摘要:

AbstractSS‐FVP ofN‐benzylidene‐4‐methoxyaniline (3b) and FVP ofN‐benzylidene‐2‐chloroaniline (3c)at 850–950 °C yielded phenanthridine (2) and its derivatives through gas phase ele

ISSN:0009-4536    

DOI:10.1002/jccs.200600162

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractPhotoisomerization of 11‐cis‐retinal in an organic glass, believed to originate from the 12‐s‐ciscon‐former, gives an unstable primary photoproduct(s). The implication of simultaneous single and double bond isomerization is only consistent with an HT mechanism of isomerization. Relation of this isomerization process in the rigid medium of organic glasses with that reported for the same 11‐cis‐retinyl chromophore confined within the binding cavity of rhodopsin (as revealed by reported X‐ray crystal structural stud

ISSN:0009-4536    

DOI:10.1002/jccs.200600163

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractEmission from charge recombination between radical cations and anions of 9‐cyano‐10‐(p‐substituted phenyl)anthracenes (RA, where R is 10‐p‐substituted phenyl: R = Phenyl (PA), anisyl (OA),p‐N,N‐dimethylaminophenyl (NA),N,N‐di‐p‐anisylaminophenyl (DA)), as donor‐acceptor type molecules, generated during the pulse radiolysis in benzene was measured together with the transient absorption of RA radical cations (RA•+) and anions (RA•−). Based on the transient absorption and density functional theory (DFT‐B3LYP/6‐31G*) calculation, a twisted geometry is assumed for all RA in the ground state, RA•+, and RA•−. It is suggested that the positive charge of PA•+, OA•+, and NA•+is delocalized on two moieties, and that of DA•+is localized on the donorN,N‐di‐p‐anisylaminophenyl moiety, while the negative charge of all RA•−is mainly on the acceptor 9‐(10‐cyano)anthracenyl moiety. When both RA•+and RA•−are generated with sufficiently high concentrations during the pulse radiolysis in benzene, the charge recombination between RA•+and RA•−occurred to give RA in the singlet excited state (1RA*) as the emissive species, but not the excimers because of the twisted geometries of RA•+and RA•−with the large torsional angles between the 9‐(10‐cyano)anthracenyl andp‐substituted phenyl moieties. Not only the fluorescence quantum yield of1RA* but also the energy differences between the annihilation enthalpy change and the excitation energy of1RA*

ISSN:0009-4536    

DOI:10.1002/jccs.200600164

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe photoluminescence (PL) properties of CuBr and CuBr/AgBr semiconductor nanocrystals (NCs) embedded in borosilicate glasses are measured under band‐to‐band excitation by a 355‐nm Nd YAG laser. We observed emission from CuBr (peaked at 520 nm) doped glass, which is associated with deep states in CuBr NCs. We also observed the sensitized blue to orange‐red emission in CuBr/AgBr‐glass systems (peaked at 520 and 570 nm), in which the luminescence intensity of CuBr decreases with increasing AgBr concentrations, while it is enhanced significantly around 570 nm. The results are discussed by the possible energy transfer between them, or by the multi‐exitonic recombination process which ejects an excited carrier from CuBr

ISSN:0009-4536    

DOI:10.1002/jccs.200600165

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThis paper describes theoretical studies on the insertion reaction of germynes XC ≡ GeY (X,Y=H, Cl and F) at the carbon site into a C‐H bond of CH4performed at the QCISD(T)/6–311G*//QCISD/6–31G* level of theory. This work was inspired by the observation by Sakamoto, Kira, and coworkers on the carbene‐like reaction mode for stannyne (RC≡SnR′). Due to the limitation in the computation for the tin atom, the study was carried out on germyne compounds instead. We found that the valence state of the germyne moiety in the transition state and reaction product can be well represented by the triplet germyne. It has a bifunctional electronic structure of a triplet cabene joined to a singlet germylene

ISSN:0009-4536    

DOI:10.1002/jccs.200600166

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe biological activity relationship of 36 flavonoid compounds was investigated using theoretical methods including quantitative structure activity relationships (QSAR) and quantum chemistry calculation. The results suggested that the 5 and/or 8 positions of the substituents of the hydroxyl group in the A ring and the 3′ and 4′ positions of substituents of the hydroxyl group in the B ring play an important role in flavonoid biological activity. This is probably due to the formation of an intra‐molecular hydrogen bond. In addition, the electronic energy, electrostatic energy and bond energy may have an effect on the biological activity of flavonoids. Also, our analysis has shown that the presence of the 1,4 and 1,2‐hydroquinone in the A ring and/or the Bring of flavonoids and the contribution of electronic energy, electrostatic energy and bond energy required consideration in the generation of the QSAR model and that the potential compounds will be predicted out of 36 fla

ISSN:0009-4536    

DOI:10.1002/jccs.200600167

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractGold nanoparticles (NPs) were synthesized by chemical reduction in sodium octyl sulfate (SOS), sodium decyl sulfate (SDeS) and sodium dodecyl sulfate (SDS) solutions. Gold NPs prepared in SDS solutions have the smallest size and the highest stability among them. The stability of gold NPs was reflected in the hydrophobic property of the protecting surfactant. Size‐controlled synthesis of gold NPs was further achieved with the addition of pyrene in all surfactant solutions. Experimental results indicated that the combination of SDS and pyrene has the extraordinary effect in decreasing the size and narrowing the dispersity of gold NPs. Micellar electrokinetic capillary chromatography (MEKC) showed that the chemical reaction between pyrene and gold complexes was attributed to the formation of gold NPs inside the micelles at the embryonic stag

ISSN:0009-4536    

DOI:10.1002/jccs.200600168

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe electrocatalytic activity of methanol oxidation at a boron‐doped diamond (BDD) electrode in alkaline solution is investigated by voltammetry and electrochemical impedance spectroscopy. Methanol oxidation in this work involves the generation of OH radicals. The intermediate, as formaldehyde, adsorbed at the BDD electrode surface is subsequently oxidized to formic acid or CO2by OH radicals. Additionally, the reaction is influenced by the ratio of methanol and OH−concentration in the solution and is enhanced with the increased OH−concentration. Methanol adsorption at the BDD electrode surface is an important factor and difficult in this work. However, formaldehyde adsorption is more difficult than methanol. Methanol oxidation in this investigation is dominated by organic adsorption at a lower potential range. With the increased potential, it is gradually dominated by the generation of OH rad

ISSN:0009-4536    

DOI:10.1002/jccs.200600169

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractAn azulenylosquaric dye (ASQ) has been synthesized to investigate its associated photophysical properties.ASQis essentially nonluminescent (Φf<3 × 10−;6) in any solvent despite its very high absorption extinction coefficient (760 nm, ε ˜ 8.2 × 104M−;1cm−;1in methanol). Femtosecond fluorescence upconversion, anisotropy kinetics and transient absorption experiments, in combination with the theoretical time‐dependent DFT approach, leads us to conclude that the 760 nm absorption is ascribed to the fully allowed S0→ Sn(n 2) transition. The observed233 ns) undergoes a dominant radiationless deactivation process (710 70 fs) possibly governed by strong interaction between S1and S0potenti

ISSN:0009-4536    

DOI:10.1002/jccs.200600170

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractA new polymeric complex, [Cd(bpym)0.5(N3)2]n(bpym = 2,2′‐bipyrimidine) has been synthesized and characterized by spectroscopic, elemental analyses and single crystal X‐ray diffraction. The title compound crystallizes in the monoclinic system, space groupP21/c, with chemical formula C4H3CdN8,a= 7.6763(5),b= 13.1539(9),c= 7.9693(5) Å, β = 109.988(1)°, andZ= 4. Structural determination reveals that the coordination environment of the cadmium atoms is distorted octahedral, consisting of two nitrogen donors of one bpym and four nitrogen donors of four azide ligands. The azide ligand acts as a bridging ligand with two different bridging modes, an end‐on (μ1,1‐) and an end‐to‐end (μ1,3‐) coordination mode, linking the CdIIions to form a two‐dimensional layer metal‐organic framework (MOF), which get cross‐linked by the bridges ofbis‐bidentate bpym ligand

ISSN:0009-4536    

DOI:10.1002/jccs.200600171

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY