Competition and interplay between σ-hole and π-hole interactions: a computational study of 1:1 and 1:2 complexes of nitryl halides (O2NX) with ammonia

Quantum calculations at the MP2/cc-pVTZ, MP2/aug-cc-pVTZ, and CCSD(T)/cc-pVTZ levels have been used to examine 1:1 and 1:2 complexes between O(2)NX (X = Cl, Br, and I) with NH(3). The interaction of the lone pair of the ammonia with the σ-hole and π-hole of O(2)NX molecules have been considered. The 1:1 complexes can easily be differentiated using the stretching frequency of the N-X bond. Thus, those complexes with σ-hole interaction show a blue shift of the N-X bond stretching whereas a red shift is observed in the complexes along the π-hole. The SAPT-DFT methodology has been used to gain insight on the source of the interaction energy. In the 1:2 complexes, the cooperative and diminutive energetic effects have been analyzed using the many-body interaction energies. The nature of the interactions has been characterized with the atoms in molecules (AIM) and natural bond orbital (NBO) methodologies. Stabilization energies of 1:1 and 1:2 complexes including the variation of the zero point vibrational energy (ΔZPVE) are in the ranges 7-26 and 14-46 kJ mol(-1), respectively.     

PT-Symmetric Talbot Effects

We show that complex PT-symmetric photonic lattices can lead to a new class of self-imaging Talbot effects. For this to occur, we find that the input field pattern has to respect specific periodicities dictated by the symmetries of the system. While at the spontaneous PT-symmetry breaking point the image revivals occur at Talbot lengths governed by the characteristics of the passive lattice, at the exact phase it depends on the gain and loss parameter, thus allowing one to control the imaging process.     

Automated Technique for Identifying Experimental Vibrational–Rotational Molecular Spectra Based on Variational Calculations

We describe a technique for automated identification of experimental vibrational–rotational molecular spectra, which is based on variational calculations. The proposed technique is used to analyze the experimental spectra of triatomic molecules H₂O and HDO. This technique significantly accelerates processing and analysis of experimental data and drastically improves accuracy and quality of the results obtained. The possibility of applying this technique for analyzing spectra of other polyatomic molecules is discussed.     

Water vapour line assignments in the 9250-26 000 cm frequency range

Line parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm⁻¹ region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm⁻¹ region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H₂¹⁶O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented.     

An Efficient Three‐Component Synthesis of Pyranoquinoline Derivatives

Pyranoquinoline derivatives have been synthesized via three‐component reaction of 4‐hydroxy‐1‐methyl‐2(1H)‐quinolinone and dialkyl acetylenedicarboxylates in the presence of nucleophiles such as alkyl isocyanides and triphenylphosphine.     

A self-dual variational approach to stochastic partial differential equations

Unlike many of their deterministic counterparts, stochastic partial differential equations are not amenable to the methods of calculus of variations à la Euler–Lagrange. In this paper, we show how self-dual variational calculus leads to variational solutions of various stochastic partial differential equations driven by monotone vector fields. We construct solutions as minima of suitable non-negative and self-dual energy functionals on Itô spaces of stochastic processes. We show how a stochastic version of Bolza's duality leads to solutions for equations with additive noise. We then use a Hamiltonian formulation to construct solutions for non-linear equations with non-additive noise such as the stochastic Navier–Stokes equations in dimension two.     

Utilization of a robust syringe-to-syringe displacement-assisted dispersive liquid-phase microextraction to the preconcentration and determination of palladium in environmental samples with the aid of experimental design

Journal of the Iranian Chemical Society - We introduce a syringe-to-syringe displacement-assisted dispersive liquid-phase microextraction to the separation and preconcentration of trace Pd(II)...     

HPLC technique for quantitation of Chimassorb 944, and its evaluation in analysis of real and standard samples of polyolefins

A high performance liquid chromatography (HPLC) method is presented for the determination of Chimassorb 944 in polymeric matrix. A reversed phase column octadecyl silane (ODS) is used as a stationary phase. As a mobile phase, a mixture of THF:methanol:triethanol amine (90:10:1.5) (v:v:w) is used. The HPLC system was equipped with an UV detector and the absorbance of the analyte was recorded at 240 nm. In the case of polymers, 0.5 g of them along with 100 mg Irganox 1010 (for preventing oxidation of Chimassorb 944) were dissolved in boiling xylene, and then extracted with sulfuric acid 1 M four times. The extract was neutralized with sodium hydroxide solution and the analyte was re-extracted into carbon tetrachloride and then injected to the HPLC system. This method is an accurate and relatively fast technique for determination of Chimassorb 944 in polymers.     

Quadratic double centralizers and quadratic multipliers

In this paper, we establish stability of quadratic double centralizers and quadratic multipliers on Banach algebras. We also prove the super stability of quadratic double centralizers on Banach algebras which are weakly commutative and weakly without order, and of quadratic multipliers on Banach algebras which are weakly without order.