Ultra-fast Microwave Synthesis of ZnO Nanowires and their Dynamic Response Toward Hydrogen Gas

Ultra-fast and large-quantity (grams) synthesis of one-dimensional ZnO nanowires has been carried out by a novel microwave-assisted method. High purity Zinc (Zn) metal was used as source material and placed on microwave absorber. The evaporation/oxidation process occurs under exposure to microwave in less than 100 s. Field effect scanning electron microscopy analysis reveals the formation of high aspect-ratio and high density ZnO nanowires with diameter ranging from 70 to 80 nm. Comprehensive structural analysis showed that these ZnO nanowires are single crystal in nature with excellent crystal quality. The gas sensor made of these ZnO nanowires exhibited excellent sensitivity, fast response, and good reproducibility. Furthermore, the method can be extended for the synthesis of other oxide nanowires that will be the building block of future nanoscale devices

Chiral Recognition of Azo-Schiff Base Ligands, Their Cu(II) Complexes, and Their Docking to Laccase as Mediators

Chiral crystals were discovered due to spontaneous resolution when enantiomers of 4-phenyldiazenyl-2-[(R or S)-(1-phenylethyl)-iminomethyl]phenol and its racemic mixture were prepared. Using two ligands per molecule, optically active R,R and S,S enantiomers and meso R,S diastereomer of Cu(II) complexes were prepared. Strong chiral recognition was expected for them. Laccase has attracted attention as a catalyst that reduces oxygen to water in a cathode of biofuel cells, which can be effectively mediated by metal complexes. Furthermore, azobenzene can align perpendicularly to the polarization direction of irradiating linearly polarized ultraviolet light (Weigert effect) as well as to the conventional cis-trans photoisomerization accompanying the shift of redox potential. Thus, we also studied the photo-induced control of cis-trans forms and the alignment of these Cu(II) complexes as a mediator to fit laccase appropriately. We discuss photo-induced control on not only electronically but also sterically-favored redox conditions. The meso(R,S)-form of the Cu(II) complex in cis-form was found to be the best at increasing the current of cyclic voltammetry (CV) among the three R,R and S,S enantiomers and the R,S diastereomer of the Cu(II) complexes