Barrier to coupled internal rotation in bis(9-triptycyl) ether. Kinetics of intramolecular exciplex formation in racemic 2,3-benzo-9-triptycyl 2-(N,N-dimethylaminomethyl)-9-triptycyl ether

1985 ◽  
Vol 107 (5) ◽  
pp. 1426-1427 ◽  
Author(s):  
Noboru Koga ◽  
Hiizu Iwamura
Keyword(s):  
Internal Rotation ◽  
Exciplex Formation ◽  
Kinetics Of

Kinetics of Internal Rotation of N,N-Dimethylacetamide: A Spin-Saturation Transfer Experiment

1997 ◽  
Vol 74 (8) ◽  
pp. 978 ◽  
Author(s):  
Russell L. Jarek ◽  
Robert J. Flesher ◽  
Seung Koo Shin
Keyword(s):  
Internal Rotation ◽  
Saturation Transfer ◽  
Transfer Experiment ◽  
Kinetics Of

The Kinetics of Rubberlike Elasticity

1942 ◽  
Vol 15 (3) ◽  
pp. 438-445
Author(s):  
D. D. Eley
Keyword(s):  
Viscous Flow ◽  
Internal Rotation ◽  
Similar Data ◽  
Chain Molecules ◽  
Polymer Systems ◽  
Vulcanized Rubber ◽  
Activated State ◽  
Main Effect ◽  
High Degree ◽  
Kinetics Of

Abstract 1. The treatments of relaxation phenomena in polymer systems, due to Kuhn, and Alexandrov and Lazurkin, are outlined and discussed. 2. Eyring's rate equation is used to analyze the rates of orientation of long-chain molecules in a stressed specimen of lightly vulcanized rubber. The data are compared with similar data on viscous flow in raw rubber, and it is suggested that the segment size for movement is the same in both cases. In viscous flow, the segmental movement occurs without appreciable internal rotation within the segment. In elastic orientation, however, it appears that a high degree of internal rotation within the segment accompanies the formation of the activated state. 3. The activation energy for the orientation of long chains is separated into two terms: (1) the energy required to free a segment from its neighbors, (2) the energy of activation for rotation around C—C bonds. It is suggested that the main effect of vulcanization and plasticizers is on term (3); vulcanization tends to increase this term, plasticizers to decrease it. 4. Data on the dielectric dispersion of polyvinyl chloride suggests the need for internal rotational activation in this case, as in orientation elasticity. This is in agreement with what we should qualitatively expect. Possible complications due to crystallinity in rubber at high extensions or low temperatures are briefly discussed.

scholarly journals Transient Exciplex Formation Electron Transfer Mechanism

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Michael G. Kuzmin ◽  
Irina V. Soboleva ◽  
Elena V. Dolotova
Keyword(s):  
Experimental Data ◽  
Electron Transfer ◽  
Excited State ◽  
Transfer Reactions ◽  
Electron Transfer Mechanism ◽  
Electron Transfer Reactions ◽  
Exciplex Formation ◽  
State Electron ◽  
Enthalpy And Entropy ◽  
Kinetics Of

Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated) mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

Studies on rotational barriers in alkyl halogenides by means of vibrational spectroscopy

1980 ◽  
Vol 45 (4) ◽  
pp. 984-996 ◽  
Author(s):  
Michal Bureš ◽  
Čestmír Černý
Keyword(s):  
Simple Model ◽  
Internal Rotation ◽  
Infrared Spectra ◽  
Conformational Transitions ◽  
Gaseous State ◽  
Rotational Barriers ◽  
Halogenated Alkanes ◽  
Kinetics Of ◽  
The Ideal ◽  
Ideal Gaseous State

A simple model describing the influence of the neighbouring molecules on the mechanism of the internal rotation in a given molecule has been proposed which allows the calculation of the barrier hindering the internal rotation in the ideal gaseous state from the temperature dependencyof the infrared spectra. To ascertain its adequacy, the kinetics of conformational transitions in seven halogenated alkanes has been investigated, and values of the activation enthalpies accompanying the internal rotation in a solution as well as the rotational barriers in the ideal gaseous state have been determined.

Kinetics of exciplex formation/dissipation in reaction following Weller Scheme II

2014 ◽  
Vol 141 (11) ◽  
pp. 114504 ◽  
Author(s):  
S. G. Fedorenko ◽  
A. I. Burshtein
Keyword(s):  
Exciplex Formation ◽  
Kinetics Of

Three-Dimensional Kinetics of the Shoulder, Elbow, and Wrist during a Penalty Throw in Water Polo

1997 ◽  
Vol 13 (3) ◽  
pp. 347-372 ◽  
Author(s):  
Michael E. Feltner ◽  
Grant Taylor
Keyword(s):  
Internal Rotation ◽  
Muscular Strength ◽  
Positive Relationship ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Upper Arm ◽  
Joint Forces ◽  
Angular Velocities ◽  
Muscle Actions ◽  
Kinetics Of

The purpose of the study was to examine the resultant joint forces (RJFs) and torques (RJTs) at the shoulder, elbow, and wrist during penalty throws and determine the relationships between muscle actions and motions of the throwing arm. Subjects with an overhand (OH) throwing technique created larger maximal and average RJTs at the shoulder and elbow compared to subjects with a sweep (SW) technique (Feltner & Nelson, 1996). Prior to release, OH technique subjects decreased their abduction torque and created adduction torques at the shoulder. Adduction torques and downward vertical motion of the trunk, together with an internal rotation torque at the shoulder, resulted in large internal rotation angular velocities at release for the OH technique subjects. The SW technique subjects did not exhibit these technique characteristics. Additionally, throwing technique exhibited a moderate but positive relationship with several chest, upper arm, and forearm circumference measures. Findings suggest that muscular strength may be a causal determinant of technique style.

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