α-Amido sulphones as useful intermediates in the preparation of C-chiral α-aminophosphonates and α-aminophosphonic acids.

α-Amido sulphones have been used as useful starting materials in the preparation of C-chiral α-aminophosphonates and α-aminophosphonic acids. The developed methodology is based on a one-pot, base-catalysed in situ generation of an imine intermediate followed by addition of a phosphorus nucleophile. The presented protocol is simple and effective and can be applied to a variety of structurally diverse α-amido sulphones and phosphorus nucleophiles, leading to the desired pure products after simple crystallization in very good yields. Importantly, the use of H-phosphonate bearing a chiral auxiliary allows the reaction to be performed with high diastereoselectivity (a single diastereoisomer is generated and isolated) and the possibility of precise control of the configuration at the newly generated C-chiral centre.

Unveiling Halogen-Bonding Interactions between a Pyridine-Functionalized Fluoroborate Dye and Perfluorohaloarenes with Fluorescence Spectroscopy.

We have studied the halogen-bonding interactions of a pyridine-functionalized fluoroborate dye with perfluorohaloarenes (C6F6, C6F5Cl, C6F5Br, and C6F5I) in the two-component-only liquid phase using fluorescence spectroscopy. Based on the results of spectroscopic measurements and electronic-structure calculations, we have confirmed the stability only for the complex between C6F5I and the emissive dye, and it has been demonstrated that halogen-bonding interactions are accompanied by significant Stokes shifts for the ππ* band. We also provide experimental evidence that for this complex, the emission is quenched due to a simultaneous decrease of radiative and increase of nonradiative decay rate constants upon halogen-bonding interactions.

Solvent effect on the vibrational spectrum of Michler's ketone. Experimental and theoretical investigations.

We examined solvent effect on the IR and Raman spectra of MK in several solvents of different polarity and proticity, for understanding of intermolecular interactions, focusing on solvent effect in detail. It has been found that change of solvent polarity has an ambiguous influence on solvatochromism of MK. We have observed that not only vibrations of carbonyl group are affected by the solvent polarity, but also mode ν(CN) and ν(CC) in IR and Raman spectra of MK. Experimental investigations have been supported by the quantum-mechanical computations to gain more insight into the solvatochromic behavior of Michler's ketone. Calculations have been carried using Kohn-Sham formulation of Density Functional Theory (DFT) and the Polarizable Continuum Model (PCM) was employed to account for solute solvent interactions.

The nature of interactions in nicotinamide crystal.

In this study, we analyze the nature of intermolecular interactions in nicotinamide complexes appearing in conformations found in the crystal structure, including many-body effects. In doing so, we employ symmetry-adapted perturbation theory based on density functional theory description of monomers, and we perform the many-body variational-perturbational interaction energy decomposition. The principal finding of this study is that the stability of nicotinamide complexes is a complicated interplay of four (large in magnitude) interaction-energy components, i.e. induction, dispersion, electrostatic and exchange repulsion. However, the last two contributions cancel each other out to a large extent. In the case of considered three-body complexes, the nonadditivity effects are found to be not important. Based on the results of topological analysis of charge densities we characterized also the properties of short H ⋯ H contact and identified it as a weak noncovalent closed shell interaction.

Dynamical disorder in 2-methyl-4-nitroaniline and its deuterated analogue crystals studied by Fourier transform infrared and nuclear magnetic resonance.

The Fourier transform infrared spectra of the thin layers of 2-methyl-4-nitroaniline (MNA) and its deuterated analog were recorded in the 500-4000 cm(-1) region in the 10-300 K temperature range. Activation energies of the -CH(3), -NH(2), and -NO(2) groups reorientations were estimated. The (1)H-NMR spin-lattice relaxation time, T(1), and the second moment of (1)H-NMR resonance line, M(2), measured in the 80-298 K temperature range, were used to determine the parameters of the -CH(3) group motion. The experimental potential barriers for the amine, nitro, and methyl group reorientations are considered in the context of strengths of the N-H([ellipsis (horizontal)])O, C-H([ellipsis (horizontal)])O intermolecular hydrogen bonds, and other short contacts, recognized recently [U. Okwieka et al., J. Raman Spectrosc. 39, 849 (2008)], and they agree with the barriers calculated by quantum chemical methods. The dynamical disorder found in the MNA crystal in the large temperature range seems to be important from the point of view of its nonlinear optical and other properties.