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Dihedral angle

About: Dihedral angle is a research topic. Over the lifetime, 15718 publications have been published within this topic receiving 174904 citations.


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TL;DR: The platinum-II complex [{cis-Pt(NH3)2(9EtG-κN7)}2(µ-pz)][NO3]3·4H2O 2 (pz = pyrazolate, 9EtGs = 9-ethylguanine) was prepared from [{ cis-pt(nh3]2}2{2( µ-OH)µpz]2 1 1 and 9 EtG and was characterized by 1H and 195Pt
Abstract: The platinum(II) complex [{cis-Pt(NH3)2(9EtG-κN7)}2(µ-pz)][NO3]3·4H2O 2 (pz = pyrazolate, 9EtG = 9-ethylguanine) was prepared from [{cis-Pt(NH3)2}2(µ-OH)(µ-pz)][NO3]2 1 and 9EtG. It was characterized by 1H and 195Pt NMR, and a crystal structure determination was performed. All 1H NMR chemical shifts from the 9EtG ligands are observed at higher fields compared with those of free 9EtG, which is ascribed to their stacking interaction. The two 9EtG ligands are in a head-to-head orientation, and two intramolecular hydrogen bonds are observed between the ammine ligands and O6 oxygen atoms of the 9EtG ligands. The dihedral angle between the guanine planes is 10.8°, and the average distance is 3.89 A.

55 citations

Journal ArticleDOI
TL;DR: In this article, the authors carried out molecular-dynamics simulations with holonomic dihedral angle constraints on two models of n-butane in CCl4 and in water to study the effects of apolar and polar solvents on the gauche-trans equilibrium.
Abstract: We have carried out molecular‐dynamics simulations with holonomic dihedral angle constraints on two models of n‐butane in CCl4 and in water to study the effects of apolar and polar solvents on the gauche‐trans equilibrium. We calculated distributions of conformers from the torsional free‐energy surfaces for each model of butane in both solvents. For a four‐atom model of butane, the gauche‐trans equilibrium constant in either solvent is unchanged relative to its gas‐phase value. For an all‐atom model of butane, the equilibrium population of gauche conformers is increased relative to its gas‐phase value by 14% and 31% in CCl4 and water, respectively. The all‐atom results are consistent with the idea of solvophobic stabilization of the gauche conformation. We also computed finite‐difference temperature derivatives of the free energy to determine its energetic and entropic components. The gauche conformer of the four‐atom model is stabilized by entropy and destabilized by energy in CCl4. We find the opposite thermodynamic driving forces for the all‐atom model in CCl4. The gauche conformer is favored entropically and opposed energetically for both models in water. This result supports the idea that the butane hydrophobic effect is a manifestation of the hydrophobic interaction. Average interaction energies show that changes in solute–solvent interactions contribute significantly to the trans‐gauche internal energy differences in CCl4, while the internal energy differences in water are dominated by changes in the solvent–solvent interactions. Solvent–solute radial distribution functions show that CCl4 packing around the butane molecular is similar to that around other CCl4 molecules, and it is not sensitive to the butane conformation. The water distributions around the butane molecule are very flat, but they show that the water is more disordered around the gauche conformer than the trans.

55 citations

Journal ArticleDOI
TL;DR: In this article, the optimized structural parameters (bond lengths, bond and dihedral angles), normal mode frequencies and corresponding vibrational assignments of 4-pypp (C 9 H 18 N 2 ) have been theoretically examined by means of B3LYP density functional method with 6-31G(d) basis set.

55 citations

Journal ArticleDOI
TL;DR: The results evidenced a cooperative fixation of Cu(2+) ions when considering the complexation of two successive metal ions on the two consecutive glucosamine residues of the dimer A-A.

55 citations

Journal ArticleDOI
TL;DR: In this article, Ab initio optical rotations have been obtained for allene, 1,3-dichloroallene, H 2 O 2, and H 2 S 2 as a function of dihedral angles, both at SCF and post-SCF levels.

55 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023203
2022473
2021160
2020195
2019193
2018216