Synthesizing a broad scope of peropyrenes and teropyrenes with tunable bandgaps is now possible via an InCl3-catalyzed one-pot multifold alkyne benzannulation reaction.

We demonstrate the controlled reduction of colloidal ZnO nanoparticles (NPs) on a Hg ultramicroelectrode (UME) and its application to determine the redox potential for the deoxygenation of ZnO. The NPs are in colloidal suspension in acetonitrile (MeCN) and reach the electrode by migrational mass transport. At the electrode surface, the Zn 2+ in zinc oxide NPs is reduced to a Zn(Hg) amalgam. The redissolution (stripping) of Zn 2+ from the amalgam into MeCN is used to determine the amount of reduced ZnO. The stripping charge is proportional to the concentration of the colloidal ZnO NPs at potentials where the reduction is found to be limited by mass transport. The charge resulting from the reduction of ZnO is a function of the reduction potential and presents a sigmoidal curve that fits a quasireversible model and is used to determine the formal reduction potential, E 0 ′.We observed that E 0 ′ is a strong function of NP size in the size regime of 11−80 nm in diameter. The ZnO particles studied are more stable than the Zn(Hg) amalgam, but smaller NPs are less stable compared to larger particles, making smaller NPs relatively easier to reduce. The reduction potential of ZnO NPs is a strong function of 1/r. This Kelvin effect is analogous to the electrochemical behavior of metal nanoparticles described by Plieth's model.

We discuss the electrolysis mechanism of colloidal ZnO NPs (10 nm diam.) in CH 3 CN. Stripping the preconcentrated Zn(Hg) allows quantification of the ZnO electrolyzed during stochastic interactions with the Hg surface. We model the mass transport taking the charged agglomerates of ZnO NPs as ionic species to calculate their migration and diffusional contributions. In unsupported suspensions, the mobility and positive zeta potential enhance transport towards the Hg UME. The NP electrolysis generates ionic species, increasing the migration rate and allowing lower detection limits compared to weakly supported suspensions, where the electrolyte modifies agglomerate charge and colloidal properties. We determine the kinetic constant (k f, in cm/s) for the ZnO reduction from the electrolysis transient model for destructive collisions of single entities, corrected for the potentiostat time constant. While most reduction events happen within 100 ms, the single entity model is consistent with mass transport studies over longer experimental times (1800 s).

Technetium / Citrate / Complexation / Solvent extraction / PHREEQCSummary. This paper presents the experimental determination of the stability constant for the citrate complexes with TcO(OH) + and TcO(OH) 2 0 at different ionic strengths (NaCl), using a solvent extraction method. Data show that the stability constants for the formation of TcO(OH)Cit 2− and TcO(OH) 2 Cit 3− are 10 7.5±0.2 and 10 2.8±0.2 , respectively, at zero ionic strength, with an average of 10 6.5±0.3 and 10 2.8±0.2 , respectively, in the 1.0-3.0 M ionic strength range. PHREEQC calculations based on these stability constants show that the TcO(OH)Cit 2− is the predominant species between pH 3 and 8 and that 50 mM citrate leads to a Tc(IV) solubility of 2 × 10 −5 M at pH 5.