@article {2548, title = {Cation-Complexation Behavior of Template-Assembled Synthetic G-Quartets}, journal = {Journal of Organic Chemistry}, volume = {74}, number = {15}, year = {2009}, note = {ISI Document Delivery No.: 476XOTimes Cited: 3Cited Reference Count: 60Nikan, Mehran Sherman, John C.}, month = {Aug}, pages = {5211-5218}, type = {Article}, abstract = {We report the preparation and solution study of a set of template-assembled synthetic G-quartets (TASQs) bound to different cations. These G-quartet baskets effectively extract cations of different sizes and valencies, They form isolated G-quartets with small cations such as Na+ and Sr2+, and dimeric assemblies with larger cations such as Cs+. Their structures were determined by using H-1 NMR spectroscopy, and their sizes were evaluated by using a series of pulsed-field gradient NMR experiments. The effect of anion has been studied, and the cation selectivities have been investigated by a series of competition experiments.}, keywords = {ALKALI-METAL CATIONS, CROWN-ETHERS, DEOXYGUANOSINE, DIFFRACTION, DIFFUSION NMR-SPECTROSCOPY, DNA, GUANOSINE, ION-BINDING, LIPOPHILIC G-QUADRUPLEX, RAY FIBER, SODIUM}, isbn = {0022-3263}, url = {://000268480300011}, author = {Nikan, M. and Sherman, J. C.} } @article {1344, title = {Solid state NMR investigation of the structure of AlPO4-14A}, journal = {Microporous and Mesoporous Materials}, volume = {88}, number = {1-3}, year = {2006}, note = {ISI Document Delivery No.: 004TCTimes Cited: 5Cited Reference Count: 14}, month = {Jan}, pages = {163-169}, type = {Article}, abstract = {The as-synthesized aluminophosphate framework material AlPO4-14A has a number of unique structural features related to the connectivities in the network of Al and P atoms. One tetrahedral Al atom is present that is linked, via Al-O(H)-Al bonds to two octahedral Al atoms and, consequently to only two P atoms. However, ail Al/P ratio of one is maintained as each of these octahedral Al atoms is connected to five P atoms in addition to the Al-O(H)-Al linkage. This connectivity network means that a framework made up of alternating Al and P atoms cannot be obtained by calcination. A variety of H-1, Al-27, and P-31 solid state NMR experiments have been employed to characterize the AlPO4-14A structure. A fast H-1 MAS experiment showed that the template was in the protonated form and a H-1 {Al-27} TRAPDOR experiment identified the resonance of the {\textquoteright}framework{\textquoteright} proton. The Al-27 and P-31 resonances were completely assigned by the Al-27 -> P-31 INEPT heteronuclear correlation experiment and the quadrupolar parameters of the Al-27 signals determined from the Al-27 MQMAS experiment. Lastly, the complete assignment of both Al-27 and P-31 resonances made it possible to qualitatively determine the location and orientation of the template molecule within the framework from two-dimensional dipolar-based H-1 -> P-31 cross-polarization and H-1 -> Al-27 TEDOR heteronuclear correlation experiments. The data from these experiments confirm in detail the AlPO4-14A structure and will be useful benchmarks for the investigation of other structures for which diffraction data are limited. (c) 2005 Elsevier Inc. All rights reserved.}, keywords = {aluminophosphate, DIFFRACTION, HETCOR, solid state NMR, SPECTRA, SPINS, STRUCTURE, zeolite}, isbn = {1387-1811}, url = {://000234774100021}, author = {Brouwer, D. H. and Chezeau, J. M. and Fyfe, C. A.} } @article {349, title = {DFT calculations of core-electron binding energies of the peptide bond}, journal = {Journal of Physical Chemistry A}, volume = {106}, number = {2}, year = {2002}, note = {ISI Document Delivery No.: 513ANTimes Cited: 24Cited Reference Count: 39}, month = {Jan}, pages = {356-362}, type = {Article}, abstract = {Although an efficient DFT method using the generalized transition-state model to calculate core-electron binding energies had been successfully applied to over 200 cases, with an average absolute deviation of only 0.21 eV from experiment, a new DeltaE(KS)(PW86-PW91)/cc-pCVTZ model based on total Kohn-Sham energy difference was recently developed. Not only was the model error-free, but also the average absolute deviation for 32 cases studied was found to be 0.15 eV. In this study, we first confirm the excellent performance of such a DeltaE(KS) approach with 46 new cases, with the result that the average absolute deviation from experiment for the 78 cases remains at 0.15 eV. With such consistent accuracy, this new method is applied to the peptide bond. The model molecules studied in this work include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and two model dipeptides, one cyclic and one acyclic. The difference in the computed nitrogen core-electron binding energy between the two model dipeptides is found to be 0.85 eV, several times our average absolute deviation. This may be of interest to other workers studying other aspects of the peptide bond.}, keywords = {AB-INITIO CALCULATIONS, ACCURATE, APPROXIMATION, DENSITY-FUNCTIONAL CALCULATION, DIFFRACTION, DIKETOPIPERAZINE, EXCHANGE-ENERGY, GAS, MOLECULAR-STRUCTURE, ZETA BASIS-SET}, isbn = {1089-5639}, url = {://000173355900019}, author = {Chong, D. P. and Aplincourt, P. and Bureau, C.} } @article {533, title = {Structure determination of Cu(410)-O using X-ray diffraction and DFT calculations}, journal = {Surface Science}, volume = {516}, number = {1-2}, year = {2002}, note = {ISI Document Delivery No.: 594AQTimes Cited: 12Cited Reference Count: 52}, month = {Sep}, pages = {16-32}, type = {Article}, abstract = {The Cu(4 1 0)-O surface, involving a 0.5 monolayer (ML) coverage of oxygen, is known to be extremely stable and a range of Cu(1 0 0) vicinal. surfaces facet to (4 1 0) in the presence of adsorbed oxygen. A new surface X-ray diffraction investigation of this surface has been conducted to determine its structure, and the detailed structural parameter values obtained are compared with the results of a density functional theory (DFT) calculation. The results show that the metal structure is unreconstructed, with the oxygen forming an overlayer with 0.25 ML O atoms at near-colinear step-edge sites and 0.25 NIL O atoms at mid-terrace hollow sites, approximately 0.6 Angstrom above the terraces. The large number of independent structural parameters potentially relevant to this vicinal surface presents a significant challenge for unique structural optimisation, but various missing row reconstruction models can be clearly excluded. Two detailed structural solutions are identified which give equally acceptable fits to the X-ray diffraction data after imposition of a Lennard-Jones penalty factor. These models differ especially in the O positions, but one is found to be more favoured by comparison with the results of the DFT calculations, and by considerations based on bond lengths and valence. Substantial relaxations from the bulk metal positions occur for the outermost Cu atoms; the ability of the vicinal surface to relax in this way may help to account for its stability compared with the missing row reconstruction induced by oxygen chemisorption on the Cu(1 0 0) surface. (C) 2002 Elsevier Science B.V. All rights reserved.}, keywords = {ADSORPTION, and, and topography, chemisorption, copper, CU(100), DETERMINATION, DIFFRACTION, ENERGY ION-SCATTERING, INITIO MOLECULAR-DYNAMICS, MISSING-ROW, MORPHOLOGY, OXYGEN, OXYGEN-INDUCED RECONSTRUCTION, RECONSTRUCTION, reflection, relaxation and reconstruction, roughness, SCANNING-TUNNELING-MICROSCOPY, SURFACE, surface structure, SURFACE-STRUCTURE, SURFACES, VICINAL COPPER SURFACES, vicinal single crystal, WAVE BASIS-SET, X-ray scattering}, isbn = {0039-6028}, url = {://000178027000003}, author = {Vlieg, E. and Driver, S. M. and Goedtkindt, P. and Knight, P. J. and Liu, W. and Ludecke, J. and Mitchell, K. A. R. and Murashov, V. and Robinson, I. K. and de Vries, S. A. and Woodruff, D. P.} } @article {4804, title = {Hfcs of the C(6)H(6)Mu radical in NaY zeolites}, journal = {Physica B-Condensed Matter}, volume = {289}, year = {2000}, note = {ISI Document Delivery No.: 330GBTimes Cited: 6Cited Reference Count: 128th International Conference on Muon Spin Rotation, Relaxation and ResonanceAUG 30-SEP 03, 1999LES DIABLERETS, SWITZERLANDEuropean Phys Soc, Paul Scherrer Inst, Eidgenoss Tech Hochschule, Univ Zurich, European Sci Fdn, Swiss Natl Sci Fdn, Neue Aargauer Bank, Sauerstoffwerk Lenzburg AG, Hamamatsu Photon, EG \& G Berthold GmbH \& Co KG, Prophysik AG, Kroger \& Co, Wenger SA, Alcatel Hochvakuum Tech GmbH, Sunrise AG, Dramer AG, Automobil \& Motoren AG}, month = {Aug}, pages = {603-606}, type = {Proceedings Paper}, abstract = {The hyperfine interactions of the MuC(6)H(6), radical in NaY zeolites at low to moderate benzene loadings have been measured by both the FT-mu SR and ALC-mu SR techniques over a wide temperature range. From a preliminary interpretation of the data, the hyperfine coupling constants for the muon and proton of the - CHMu methylene group in two different orientations for the radical bound to the S-II cation site have been determined. At 322 K these values are: A(mu)(1)= 606 +/- 2 MNz and A(p)(1)= 108 +/- 2 MHz, for the muon on the opposite side of the ring from the cation; and A(mu)(2) = 430 +/- 2 MHz and A(p)(2) = 70 +/- 5 MHz, for the muon on the same side. These results as well as their trends with temperature demonstrate that the MuC(6)H(6) radical adopts a non-planar equilibrium geometry due to the strong interaction of the pi electron density with the Na cation. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {benzene, cyclohexadienyl radical, DIFFRACTION, DIFFUSION, DYNAMICS, hyperfine couplings, NaY zeolite, NEUTRON, SILICA, SUBSTITUTED CYCLOHEXADIENYL RADICALS}, isbn = {0921-4526}, url = {://000087953500158}, author = {Fleming, Donald G. and Shelley, M. and Arseneau, D. J. and Senba, M. and Pan, J. J. and Kreitzman, S. R. and Roduner, E.} } @article {3488, title = {A STRUCTURAL STUDY OF PD/CU(100) SURFACE ALLOYS}, journal = {Surface Science}, volume = {337}, number = {1-2}, year = {1995}, note = {ISI Document Delivery No.: RQ749Times Cited: 33Cited Reference Count: 54}, month = {Aug}, pages = {79-91}, type = {Article}, abstract = {The structures formed by one-half and one monolayer (ML) of Pd evaporated onto Cu(100) at 300 K were studied by low energy electron diffraction (LEED), medium energy ion scattering (MEIS), thermal desorption spectroscopy (TDS), and embedded atom method (EAM) calculations. In the half monolayer case, the LEED I(E) curves are consistent with the established c(2 x 2) surface alloy model. The MEIS data, however, suggest that a fraction of the Pd (similar to 1/4) is in {\textquoteright}{\textquoteright}second layer{\textquoteright}{\textquoteright} sites, in agreement with previous LEIS, TDS and XPS forward scattering measurements. The EAM simulations support the formation of alloy islands, providing a mechanism for the covering of some Pd atoms. As the deposition proceeds, however, this island formation is indicated to occur preferentially over clean copper. In the one monolayer case, a p(2 x 2)-p4g LEED pattern is observed. Analysis of the I(E) curves suggests that this arises from (100) Pd packed above the c(2 x 2) alloy. EAM calculations confirm the stability of this model. Evidence from MEIS and TDS, however, shows that the one monolayer surface as prepared in this work is inhomogeneous. c(2 x 2) and Cu rich surface domains exist in addition to those having the p4g Pd/c(2 x 2)PdCu structure.}, keywords = {(MEIS), ABSORPTION FINE-STRUCTURE, ADSORPTION, CU(100), DIFFRACTION, GROWTH, HYDROGEN, ION-SCATTERING, LOW ENERGY ELECTRON DIFFRACTION (LEED), LOW-ENERGY ELECTRON, MEDIUM ENERGY ION SCATTERING, molecular dynamics, RECONSTRUCTION, SPECTROSCOPY, surface structure, THERMAL DESORPTION, ULTRATHIN PD FILMS}, isbn = {0039-6028}, url = {://A1995RQ74900017}, author = {Pope, T. D. and Vos, M. and Tang, H. T. and Griffiths, K. and Mitchell, I. V. and Norton, P. R. and Liu, W. and Li, Y. S. and Mitchell, K. A. R. and Tian, Z. J. and Black, J. E.} } @article {7243, title = {THE MOLECULAR AND ELECTRONIC-STRUCTURE OF 1-PYRAZOLYLPHOSPHAZENES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {70}, number = {6}, year = {1992}, note = {ISI Document Delivery No.: JR097Times Cited: 1Cited Reference Count: 62}, month = {Jun}, pages = {1855-1868}, type = {Article}, abstract = {{The nature of the interactions between pyrazolyl and phosphazene rings has been investigated through the study of the structures of bis(1-pyrazolyl)methane, CH2(H2pz)2, 1, bis[1-(3,5-dimethylpyrazolyl)]methane, CH2(Me2pz)2, 2, the pyrazolylphosphazenes N3P3(Me2pz)6, 3, N4P4(H2pz)8, 4, and N4P4(Me2pz)8, 5, and the partially substituted gem-N3P3Ph2(Me2pz)4, 6. Crystal data are as follows: 1, orthorhombic, P2(1)2(1)2(1)}, keywords = {COMPLEXES, CRYSTAL, CYCLOPHOSPHAZENES, CYCLOTRIPHOSPHAZENE, DIFFRACTION, PHOSPHAZENES, PHOSPHONITRILIC DERIVATIVES, PYRAZOLE, SPECTRA, SUBSTITUENTS}, isbn = {0008-4042}, url = {://A1992JR09700038}, author = {Gallicano, K. D. and Paddock, N. L. and Rettig, S. J. and Trotter, J.} } @article {7022, title = {NATURAL ABUNDANCE, 2-DIMENSIONAL SI-29 MAS NMR INVESTIGATION OF THE 3-DIMENSIONAL BONDING CONNECTIVITIES IN THE HIGH-TEMPERATURE AND LOW-TEMPERATURE FORMS OF ZEOLITE ZSM-11}, journal = {Journal of Physical Chemistry}, volume = {95}, number = {9}, year = {1991}, note = {ISI Document Delivery No.: FK322Times Cited: 20Cited Reference Count: 29}, month = {May}, pages = {3747-3751}, type = {Article}, abstract = {Two-dimensional 29Si solid-state NMR experiments have been used to investigate the three-dimensional bonding connectivities in ZSM-11 in both its high- and low-temperature forms, which are related to each other by a temperature-induced phase transition. The high-temperature form is known to have tetragonal symmetry with space group I4BARm2, while the details of the ZSM-11 structure at low temperatures are not known to date from diffraction measurements. 2-D INADEQUATE experiments at high temperature (340 K) confirmed the postulated structure. All of the nine expected connectivities were observed, permitting an unambiguous assignment of the spectrum. In the low-temperature (303 K) 2-D experiments, enough information was obtained that, combined with the knowledge of the high-temperature structure, a structure could be suggested for the low-temperature form. The complete connectivities of T sites in the structure were established, and at least one space group, I4BAR, is compatible with the NMR data.}, keywords = {coherence, DIFFRACTION, LATTICE CONNECTIVITIES, SITES, SOLID-STATE NMR, SPECTROSCOPY}, isbn = {0022-3654}, url = {://A1991FK32200057}, author = {Fyfe, C. A. and Feng, Y. and Grondey, H. and Kokotailo, G. T. and Mar, A.} } @article {6947, title = {FURTHER LEED INVESTIGATIONS OF MISSING ROW MODELS FOR THE CU(100)-(2-SQUARE-ROOT-2XSQUARE-ROOT-2)R45-DEGREES-O SURFACE-STRUCTURE}, journal = {Surface Science}, volume = {239}, number = {3}, year = {1990}, note = {ISI Document Delivery No.: EP148Times Cited: 50Cited Reference Count: 17}, month = {Dec}, pages = {L571-L578}, type = {Letter}, abstract = {Multiple scattering calculations have been made for a series of models for the O on Cu(100) chemisorption system in which there are missing atoms in the topmost metal layer, as well as additional missing row models to those considered previously. The best correspondence between experimental and calculated LEED intensities yet reached for the (2 square-root 2 X square-root 2)R45-degrees surface structure is obtained by extending the recently proposed missing row model [Surf. Sci. 208 (1989) L7] to include a 0.30 angstrom lateral relaxation for top layer copper atoms adjacent to the missing rows, and small (around 0.10 angstrom) vertical relaxations in both the first and second copper layers.}, keywords = {chemisorption, CU(100), DIFFRACTION, OXYGEN}, isbn = {0039-6028}, url = {://A1990EP14800005}, author = {Zeng, H. C. and Mitchell, K. A. R.} }