Studies using chemical structure

Figure I. Flow chart of steps involved in structure-activity studies using chemical structure information handling and pattern recognition techniques...

MOPAC is a general-purpose semiempirical molecular orbital program for the study of chemical structures and reactions. It is available in desktop PC running Windows, Macintosh OS, and Unix-based workstation versions. It uses semiempirical quantum mechanical methods that are based on Hartree-Fock (HF) theory with some parameterized functions and empirically determined parameters replacing some sections of the complete HF treatment. The approximations in... 

M. A. C. Nascimento, Studies on Chemical Structure, Spectroscopy and Electron Scattering Using Generalized Multistructural Wavefunctions, in Quantum Systems in Chemistry and Physics, R. McWeeny, J. Maruani, Y. G. Smeyers and S. Wilson Ed., Kluwer, Dordrecht, 1997... 

The last decade witnessed a dramatic growth in the use of energetic beam techniques to elucidate the electronic structures of atoms and molecules. Photon, electron, and ion spectroscopies applied to solids gave birth to a new level of surface sensitivity for studies of chemical structure and bonding. The time was right to provide a benchmark for the state of current knowledge and future possibilities in the field. 

Studies of Chemical Structure-Biological Activity Relations Using Pattern Recognition... 

Theoretical chemistry is the discipline that uses quantum mechanics, classical mechanics, and statistical mechanics to explain the structures and dynamics of chemical systems and to correlate, understand, and predict their thermodynamic and kinetic properties. Modern theoretical chemistry may be roughly divided into the study of chemical structure and the study of chemical dynamics. The former includes studies of (1) electronic structure, potential energy surfaces, and force fields (2) vibrational-rotational motion and (3) equilibrium properties of condensed-phase systems and macromolecules. Chemical dynamics includes (1) bimolecular kinetics and the collision theory of reactions and energy transfer (2) unimolecular rate theory and metastable states and (3) condensed-phase and macromolecular aspects of dynamics. 

Jurs, P. C., Chou, J. T. and Yuan, M. (1979). Studies of chemical structure-biological activity relations using pattern recognition. In Computer-Assisted Drug Design. 

NMR spectroscopy along with and combined with other physicochemical methods is widely used to study the chemical structures of thienothiophenes and their hetero-analogues. In the study (82CS75), CNDO/2 calculations were carried out for selenophene and [2,3-Z>]-, [3,2-ft]- and [3,4-Z)]-annulated selenolothiophenes 143,144,146 and 149-151. Correlations between the calculated electron density and experimental Se NMR chemical shifts in the spectra of these compounds were revealed. The chemical shifts were demonstrated to depend substantially on both the total and 71-electron density on the selenium atom. 

Computer-Assisted Studies of Chemical Structure and Olfactory Quality Using Pattern Recognition Techniques... 

C-NMR spectroscopy was used extensively to investigate the chemical structures of phenolic resins (11,15-18) and related model compounds (17-19). These studies provided useful information on the complex chemical structure of PF resins. C-NMR spectroscopy was also used to study the chemical structure and to determine the copolymer composition of novolac resins prepared from 2-methylphenol, 3-methylphenol or 4-methylphenol (20,21) or from mixtures of... 

Chen et al. (2007) used FTIR to study the chemical structure of Nafion membranes before and after Fenton s test. After Fenton s test, a very weak absorption at 1434 cm is evident and assigned to a... 

In this third edition, the general plan of the previous editions has been retained in order to provide a book that covers in one volume those aspects of vibrational spectroscopy that a chemical spectroscopist will find useful in the study of chemical structure or composition. This includes introductory theory of vibrational and rotational spectra, basic infrared instrumental components and experimental techniques, quantitative analysis, the use of symmetry in vibrational spectroscopy, and a detailed example of theoretical vibrational analysis. The most extensive part of this book (Chapters 4-13) is an in-depth study of group frequency correlations and how to use them in spectral interpretation. 

In this study (Deeb and Goodarzi, 2010), a data set of 46 non-peptide HIV-1 protease inhibitors and their inhibitory activity reported by Tummino et al. (Tummino et al. 1996) are used in this study. Molecular chemical structure was built using Hyperchem. AMI method was applied to optimize the molecular structure of the compounds. All calculations were carried out at the restricted Hartree-Fock level with no configuration interaction. The... 

The structures of three bacillomycins D, F and L have been completely established as (59), (58) and (60) respectively. All of them contained the characteristic iturinic acids and seven a-amino acids. The sequence of amino acids was studied using chemical methods, in particular Edman degradation of the product obtained by specific cleavage of the peptide moiety with N-bromosuccinimide. Confirmatory results were obtained by chemical ionisation (isobutane) mass spectrometry and various techniques of NMR spectroscopy. The exact molecular weights of the various species were obtained by FAB mass spectrometry 146, 147) (see Table 7). 

To study the chemical structure of the interface, with the help of XPS method, a layer of Bap2 1 nm thick was grown at a substrate temperature 780°C. The spectra of Si-Bap2 specimen were obtained using Al K line as the source of radiation spectra were acquired with 0.6 eV resolution with analyzer inclination 20° and 70° off the normal to the sample surface in order to vary the effective depth of analysis. 

Serrano-P rez, J., Olaso-Gonzalez, G., Merchan, M.> Serrano-Andres, L. (2009). Singlet oxygen generation in PUVA therapy studied using electronic structure calculations. Chemical Physics, 360, 85-96. 

Kruppa, G. H. Schoeniger, J. Young, M. M. A top down approach to protein structural studies using chemical cross-linking and Former transform mass spectrometry. Rapid Common. Mass Spectrom. 2003, 17, 155-162. 

The study used a structured approach based on experience with carrying out similar studies within the chemical/petrochemical industry to identify the hazards, evaluate the risk, and to identify practical risk reduction measures. 

Inelastic scattering processes are not used for structural studies in TEM and STEM. Instead, the signal from inelastic scattering is used to probe the electron-chemical environment by interpreting the specific excitation of core electrons or valence electrons. Therefore, inelastic excitation spectra are exploited for analytical EM. 

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