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Abstract: Encapsulation of nanoparticles has attracted a great attention as a method for stabilizing nanoparticles and subsequently applying them to various areas of technologies. Especially, the encapsulation of nanoparticles with silica shells has proven advantageous for applications to (nano)biotechnology with the well-established silica chemistry. However, current chemical approaches to the formation of silica shells generally require harsh conditions. In contrast, biological processes are capable of generating silica nano/microstructures under ambient conditions. In this work, we formed ultrathin (∼1.5nm) silica shell-coated nanomaterials by mimicking the biological processes. The procedure consists of simple two steps: immobilization of a thiol-terminated imidazolium ion onto gold nanoparticles (AuNPs) and biomimetic polycondensation of silicic acids. The resulting AuNP/silica hybrids were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and UV–vis spectroscopy. [Copyright &y& Elsevier]

Abstract: In this work, we studied interfacial proton transfer of the self-assembled monolayer (SAM) of 1-(12-mercaptododecyl)imidazole on a gold electrode by faradaic impedance titration method with Fe(CN)6 3− as an anionic redox probe molecule. The surface pK 1/2 was found to be 7.3, which was nearly the same as that of 1-alkylimidazole in solution. We also investigated the electrochemical properties of the SAM-modified electrode by cyclic voltammetry. Cyclic voltammetry was performed (1) in the solution containing Fe(CN)6 3− with repeated alternation of pH values to investigate the electrostatic interaction of the protonated or deprotonated imidazole with Fe(CN)6 3− and (2) in the acidic or basic electrolyte containing Ru(NH3)6 3+ as a cationic redox probe to verify the effect of the polarity of a redox probe. We observed the reversible adsorption/desorption of Fe(CN)6 3− and concluded that the adsorbed Fe(CN)6 3− catalyzed the electron transfer of both Fe(CN)6 3− itself and cationic Ru(NH3)6 3+. [Copyright &y& Elsevier]

Abstract: Monolayer-protected gold cluster (Au-MPC)-bound Ru–carbene complex (MPC-7 ) has been synthesized and examined its catalytic activity in ring-closing olefin metathesis. The MPC-7 showed almost the same catalytic activity with that of simple molecules (Grubbs Ru-complex 1b and the thioacetate-functionalized Ru-complex 8 ) and reused several times. [Copyright &y& Elsevier]

New large-bandgap host materials with carbazole and carboline moieties were designed and synthesized for high-performance blue phosphorescent organic light-emitting diodes (PhOLEDs). The two kinds of host materials, 9-(4-(9 H -carbazol-9-yl)phenyl)-6-(9 H -carbazol-9-yl)-9 H -pyrido[2,3- b ]indole ( pP2CZCB ) and 9-(3-(9 H -carbazol-9-yl)phenyl)-6-(9 H -carbazol-9-yl)-9 H -pyrido[2,3- b ]indole ( mP2CZCB ), displayed promisingly high triplet energies of ∼2.92–2.93 eV for enhancing the exothermic energy transfer to bis[2-(4,6-difluorophenyl)pyridinato-C 2 , N ](picolinato)iridium(III) (FIrpic) in PhOLED devices. It was found that the blue PhOLEDs bearing the new host materials and the FIrpic dopant exhibited markedly higher external quantum efficiencies (EQEs) than a device made with 1,3-bis( N -carbazolyl)benzene (mCP) as the host. In particular, the PhOLED device made with 3 wt% FIrpic as the dopant and mP2CZCB as the host material displayed a low driving voltage of 4.13 V and the high EQE of 25.3% at 1000 cd m −2 . [ABSTRACT FROM AUTHOR]