Is the Trigonal Prismatic Distortion the Answer for the Geometry of InIII four Members Dithiochelate Compounds? The Crystal and Molecular Structure of In(S2AsR2)3 (R = Me,Ph)

The distortion from the octahedral geometry is discussed for Indium(III) 1,1‐dithio complexes (dithiophosph(in)ates, dithiocarbamates, dithioarsinates) and isostructural chromium(III) compounds in relation with the bite of the ligands, the S…S repulsion within the four members rings and S…S interligand distances. The crystal and molecular structures of In(S₂AsR₂)₃ (R = Me, Ph) have been determined by single crystal X‐ray diffraction. The dithioarsinate ligands are basically monomeric and isobidentate, with average values for arsenic‐sulphur bond distances of 2.135 Å for dimethyl and 2.137 Å for diphenyl complex. The average In–S distances are identical (2.634 Å) in both cases.     

Study by Optical Spectroscopy of Bismuth Emission in a Nanosecond-Pulsed Discharge Created in Liquid Nitrogen

Time-resolved optical emission spectroscopy of nanosecond-pulsed discharges ignited in liquid nitrogen between two bismuth electrodes is used to determine the main discharge parameters (electron temperature, electron density and optical thickness). Nineteen lines belonging to the Bi I system and seven to the Bi II system could be recorded by directly plunging the optical fibre into the liquid in close vicinity to the discharge. The lack of data for the Stark parameters to evaluate the broadening of the Bi I lines was solved by taking advantage of the time-resolved information supported by each line to determine them. The electron density was found to decrease exponentially from 6.5 ± 1.5 × 10¹⁶ cm⁻³ 200 ns after ignition to 1.0 ± 0.5 × 10¹⁶ cm⁻³ after 1050 ns. The electron temperature was found to be 0.35 eV, close to the value given by Saha’s equation.     

DFT computational schemes for 15N NMR chemical shifts of the condensed nitrogen-containing heterocycles

A systematic density functional theory (DFT) study of the accuracy factors (functionals, basis sets, and solvent effects) for the computation of ¹⁵N NMR chemical shifts has been performed in the series of condensed nitrogen-containing heterocycles. The behavior of the most representative functionals was examined based on the benchmark calculations of ¹⁵N NMR chemical shifts in the reference set of compounds. It was found that the best agreement with experiment was achieved with OLYP functional in combination with aug-pcS-3(N)//pc-2 locally dense basis set scheme providing mean absolute error of 5.2 ppm in the range of about 300 ppm. Taking into account solvent effects was performed within a general Tomasi's polarizable continuum model scheme. It was also found that computationally demanding supermolecular solvation model computations essentially improved some “difficult” cases, as was illustrated with phenanthroline dissolved in methanol. Based on the performed calculations, some 200 unknown ¹⁵N NMR chemical shifts were predicted with a high level of confidence for about 50 real-life condensed nitrogen-containing heterocycles, which could serve as a practical guide in structural elucidation of this class of compounds.     

Near-infrared light for polymer re-shaping and re-processing applications

The re-shaping and reprocessing of polymers are usually associated with strong energetic costs, strongly limiting their practical usage. In this article, a new approach is proposed based on a near-infrared (NIR) activation of the material in presence of a NIR heater for a highly efficient process upon ecofriendly NIR light emitting diodes irradiation. Markedly, due to this light-triggered process, a spatial control of the shaping/reprocessing behavior can be obtained, that is, only the needed parts are irradiated preventing a heating of all the sample. In this work, different thermoplastics are reshaped or reprocessed due to NIR activation in presence of an organic NIR dye used as heater. As other examples of photothermal treatment upon NIR light, the on-demand dehydration of polyethylene glycol (PEG-based) hydrogels are also provided. All the processes are followed in real time by thermal imaging camera.     

Uniform subconvexity and symmetry breaking reciprocity

A non-symmetric reciprocity formula is established that expresses the fourth moment of automorphic L-functions of level q and primitive central character twisted by the ?-th Hecke eigenvalue as a twisted mixed moment of automorphic L-functions of level ? and trivial central character. As an application, uniform subconvexity bounds for L-functions in the level and the eigenvalue aspect are derived.     

Modification of proline‐based 2,5‐diketopiperazines by anionic ring‐opening polymerization

2,5‐Diketopiperazines (DKPs) are the smallest cyclic dipeptides found in nature with various attractive properties. In this study, we have demonstrated the successful modification of proline‐based DKPs using anionic ring‐opening polymerization (AROP) as a direct approach. Four different proline‐based DKPs with various side chains and increasing steric hindrance were used as initiating species for the polymerization of 1,2‐epoxybutane or ethoxyethyl glycidyl ether in the presence of t‐BuP₄ phosphazene base. The addition of a Lewis acid, tri‐isobutyl aluminum, to the reaction mixture strongly decreased the occurrence of side reactions. Impact of the DKP side‐chain functionalities on molar mass control and dispersity was successfully evidenced. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1008–1016