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1. Synthesis, structure and photophysical properties of a 2D network with gold dicyanide donors coordinated to aza[5]helicene viologen acceptors

   https://doi.org/10.1039/c9dt01823a  

   Patel, Ealin N.; Arthur, Robert B.; Nicholas, Aaron D.; Reinheimer, Eric W.; Omary, Mohammad A.; Brichacek, Matthew; Patterson, Howard H. (July 2019, Dalton Transactions)

   A recently synthesized photoluminescent organic acceptor, 5,10-dimethyl-5,10-diaza[5]helicene is shown to react with dicyanoaurate anions to form a 2D network N , N -dimethylaza[5]helicene dicyanoaurate. The structure of the synthesized complex was investigated via X-ray crystallography showing the presence of [Au(CN) 2 ] − dimers and monomers within the helicene framework. Photophysical measurements between 298 K and 10 K indicate quenching of the [Au(CN) 2 ] − anion by 5,10-dimethyl-5,10-diaza[5]helicene via an electron transfer. A Stern–Volmer and Rehm–Weller analysis shows that this is a result of quenching from transfer of an electron from [Au(CN) 2 ] − anions to 5,10-dimethyl-5,10-diaza[5]helicene as opposed to resonance energy transfer. DFT calculations were performed to support the assignment of an electron transfer. 

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2. Long-Range Electron Transfer through Ultrathin Polyelectrolyte Complex Films: A Hopping Model

   https://doi.org/10.1021/acs.jpcc.1c06040  

   Shaheen, Samir Abou; Abbett, Rachel L.; Akkaoui, Khalil; Schlenoff, Joseph B. (October 2021, The Journal of Physical Chemistry C)

   null (Ed.)

   Pinhole-free ultrathin films of polyelectrolyte complex assembled using layer-by-layer deposition were used to evaluate electron transfer from a redox species in solution to an electrode over the distance range 1 to 9 nm. Over this thickness, the polyelectrolytes employed wet the surface and the polymer molecules flatten to less than their equilibrium size in 3-dimensions. A decay constant β for current as a function of distance of about 0.3 nm-1 placed this system in the regime expected for multistep hopping versus a one-step tunneling event. Discreet hopping sites within the films were identified as ferrocyanide ions with an equilibrium concentration of 0.032 M and an average separation of 3.7 nm. The Butler-Volmer (BV) expression for electron transfer as a function of overpotential was modified by distributing the applied voltage evenly amongst the hopping sites. This modified BV expression fit both the distance dependence and the applied potential dependence well, wherein the only freely adjustable parameter was the electron transfer coefficient. The finding that β is simply the inverse of the hopping range is consistent with previous conclusions that electrons within conjugated molecule sites are delocalized, or, for non-conjugated systems, spread over more than one repeat unit by lattice distortions 

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3. H ₂ evolution from H ₂ O via O–H oxidative addition across a 9,10-diboraanthracene

   https://doi.org/10.1039/D0CC05261B  

   Taylor, Jordan W.; Harman, W. Hill (November 2020, Chemical Communications)

   null (Ed.)

   The water reactivity of the boroauride complex ([Au(B 2 P 2 )][K(18-c-6)]; (B 2 P 2 , 9,10-bis(2-(diisopropylphosphino)-phenyl)-9,10-dihydroboranthrene) and its corresponding two-electron oxidized complex, Au(B 2 P 2 )Cl, are presented. Au(B 2 P 2 )Cl is tolerant to H 2 O and forms the hydroxide complex Au(B 2 P 2 )OH in the presence of H 2 O and triethylamine. [Au(B 2 P 2 )]Cl and [Au(B 2 P 2 )]OH are poor Lewis acids as judged by the Gutmann–Becket method, with [Au(B 2 P 2 )]OH displaying facile hydroxide exchange between B atoms of the DBA ring as evidenced by variable temperature NMR spectroscopy. The reduced boroauride complex [Au(B 2 P 2 )] − reacts with 1 equivalent of H 2 O to produce a hydride/hydroxide product, [Au(B 2 P 2 )(H)(OH)] − , that rapidly evolves H 2 upon further H 2 O reaction to yield the dihydroxide compound, [Au(B 2 P 2 )(OH) 2 ] − . [Au(B 2 P 2 )]Cl can be regenerated from [Au(B 2 P 2 )(OH) 2 ] − via HCl·Et 2 O, providing a synthetic cycle for H 2 evolution from H 2 O enabled by O–H oxidative addition at a diboraanthracene unit. 

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4. Effect of Random Nanostructured Metallic Environments on Spontaneous Emission of HITC Dye

   https://doi.org/10.3390/nano10112135  

   Rout, Sangeeta; Qi, Zhen; Petrosyan, Ludvig S.; Shahbazyan, Tigran V.; Biener, Monika M.; Bonner, Carl E.; Noginov, Mikhail A. (November 2020, Nanomaterials)

   null (Ed.)

   We have studied emission kinetics of HITC laser dye on top of glass, smooth Au films, and randomly structured porous Au nanofoams. The observed concentration quenching of luminescence of highly concentrated dye on top of glass (energy transfer to acceptors) and the inhibition of the concentration quenching in vicinity of smooth Au films were in accord with our recent findings. Intriguingly, the emission kinetics recorded in different local spots of the Au nanofoam samples had a spread of the decay rates, which was large at low dye concentrations and became narrower with increase of the dye concentration. We infer that in different subvolumes of Au nanofoams, HITC molecules are coupled to the nanofoams weaker or stronger. The inhibition of the concentration quenching in Au nanofoams was stronger than on top of smooth Au films. This was true for all weakly and strongly coupled subvolumes contributing to the spread of the emission kinetics. The experimental observations were explained using theoretical model accounting for change in the Förster radius caused by the strong energy transfer to metal. 

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5. Mechanism of supplemental activator and reducing agent atom transfer radical polymerization mediated by inorganic sulfites: experimental measurements and kinetic simulations

   https://doi.org/10.1039/c7py01319a  

   Krys, Pawel; Fantin, Marco; Mendonça, Patrícia V.; Abreu, Carlos M.; Guliashvili, Tamaz; Rosa, Jaquelino; Santos, Lino O.; Serra, Arménio C.; Matyjaszewski, Krzysztof; Coelho, Jorge F. (January 2017, Polymer Chemistry)

   The mechanism of atom transfer radical polymerization (ATRP) mediated by sodium dithionite (Na 2 S 2 O 4 ), with Cu II Br 2 /Me 6 TREN as catalyst (Me 6 TREN: tris[2-(dimethylamino)ethyl]amine) in ethanol/water mixtures, was investigated experimentally and by kinetic simulations. A kinetic model was proposed and the rate coefficients of the relevant reactions were measured. The kinetic model was validated by the agreement between experimental and simulated results. The results indicated that the polymerization followed the SARA ATRP mechanism, with a SO 2 ˙ − radical anion derived from Na 2 S 2 O 4 , acting as both supplemental activator (SA) of alkyl halides and reducing agent (RA) for Cu II /L to regenerate the main activator Cu I /L. This is similar to the reversible-deactivation radical polymerization (RDRP) procedure conducted in the presence of Cu 0 . The electron transfer from SO 2 ˙ − , to either Cu II Br 2 /Me 6 TREN or R–Br initiator, appears to follow an outer sphere electron transfer (OSET) process. The developed kinetic model was used to study the influence of targeted degree of polymerization, concentration of Cu II Br 2 /Me 6 TREN and solubility of Na 2 S 2 O 4 on the level of polymerization control. The presence of small amounts of water in the polymerization mixtures slightly increased the reactivity of the Cu I /L complex, but markedly increased the reactivity of sulfites. 

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