Molecular structures from

W. A. Wilson and D. C. Grimm, Molecular Structures from Polymerisation and Vulcanisation, Southern Rubber Group, Knoxville, Term., 1994. 

Knowing the substitution pattern of both benzene rings A and B, one can deduce the molecular structure from the CH connectivities of the CH COSY and CH COLOC plots. The interpretation of both experiments leads firstly to the correlation Table 41.1. 

As already explained in the relevant section, the use of X-ray crystallography (Section V,D,2), the possibility to determine the molecular structure from powder diffraction without the need to obtain monocrystals, and the many variants of solid-state NMR (Section VI,F) have profoundly enhanced the study of tautomerism in the solid state. 

The ligand used for determination of nonspecific binding has a different molecular structure from the tracer ligand. 

Poly(p-pheny lene)s, PPPs, constitute the prototype of rigid-rod polymers and are currently being intensively investigated [1]. The key role of PPPs follows from their conceptually simple and appealing molecular structure, from their chemical stability, and from their superior physical properties [2], In turn, this is the result of important advances made in aromatic chemistry over the last few years. The following section gives an overview of the most common methods to generate poly(p-phenylene)s via different synthetic approaches. 

The identification of a molecular structure from a mass spectrum requires good chemical detective work. Let s see how that is done by trying to identify a simple compound,... 

One is purely formal, it concerns the departure from symmetry of an approximate solution of the Schrodinger equation for the electrons (ie within the Bom-Oppenheimer approximation). The most famous case is the symmetry-breaking of the solutions of the Hartree-Fock equations [1-4]. The other symmetry-breaking concerns the appearance of non symmetrical conformations of minimum potential energy. This phenomenon of deviation of the molecular structure from symmetry is so familiar, confirmed by a huge amount of physical evidences, of which chirality (i.e. the existence of optical isomers) was the oldest one, that it is well accepted. However, there are many problems where the Hartree-Fock symmetry breaking of the wave function for a symmetrical nuclear conformation and the deformation of the nuclear skeleton are internally related, obeying the same laws. And it is one purpose of the present review to stress on that internal link. 

The increased interest in 3D aspects of organic chemistry and quantitative structure-activity relationship (QSAR) studies has caused an increasing need for a much broader access to 3D molecular structures from experiment or calculation. 

Molecular structures from mass-spectral fragmentation patterns... 

The molecular structures from electron diffraction of zinc dichloride, zinc dibromide, and zinc diiodide have been reinvestigated.612 The important effects halides have on geometry have also been investigated, in particular the changes from octahedral to tetrahedral geometry in the presence of chloride ions have been studied.613... 

Costain, C. C. Determination of molecular structures from ground state... 

This sub-problem considers the pure component properties. This sub-problem is also a function of binary variables alone (because these constraints only handle primary structure based properties). The feasible molecular structures from Subproblem 1 are solved for the pure component properties. Those molecules, which satisfy the pure component property constraints, are then passed into subproblem 3. 

Drablos, F. Anal. Chim. Acta 256, 1992, 145-151. Transformation of mass spectra. Elyashberg, M. E., Blinov, K. A., Molodtsov, S. G., Smumyi, E. D. J. Anal. Chem. 63, 2008, 13-20. New computer-assisted methods for the elucidation of molecular structures from 2-D spectra. 

Molecular spectroscopy provides a means of detecting single compounds sometimes even in complex mixtures and of deducing information about the molecular structure from the spectra of pure compounds. In the case of homocyclic sulfur molecules, however, only a few spectroscopic techniques can be successfully applied. 

Hendrickson, W. A. (1991). Determination of macro-molecular structures from anomalous diffraction of synchrotron radiation. Science 254, 51-58. 

Certain mathematical techniques can determine molecular structure from X-ray diffraction images, such as this X-ray diffraction image of a protein. [Alfred Pasleka/Photo Researchers, Inc.]... 

Partial least squares regression analysis (PLS) has been used to predict intensity of sweet odour in volatile phenols. This is a relatively new multivariate technique, which has been of particular use in the study of quantitative structure-activity relationships. In recent pharmacological and toxicological studies, PLS has been used to predict activity of molecular structures from a set of physico-chemical molecular descriptors. These techniques will aid understanding of natural flavours and the development of synthetic ones. 

Click on the Convert SMILES button to perform the conversion of the linear SMILES strings into 3D coordinates (SDF format). To browse automatically, click the Start Visualizer button for the systematic viewing of the 3D molecular structures from the chemical library (Fig. 18.3). 

Molecular Structures from Ultrafast Coherence Spectroscopy, P. M. Felker and A. H. Zewail, in Femtosecond Chemistry, J. Manz and L. Woste, Eds., Verlag Chemie, New York, 1994. 

The ingenuity and effective logic that enabled chemists to determine complex molecular structures from the number of isomers, the reactivity of the molecule and of its fragments, the freezing point, the empirical formula, the molecular weight, etc., is one of the outstanding triumphs of the human mind. ... 

What information can we derive about molecular structure from the vibrational bands of infrared spectra Absorption of radiation in the range of 5000-1250 cm-1 is characteristic of the types of bonds present in the molecule, and corresponds for the most part to stretching vibrations. For example, we know that the C—H bonds of alkanes and alkyl groups have characteristic absorption bands around 2900 cm-1 an unidentified compound that shows absorption in this region will very likely have alkane-type C—H bonds. 

Films formed by y-APS deposited onto inorganic substrates from aqueous acidified solutions have a different molecular structure from those deposited at... 

The determination of a molecular structure from X-ray diffraction data is of critical importance to modem chemical and biological sciences. For small molecules, the structure is normally determined by direct methods. The X-ray diffraction pattern resulting from the interaction of X-rays with the electron clouds of different elements gives a pattern from which the elements present and their connectivity may be deduced. The expected diffraction pattern calculated for an apparent structure is then compared with the observed data to refine the result. Refinement factors (usually expressed as Rw) of 1-3% are common in modem small molecule structure determinations. 

Lautz, J., Kessler, H., Blaney, J. M., Scheek, R. M. and Van Gunsteren, W. F. (1989) Calculating three-dimensional molecular structure from atom-atom distance information cyclosporin A. Ini. J. Pept. Protein. Res. 33, 281-288. 

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