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Articles 91 - 116 of 116
Full-Text Articles in Physical Sciences and Mathematics
Amyloid-Β Protofibrils Differ From Amyloid-Β Aggregates Induced In Dilute Hexafluoroisopropanol In Stability And Morphology, Michael Nichols, Melissa Moss, Dana Reed, Stephanie Cratic-Mcdaniel, Jan Hoh, Terrone Rosenberry
Amyloid-Β Protofibrils Differ From Amyloid-Β Aggregates Induced In Dilute Hexafluoroisopropanol In Stability And Morphology, Michael Nichols, Melissa Moss, Dana Reed, Stephanie Cratic-Mcdaniel, Jan Hoh, Terrone Rosenberry
Chemistry & Biochemistry Faculty Works
The brains of Alzheimer’s disease (AD) patients contain large numbers of amyloid plaques that are rich in fibrils composed of 40- and 42-residue amyloid-β (Aβ) peptides. Several lines of evidence indicate that fibrillar Aβ and especially soluble Aβ aggregates are important in the etiology of AD. Recent reports also stress that amyloid aggregates are polymorphic and that a single polypeptide can fold into multiple amyloid conformations. Here we demonstrate that Aβ-(1–40) can form soluble aggregates with predominant β-structures that differ in stability and morphology. One class of aggregates involved soluble Aβ protofibrils, prepared by vigorous overnight agitation of monomeric Aβ-(1–40) …
Response To "Kinetic And Mechanistic Studies Of The Recombination Of Oh With No2: Vibrational Deactivation, Isotopic Scrambling And Product Isomer Branching Ratios", J. Stutz, A. R. Ravishankara, J. A. Pyle, A. Tuck, M. J. Evans, H. Herrmann, M. P. Chipperfield, R. Zellner, H. Roscoe, D. E. Shallcross, R. A. Cox, P. S. Monks, S. R. Arnold, D. S. Stevenson, D. E. Heard, J. J. Remedios, R. P. Wayne, E. A. Cohen, T. Brauers, A. J. Orr-Ewing, M. A. Blitz, L. Wang, G. Duxbury, T. Dibble, C. A. Taatjes, W. Eisfeld, P. W. Seakins, A. Kovács, S. Dóbé, E. Farkas, T. Ingham, D. Rowley, C. E. Kolb, Thomas Alex Stephenson, A. J. Hynes, N. M. Donahue, I. W. M. Smith, D. Self, D. J. Donaldson
Response To "Kinetic And Mechanistic Studies Of The Recombination Of Oh With No2: Vibrational Deactivation, Isotopic Scrambling And Product Isomer Branching Ratios", J. Stutz, A. R. Ravishankara, J. A. Pyle, A. Tuck, M. J. Evans, H. Herrmann, M. P. Chipperfield, R. Zellner, H. Roscoe, D. E. Shallcross, R. A. Cox, P. S. Monks, S. R. Arnold, D. S. Stevenson, D. E. Heard, J. J. Remedios, R. P. Wayne, E. A. Cohen, T. Brauers, A. J. Orr-Ewing, M. A. Blitz, L. Wang, G. Duxbury, T. Dibble, C. A. Taatjes, W. Eisfeld, P. W. Seakins, A. Kovács, S. Dóbé, E. Farkas, T. Ingham, D. Rowley, C. E. Kolb, Thomas Alex Stephenson, A. J. Hynes, N. M. Donahue, I. W. M. Smith, D. Self, D. J. Donaldson
Chemistry & Biochemistry Faculty Works
No abstract provided.
Franck-Condon Effects In Collision-Induced Electronic Energy Transfer: I2(E;V=1,2)+He,Ar, Pooja P. Chandra , '03, Thomas Alex Stephenson
Franck-Condon Effects In Collision-Induced Electronic Energy Transfer: I2(E;V=1,2)+He,Ar, Pooja P. Chandra , '03, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
Collisions of I-2 in the E electronic state with rare gas atoms result in electronic energy transfer to the D, beta, and D-' ion-pair electronic states. Rate constants for each of these channels have been measured when I-2 is initially prepared in the J=55, v=1 and 2 levels in the E state. The rate constants and effective hard sphere collision cross sections confirm the trends observed when v=0 in the E state is initially prepared: He collisions favor population of the D state, while Ar collisions favor population of the beta state. Final state vibrational level distributions are determined by …
Collision-Induced Non-Adiabatic Transitions Between The Ion-Pair States Of Molecular Iodine: A Challenge For Experiment And Theory, T. V. Tscherbul, A. A. Buchachenko, M. E. Akopyan, S. A. Poretsky, A. M. Pravilov, Thomas Alex Stephenson
Collision-Induced Non-Adiabatic Transitions Between The Ion-Pair States Of Molecular Iodine: A Challenge For Experiment And Theory, T. V. Tscherbul, A. A. Buchachenko, M. E. Akopyan, S. A. Poretsky, A. M. Pravilov, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The ion-pair states of molecular iodine provide a unique system for studying the efficiency, selectivity, and mechanisms of collision-induced non-adiabatic transitions. Non-adiabatic transitions between the first-tier ion-pair states in collisions with molecular partners and rare gases are analyzed and discussed. The qualitative features of the rate constants and product state distributions under single collision conditions are summarized and interpreted in terms of appropriate theoretical approaches. Two mechanisms for the non-adiabatic transitions are clearly identified. The first, operative for collisions involving molecular partners possessing permanent or transition electrostatic moments, is highly selective. It connects the initially prepared level in the E …
Finite Concentration Effects On Diffusion-Controlled Reactions, Chung Wong
Finite Concentration Effects On Diffusion-Controlled Reactions, Chung Wong
Chemistry & Biochemistry Faculty Works
The algorithm by Northrup, Allison, and McCammon has been used for two decades for calculating the diffusion-influenced rate-constants of enzymatic reactions. Although many interesting results have been obtained, the algorithm is based on the assumption that substrate-substrate interactions can be neglected. This approximation may not be valid when the concentration of the ligand is high. In this work, we constructed a simulation model that can take substrate-substrate interactions into account. We first validated the model by carrying out simulations in ways that could be compared to analytical theories. We then carried out simulations to examine the possible effects of substrate-substrate …
Reactions Of Boranes And Metallaboranes With Phosphines, Lawrence Barton, Oleg Volkov, Mitsuhiro Hata, Paul Mcquade, Nigam Rath
Reactions Of Boranes And Metallaboranes With Phosphines, Lawrence Barton, Oleg Volkov, Mitsuhiro Hata, Paul Mcquade, Nigam Rath
Chemistry & Biochemistry Faculty Works
This paper reports extensions of the well-established field of phosphine–borane chemistry. Linked clusters, for example, {[(PPh3)2(CO)OsB4H7-3-BH2-PPh2]2 [(Fe(C5H4)2]}, are formed in reactions of rigid backboned bidentate phosphines with {2,2,2-(PPh3)2(CO)-nido-2-OsB5H9]. Reaction of bidentate phosphines with the unsaturated clusters [8,8-PPh3)2-nido-8,7-RhSB9H10] and [9,9-(PPh3)2-nido-9,7,8-RhC2B8 H11] leads to the isolation of novel species such as {1-(PPh3)[1,3-(µ-dppm)]-closo -1,2-RhSB9H8},with a dppm molecule bridging adjacent metal and boron vertices in the cage, [1,1-(ç2-dppe)-3-(ç1-dppm)-closo-1,2-RhSB 9H8], a mixed ligand system, and {9,9-ç2-[(ç2-BH3)PPh2PCH2 PPh2]-nido- 9,7,8-RhC2B8H11} which contains a bidentate dppm BH3 moiety. The formation of bidentate phosphine-linked main group transition-metal moieties such as [BH3PPh2(CH)nPPh2IrCp*Cl2] is also described as is an example of …
C-Cl Bond Fission, Hcl Elimination, And Secondary Radical Decomposition In The 193 Nm Photodissociation Of Allyl Chloride, M. L. Morton, L. J. Butler, Thomas Alex Stephenson, F. Qi
C-Cl Bond Fission, Hcl Elimination, And Secondary Radical Decomposition In The 193 Nm Photodissociation Of Allyl Chloride, M. L. Morton, L. J. Butler, Thomas Alex Stephenson, F. Qi
Chemistry & Biochemistry Faculty Works
The primary photodissociation dynamics of allyl chloride upon excitation at 193 nm is investigated in a crossed laser-molecular beam scattering apparatus. Tunable vacuum ultraviolet (VUV) photoionization of the products provides a unique ability to learn about the secondary reaction products of the nascent photoproducts formed. The data show evidence for four significant primary reaction channels: a previously unidentified low kinetic energy C-Cl bond fission channel producing unstable allyl radicals, an excited state C-Cl bond fission channel producing Cl atoms with high translational energy, an HCl elimination pathway releasing significant energy to product translation to HCl and its momentum-matched mass 40 …
Collision-Induced Electronic Energy Transfer From V=0 Of The E(0+G) Ion-Pair State In I2: Collisions With He And Ar, Christopher J. Fecko , '98, Miriam Arak Freedman , '00, Thomas Alex Stephenson
Collision-Induced Electronic Energy Transfer From V=0 Of The E(0+G) Ion-Pair State In I2: Collisions With He And Ar, Christopher J. Fecko , '98, Miriam Arak Freedman , '00, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The electronic energy transfer pathways that occur following collisions between I-2 in the E ion-pair electronic state (v = 0, J = 55) and He and Ar atoms have been determined. The nearby D, D', and beta ion-pair states are populated, but with relative branching ratios that vary with the rare gas collision partner. In He/I-2 collisions, the D state is preferentially populated, while Ar/I-2 collisions preferentially populate the beta electronic state. Bimolecular rate constants and effective hard sphere collision cross sections have been determined for each channel; the cross sections range from 7.0 +/- 1.0 Angstrom(2) for populating the …
Collision-Induced Electronic Energy Transfer From V=0 Of The E(0g+) Ion-Pair State In I2: Collisions With I2(X), Christopher J. Fecko , '98, Miriam Arak Freedman , '00, Thomas Alex Stephenson
Collision-Induced Electronic Energy Transfer From V=0 Of The E(0g+) Ion-Pair State In I2: Collisions With I2(X), Christopher J. Fecko , '98, Miriam Arak Freedman , '00, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The collision-induced electronic energy transfer that occurs when I-2 in the E(0(g)(+)) ion-pair electronic state collides with ground electronic state I-2 has been investigated. We prepare I-2 in single rotational levels in v = 0 of the E state using two-color double resonance laser excitation. The resulting emission spectrum shows that the nearby (DeltaT(e) = -385 cm(-1)) D(0(u)(+)) electronic state is populated. The cross section for collision-induced E -->D energy transfer is found to be IS - 3 Angstrom (2). A range of D state vibrational levels are populated, consistent with a model in which overlap between the initial …
Quantum Calculations On The Vibrational Predissociation Of Nebr2: Evidence For Continuum Resonances, Thomas Alex Stephenson, N. Halberstadt
Quantum Calculations On The Vibrational Predissociation Of Nebr2: Evidence For Continuum Resonances, Thomas Alex Stephenson, N. Halberstadt
Chemistry & Biochemistry Faculty Works
Quantum mechanical calculations on the vibrational predissociation dynamics of NeBr2 in the B electronic state have been performed and the results compared with both experimental data and other computational studies. For vibrational levels with v less than or equal to 20 we find that the vibrational state dependence of the predissociation lifetimes is in qualitative agreement with experimental measurements, as are the calculated Br-2 fragment rotational distributions. For higher vibrational levels, the B <-- X excitation profiles are well represented by a sum of two Lorentzian line shapes. We attribute this result to the presence of long-lived resonances in the dissociative continuum that are reminiscent of long-lived dissociative trajectories in previous classical studies of NeBr2. (C) 2000 American Institute of Physics. [S0021-9606(00)00205-1].
Is Hyperconjugation Responsible For The "Gauche Effect" In 1-Fluoropropane And Other 2-Substituted-1-Fluoroethanes?, Paul R. Rablen, R. W. Hoffman, D. A. Hrovat, W. T. Borden
Is Hyperconjugation Responsible For The "Gauche Effect" In 1-Fluoropropane And Other 2-Substituted-1-Fluoroethanes?, Paul R. Rablen, R. W. Hoffman, D. A. Hrovat, W. T. Borden
Chemistry & Biochemistry Faculty Works
The energies and geometries of a series of 2-substituted-1-fluoroethanes were computed at the MP2/6-311++G**(6D)//MP2/6-31+G* level of theory for both the maxima and minima of the rotation about the C-C bond. The results did not support the predictions of a hyperconjugative model, that both 1,2-difluoroethane and 1-chloro-2-fluoroethane would strongly prefer a gauche conformation, and that 1-fluoro-2-silylethane would strongly prefer an anti conformation. The existence of competing electrostatic interactions between the fluorine and the substituents at C-2 was indicated by the detailed geometries of the gauche conformers and by the calculated sensitivity of the gauche-anti energy differences to the presence of a …
2-Phenyl-3-(5,6,7,7a-Tetrahydro-1h,3h-Pyrrolo[1,2-C]Oxazol-3-Ylidene)-1-Propene-1,1-Dicarbonitrile And 4-(4-Methoxyphenyl)-2,6-Bis(Methylthio)Pyridine-3-Carbonitrile, M. George, S. Das, C.V. Ashokan, N.P. Rath, M.V. George
2-Phenyl-3-(5,6,7,7a-Tetrahydro-1h,3h-Pyrrolo[1,2-C]Oxazol-3-Ylidene)-1-Propene-1,1-Dicarbonitrile And 4-(4-Methoxyphenyl)-2,6-Bis(Methylthio)Pyridine-3-Carbonitrile, M. George, S. Das, C.V. Ashokan, N.P. Rath, M.V. George
Chemistry & Biochemistry Faculty Works
The reaction of 3-aryl-2-cyano-5,5-bis(methylthio)penta-2,4-dienenitrile, (1), with (L)-(-)-2-hydroxymethylpyrrolidine, (2), gave two types of product, the normal substitution product, (3), and a pyridine derivative, (4). The structures of two representative examples, 2-phenyl-3-(5,6,7,7a-tetrahydro1H,3H-pyrrolo[1,2-c]oxazol-3-ylidene)-1-propene-1,1-dicarbonitrile, (3a), as its hemibenzene solvate, C17H14N3O.0.5C6H6, and 4-(4-methoxyphenyl)-2,6-bis(methylthio)pyridine-3-carbonitrile, (4b), C15H14N2OS2, have been unambiguously established by X-ray crystallographic analysis. The molecular packing of (4b) involves loosly held dimers with S1...S1' distances of 3.424 (1) Å.
Exo- And Endo-Tricarbonyl[(4b,5,6,7,8,8a-Η)-Cis-N-Methyl-2,3,4,4a,9,9a-Hexahydro-1h- Carbazole]Chromium(0), Nigam Rath, F. Pigge, Shiyue Fang
Exo- And Endo-Tricarbonyl[(4b,5,6,7,8,8a-Η)-Cis-N-Methyl-2,3,4,4a,9,9a-Hexahydro-1h- Carbazole]Chromium(0), Nigam Rath, F. Pigge, Shiyue Fang
Chemistry & Biochemistry Faculty Works
Acid-mediated hydride reduction of tricarbonyl([eta]6-N-methyl-1,2,3,4-tetrahydrocarbazole)chromium(0) affords either the cis-fused exo-hexahydrocarbazole chromium(0) complex {[Cr(C13H17N)(CO)3], (I)} exclusively, or a separable mixture of (I) and the endo-isomer {[Cr(C13H17N)(CO)3], (II)}, depending upon the choice of hydride donor. The conformations of the hexahydrocarbazole systems differ in the orientation of the indoline moiety with respect to the saturated hexahydrocarbazole rings. The isolation of the exo isomer is unusual, as this complex arises via reaction at the sterically more hindered endo face of the coordinated ligand.
Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, N. Rath, C. Spilling
Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, N. Rath, C. Spilling
Chemistry & Biochemistry Faculty Works
The crystal structure of the racemic title compound, C18H20NO6P, m.p. 428-431 K, has been determined by X-ray diffraction. The title compound consists of a tetrahedral P atom bonded to two methoxy groups, and an alkyl chain. The alkyl chain was substituted at position 1 with a carbamate and with an epoxide at positions 2 and 3. The relative configuration of the 1-carbamate and 2,3-epoxide substituents was confirmed as anti (1S,2R,3S). The crystal structure contains an enantiomeric pair with two intermolecular hydrogen bonds in a 14-membered ring. The hydrogen bonds are formed between the P=O of one enantiomer and the N-H …
Fragment Rotational Distributions From The Dissociation Of Nebr2: Experimental And Classical Trajectory Studies, Mehdi Nejad-Sattari , '95, Thomas Alex Stephenson
Fragment Rotational Distributions From The Dissociation Of Nebr2: Experimental And Classical Trajectory Studies, Mehdi Nejad-Sattari , '95, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The Br-2 fragment rotational distributions that result from the vibrational predissociation of NeBr2 in the B electronic state have been measured for several initial vibrational levels. In each case, the rotational distributions extend to the effective energetic Limit determined by the amount of energy available (E(av1)) for disposal into the fragment rotational and translational degrees of freedom. Analysis of the data allows refinement of the NeBr2 dissociation energy; we find that D-0=70.0 +/- 1.1 cm(-1) for the X electronic state, v = 0. Both Delta v = - 1 and -2 dissociation events have been examined. For dissociation pathways with …
Experimental Evidence For Self-Similar Structures In The Aggregation Of Porphyrins In Aqueous Solutions, F. Mallamace, N. Micali, S. Trusso, L. M. Scolaro, A. Romeo, A. Terracina, Robert F. Pasternack
Experimental Evidence For Self-Similar Structures In The Aggregation Of Porphyrins In Aqueous Solutions, F. Mallamace, N. Micali, S. Trusso, L. M. Scolaro, A. Romeo, A. Terracina, Robert F. Pasternack
Chemistry & Biochemistry Faculty Works
We have studied the aggregation of the porphyrin t-H₂Pagg in aqueous solution by light scattering. The intensity profile of the elastically scattered light, studied in the exchanged wave-vector range 0.2 ≤ q ≤ 31.4 μ m⁻¹, indicates that the aggregation produces large monodisperse clusters having a fractal structure, and is driven by diffusion-limited aggregation kinetics. Additional measurements performed at different q values confirm such a picture giving a hydrodynamic radius R(H) consistent with the radius of gyration R(g) measured by elastic scattering. This is explained taking into account the q² dependence observed in the mean decay rate of the intensity-intensity …
[(Co)H(Pph3)2-Arachno-Osb3h8], Nigam Rath, J. Bould, L. Barton
[(Co)H(Pph3)2-Arachno-Osb3h8], Nigam Rath, J. Bould, L. Barton
Chemistry & Biochemistry Faculty Works
A single-crystal X-ray diffraction study of the species 2-carbonyl2-hydrido-trans-2,2-bis(triphenylphosphine)-2-osma-arachno-tetraborane confirms the structure as a tetraborane(10) butterfly with a trans-[(CO)H(PPh3)2Os] group replacing a BH2 group at a wing-tip or 2-position. It is compared with the previously reported ruthenaborane analogue (CO)H(PPh3)2-arachno-RuB3H8.
Aggregation Of Chlorophyll A Probed By Resonance Light Scattering Spectroscopy, J. C. De Paula, J. H. Robblee, Robert F. Pasternack
Aggregation Of Chlorophyll A Probed By Resonance Light Scattering Spectroscopy, J. C. De Paula, J. H. Robblee, Robert F. Pasternack
Chemistry & Biochemistry Faculty Works
We report the resonance light scattering (RLS) spectra of chlorophyll a aggregated in a 9:1 solution of formamide and pH 6.8 phosphate buffer. The aggregate formed after 2 h of mixing, referred to as Chl(469), shows a strong scattering feature at 469 nm (Soret band) and a much weaker feature at 699 nm (Q(y) band). A kinetic investigation confirmed that the aggregation process is cooperative, and also detected one intermediate (Chl(458)) with a strong RLS spectrum but only a weak CD spectrum. We propose that aggregation proceeds via at least three steps: 1) formation of a nucleating species, probably a …
Fragment Rotational State Distributions From The Dissociation Of Neibr: Experimental And Theoretical Results, Thomas Alex Stephenson
Fragment Rotational State Distributions From The Dissociation Of Neibr: Experimental And Theoretical Results, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The IBr fragment rotational state distributions that result when the NeIBr van der Waals molecule undergoes vibrational predissociation have been measured in a pump-probe laser-induced fluorescence experiment. Independent of initial vibrational state and the number of quanta of vibrational energy lost from the I-Br coordinate, the rotational distributions extend over the full range of energetically accessible states. From the observation of energetic constraints on the rotational distribution, the dissociation energy (D0) is calculated to be 65.5 +/- 1.2 cm-1 for the A electronic state, v=16. For the X electronic state, v=0, D0=71.8 +/- 1.2 cm-1. Quantum mechanical bound state calculations …
Vibrational Branching Ratios From The Dissociation Of The Neibr Van Der Waals Molecule, Sarah Anne Walter , '91, Thomas Alex Stephenson
Vibrational Branching Ratios From The Dissociation Of The Neibr Van Der Waals Molecule, Sarah Anne Walter , '91, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The degree of vibrational excitation in the IBr fragment from the vibrational predissociation of NeIBr (A (3)PI(1)) has been measured using two-color pump-probe laser-induced fluorescence spectroscopy. We find that for the lowest initial vibrational states examined, DELTA-upsilon = -1 dissociation pathways dominate the dynamics, while this channel is closed for upsilon greater-than-or-equal-to 17. From this result, the A state binding energy (D0) of the complex is determined to be 67 +/- 4 cm-1, while that in the X electronic state is found to be 73 +/- 4 cm-1. The X state binding energy is identical to that for NeI2 and …
Evidence For An Unusual Kinetic Phenomenon In The Metallation Of Porphyrins, F. González-Vílchez, R. A. Vilaplana, Robert F. Pasternack
Evidence For An Unusual Kinetic Phenomenon In The Metallation Of Porphyrins, F. González-Vílchez, R. A. Vilaplana, Robert F. Pasternack
Chemistry & Biochemistry Faculty Works
Reaction of copper(II) with water soluble porphyrins (H₂porph) in the presence of ethylenediamine shows an unusual and so far unreported kinetic phenomenon that can be explained in terms of supramolecular assembly formation apparently involving all solute species as confirmed via light scattering and conductivity measurements.
Nonadiabatic Electronic Interactions In The Ion-Pair States Of Nelcl, Thomas Alex Stephenson, Y. Hong, M. I. Lester
Nonadiabatic Electronic Interactions In The Ion-Pair States Of Nelcl, Thomas Alex Stephenson, Y. Hong, M. I. Lester
Chemistry & Biochemistry Faculty Works
Nonadiabatic interactions in the NeIC1 van der Waals complex have been explored in the lowest energy triad of IC1 ion-pair states (approximately 39 000 cm-1). Dispersed fluorescence measurements reveal emission characteristic of multiple ion-pair electronic states, with the relative contributions from the E(O+ ), beta(1), and D'(2) states changing with the initial IC1 vibrational excitation (v(IC1)). Emission directly from NeIC1 (v(IC1) = O) complexes indicates that the initially prepared NeIC1 levels have mixed electronic character and that the IC1 electronic parentage changes with the initial van der Waals vibrational level selected. NeIC1 complexes prepared with 1-4 quanta of IC1 stretch …
The Spectroscopy And A State Dynamics Of The Neibr Van Der Waals Complex, William Robert Simpson , '88, Thomas Alex Stephenson
The Spectroscopy And A State Dynamics Of The Neibr Van Der Waals Complex, William Robert Simpson , '88, Thomas Alex Stephenson
Chemistry & Biochemistry Faculty Works
The A 3Π1←X 1Σ+ laser‐induced fluorescence excitation spectrum of the NeIBr van der Waals complex is reported and analyzed to extract information regarding the structure and vibrational predissociation dynamics of the complex. While no definitive geometric information regarding NeIBr is obtained, our data indicate that a linear geometry is at least plausible. The vibrational predissociation lifetimes are a strong function of A state vibrational level and range from 2.6 to 23 ps. The variation in lifetime with vibrational level is consistent with the results of previous measurements on rare gas–halogen complexes, particularly NeBr2.
Influence Of Dna On The Rate Of Porphyrin Metallation, Robert F. Pasternack, E. J. Gibbs, R. Santucci, Stephanie A. Schaertel , '86, Panayiotis A. Ellinas , '87, Stanley C. Mah , '87
Influence Of Dna On The Rate Of Porphyrin Metallation, Robert F. Pasternack, E. J. Gibbs, R. Santucci, Stephanie A. Schaertel , '86, Panayiotis A. Ellinas , '87, Stanley C. Mah , '87
Chemistry & Biochemistry Faculty Works
Poly(dG–dC)₂ and poly(dA–dT)₂ have marked influences on the rate of insertion of copper(II) into cationic porphyrins reflecting the interaction mode of the porphyrin with the nucleic acid.
Freezing Points Of Aqueous Alcohols: Free Energy Of Interaction Of The Choh, Ch₂, Conh And C[Double Bond]C Functional Groups In Dilute Aqueous Solutions, B. Y. Okamoto, R. H. Wood, Peter T. Thompson
Freezing Points Of Aqueous Alcohols: Free Energy Of Interaction Of The Choh, Ch₂, Conh And C[Double Bond]C Functional Groups In Dilute Aqueous Solutions, B. Y. Okamoto, R. H. Wood, Peter T. Thompson
Chemistry & Biochemistry Faculty Works
The freezing temperatures of dilute aqueous solutions of methanol, ethanol, 2-propanol, butanol, t-butanol, cyclohexanol and ethylene glycol were measured over the concentration range 0.1 to 1 mol kg–1. Osmotic coefficients at 0°C were calculated. The limiting pairwise interaction coefficients of the alcohols, plus a variety of polyhydroxy compounds and carbohydrates, were calculated at 25°C from the available data and then correlated using the additivity principle of Savage and Wood. This correlation approximates effective free energies of CH2 and CHOH group interactions with themselves and with each other. Literature data were used to estimate interactions between CONH and C[double bond]C groups. …
Rapidly Converging Activity Expansions For Representing The Thermodynamic Properties Of Fluid Systems: Gases, Non-Electrolyte Solutions, Weak And Strong Electrolyte Solutions, R. H. Wood, T. H. Lilley, Peter T. Thompson
Rapidly Converging Activity Expansions For Representing The Thermodynamic Properties Of Fluid Systems: Gases, Non-Electrolyte Solutions, Weak And Strong Electrolyte Solutions, R. H. Wood, T. H. Lilley, Peter T. Thompson
Chemistry & Biochemistry Faculty Works
For dilute gases and non-electrolyte solutions in the McMillan–Mayer standard state, an activity expansion due to Mayer has great advantages over the normal concentration expansion (virial equation) for strongly associating species. For weakly interacting systems, both approaches are suitable. The activity expansion eliminates the need to differentiate between strong “chemical” interactions and weak “physical” interactions since the same equation is used in each situation. The equation has been modified to represent electrolyte solutions in the McMillan–Mayer standard state by requiring that it be consistent with the Debye–Hückel and higher order limiting laws for strong electrolytes and that it be equivalent …