Electronic structure,physico-chemical,linear and non linear optical properties analysis of coronene, 6B-, 6N-, 3B3N- substituted C24H12 using RHF,B3LYP and wB97XD methods

In this work we have investigated the effects of substituting carbon atoms with B, N and BN on the electronic structure, physico-chemical, linear and non linear optical properties of Coronene (C24H12) using HF and DFT methods. We have calculated total electronic energy E₀, zero point vibrational energy ZPVE, the enthalpy H, entropy S, molar heat capacity at constant volume C_v, ionization potential IP, electron affinity EA, hardness \(\kappa\), softness \(\vartheta\), electronegativity EN, dipole moment µ, average polarizability \(< \alpha >\), anisotropy \(\Delta \alpha\), the first molecular hyperpolarizability β_mol, second order hyperpolarizability \(\gamma_{av}\), HOMO–LUMO Energy gap E_gap, work function E_F, refractive index n, susceptibility χ, dielectric constant ε and molar refractivity MR of coronene (C24H12), the 6B-, 6N- and 3B3N- substitute-doped C24H12 C18B6H12 C18N6H12 and C18B3N3H12. The E_gap values of the molecules are between 0.91 and 2.36 eV. We observed that β_mol changes slightly when C24H12 is doped with either 6B or 6N even though their β_mol values are too small. However, by doping C24H12 with both 3B and 3N, creating a strong donor–acceptor system, a very large increase in µ and β_mol was found for C18B3N3H12. This study was done using RHF, B3LYP and wB97XD methods with the cc-pVDZ basis set. The studies have shown that doping decreases some of the above properties significantly while some increases significantly compared to pure coronene, suggesting that 6B-, 6N-, and 3B3N-doped Coronene as serious candidates for electronics, optoelectronics and photonic devices.     

Theoretical modelling and experimental study of the fatigue of elastomers under cyclic loadings of variable amplitude

Deviations from Miner's linear law of cumulative damage have been modelled and observed many times for the fatigue of metals, but almost no analogous studies have been performed for elastomers. Such a study is reported here.     

Diffraction et mesure de Palm des processus ponctuels

Using the notion of Palm measure, we prove the existence of the diffraction measure of all stationary and ergodic point processes. We get precise expressions of those measures in the case of specific processes: stochastic subsets of $\text{Z}{}^{\mathrm{d}}$, sets obtained by the “cut-and-project” method. To cite this article: J.-B. Gouéré, C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

Steroids as organising elements in anion receptors

The steroid nucleus has proved useful in various areas of supramolecular chemistry, acting as a building-block for extended, well-defined molecular architectures, and a scaffold for preorganised arrays of functionality. This article discusses its applications in the area of anion recognition, where cholic acid (2) has been especially valuable. The three secondary hydroxyl groups on 2 are nicely arranged for H-bond donation to a single anion, and may be converted into stronger neutral or positively-charged H-bond donors. Macrocyclic and acyclic receptors derived from 2 have been used to bind inorganic anions, carboxylates and nucleic acids.     

Electrochemical quantification of high-affinity halide binding by a steroid-based receptor

The strength of binding between a cholapod receptor and halide anions is quantified using voltammetry at the liquid/liquid interface, revealing very high affinities and size-selectivity peaking at chloride.     

Cycloruthenated primary and secondary amines as efficient catalyst precursors for asymmetric transfer hydrogenation

[reaction: see text] Ruthenacycles obtained by cyclometalation of enantiopure aromatic primary or secondary amines with [(eta6-benzene)RuCl2]2 or with [(eta6-p-cymene)RuCl2]2 are efficient catalysts for asymmetric transfer hydrogenation (TOF up to 190 h(-1) at room temperature). Enantioselectivities in the transfer hydrogenation of acetophenone ranged from 38% to 89%. It is possible to prepare the catalysts in situ, which allows the use of high throughput experimentation.     

PHOTOCLEAVAGE OF DNA IN THE PRESENCE OF SYNTHETIC WATER-SOLUBLE PORPHYRINS

In the presence of oxygen and visible light, various synthetic water-soluble porphyrins cleave pBR 322 plasmid supercoiled DNA (form I) producing relaxed (form II) and linear (form III) DNA corresponding to single-strand and double-strand breaks respectively. Large variations are observed in the efficiency of the porphyrins containing a diamagnetic metal or no metal at all. Singlet oxygen (¹O₂) seems to be involved in the mechanism of cleavage consistent with the inhibitory effect of the azide anion, N^–₃. The higher efficiency of cationic porphyrins (as compared to anionic ones) is due to their greater affinity for DNA as shown by experiments carried out at either high ionic strength or in the presence of the surfactant, sodium dodecyl sulfate.     

1,3-Diborata-2,4-diphosphoniocyclobutane-1,3-diyls communicate through a para-phenylene linker

The presence of a second 1,3-diborata-2,4-diphosphoniocyclobutane-1,3-diyl in the para-position of a phenylene linker favors the diradical form over the 1,3-diborata-2,4-diphosphoniobicyclo[1.1.0]butane bond stretch isomer, as long as the two planar diradical units are coplanar with the linker. This demonstrates that two BPBP diradicals communicate through the phenyl ring.