Search

Research has been conducted on the diastereoselective 1,4-addition of organocuprates to 3-O-, 4-O, or 6-O-crotonyl derivatives of methyl alpha-D-hexopyranosides. The results of this addition are described.

Pedal-like conformational changes and dimerization of trans-cinnamamide in cocrystals with phthalic acid were observed by in situ x-ray.

A novel ammonium ionophore, which exhibits superior NH(sub 4)(super +) selectivity compared with that of the natural antibiotic nonactin, was successfully designed and synthesized based on a 19-membered crown compound (TD19C6) having three decalino subunits in the macrocyclic system. This bulky decalino subunit is effective for (1) increasing the structural rigidity of the cyclic compound, (2) introducing the 'block-wall effect', which prevents forming a complex with a large ion, and (3) increasing the lipophilicity of the ionophore molecule. In the ammonium ionophore design, the first factor contributes to increasing the NH(sub 4)(super +) selectivity relative to smaller ions such as Li(super +), Na(super +), or even the closest size, K(super +), and the second factor increases the NH(sub 4)(super +) selectivity over larger ions such as Rb(super +) and Cs(super +). The X-ray structural analysis proved that TD19C6 forms a size-fit complex with NH(sub 4)(super +) in its crown ring cavity. As an application of this ionophore, an ion sensor (ion-selective electrode) was prepared, which exhibited NH(sub 4)(super +) to K(super +) and Na(super +) selectivity of 10 and 3000 times, respectively. This electrode showed a better performance compared to the electrode based on nonactin, which is the only ammonium ionophore presently used in practical applications.

Research has been conducted on the Wieland-Miescher ketone enantiomers. Results from yeast strains screening are discussed.

An X-ray study for photoinert 2,4,6-triisopropyl-4'-(methoxycarbonyl)-benzophenone was conducted to identify the possible origin of its remarkable photostability. Results of the study indicated that the distances between the carbonyl oxygen and the o-i-Pr methine hydrogens are within the critical limits for hydrogen abstraction to occur but a narrow reaction cavity or the compact crystal packing around both of the o-i-Pr groups interfering with the photocyclization.

(VO-(Xsalton)), with a C=C double bond in the five-membered chelate ring moiety, was formed from the dehydrogenation of Schiff base-oxovanadium(IV) complexes upon heating at 210 degrees Centigrade for three to 15 hours in the solid state in the air. X-ray structure analyses showed the structure of (VO(3-EtOsal-meso-stien)) to adopt a distorted square pyramid with the oxo atom at the apical position, while the vanadium atom of (VO(3-EtOsalton)) takes on a distorted octahedron conformation.

The preparation and characterization of new tetradentate Schiff base-oxovanadium(IV) complexes (VO-(3-Xsal-(R,R)-2,4-ptn)) containing the H2(3-Xsal-(R,R)-2,4-ptn) N,N'-di-3-Xsalicylidene-(R,R)-2,4-pentanediamine where X = EtO,MeO,H were performed. Consequently, the conversion of the 3-ethoxy substituted complex from an orange polymeric crystal to a green monomeric crystal was achieved after heating for 10 mins. at 170 degrees Celsius. Likewise, its conversion to orange upon suspension in water-acetonitrile solution was carried out.

An experiment of photoirradiation to single, powdered crystals consisting of a chiral host and guest results in the first in situ observation of intramolecular rotation and cyclization of N-methyl-N-{(E)-methylmethacryloyl} anilide.

The selective photocoupling reaction occurring in crystalline adduct of tetracyanobenzene (TCNB) with benzyl cyanide was described. The crystal structural conformation suggested that TCNB and BzCN were interacting through weak charge-transfer (CT) forces. The photochemistry between TCBN-BzCN system in the solution was very different from that in the solid state.