Topic
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: V vibrational spectroscopy is introduced as a suitable tool for the structure analysis of peptides in solution and tripeptides as suitable model systems for investigating the role of local interactions in determining the propensity of peptide segments for distinct secondary structure motifs.
93 citations
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TL;DR: In this article, two Schiff base compartmental ligands derived from the condensation of 3-ethoxysalicylaldehyde with 1,2-diaminocyclohexane and orthophenylenediamine, respectively, were used to isolate two diphenoxo-bridged discrete dinuclear Cu I I Gd I I I complexes.
Abstract: Two Schiff base compartmental ligands, H 2 L 1 and H 2 L 2 , derived from the condensation of 3-ethoxysalicylaldehyde with 1,2-diaminocyclohexane and orthophenylenediamine, respectively, have been utilized to isolate two diphenoxo-bridged discrete dinuclear Cu I I Gd I I I complexes, [Cu I I (H 2 O)-L 1 Gd I I I (NO 3 ) 3 ] (3) and [Cu I I L 2 Gd I I I (NO 3 ) 3 ] (4). This is the first report on the 3d-4f compounds derived from compartmental Schiff base ligands with cyclic diamines. The compounds 3 and 4 crystallize in the triclinic Pi and orthorhombic Pna2(1) space groups, respectively, with the following unit cell parameters - 3: a = 8.8713(2) A, b = 12.8399(3) A, c = 14.0067(3) A, a = 80.6649(5)°, β = 77.4059(5)°, γ = 76.8879(5)°, and Z = 2; 4: a = 9.2210(1) A, b = 16.5407(2) A, c = 19.9248(4) A, and Z = 4. Structural analysis reveals that both are discrete dinuclear complexes. In 3, one water molecule is coordinated to the copper(II) ion to result in a square-pyramidal coordination geometry, while the geometry of the coppe(II) center in 4 is square planar. In both complexes, the gadolinium(III) center has an O 1 0 coordination environment. In contrast to expectation, although the N 2 O 2 cavity affords a better planar environment for the copper(II) center in 4, the bridging moiety in complex 3 is more planar than that in 4 or in most of the previously reported examples (the dihedral angle between two CuO 2 Gd planes: 2.1° for 3 and 7.1° for 4). Variable-temperature and variable-field magnetic measurements reveal that the metal centers in both the complexes are ferromagnetically coupled (J values: 6.3 cm - 1 for 3 and 5.4 cm - 1 for 4; H = -2JS C u .S G d ). Interestingly, complex 3 exhibits strongest ferromagnetic interaction among the related compounds.
93 citations
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TL;DR: A modification is described that completely eliminates problems by replacing the original potential surfaces by a sum of multidimensional Gaussian functions and structures refined with the new Gaussian implementation now simultaneously enjoy excellent global sampling and excellent local choices of torsion angles.
93 citations
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TL;DR: The hypothesis that conventional molecular dynamics simulations can be used to predict the yield of cyclobutane pyrimidine dimer formation is explored and the mean dimerizable structure computed by averaging all of theDimerizable cis-syn conformations is structurally similar to the actual cis- syn dimer.
93 citations
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TL;DR: The energy storage and the molecular rearrangements due to the primary photochemical event in rhodopsin are investigated by using quantum mechanics/molecular mechanics hybrid methods in conjunction with high-resolution structural data of bovine visual r Rhodopsin to develop a first-principles understanding of the structure-function relations in prototypical G-protein-coupled receptors.
93 citations