A calix[4]pyrrole receptor bearing two proximally meso-meso linking isophthaloyl straps displays open and closed states depending on the conformation. In crystal structures in non-polar solvent, adopts 1,3-alternate conformation with sides. Anion binding triggers a state of providing types interactions an aromatic benzoate guest: hydrogen bonds from pyrrolic NH groups ????? phenyl straps. Slow ...

A helical aromatic oligoamide foldamer encapsulates tartaric acid with exceptional affinity, selectivity, and diastereoselectivity. The structure of the complex has been elucidated both in solution by NMR spectroscopy and in the solid state by X-ray crystallography, making it possible to rationalize the strong effects observed, particularly the role of hydrogen bonds between the hydroxyl and ca...

The highly anisotropic environment of the lipid bilayer membrane imposes significant constraints on the structures and functions of membrane proteins. However, NMR structure calculations typically use a simple repulsive potential that neglects the effects of solvation and electrostatics, because explicit atomic representation of the solvent and lipid molecules is computationally expensive and i...

The isotropic (129)Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the (129)Xe NMR CS. The (129)Xe shielding constant was obtained by averaging the (129)Xe nuclear magnetic shieldings calcula...

The Poisson-Boltzmann equation is widely used for modeling the electrostatics of biomolecules, but the calculation results are sensitive to the choice of the boundary between the low solute dielectric and the high solvent dielectric. The default choice for the dielectric boundary has been the molecular surface, but the use of the van der Waals surface has also been advocated. Here we review rec...

Thiosemicarbazones possessing electron-donating and electron-withdrawing groups were prepared, and their spectral characteristics determined. In all cases, the spectra showed that one isomer was formed, allowing further functionalization to molecules of biological interest. We provide NMR data for some of the thiosemicarbazones and semicarbazones. We also provide evidence that for 2-pyridyl thi...

nowadays nmr spectroscopy becomes a powerful tool in chemistry because of the nmr chemical shifts. hartree–fock theory and the gauge-including atomic orbital (giao) methods are used in the calculation of 29si nmr chemical shifts of various silicate species in the silicate solution as initial components for zeolite synthesis both in gas and solution phase. calculations have been performed at geo...

Dihydroxybenziphthalocyanine 1, with bulky aryloxy groups, has been synthesized and characterized by X-ray crystallography, NMR and UV/Vis-NIR spectroscopy, and theoretical calculations. Macrocycle 1 is the first example of an aromatic benziphthalocyanine with an 18π-electron structure, and was found to exist as an equilibrium mixture of weakly aromatic and strongly aromatic tautomers. The arom...

Nitrous oxide (N2O) is known as an important "greenhouse gas" but also a scavenger of hydrated electron and a source of OH radical. While there has been considerable interesting research on the electron attachment to N2O in the gas phase, the presence of solvent molecules will significantly alter the electron affinity, molecular structure and chemical reactivity of N2O. Ab initio calculations o...

in this work, we investigated the stability of molybdate-phosphonic acid (mpa) complex by density functionaltheory (dft) computations in six solvents with the dielectric constant ranging from 1.92 to 10.36. the methodsare used for calculations are b3lyp and b3pw9 i that have been studied in two series of basis sets: d95nand6-31+g (d,p) for hydrogen and oxygen atoms; lanl2dz for mo and phosphoru...