Home About us Contact
|
Home About us Contact | ||
|
|
||
Electronic Communication (electronic + communication)
Selected AbstractsTuning the Electronic Communication between Redox Centers Bound to Insulating Surfaces,ANGEWANDTE CHEMIE, Issue 18 2010Dodzi Zigah Kommunikationskontrolle: Die elektronische Kommunikation zwischen Ferrocenylzentren an Siliciumoberflächen kann effizient gesteuert werden, und zwar laut elektrochemischer Rastermikroskopie (SECM) sowohl über die Oberflächenbedeckung der elektroaktiven Einheiten als auch über die Art des Redoxvermittlers. Die laterale Ladungspropagation kann so von einem extrem langsamen bis zu einem sehr schnellen Prozess genau abgestimmt werden. [source] Naphthalene-Mediated Electronic Communication in Tetrakis(imino)pyracene Complexes,ANGEWANDTE CHEMIE, Issue 44 2009Kalyan Ein heißer Tip: Difunktionelle Tetrakis(imino)pyracen(Tip)-Liganden erfahren durch Kaliummetall, Germaniumdichlorid oder Decamethyleuropocen an beiden Diiminfunktionalitäten eine Einelektronenreduktion (siehe Schema, Cp*=C5Me5). Die übertragenen Elektronen besetzen gemeinsam ein über beide Diazabutadieneinheiten und die Naphthalinbrücke delokalisiertes Orbital. [source] "Tail,Tail Dimerization" of Ferrocene Amino Acid DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2010Daniel Siebler Abstract Acid anhydrides of N-protected 1,-aminoferrocene-1-carboxylic acid (Fca) have been prepared and spectroscopically characterized (protection group Boc, Fmoc, Ac; 4a,4c). The structure of the Boc-derivative 4a has been determined by single-crystal X-ray crystallography. An intramolecular N,H···O hydrogen bond involving the carbamate units results in a ring structure containing the two ferrocene units, the anhydride moiety, and the hydrogen bond. In the crystal, the individual molecules are connected by intermolecular N,H···O hydrogen bonds of the carbamate unit. Experimental and theoretical studies suggest that the ring motif is also a dominant species in solution. Electronic communication across the anhydride moiety is found to be very weak as judged from electrochemical, spectroscopic, and theoretical experiments. [source] Electronic Interactions in Ferrocene- and Ruthenocene-Functionalized Tetraazamacrcocyclic Ligand Complexes of FeII/III, CoII, NiII, CuII and ZnIIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2005Peter Comba Abstract The syntheses of ferrocene- and ruthenocene-functionalized tetraazamacrocyclic ligands and their corresponding transition metal complexes are described. Reaction of N,N, -bis(2-aminoethyl)-1,3-propanediamine (2,3,2-tet) with 1,1,-diformylferrocene and 1,1,-diformylruthenocene produces the ligands fcmac and rcmac in 81,85% yield. Examination of their CuII, NiII, CoII, ZnII and FeII/III complexes by IR, UV/Vis, EPR and Mössbauer spectroscopy as well as by electrochemical studies suggests electronic communication between the two metal centers of each complex. The molecular structure of [CuII(fcmac)(FBF3)]BF4, determined by X-ray structure analysis, is reported and shows that the distance between the two metals is 4.54 Å. Stability constants, determined by potentiometric titration, indicate that the copper(II) complexes are of similar stability as those with unfunctionalized tetraazamacrocyclic ligands (e.g. cyclam = 1,4,8,11-tetraazacyclotetradecane); stability constants of cobalt(II) complexes are about 2 log units smaller, those of nickel(II) and zinc(II) complexes are reduced by more than 10 log units. This selectivity is discussed on the basis of the structural studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Cyanide-Bridged Oligonuclear Complexes Containing Ni-CN-Cu and Pt-CN-Cu LinkagesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2003Marie-Louise Flay Abstract The central building blocks Ni(CN)42, and Pt(CN)42, can be combined with one, two or four CuIIL units (L = tren, Me6tren, tpa) to form di-, tri- and pentanuclear complexes with Ni-CN-Cu and Pt-CN-Cu linkages. Structure determinations of these and the side product [(tren)Cu,CN,Cu(tren)] (ClO4)2 reveal mostly linear M-C-N-Cu arrays and cis -, trans - and star-like arrangements of the CN-Cu units around the central Ni or Pt ions. The (CN) IR data for the bridging cyanides show a characteristic hypsochromic effect compared to the data for the free M(CN)42, complexes. The absorption bands in the visible spectra of the oligonuclear complexes are shifted to shorter wavelengths than those of the free LCuII -X complexes. The CuII/CuI redox steps in the cyclic voltammograms allow the conclusion that there is electronic communication between the external CuL units when they are arranged in a trans -orientation at PtII, but not NiII, centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Photoinduced Electron Transfer in Zinc Phthalocyanine Loaded on Single-Walled Carbon Nanohorns in Aqueous SolutionADVANCED MATERIALS, Issue 43 2009Atula S. D. Sandanayaka Notable electronic communication within ZnPc-SWNHox nanoensembles, where ZnPc is zinc phthalocyanine and SWNHox is an oxidized single-walled nanohorn, in both the ground and excited states is revealed by steady-state absorption and fluorescence spectroscopy measurements. The details of electron transfer reported here with time-resolved absorption and fluorescence measurements may broaden the use of SWNHox nanoensembles in photochemistry and photobiology. [source] Organizational emergence in networked collaborationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2002Ari-Pekka Hameri Abstract Research on complex adaptive systems has generated several conceptual parables to explain systems with emergent behaviour. One prominent use for terms such as self-organization, evolutionary trajectories, co-evolution and punctuated equilibrium has been in understanding human organizations. In such systems, emergent behaviour is demonstrated in novel structures, processes and spin-offs that cannot be explained just by studying single components of the organization and the intelligence embedded in them. Instead of solely exploiting the qualitative explanatory power of the evolutionary concepts, this paper focuses also on quantitative methods to track emergent behaviour in a globally distributed, constantly fluctuating and highly networked project organization. The underlying case is that of CERN (CERN, the European Laboratory for Particle Physics, has its headquarters in Geneva. At present, its Member States are Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, the Slovak Republic, Spain, Sweden, Switzerland and the United Kingdom. Israel, the Russian Federation, Turkey, Yugoslavia (status suspended after the UN embargo, June 1992), the European Commission and UNESCO have observer status.) and its decade long accelerator project, which strongly relies on electronic communication and networking to achieve its major objectives due to be accomplished by the year 2006. By using time series and self-organizing maps to analyse the global interaction among project groups and individuals the paper provides new insight to the understanding of emergent behaviour in human organizations. The key result of the study concerns the rigid deep structure of each case organization that seems to remain intact for the duration of the whole project. Copyright © 2002 John Wiley & Sons, Ltd. [source] Advancing zoo animal nutrition through global synergyINTERNATIONAL ZOO YEARBOOK, Issue 1 2005E. S. Dierenfeld Global communication and dissemination of information are two fundamental factors that are necessary to advance zoo animal nutrition. To achieve global synergy for nutrition, regional needs must be identified, modified for zoo application and linked through the proper Internet portals so that the information is readily available to the international zoo community. For all groups of animals, the continued development of food composition databases, updated as and when more information becomes available, is an important part of this desired synergy. If balanced nutrition for wild animals in captivity at a global level is to be achieved, then a heightened recognition of the value of implementing science-based nutrition into animal-management programmes and enhanced levels of electronic communication are essential. [source] Intramolecular electronic communication in a dimethylaminoazobenzene,fullerene C60 dyad: An experimental and TD-DFT studyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2010K. Senthil Kumar Abstract An electronically push,pull type dimethylaminoazobenzene,fullerene C60 hybrid was designed and synthesized by tailoring N,N -dimethylaniline as an electron donating auxochrome that intensified charge density on the ,-azonitrogen, and on N -methylfulleropyrrolidine (NMFP) as an electron acceptor at the 4 and 4, positions of the azobenzene moiety, respectively. The absorption and charge transfer behavior of the hybrid donor-bridge-acceptor dyad were studied experimentally and by performing TD-DFT calculations. The TD-DFT predicted charge transfer interactions of the dyad ranging from 747 to 601 nm were experimentally observed in the UV-vis spectra at 721 nm in toluene and dichloromethane. A 149 mV anodic shift in the first reduction potential of the NN group of the dyad in comparison with the model aminoazobenzene derivative further supported the phenomenon. Analysis of the charge transfer band through the orbital picture revealed charge displacement from the n(NN) (nonbonding) and , (NN) type orbitals centered on the donor part to the purely fullerene centered LUMOs and LUMO+n orbitals, delocalized over the entire molecule. The imposed electronic perturbations on the aminoazobenzene moiety upon coupling it with C60 were analyzed by comparing the TD-DFT predicted and experimentally observed electronic transition energies of the dyad with the model compounds, NMFP and (E)-N,N -dimethyl-4-(p-tolyldiazenyl)aniline (AZNME). The n(NN) , ,*(NN) and ,(NN) , ,*(NN) transitions of the dyad were bathochromically shifted with a significant charge transfer character. The shifting of ,(NN) , ,*(NN) excitation energy closer to the n , ,*(NN) in comparison with the model aminoazobenzene emphasized the predominant existence of charge separated quinonoid-like ground state electronic structure. Increasing solvent polarity introduced hyperchromic effect in the ,(NN) , ,*(NN) electronic transition at the expense of transitions involved with benzenic states, and the extent of intensity borrowing was quantified adopting the Gaussian deconvolution method. On a comparative scale, the predicted excitation energies were in reasonable agreement with the observed values, demonstrating the efficiency of TD-DFT in predicting the localized and the charge transfer nature of transitions involved with large electronically asymmetric molecules with HOMO and LUMO centered on different parts of the molecular framework. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Using computer conferencing and case studies to enable collaboration between expert and novice teachersJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 2 2005Eileen C. Winter Abstract This paper reports on a teaching innovation where groups of experienced and novice teachers collaborated in analyzing case studies involving the education of students with special learning needs. The teachers collaborated in an asynchronous computer conferencing system (Web Knowledge Forum). All participants were enrolled in special education graduate courses taught by the authors. The authors discuss the use of case studies in teacher education, collaboration between novice and expert teachers, and highlight some of the demands of computer conferencing particularly in relation to the loss of face-to-face interactions and the interpretive demands of electronic communication. [source] Electronic Communication Training: Reconciling Gaps Created by the Virtual OfficePERFORMANCE IMPROVEMENT QUARTERLY, Issue 1 2001Jackie L. Jankovich Hartman ABSTRACT The virtual organization is one result of the rapid advances of technology. These advances, however, bring about setbacks when communicating electronically,primarily a loss of face-to-face interaction. Yet interpersonal skills are still deemed one of the most desirable communication skills in today's workplace. A gap analysis of the traditional versus the virtual office reveals that voids exist when communicating solely electronically. Electronic communication training is essential in order to eliminate these voids and lessen the chance for unclear messages, enhance "faceless" interactions, and avoid communication overload. Therefore, it is incumbent upon educators and trainers to augment development programs with electronic communication training in order for employees to be prepared for the challenges of the virtual office. [source] Malaysia's government publishing house: a quest for increased performance through technologyPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 1 2007Dahlina Daut Mohmud Abstract Electronic publishing, which is the production of a book or an e-book electronically, encompasses all processes involved in the production such as electronic communication, production, authoring, submission, reviewing, transfer and output. This study examines a radical transformation process to turn a conventional sector into an electronic sector. Studies were carried out in a government run publishing house in Malaysia, where the course of the public sectors and the interests of the private sectors meet. Factors that hindered progress, such as data management issues and transparencies are identified, and suggestions made to overcome them. Some concerns over disruption, such as creative destruction, often viewed as negative and destructive were identified with the introduction of technology. As disruption is also considered as one of the main hindrances in innovation, the study focuses on determining other effects of disruption on transformation. Business and management strategies are combined and a system that could increase performance and efficiency in the sector is proposed. However, the main concern in e-government efforts will have to be looked into from the root issues expanding from top level management to users and an innovative platform furnished with knowledge and skills at all levels. Copyright © 2007 John Wiley & Sons, Ltd. [source] A Spectroscopic Study of the Reduction of Geometrically Restrained ViologensCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2007Andrew Abstract A small series of N,N,-dimethyl-4,4,-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3,-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant ,-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the ,-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether. [source] Efficient Charge Injection from the S2 Photoexcited State of Special-Pair Mimic Porphyrin Assemblies Anchored on a Titanium-Modified ITO AnodeCHEMISTRY - A EUROPEAN JOURNAL, Issue 31 2006Mitsuhiko Morisue Dr. Abstract A novel surface fabrication methodology has been accomplished, aimed at efficient anodic photocurrent generation by a photoexcited porphyrin on an ITO (indium,tin oxide) electrode. The ITO electrode was submitted to a surface sol,gel process with titanium n -butoxide in order to deposit a titanium monolayer. Subsequently, porphyrins were assembled as monolayers on the titanium-treated ITO surface via phosphonate, isophthalate, and thiolate groups. Slipped-cofacial porphyrin dimers, the so-called artificial special pair at the photoreaction center, were organized through imidazolyl-to-zinc complementary coordination of imidazolylporphyrinatozinc(II) units, which were covalently immobilized by ring-closing olefin metathesis of allyl side chains. The modified surfaces were analyzed by means of X-ray photoelectron spectroscopy. Photoirradiation of the porphyrin dimer generated a large anodic photocurrent in aqueous electrolyte solution containing hydroquinone as an electron sacrificer, due to the small reorganization energy of the dimer. The use of different linker groups led to significant differences in the efficiencies of anodic photocurrent generation. The apparent flat-band potentials evaluated from the photocurrent properties at various pH values and under biased conditions imply that the band structure of the ITO electrode is modified by the anchoring species. The quantum yield for the anodic photocurrent generation by photoexcitation at the Soret band is increased to 15,%, a surprisingly high value without a redox cascade structure on the ITO electrode surface, while excitation at the Q band is not so significant. Extensive exploration of the photocurrent properties has revealed that hot injection of the photoexcited electron from the S2 level into the conduction band of the ITO electrode takes place before internal conversion to the S1* state, through the strong electronic communication of the phosphonyl anchor with the sol,gel-modified ITO surface. [source] Reductive Benzylation of Dimetallo Hexaaryl[70]Fullerenes on the Equatorial RegionCHEMISTRY - AN ASIAN JOURNAL, Issue 4 2010Takeshi Fujita Abstract Dianions of dimetallic hexa(organo)[70]fullerene [(C5R5)2Ru2C70Ar6]2, (R=H, Me; Ar=Ph, 4-MeC6H4, 4- tBuC6H4) react with benzylic bromide to yield the dibenzylated product dimetallic octa(organo)[70]fullerene (C5R5)2Ru2C70Ar6(CH2Ar,)2 (Ar,=Ph, 4-MeO2CC6H4), where the benzylic groups are attached to the equatorial belt region of [70]fullerene; this region is generally considered to be rather unreactive. This unusual structure was unambiguously determined by X-ray crystallography. Theoretical studies on the electronic properties of the monoanionic intermediate indicated that the highest spin density resides on the two carbon atoms in the belt region; one of them then couples with a benzylic radical to yield the octa(organo)fullerene product after ionic substitution of the fullerene anion with a benzylic bromide. Electrochemical analysis of the hexa(organo) and octa(organo) ruthenium complexes suggests that the modification of the belt region does not affect the electronic communication between the two metal centers. [source] The Presence of a Ferrocenyl Unit on an Estrogenic Molecule is Not Always Sufficient to Generate in,vitro CytotoxicityCHEMMEDCHEM, Issue 11 2006Anne Vessières Dr. Abstract We recently reported the dual (antihormonal and cytotoxic) functionality of ferrocifens, which are organometallic complexes derived from hydroxytamoxifen, the standard molecule in the treatment of hormone-dependent breast cancers. To test the hypothesis that the presence of a ferrocenyl substituent on molecules with an affinity for the estrogen receptor is sufficient to give them cytotoxic properties in,vitro, we prepared complexes derived from estradiol with a ferrocenyl substituent at positions 7, and 17,. The complexes thus obtained retain a satisfactory level of affinity for the estrogen receptor (RBA values higher than 12,%). At low concentrations (0.1,1,,M) the complexes show an estrogenic effect in,vitro equivalent to that of estradiol on hormone-dependent (MCF-7) breast cancer cells, and no cytotoxic effect on hormone-independent (MDA-MB-231) breast cancer cells. At high concentrations (up to 50,,M) the 17, -ethynylferrocenyl estradiol and 7, -ferrocenylmethylthio estradiol become cytotoxic (IC50=13.2,,M and 18.8,,m, respectively) while the 17, -ferrocenylestradiol remains non toxic. The low toxicity of these compounds support our hypothesis that electronic communication between the ferrocenyl and phenol moieties in the hydroxyferrocifens series is a key parameter in the generation of cytotoxic effects at submicromolar concentrations. [source] | ||||||||||