Vibrational spectroscopy and conformational

Krimm S, Bandekar J. Vibrational spectroscopy and conformation of peptides, polypeptides and proteins. Adv Protein Chem 1986 38 181-365. 

Vibrational Spectroscopy and Conformation of Peptides, Polypeptides, and Proteins... 

Vibrational spectroscopy and conformational analysis of oligonucleotides 20.3.3 Studies of chromophore-DNA interaction by vibrational spectroscopy... 

K. Ohno, H. Yoshida, H. Watanabe, T. Fujita, and H. Matsuura, Conformational study of 1 butanol by the combined use of vibrational spectroscopy and ab initio molecular orbital calculations. J. Phys. Chem. 98, 6924 6930 (1994). 

Vibrational Spectroscopy and Ultrasonic Absorption, Use of, to Determine the Energies Associated with Conformational Changes... 

Since the oxides do not have to be isolated, the sulfur solution after addition of the peroxyacid solution is simply kept in the refrigerator until S,(, has formed which is then isolated by cooling and recrystallization When both Sg and S g are dissolved in CS and the solution is cooled, then, under special concentration conditions, a new sulfur allotrope crystallizes out as orange-yellow opaque crystals of m.p. 92 °C. This compound has been shown by vibrational spectroscopy and X-ray structural analysis to consist of equal amounts of Sg and molecules in their usual conformations. In solution the mean molecular weight of 258 corresponding to 8 atoms per molecule indicates complete dissociation This is the first example of an allotrope of a chemical element consisting of molecules of different sizes. 

Often, these adducts were characterized by vibrational spectroscopy, and Raman spectroscopic investigations were particularly informative and indicative for the occurrence of E E bonds. Some E E stretching vibrations vE E are summarized in Table I. They nicely show the expected dependency of vE E on the atomic masses of the respective elements and on the masses of the substituents. Some compounds were further characterized by nuclear quadrupole resonance spectroscopy, which gave indications for phase transfer processes and for the extent of electron transfer from the ligands to Ga or In atoms.15,16 Most helpful for the discussion of the constitution and conformation of these subhalides are the results of X-ray... 

Conformational isomerism around the C(2)—C(3) bond could not be observed by NMR due either to a low barrier to interconversion or to the existence of a single conformed This isomerism has been studied in compounds 554 (R1 = H, Me R2 = Me, OMe) by a combination of vibrational spectroscopy and quantum-mechanical calculations134,185,186,193-195. The EE isomer, predicted to be the less stable185,186, has never... 

A complete presentation of all the methods used to determine polymer structure at all these levels is best reserved for technical monographs, hr the present text, three experimental techniques have been selected to illustrate the issues involved in measuring polymer structure. The measurement of primary structure is demonstrated using nuclear magnetic resonance (NMR) spectroscopy. The local conformation of a chain molecule is related to vibrational spectroscopy. And the global conformation of a chain molecule is derived from measurements of the scattering fimction, S q). 

Vibrational Spectroscopy.— The conformational equilibrium in a series of aziridines has been studied through i.r. intensities. Values of Ka ti/avn aziridines (16) and (17) were 1.86 and 3.76 respectively. Analysis of the i.r., far-i.r., and Raman spectra of 1-aziridinylcarboxamide (18) and its rA,V- H2]analogue indicate a planar CCONHg structure. 

Vibrational spectroscopy and, in particular, Raman scattering have been used to elucidate selected interactions of DNAs. The B Z conformational transition of oligo-DNA duplexes and the interaction of the intercalating dye AO with calf thymus DNA have been explicitly analyzed in the preceding sections. 

Reference is made in Chapter 21 to the use of vibrational spectroscopy in conformational analysis of mono- and polysaccharides. 

The use of theoretical and computational methods in 2011 has continued to rise phenomenally in accordance with Moore s law. These methods are covered comprehensively in the second section of the Physical Methods chapter. This year s highlights include confirmation of the four conformations of trimethylphosphite by matrix isolation infrared spectroscopy supported by ab initio calculations. The trimethylphosphite was trapped in a N2/Ar matrix and deposited onto a cold KBr substrate at 12 K for analysis. For the first-time a complete and accurate vibrational frequency assignment was performed on Dimethoate from vibrational spectroscopy and theoretical calculations. Ion Mobility Spectrometry, as a stand-alone technique from Mass Spectrometry, was used in the detection of chemical nerve agents, which also have attracted an increasing use of rapid electrochemical sensors. 

Vibrational spectroscopy has played a very important role in the development of potential functions for molecular mechanics studies of proteins. Force constants which appear in the energy expressions are heavily parameterized from infrared and Raman studies of small model compounds. One approach to the interpretation of vibrational spectra for biopolymers has been a harmonic analysis whereby spectra are fit by geometry and/or force constant changes. There are a number of reasons for developing other approaches. The consistent force field (CFF) type potentials used in computer simulations are meant to model the motions of the atoms over a large ranee of conformations and, implicitly temperatures, without reparameterization. It is also desirable to develop a formalism for interpreting vibrational spectra which takes into account the variation in the conformations of the chromophore and surroundings which occur due to thermal motions. 

In addition to the surface/interface selectivity, IR-Visible SFG spectroscopy provides a number of attractive features since it is a coherent process (i) Detection efficiency is very high because the angle of emission of SFG light is strictly determined by the momentum conservation of the two incident beams, together with the fact that SFG can be detected by a photomultiplier (PMT) or CCD, which are the most efficient light detectors, because the SFG beam is in the visible region, (ii) The polarization feature that NLO intrinsically provides enables us to obtain information about a conformational and lateral order of adsorbed molecules on a flat surface, which cannot be obtained by traditional vibrational spectroscopy [29-32]. (iii) A pump and SFG probe measurement can be used for an ultra-fast dynamics study with a time-resolution determined by the incident laser pulses [33-37]. (iv) As a photon-in/photon-out method, SFG is applicable to essentially any system as long as one side of the interface is optically transparent. 

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