ChemInform Abstract: INVESTIGATION OF FACTORS AFFECTING CONFORMATIONAL PREFERENCE IN COMPLEX HALOETHANE DERIVATIVES BY CLASSICAL ENERGY CALCULATIONS

1973 ◽  
Vol 4 (45) ◽  
pp. no-no
Author(s):  
WILLIAM F. REYNOLDS ◽  
DONALD J. WOOD
Keyword(s):  
Conformational Preference ◽  
Factors Affecting ◽  
Energy Calculations ◽  
Classical Energy

Investigation of Factors Affecting Conformational Preference in Complex Haloethane Derivatives by Classical Energy Calculations

1973 ◽  
Vol 51 (16) ◽  
pp. 2659-2670 ◽  
Author(s):  
William F. Reynolds ◽  
Donald J. Wood
Keyword(s):  
Solvation Energy ◽  
Coupling Constants ◽  
Conformational Preference ◽  
Factors Affecting ◽  
Energy Calculations ◽  
Vicinal Coupling Constants ◽  
Classical Energy ◽  
Dipole Interactions ◽  
Related Compounds ◽  
Good Agreement

Classical energy calculations are used in combination with Abraham's electrostatic theory of solvation energy to estimate rotamer energy differences for haloethane derivatives. The calculations are tested by comparing experimental and calculated ΔE values for several di- and tetrahaloethanes. There is good agreement for chloro and bromo derivatives but poorer agreement for fluoro and iodo derivatives. ΔE values in solution are also estimated for l4 complex chloro- and bromoethanes which we have previously investigated by n.m.r. spectroscopy. The calculations generally parallel the experimental results as reflected by vicinal coupling constants. They are particularly useful for trends in conformational preference for closely related compounds and are used in conjunction with vicinal coupling constants to identify diastereomers produced by halogenation of alkenes. Steric interactions, dipole–dipole interactions and solvation energy are all important in determining conformational preference for complex haloethanes in solution.

scholarly journals Effects of charge states, charge sites and side chain interactions on conformational preferences of a series of model peptide ions

The Analyst ◽  
2015 ◽  
Vol 140 (20) ◽  
pp. 6933-6944 ◽  
Author(s):  
Chunying Xiao ◽  
Lisa M. Pérez ◽  
David H. Russell
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Gas Phase ◽  
Dynamics Simulation ◽  
Side Chain ◽  
Peptide Ions ◽  
Conformational Preference ◽  
Model Peptide ◽  
Factors Affecting ◽  
Conformational Preferences

The factors affecting conformational preference of gas phase peptide ions are investigated by IM-MS and molecular dynamics simulation.

Factors Affecting the Conformational Preference and Magnetic Shielding of Isobutenylene Chains in Macrocyclic Salicylideneaniline Derivatives

2003 ◽  
Vol 76 (12) ◽  
pp. 2405-2411 ◽  
Author(s):  
Hirohiko Houjou ◽  
Seiji Tsuzuki ◽  
Yoshinobu Nagawa ◽  
Masatoshi Kanesato ◽  
Kazuhisa Hiratani
Keyword(s):  
Magnetic Shielding ◽  
Conformational Preference ◽  
Factors Affecting

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

The annealed (0001) α-alumina surface and its influence on thin-film growth

1995 ◽  
Vol 53 ◽  
pp. 336-337
Author(s):  
Michael W. Bench ◽  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Surface Energy ◽  
Film Growth ◽  
Thin Film Growth ◽  
Energy Calculations ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Low Energy Electron ◽  
Surface Nature

The growth of semiconductors, superconductors, metals, and other insulators has been investigated using alumina substrates in a variety of orientations. The surface state of the alumina (for example surface reconstruction and step nature) can be expected to affect the growth nature and quality of the epilayers. As such, the surface nature has been studied using a number of techniques including low energy electron diffraction (LEED), reflection electron microscopy (REM), transmission electron microscopy (TEM), molecular dynamics computer simulations, and also by theoretical surface energy calculations. In the (0001) orientation, the bulk alumina lattice can be thought of as a layered structure with A1-A1-O stacking. This gives three possible terminations of the bulk alumina lattice, with theoretical surface energy calculations suggesting that termination should occur between the Al layers. Thus, the lattice often has been described as being made up of layers of (Al-O-Al) unit stacking sequences. There is a 180° rotation in the surface symmetry of successive layers and a total of six layers are required to form the alumina unit cell.

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