and Chlorination(III)

A convenient method for the bromination or chlorination of 4-unsubstituted sydnone with NBS or NCS in DMF solution was carefully investigated. Tweleve bromo-compounds (yield 74-96%) and seven chloro-compounds (yield 75-93%) were obtained.     

Cycloaddition reactions of β-trifluoroacetylvinyl ethers

β-Trifluoroacetyl vinyl ethers ROCHCHCOCF₃ react smoothly as dienophiles with α,β-unsaturated carbonyl compounds to give the unexpected 2-alkoxyl-5-trifluoroacetyl-3,4-dihydro-2H pyrans. These products are formed by elimination and addition of the alcohol to the products of the normal hetero Diels-Alder reaction (2-alkoxyl-3-trifluoroacetyl-2,3-dihydro-2H pyrans). In contrast, 1,3-dipolar cycloaddition of ROCHCHCOCF₃ with ArCHN(O)Me proceeds via a Z-endo transition state to give regio- and stereospecific 4-trifluoroacetyl substituted isoxazolidines and their derivatives.     

Long-lived triplet charge-separated state in naphthalenediimide based donor–acceptor systems

1,4,5,8-Naphthalenediimides (NDIs) are widely used motifs to design multichromophoric architectures due to their ease of functionalisation, their high oxidative power and the stability of their radical anion. The NDI building block can be incorporated in supramolecular systems by either core or imide functionalization. We report on the charge-transfer dynamics of a series of electron donor–acceptor dyads consisting of a NDI chromophore with one or two donors linked at the axial, imide position. Photo-population of the core-centred π–π* state is followed by ultrafast electron transfer from the electron donor to the NDI. Due to a solvent dependent singlet–triplet equilibrium inherent to the NDI core, both singlet and triplet charge-separated states are populated. We demonstrate that long-lived charge separation in the triplet state can be achieved by controlling the mutual orientation of the donor–acceptor sub-units. By extending this study to a supramolecular NDI-based cage, we also show that the triplet charge-separation yield can be increased by tuning the environment.

Ultrafast electron transfer from singlet and triplet excited states in equilibrium results in the population of both singlet and triplet charge-separated states.     

Electronic structures of dihedral (D5h, D5d, D6h, D6d) fullerenes

By means of our proposed method for Hückel theory calculation, we have calculated the electronic structures of dihedral (D_5h, D_5d, D_6h, D_6d) fullerences, which are generated from icosahedral C₂₀, C₆₀, C₈₀, C₁₈₀, C₂₄₀ and C₅₄₀, respectively. From the calculated results of 1224 fullerence molecules, certain rules on the stability and chemical reactivity have been drawn for such types of dihedral fullerenes.     

Cytokine antibody arrays: a promising tool to identify molecular targets for drug discovery

Cytokines play important roles in normal cell functions and changes in cytokines have been implicated in many diseases. Recent efforts have focused on developing cytokine antibody arrays. These arrays allow investigators to simultaneously detect multiple cytokines in qualitative and quantitative ways. Cytokine antibody array systems feature high sensitivity, specificity and throughput. This novel technology opens up an expanding spectrum of applications in drug discovery, including target discovery, target validation, screening for lead compounds, compound optimization and clinical trials.     

6AZO-CONTAINING SELF-ASSEMBLY ULTRA-THIN FILMS AND THEIR PHOTOVOLTAIC PROPERTIES

A kind of azo-containing resin (Azo-R) was synthesized by a simple way through the coupling reaction of 2-nitro-N-methyldiphenylamine-4-diazoresin (NDR) with phenol, and a new covalentely attached multilayer film from Azo-R as H-donor and photosensitive diazoresin, diphenylamine-4-diazoresin (DR) as H-acceptor via H-bonding attraction by selfassembly technique has been fabricated. Following the decomposition of diazonium group of DR under exposure to UV light, the H-bonds between the layers of the film convert to covalent bonds and the film becomes very stable toward polar solvents or electrolyte aqueous solutions. Thus the UV-irradiated azo-containing films can be used to measure photocurrent in a conventional three-electrode photoelectrochemical cell using KCl as supporting electrolyte. It was confirmed that the azo-containing multilayer film is responsible for the photocurrent generation.     

A supramolecular poly[3]pseudorotaxane by self-assembly of a homoditopic cylindrical bis(crown ether) host and a bisparaquat derivative

A supramolecular poly[3]pseudorotaxane was prepared by self-assembly of a homoditopic cylindrical bis(crown ether) host and a bisparaquat derivative in solution by host-guest complexation.     

Synthesis and antiplatelet activities of N-arylmethyl-3,4-dimethylpyrano[2,3-c]pyrazol-6-one derivatives.

A series of new 1- and 2-arylmethyl-3,4-dimethylpyrano[2,3-c]pyrazol-6-one derivatives were synthesized and examined for their antiplatelet activities. Some of these compounds showed significant inhibitory activities. Among them, 1-phenylmethyl-3,4-dimethylpyrano[2,3-c]pyrazol-6(1H)-one (4a), 2-(2'-methoxyphenyl)methyl-3,4-dimethylpyrano[2,3-c]pyrazol-6(2H)- one (3e) and 2-(3'-methoxyphenyl)methyl-3,4-dimethylpyrano[2,3-c]pyrazol-6-(2H) - one (3f) were the most effective. These inhibitors acted in a concentration-dependent manner. The antiplatelet effect of compound 3f is due to the inhibition of thromboxane A2 formation and the blockade of thromboxane A2/prostaglandin endoperoxide receptor in washed rabbit platelets.     

Renewable amperometric immunosensor for complement 3 assay based on the sol-gel technique

A renewable amperometric immunosensor based on the sol-gel technique has been constructed by dispersing graphite, complement 3 (C3) antiserum, and sol-gel at low temperature. The prepared immunosensor is rigid, porous, and has a renewable external surface. A competitive binding assay has been used to determine C3 in human serum with the aid of C3 labeled with horseradish peroxidase. The enzyme-labeled antigen can readily diffuse toward the encapsulated antibody, which retains its binding properties. The experimental conditions for the assay with the biocomposite, including the loading of C3 antiserum in the biocomposite, the amount of labeled C3 in incubation solution, incubation time, and temperature, have been optimized. Using C3 labeled with horseradish peroxidase, and o-AP as the substrate, amperometric detection at -150 mV (relative to the SCE) results in a linear detection range of 1.17-35.1 microg mL(-1), with a detection limit of 0.56 microg mL(-1). Serum samples have been assayed and the results demonstrate the feasibility of the proposed immunosensor for clinical analysis. The surface of the immunosensor can be renewed simply by polishing to obtain a fresh immunocomposite ready to use in a new competitive assay.