Dipole moment direction

Rosell FI, Boxer SG (2003) Polarized absorption spectra of green fluorescent protein single crystals Transition dipole moment directions. Biochemistry 42 177-183... 

The quadrupole-dipole interaction differs by a factor of 2 from the usual definition of this term.48 However, the effect of this difference on the overall results of the simulation that it was used in is thought to be small. The sign of Q was taken as positive and the dipole moment direction was from the oxygen atom to the carbon atom.50... 

Fig. 2 Left. The basic 2D structure in the rod-like liquid crystals made by strongly polar molecules (the dipole moment directions are represented by arrows). The asymmetric rod-like molecules tend to form double layer structures in order to compensate dipole moments. Since the thickness of a double layer is smaller than twice the thickness of a single layer the resulting stress in the system is relieved by the in-layer modulation. Right. 2D structures in polycatenar rod-like liquid crystals. The ribbon like structure is formed by the asymmetric polycatenar molecules. To accommodate the additional alkyl chains layers become slightly bent. Both structures possess the body centered crystallographic unit cell...

Fig. 2.63. Dependence of ion-HjO interaction on ion-0 distance. 1 Symmetric H O molecule orientation (ion-0 vector coincides with the water dipole moment direction) 2 lone pair-to-ion orientation, (a) Na, (b) K (1 A = 100 pm). (Reprinted from G. G. Malenkov, Modelsforthe Structure of Hydrated Shells of Simple Ions Based on Crystal Structure Data and Computer Simulation, in The Chemical Physics of Solvation, Part A, R. R. Dogonadze, E. Kalman, A. A. Komyshev, and J. Ulstrup, eds., Elsevier, New York, 1985.)...

Thus the structure of the SO2 molecule is expected to be V-shaped with a 120-degree bond angle. The molecule has a dipole moment directed as shown ... 

The dipole moment direction in cyclopropyne again is the reverse of that normally associated with a saturated hydrocarbon fragment attached to a triple bond (e.g. propyne). 

Dipolar structure of amino acids—The dipole moment data support the dipolar, zwitterionic, structure of the amino acids, viz HgRGHCOO-. If the molecule at its iso-electric point possesses this structure, it will have a very large dipole moment of the order of 13 9 D since the distance between the charges is approximately 2-9 A. Unfortunately such compounds are only soluble in polar solvents and it is therefore impossible to measure the dipole moments directly. The dielectric constant of aqueous solutions of amino acids is, however, greater than that of water and furthermore increases in direct proportion to the concentration. The value of A el Ac... 

Further information comes from Sutton s research with additional assumptions. For the phenol-amine complex Sutton computed the relative bond character of the H bond—75 to 85 percent ionic and 25 to 15 percent covalent—on the basis of the calculated dipole moment direction corrected for induced moments. These figures are in general agreement with other estimates based on electrostatic models. The tenuous nature of the argument must be kept in mind. 

They have dipole moments directed one along the line joining the atoms 0 and 3, and one perpendicular to this line. (Cf. Figure 2.12c.)... 

Benko et al, 2004). Furthermore, anisotropy of the absorption signal can also be used to differentiate these species, as they often have different transition-dipole moment directions (Martini et al, 1998). Shown in Fig. 11.3 is an example of a careful transient absorption study of NS/TiOa (Benko et al, 2002 KaUioinen et al, 2002). By measuring the transient spectral evolution of the reactant (adsorbate excited states) and products (cation and injected electrons) over the visible and near-IR range, the injection kinetics (shown in the inset) were unambiguously determined. 

Normalized dipole moment (direction cosine) Covalent-bond length (see Fig. 1)... 

The dipole moments wctc related to hydrogen bond strength and to the ability of the proton acceptors (compounds with phosphoryl and carbonyl groups) to associate with phenol. Hydrogen bonded complexes of pyridines, quinolines and acridine with phenol are studied, in carbon tetrachloride, by dipole moment measures . Dipole moments of the complexes were related to the ability of the acceptors to associate with phenol and with their basicity. Hydrogen bonds may either reinforce the dipole moments of the resultant of the group moments or may oppose the dipole moment direction, depending on the nature of the acceptor. 

Recently, van Eijck and Kroon discussed the implications of dependence of the electrostatic energy of a crystal on its macroscopic shape if the crystal has a nonzero dipole moment. Ewald summation then results in the lowest possible energy. This minimum energy corresponds to the situation that the crystal finds an energetically optimal shape (a needle, with the dipole moment directed along the needle axis, or a platelet with the dipole moment in its plane) and/or... 

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