@article {2674,
	title = {Competitive Adsorption of Toluene and n-Alkanes at Binary Solution/Silica Interfaces},
	journal = {Journal of Physical Chemistry C},
	volume = {113},
	number = {47},
	year = {2009},
	note = {ISI Document Delivery No.: 520FMTimes Cited: 2Cited Reference Count: 48Yang, Zheng Li, Qifeng Hua, Rui Gray, Murray R. Chou, Keng C.},
	month = {Nov},
	pages = {20355-20359},
	type = {Article},
	abstract = {The competitive adsorption of toluene and n-alkanes at binary solution/silica interfaces was studied at room temperature using IR-visible sum frequency generation vibrational spectroscopy. The Surface coverage of toluene for toluene-pentane, toluene-heptane, and toluene-tetradecane mixtures was measured over the complete mole fraction range from 0 to 1. The competitive adsorption process was reversible, and the toluene coverage only depended oil the bulk mole fraction, not on the history of the system. The estimated molar adsorption free energy of toluene is 3.4 +/- 0.3, 1.8 +/- 0.3, and 0.84 +/- 0.3 kJ/mol higher than pentane, heptane, and tetradecane, respectively. Overall, toluene competes favorably on silica, and the molar adsorption free energy of alkanes increases as the chain length increases. It is consistent with the observed SFG spectra, indicating that the alkanes lie flat on the silica surface.},
	keywords = {ACCELERATED SOLVENT-EXTRACTION, bitumen, CONFORMATION, FREQUENCY VIBRATIONAL SPECTROSCOPY, H STRETCHING MODES, LIQUID-CHROMATOGRAPHY, NORMAL-ALKYL CHAINS, ORIENTATION, SUM-FREQUENCY, SURFACE},
	isbn = {1932-7447},
	url = {<Go to ISI>://000271826100033},
	author = {Yang, Z. and Li, Q. F. and Hua, R. and Gray, M. R. and Chou, K. C.}
}
@article {1195,
	title = {High yielding synthesis of 3a-hydroxypyrrolo[2,3-b]indoline dipeptide methyl esters: Synthons for expedient introduction of the hydroxypyrroloindoline moiety into larger peptide-based natural products and for the creation of tryptathionine bridges},
	journal = {Journal of Organic Chemistry},
	volume = {70},
	number = {21},
	year = {2005},
	note = {ISI Document Delivery No.: 971SRTimes Cited: 12Cited Reference Count: 33},
	month = {Oct},
	pages = {8424-8430},
	type = {Article},
	abstract = {This work describes a rapid and high yielding oxidation of 14 tryptophanylated amino acid methyl esters to the corresponding 3 alpha-hydroxypyrrolo[2,3-b]indoline (Hpi) amino acids with generally facile separation of syn-cis and anti-cis diastereomers. Structural X-ray diffraction data are presented for both diastereomers of Tr-Hpi-Gly-OMe, which allow for a putative assignment of the other 13 pairs of diastereomers reported herein, based on correlations with H-1 NMR chemical shifts. Selective and high yielding deprotection at either the N or C terminus is described, allowing the Hpi motif to be introduced efficiently into potential targets with minimal protecting group manipulation. Two tripeptides containing Hpi and cysteine were prepared and treated with acid in the Savige-Fontana reaction to produce a cyclic tryptathionine linkage, characteristic of both amatoxins and phallotoxins.},
	keywords = {ANALOGS, ASYMMETRIC EPOXIDATION METHOD, CONFIGURATION, CONFORMATION, CYCLIZATION, CYSTEINE SULFHYDRYL-GROUPS, DERIVATIVES, HIMASTATIN, OXYGENATION, TRYPTOPHAN},
	isbn = {0022-3263},
	url = {<Go to ISI>://000232405500022},
	author = {May, J. P. and Fournier, P. and Pellicelli, J. and Patrick, B. O. and Perrin,David M.}
}
@article {1291,
	title = {Plasticity of influenza haemagglutinin fusion peptides and their interaction with lipid bilayers},
	journal = {Biophysical Journal},
	volume = {88},
	number = {1},
	year = {2005},
	note = {ISI Document Delivery No.: 884MYTimes Cited: 36Cited Reference Count: 72},
	month = {Jan},
	pages = {25-36},
	type = {Article},
	abstract = {A detailed molecular dynamics study of the haemagglutinin fusion peptide (N-terminal 20 residues of the HA2 subunits) in a model bilayer has yielded useful information about the molecular interactions leading to insertion into the lipids. Simulations were performed on the native sequence, as well as a number of mutant sequences, which are either fusogenic or nonfusogenic. For the native sequence and fusogenic mutants, the N-terminal 11 residues of the fusion peptides are helical and insert with a tilt angle of similar to30degrees with respect to the membrane normal, in very good agreement with experimental data. The tilted insertion of the native sequence peptide leads to membrane bilayer thinning and the calculated order parameters show larger disorder of the alkyl chains. These results indicate that the lipid packing is perturbed by the fusion peptide and could be used to explain membrane fusion. For the nonfusogenic sequences investigated, it was found that most of them equilibrate parallel to the interface plane and do not adopt a tilted conformation. The presence of a charged residue at the beginning of the sequence (G1E mutant) resulted in a more difficult case, and the outcomes do not fall straightforwardly into the general picture. Sequence searches have revealed similarities of the fusion peptide of influenza haemagglutinin with peptide sequences such as segments of porin, amyloid ab peptide, and a peptide from the prion sequence. These results confirm that the sequence can adopt different folds in different environments. The plasticity and the conformational dependence on the local environment could be used to better understand the function of fusion peptides.},
	keywords = {ANALOGS, CONFORMATION, HEMAGGLUTININ, MEDIATED MEMBRANE-FUSION, MODEL MEMBRANES, MOLECULAR-DYNAMICS SIMULATION, MULTIPLE ALIGNMENT, RECEPTOR-BINDING, SEQUENCE, VIRAL FUSION, VIRUS},
	isbn = {0006-3495},
	url = {<Go to ISI>://000226090900006},
	author = {Vaccaro, L. and Cross, K. J. and Kleinjung, J. and Straus, S. K. and Thomas, D. J. and Wharton, S. A. and Skehel, J. J. and Fraternali, F.}
}
@article {1040,
	title = {Laser-light-scattering study of internal motions of polymer chains grafted on spherical latex particles},
	journal = {Journal of Physical Chemistry B},
	volume = {108},
	number = {48},
	year = {2004},
	note = {ISI Document Delivery No.: 875JUTimes Cited: 6Cited Reference Count: 35},
	month = {Dec},
	pages = {18479-18484},
	type = {Article},
	abstract = {Using atom-transfer radical polymerization, we have prepared core-shell particles by grafting thermally sensitive poly(N-isopropylacrylamide) (PNIPAM) chains on a spherical polystyrene latex core (with a radius of similar to287 nm) via the "grafting-from" approach. As the temperature increases from 25 degreesC to 35 degreesC, the PNIPAM shell shrinks from a thickness of 625 nm to 110 nm and the chain density near the core increases from 7.3 x 10(-3) g/cm(3) to 7.2 x 10(-2) g/cm(3). Using such core-shell particles, we have, for the first time, been able to study dynamics of long chains anchored on a particle in dilute dispersion by laser-light scattering. Our results showed that, besides the translational diffusion of the particle as a whole, there also exists an additional slow relaxation mode that is only observable at larger scattering vectors (q),which are presumably related to internal motions of the shell. In the fully swollen state, the relaxation rate of the slow motion (<Gamma>(slow)) is insensitive to the observation length (1/q); however, its contribution to the scattering intensity (A(slow)) increases as q increases. In the shrunken state, <Gamma>(slow) slightly decreases as q increases. <Gamma>(slow) can be scaled to the shell thickness (<L>(brush)) as <Gamma>(slow) proportional to <L>(alpha)(brush), with alpha = -2.5 +/- 0.2, which is smaller than the predicated value of 3.},
	keywords = {AQUEOUS ATRP, BRUSHES, CONFORMATION, DYNAMICS, GLOBULE TYPE TRANSITIONS, INTERFACE, LAYERS, MODEL, POLY(N-ISOPROPYLACRYLAMIDE), SIMULATION},
	isbn = {1520-6106},
	url = {<Go to ISI>://000225417200015},
	author = {Yang, C. and Kizhakkedathu, J. N. and Brooks, D. E. and Jin, F. and Wu, C.}
}
@article {449,
	title = {Collision cross sections of gas phase DNA ions},
	journal = {International Journal of Mass Spectrometry},
	volume = {219},
	number = {1},
	year = {2002},
	note = {ISI Document Delivery No.: 591BVTimes Cited: 4Cited Reference Count: 27},
	month = {Aug},
	pages = {161-170},
	type = {Article},
	abstract = {Collision cross sections of negative ions of a 28-, 40- and 55-mer of single stranded DNA have been measured by an energy loss method, and compared to collision cross sections of proteins of nearly the same molecular weight-ubiquitin, cytochrome c and apomyoglobin, respectively. The oligonucleotides produce negative charge states in electrospray ionization (ESI) similar to the positive charge states produced by the proteins denatured in solution. Cross sections for deoxynucleotide ions increase with charge state in a manner similar to those of protein ions. However, for a given molecular weight and charge state, the cross sections of the oligodeoxynucleotide ions are about 22\% lower than those of the proteins. (C) 2002 Elsevier Science B.V. All rights reserved.},
	keywords = {collision cross sections, CONFORMATION, CONFORMERS, DNA ions, ELECTROSPRAY MASS-SPECTROMETRY, gas phase, MYOGLOBIN, PROTEIN IONS, SEQUENCE, VACUUM},
	isbn = {1387-3806},
	url = {<Go to ISI>://000177860600015},
	author = {Moradian, A. and Scalf, M. and Westphall, M. S. and Smith, L. M. and Douglas, D. J.}
}
@article {4469,
	title = {Mobilities of NO+ drifting in helium: A molecular dynamics study},
	journal = {Journal of Chemical Physics},
	volume = {110},
	number = {23},
	year = {1999},
	note = {ISI Document Delivery No.: 200CHTimes Cited: 10Cited Reference Count: 23},
	month = {Jun},
	pages = {11383-11389},
	type = {Article},
	abstract = {A new molecular dynamics (MD) method is introduced, and used to study NO+ ions drifting in helium under the influence of a uniform electric field. Mobilities, average values of squared velocities, and self-diffusion coefficients parallel and perpendicular to the electric field are reported for two recent ab initio potential surfaces: a coupled cluster singles-doubles with perturbative treatment of triple excitations [CCSD(T)] surface [S. K. Pogrebnya et al., Int. J. Mass Spectrom. Ion Processes 149/150, 207 (1995)] and a MP4SDTQ/6-311 + G(2df, p) surface [L. A. Viehland et al., Chem. Phys. 211, 1 (1996)]. Average values of angular momentum and alignment parameters are also reported and compared. In all cases, no significant differences were found in the calculated values for the two different potential surfaces. Finally, mobility values are compared with experimental measurements [J. A. de Gouw et al., J. Chem. Phys. 105, 10398 (1996)] and good agreement is obtained for both potential surfaces. (C) 1999 American Institute of Physics. [S0021-9606(99)51623-1].},
	keywords = {CONFORMATION, ELECTROSTATIC FIELDS, GAS, ION-MOTION, SIMULATION, TRANSPORT, TUBE},
	isbn = {0021-9606},
	url = {<Go to ISI>://000080521200033},
	author = {Baranowski, R. and Thachuk, M.}
}
@article {4227,
	title = {Stability of a highly charged noncovalent complex in the gas phase: Holomyoglobin},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {12},
	number = {15},
	year = {1998},
	note = {ISI Document Delivery No.: 105GATimes Cited: 33Cited Reference Count: 56},
	pages = {1003-1010},
	type = {Article},
	abstract = {Gas phase holomyoglobin (hMb) ions in charge states +7 to +21 were formed by electrospray ionization in combination with a continuous-flow mixing apparatus. Collision cross section measurements show that the highly charged ions are somewhat unfolded in comparison to low charge states but still retain a considerable degree of folding. A new collision model is presented which calculates the relative energies transferred to complexes in tandem mass spectrometry. Tandem mass spectrometry and ion trapping experiments both show that the energies required to dissociate heme from the highly charged heme-protein complexes in the gas phase are similar to those of low charge states, previously shown in literature ion cyclotron resonance experiments to be 0.7-1.0 eV, These energies are comparable to those of the heme binding energy in solution. The results suggest that even for the highly charged hMb ions which have unfolded somewhat, the heme-protein interactions remain relatively unperturbed. (C) 1998 John Wiley \& Sons, Ltd.},
	keywords = {CONFORMATION, CYTOCHROME-C, ELECTROSPRAY-IONIZATION, ion-molecule, IONIZATION MASS-SPECTROMETRY, METMYOGLOBIN, MYOGLOBIN, PROTEIN IONS, PROTON-TRANSFER REACTIVITY, QUADRUPOLE, reaction},
	isbn = {0951-4198},
	url = {<Go to ISI>://000075063300003},
	author = {Chen, Y. L. and Campbell, J. M. and Collings, B. A. and Konermann, L. and Douglas, D. J.}
}
@article {4006,
	title = {Dissociation of heme from myoglobin and cytochrome b(5): Comparison of behavior in solution and the gas phase},
	journal = {Biochemistry},
	volume = {36},
	number = {5},
	year = {1997},
	note = {ISI Document Delivery No.: WG072Times Cited: 79Cited Reference Count: 6144th ASMS Conference on Mass Spectrometry and Allied TopicsMAY 12-16, 1996PORTLAND, ORASMS},
	month = {Feb},
	pages = {1018-1025},
	type = {Proceedings Paper},
	abstract = {The relationship of the structure of a protein in solution to the structure of a gas-phase protein ion and the manner in which gas-phase protein ions bind small molecules noncovalently are topics of current debate. To address these issues, the stability of heme binding to wild-type and variant forms of apomyoglobin and apocytochrome bs has been studied in the gas phase by electrospray mass spectrometry (ES-MS) and compared with the stability of heme binding to the same proteins in solution. The voltage required to dissociate ions of the heme-protein complexes in the orifice-skimmer region of an electrospray mass spectrometer, a measure of the complex stability, is found to be correlated with the activation energy for dissociation of the complexes in solution across a series of proteins in which the number of hydrogen bonds between the heme propionate groups and surface residues is systematically reduced. However, variants in which the hydrogen bonds to the proximal histidine have been removed are destabilized in solution but stabilized in the gas-phase ions. These results suggest that on the millisecond time scale of the ES-MS experiment, the gas-phase protein ion may retain much of the structure of the protein in solution, at least for those residues surrounding the heme group. Furthermore, the ability of ES-MS to detect relatively subtle differences in protein-small molecule complex stability demonstrated in this work suggests that this technique may be a convenient, sensitive, and generally useful strategy for physical characterization of such complexes.},
	keywords = {ATMOSPHERIC-PRESSURE, CONFORMATION, ELECTROSPRAY MASS-SPECTROMETRY, FEATURES, IONIZATION, LARGE MOLECULES, NONCOVALENT INTERACTIONS, PROTEIN IONS, REORIENTATION, STABILITY},
	isbn = {0006-2960},
	url = {<Go to ISI>://A1997WG07200006},
	author = {Hunter, C. L. and Mauk, A. G. and Douglas, D. J.}
}
@article {3675,
	title = {Crystal structure-reactivity relationships in the solid state photochemistry of 2,4,6-triisopropylthiobenzophenone: C=O...H versus C=S...H abstraction geometry},
	journal = {Tetrahedron Letters},
	volume = {37},
	number = {13},
	year = {1996},
	note = {ISI Document Delivery No.: UC590Times Cited: 6Cited Reference Count: 19},
	month = {Mar},
	pages = {2125-2128},
	type = {Article},
	abstract = {X-ray crystal structure solid state photoreactivity correlations are reported for 2,4,6-triisopropylthiobenzophenone (1a) and its p-methoxy derivative 1b. The results reveal interesting differences in the geometry of gamma-hydrogen atom abstraction for ketones and thiones.},
	keywords = {2, 4, 6-TRIISOPROPYLBENZOPHENONES, CONFORMATION, KETONES, PHOTOCYCLIZATION, TRIPLET-STATES},
	isbn = {0040-4039},
	url = {<Go to ISI>://A1996UC59000003},
	author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.}
}
@article {3675,
	title = {Crystal structure-reactivity relationships in the solid state photochemistry of 2,4,6-triisopropylthiobenzophenone: C=O...H versus C=S...H abstraction geometry},
	journal = {Tetrahedron Letters},
	volume = {37},
	number = {13},
	year = {1996},
	note = {ISI Document Delivery No.: UC590Times Cited: 6Cited Reference Count: 19},
	month = {Mar},
	pages = {2125-2128},
	type = {Article},
	abstract = {X-ray crystal structure solid state photoreactivity correlations are reported for 2,4,6-triisopropylthiobenzophenone (1a) and its p-methoxy derivative 1b. The results reveal interesting differences in the geometry of gamma-hydrogen atom abstraction for ketones and thiones.},
	keywords = {2, 4, 6-TRIISOPROPYLBENZOPHENONES, CONFORMATION, KETONES, PHOTOCYCLIZATION, TRIPLET-STATES},
	isbn = {0040-4039},
	url = {<Go to ISI>://A1996UC59000003},
	author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.}
}
@article {3763,
	title = {Driving forces for DNA adsorption to silica in perchlorate solutions},
	journal = {Journal of Colloid and Interface Science},
	volume = {181},
	number = {2},
	year = {1996},
	note = {ISI Document Delivery No.: UZ536Times Cited: 112Cited Reference Count: 43},
	month = {Aug},
	pages = {635-644},
	type = {Article},
	abstract = {The adsorption of both plasmid and chromosomal duplex DNA to silica is investigated with the aim of determining the dominant forces involved in the binding reaction. Changes in the initial slopes and plateau values of adsorption isotherms for DNA on microcrystalline silica particles are used to establish the sensitivity of the binding reaction to ionic strength, temperature and pH, and DNA size and conformation. Binding is driven by an increase in entropy, with little or no enthalpic contribution. Adsorption isotherm results indicate that three effects, namely: (i) shielded intermolecular electrostatic forces, (ii) dehydration of the DNA and silica surfaces, and (iii) intermolecular hydrogen bond formation in the DNA-silica contact layer, make the dominant contributions to the overall driving force for adsorption. (C) 1996 Academic Press, Inc.},
	keywords = {adsorption isotherms, ARRAYS, CHIPS, CONFORMATION, DNA, DNA adsorption, DNA binding, DNA PURIFICATION, DNA-silica interactions, ELECTROPHORESIS, GLOBULAR-PROTEINS, PLASMID DNA, PURIFICATION, SURFACES, TRANSITION},
	isbn = {0021-9797},
	url = {<Go to ISI>://A1996UZ53600031},
	author = {Melzak, K. A. and Sherwood, C. S. and Turner, R. F. B. and Haynes, C. A.}
}
@article {3687,
	title = {Geometric requirements for hydrogen abstractability and 1,4-biradical reactivity in the Norrish/Yang type II reaction: Studies based on the solid state photochemistry and X-ray crystallography of medium-sized ring and macrocyclic diketones},
	journal = {Journal of the American Chemical Society},
	volume = {118},
	number = {26},
	year = {1996},
	note = {ISI Document Delivery No.: UV292Times Cited: 41Cited Reference Count: 76},
	month = {Jul},
	pages = {6167-6184},
	type = {Article},
	abstract = {The Norrish/yang type II photochemistry of ten even-numbered cyclic diketones ranging in ring size from 10-membered to 26-membered has been studied in the crystalline state as well as in solution, In the solid state, the diketones undergo stereoselective cyclobutanol formation in which the cis or trans ring fusion stereochemistry of the photoproducts is governed by the conformation of the diketone present in the crystal as determined by X-ray crystallography. The reactive gamma-hydrogen atoms are identified and the distance and angular parameters associated with their abstraction are derived from the crystallographic data. For the most part, the abstractions occur through boatlike rather than chairlike six-atom geometries, and the average value of d, the C=O ... H abstraction distance, for 16 reactive gamma-hydrogens was found to be 2.74 +/- 0.04 Angstrom; the average values of the angular parameters omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H-gamma angle), and theta (the C-H gamma ... O angle) are 53 +/- 5 degrees, 83 +/- 4 degrees, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that both the pre-cis and pre-trans biradicals are poorly aligned for cleavage but are well oriented for closure, with radical separations of 3.1-3.2 Angstrom. For four of the diketones, the solid state photoproduct ratios were found to be temperature dependent as a result of enantiotropic phase transitions. For two of the diketones, the high-temperature, metastable phases were characterized by solid state C-13 and H-2 NMR spectroscopy. Crystals of 1,14-cyclohexacosanedione were found to be dimorphic, and the conformation adopted by the macrocycle is very different in the two dimorphs. As a result, irradiation of one of the dimorphs leads to cis-cyclobutanol and photolysis of the other gives trans, a particularly clear demonstration of the effect of conformational polymorphism on solid state chemical reactivity. Overall, the solid state results indicate that the product distribution is determined by the relative rates of forward rather than reverse hydrogen atom transfer and that the biradicals react in a least-motion, conformation-specific manner. In solution, on the other hand, the photoreaction is ring size-dependent, resembling the solid state results for the 12- and 14-membered-ring diketones, and consisting mainly of type II elimination accompanied by reduced amounts of nonstereoselective cyclobutanol formation for the 16-26-membered-ring compounds. It is suggested that this ring size dependence stems from the relative conformational freedom of the intermediate 1,4-biradicals in the fluid medium-motions that are slow compared to closure for the 12- and 14-membered rings, but that permit alignment for biradical cleavage and alternative modes of closure in the {\textquoteright}{\textquoteright}floppier{\textquoteright}{\textquoteright} 16-membered and larger rings. The one exception to the above generalizations is 1,6-cyclodecanedione, which was found to be photochemically inert both in the solid state and solution despite having a crystal conformation favorable for type II photochemistry. Possible reasons for this behavior are presented and discussed.},
	keywords = {ATOM TRANSFERS, C-H...O, CONFORMATION, CYCLOALKANONES, CYCLODODECANONE, CYCLOHEXADECANE, MOLECULAR MECHANICS METHODOLOGY, PHENYL KETONES, PHOTOPROCESSES, TRANSITION STRUCTURES},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1996UV29200012},
	author = {Gudmundsdottir, A. D. and Lewis, T. J. and Randall, L. H. and Scheffer, J. R. and Rettig, S. J. and Trotter, J. and Wu, C. H.}
}
@article {3687,
	title = {Geometric requirements for hydrogen abstractability and 1,4-biradical reactivity in the Norrish/Yang type II reaction: Studies based on the solid state photochemistry and X-ray crystallography of medium-sized ring and macrocyclic diketones},
	journal = {Journal of the American Chemical Society},
	volume = {118},
	number = {26},
	year = {1996},
	note = {ISI Document Delivery No.: UV292Times Cited: 41Cited Reference Count: 76},
	month = {Jul},
	pages = {6167-6184},
	type = {Article},
	abstract = {The Norrish/yang type II photochemistry of ten even-numbered cyclic diketones ranging in ring size from 10-membered to 26-membered has been studied in the crystalline state as well as in solution, In the solid state, the diketones undergo stereoselective cyclobutanol formation in which the cis or trans ring fusion stereochemistry of the photoproducts is governed by the conformation of the diketone present in the crystal as determined by X-ray crystallography. The reactive gamma-hydrogen atoms are identified and the distance and angular parameters associated with their abstraction are derived from the crystallographic data. For the most part, the abstractions occur through boatlike rather than chairlike six-atom geometries, and the average value of d, the C=O ... H abstraction distance, for 16 reactive gamma-hydrogens was found to be 2.74 +/- 0.04 Angstrom; the average values of the angular parameters omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H-gamma angle), and theta (the C-H gamma ... O angle) are 53 +/- 5 degrees, 83 +/- 4 degrees, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that both the pre-cis and pre-trans biradicals are poorly aligned for cleavage but are well oriented for closure, with radical separations of 3.1-3.2 Angstrom. For four of the diketones, the solid state photoproduct ratios were found to be temperature dependent as a result of enantiotropic phase transitions. For two of the diketones, the high-temperature, metastable phases were characterized by solid state C-13 and H-2 NMR spectroscopy. Crystals of 1,14-cyclohexacosanedione were found to be dimorphic, and the conformation adopted by the macrocycle is very different in the two dimorphs. As a result, irradiation of one of the dimorphs leads to cis-cyclobutanol and photolysis of the other gives trans, a particularly clear demonstration of the effect of conformational polymorphism on solid state chemical reactivity. Overall, the solid state results indicate that the product distribution is determined by the relative rates of forward rather than reverse hydrogen atom transfer and that the biradicals react in a least-motion, conformation-specific manner. In solution, on the other hand, the photoreaction is ring size-dependent, resembling the solid state results for the 12- and 14-membered-ring diketones, and consisting mainly of type II elimination accompanied by reduced amounts of nonstereoselective cyclobutanol formation for the 16-26-membered-ring compounds. It is suggested that this ring size dependence stems from the relative conformational freedom of the intermediate 1,4-biradicals in the fluid medium-motions that are slow compared to closure for the 12- and 14-membered rings, but that permit alignment for biradical cleavage and alternative modes of closure in the {\textquoteright}{\textquoteright}floppier{\textquoteright}{\textquoteright} 16-membered and larger rings. The one exception to the above generalizations is 1,6-cyclodecanedione, which was found to be photochemically inert both in the solid state and solution despite having a crystal conformation favorable for type II photochemistry. Possible reasons for this behavior are presented and discussed.},
	keywords = {ATOM TRANSFERS, C-H...O, CONFORMATION, CYCLOALKANONES, CYCLODODECANONE, CYCLOHEXADECANE, MOLECULAR MECHANICS METHODOLOGY, PHENYL KETONES, PHOTOPROCESSES, TRANSITION STRUCTURES},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1996UV29200012},
	author = {Gudmundsdottir, A. D. and Lewis, T. J. and Randall, L. H. and Scheffer, J. R. and Rettig, S. J. and Trotter, J. and Wu, C. H.}
}
@article {2920,
	title = {THE ORIENTATION OF MOLECULES WITH INTERNAL-ROTATION IN NEMATIC PHASES},
	journal = {Molecular Physics},
	volume = {80},
	number = {1},
	year = {1993},
	note = {ISI Document Delivery No.: LW723Times Cited: 10Cited Reference Count: 33},
	month = {Sep},
	pages = {177-189},
	type = {Article},
	abstract = {The anisotropic couplings obtained from the H-1 nuclear magnetic resonance (NMR) spectra of partially oriented molecules with internal rotation are difficult to analyse because the order parameters for each conformer cannot be deduced without assumptions. The purpose of this paper is to show how a model for the anisotropic short-range potential can be useful in the interpretation of the high-resolution H-1 NMR spectra of the flexible molecules furfural, 2-chlorobenzaldehyde, and 2,2{\textquoteright}-dithiophene dissolved in a 55\% Merck ZLI 1132-45\% N-(p-ethoxybenzylidene)-2,6-dideutero-p{\textquoteright}-n-butylaniline (w/w) mixture. In this nematic mixture there is no contribution to the anisotropic potential from the interaction between the solute molecular quadrupole moment and the average electric field gradient of the liquid crystal solvent; the dominant anisotropic intermolecular potential in this mixture is taken to result solely from short-range interactions. We find good agreement between experiment and the order parameters calculated by the model of short-range interactions. The ratios of order parameters for the s-cis and s-trans conformers predicted by the model are used to calculate the statistical weights of the s-trans conformation for the solutes: at 304 K, p(trans)(furfural) = 0.45 +/- 0.02, p(trans)(2-chlorobenzaldehyde) = 0.901 +/- 0.006 and p(trans)(2,2{\textquoteright}-dithiophene) = 0.6094 +/- 0.0008.},
	keywords = {BARRIER, CONFORMATION, LIQUID-CRYSTALS, ORDER, SIZE, SOLUTES},
	isbn = {0026-8976},
	url = {<Go to ISI>://A1993LW72300013},
	author = {ter Beek, L. C. and Zimmerman, D. S. and Burnell, E. E.}
}
@article {7049,
	title = {STRUCTURAL STUDIES OF ORGANOBORON COMPOUNDS .42. 4,6-BIS(1-CYANO-1-METHYLETHYL)-2-MESITYL-1,3-DIOXA-4,6-DIAZA-2-BORACYCLO HEXANE},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {69},
	number = {2},
	year = {1991},
	note = {ISI Document Delivery No.: FA876Times Cited: 9Cited Reference Count: 28},
	month = {Feb},
	pages = {234-238},
	type = {Article},
	abstract = {{The condensation of N,N{\textquoteright}-bis(1-cyano-1-methylethyl)-N,N{\textquoteright}-dihydroxymethanediamine and mesitylboronic acid gives 4,6-bis(1-cyano-1-methylethyl)-2-mesityl-1,3-dioxa-4,6-diaza-2-boracyclo hexane in good yield. Crystals of the latter compound are orthorhombic},
	keywords = {BORON COMPOUND, CONFORMATION, CRYSTAL, crystal structure, organoboron compound},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1991FA87600010},
	author = {Kliegel, W. and Lubkowitz, G. and Rettig, S. J. and Trotter, J.}
}
