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Rooney, P.; Rezaee, A.;Xu, S.; Manifar, T.; and Rangan, Chitra. (2008 We present experimental and theoretical results for the changes in the optical-plasmon resonance of goldnanoparticle dimers immobilized on a surface when coated with an organic dielectric material. The plasmon band of a nanoparticle dimer shifts to a higher wavelength when the distance between neighboring particles is decreased, and a well-separated second peak appears. This phenomenon is called cross-talk. We find that an organic coating lets cross-talk start at larger separation distances than for uncoated dimers by bridging the gap between immobilized nanoparticles ͑creating optical clusters͒. We study this optical clustering effect as a function of the polarization of the applied light, of the inter-particle distance, of the surrounding environment, and of the optical properties of the coating layer. Theoretical discrete-dipole approximation calculations support the experimental absorption spectroscopy results of gold nanoparticles on glass substrates and on optical waveguides.

Screening of eight ligands for the copper-catalyzed ligand-accelerated Ullmann condensation of p-toluidine with 4-iodotoluene to produce tri-p-tolylamine (TTA) revealed that 2,2‘-dipyridyl and 4,4‘-dipyridyl gave the highest conversion to TTA in the shortest time. Based on the ligand-screening results, a mechanistic structure of the active reaction complex between copper and the two fastest ligands was proposed. The TTA synthesis reaction kinetics was followed by an HPLC method, and kinetic parameters of the reaction were determined in temperature range 128−196 °C. The condensation of p-toludine with 4-iodotoluene to give TTA was modeled as a parallel-consecutive reaction system composed of two condensation reactions. Reaction orders for the first condensation reaction to give di-p-tolylamine were determined to be 1.18 and 1.16 with respect to 4-iodotoluene and p-toluidine, respectively. For the second condensation reaction, the reaction orders were determined to be 0.13 and 0.11 with respect to 4-iodotoluene and di-p-tolylamine, respectively. Activation energies for the first and second reaction were determined as 53.6 and 53.8 kJ mol-1, respectively. The preexponential constants (k o) in the Arrhenius equation for the first and second reaction were determined as 1774.4 min-1(mol/L)-1.34 and 5657.8 min-1(mol/L)0.76, respectively. Finally, the model predictions gave very good agreement with experimental results for low, medium, and high reaction temperature.

In this paper, synthesis and characteristic of arylaminetype molecules, particularly triphenylamine are discussed. An overview of the physical properties and chemical characteristics of these types of molecules is provided. Different synthesis methods and mechanisms involved for the production of these molecules and their analysis by HPLC are presented. Finally, a brief HPLC are presented. Finally, a brief HPLC note about their purifi cation is presented.Dans cet article, on analyse la synthèse et la caractéris-tique des molécules de type arylamine, et particulière-ment la triphénylamine. On donne un aperçu général des propriétés physiques et des caractéris-tiques chimiques de ce type de molécules. Plusieurs méthodes et mécanismes de synthèse intervenant dans la production de ces molécules et leur analyse par HPLC sont présentés. Enfi n, leur purifi cation est brièvement décrite.