| 1. |
- MURRAY, JS, et al.
(författare)
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Electrostatic potentials on the molecular-surfaces of cyclic ureides
- 1991
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : American Chemical Society (ACS). - 0022-3654 .- 1541-5740. ; 95:2, s. 844-848
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio SCF-MO electrostatic potentials have been computed at the STO-5G/STO-3G level on the molecular surfaces of a group of cyclic ureides, in order to assess their relative reactivities toward nucleophiles, as in hydrolysis. The surfaces were defined by the 0.002 electron/bohr3 contour of the molecular electronic density. The relative hydrolytic stabilities within a series of NO2 and NF2 derivatives are predicted, on the basis of the magnitudes of the potentials above the acyl carbons. The surface electrostatic potentials of the polycarbonyl systems parabanic acid and alloxan are shown to be fully consistent with unusually short intermolecular distances that have been observed in crystallographic studies of these compounds.
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| 2. |
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| 3. |
- Brinck, Tore, et al.
(författare)
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Segmental analysis of molecular surface electrostatic potentials : application to enzyme inhibition
- 2003
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Ingår i: Journal of Molecular Modeling. - : Springer Science and Business Media LLC. - 1610-2940 .- 0948-5023. ; 9:2, s. 77-83
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Tidskriftsartikel (refereegranskat)abstract
- We have recently shown that the anti-HIV activities of reverse transcriptase inhibitors can be related quantitatively to properties of the electrostatic potentials on their molecular surfaces. We now introduce the technique of using only segments of the drug molecules in developing such expressions. If an improved correlation is obtained for a given family of compounds, it would suggest that the segment being used plays a key role in the interaction. We demonstrate the procedure for three groups of drugs, two acting on reverse transcriptase and one on HIV protease. Segmental analysis is found to be definitely beneficial in one case, less markedly so in another, and to have a negative effect in the third. The last result indicates that major portions of the molecular surfaces are involved in the interactions and that the entire molecules need to be considered, in contrast to the first two examples, in which certain segments appear to be of primary importance. This initial exploratory study shows that segmental analysis can provide insight into the nature of the process being investigated, as well as possibly enhancing the predictive capability.
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| 4. |
- Jin, P., et al.
(författare)
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Computational prediction of relative group polarizabilities
- 2003
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Ingår i: International Journal of Quantum Chemistry. - : Wiley. - 0020-7608 .- 1097-461X. ; 95:05-apr, s. 632-637
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Tidskriftsartikel (refereegranskat)abstract
- Earlier work has shown that molecular polarizabilities correlate well with the quantity V/(I) over bar (S,ave), where V is the volume of the molecule and (I) over bar (S,ave) is the average value of the local ionization energy on its surface. We now extend this to group polarizabilities; we computed V/(I) over bar (S,ave) for four common chemical groups (NO2, CH3, NH2, and OH) in a variety of molecules. The transferabilities of (I) over bar (S,ave), V, and V/(I) over bar (S,ave) are examined, as well as the correlation between V/(I) over bar (S,ave) and literature polarizabilities of CH3, NH2, and OH. This permits the value for NO2 to be predicted (alpha = 2.77 Angstrom(3)). The dependence of (I) over bar (S,ave), and therefore V/(I) over bar (S,ave), upon the remainder of the molecule is discussed.
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| 5. |
- MURRAY, JS, et al.
(författare)
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RELATIONSHIPS BETWEEN COMPUTED MOLECULAR-PROPERTIES AND SOLUTE SOLVENT INTERACTIONS IN SUPERCRITICAL SOLUTIONS
- 1993
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - UNIV NEW ORLEANS,DEPT CHEM,NEW ORLEANS,LA 70148. : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 97:19, s. 5144-5148
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Tidskriftsartikel (refereegranskat)abstract
- We focus specifically on solute-solvent interactions in supercritical solutions, as reflected in the enhancement factor E = y2P/P2sat, where Y2 and P2sat are the solubility and vapor pressure of the solute and P is the pressure of the system. For a series of 12 organic solutes in supercritical CO2, We find that E can be represented well in terms of three key solute molecular properties: (a) surface area, (b) the sum of the variances of the positive and negative electrostatic potentials on the surface, and (c) a ''balance' parameter which indicates the degree to which the solute molecule can interact to a similar extent through both its positive and negative regions. These three solute properties were computed at an ab initio self-consistent field minimum basis set level. On the basis of limited data, the same type of relationship appears to be applicable for a given solute-cosolvent combination. When various solvents or cosolvents are used, the enhancement factor of a weakly polar solute correlates well with the solvent/cosolvent molecular sizes. For polar solutes, however, an explicit dependence upon electrostatic interaction tendencies must be included.
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| 6. |
- MURRAY, JS, et al.
(författare)
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RELATIONSHIPS OF CRITICAL CONSTANTS AND BOILING POINTS TO COMPUTED MOLECULAR-SURFACE PROPERTIES
- 1993
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - UNIV NEW ORLEANS,DEPT CHEM,NEW ORLEANS,LA 70148. : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 97:37, s. 9369-9373
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Tidskriftsartikel (refereegranskat)abstract
- It is shown, for a large number of organic compounds of a variety of types, that their critical constants (T(c), V(c), and P(c)) and normal boiling points can be related to computed properties of the respective molecular surfaces. One of these is the surface area; the other is a measure of the molecule's tendency for electrostatic interactions. These properties are obtained by ab initio SCF computations at the STO-5G* level, using STO-3G* optimized geometries.
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| 7. |
- MURRAY, JS, et al.
(författare)
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STATISTICALLY-BASED INTERACTION INDEXES DERIVED FROM MOLECULAR-SURFACE ELECTROSTATIC POTENTIALS - A GENERAL INTERACTION PROPERTIES FUNCTION (GIPF)
- 1994
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Ingår i: Journal of Molecular Structure. - UNIV NEW ORLEANS, DEPT CHEM, NEW ORLEANS, LA 70148 USA. : ELSEVIER SCIENCE BV. - 0166-1280. ; 113, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- A number of physical properties determined primarily by non-covalent interactions can be expressed quantitatively in terms of molecular surface area plus three statistically-based quantities obtained from the surface electrostatic potential: II, a measure of local polarity; sigma(tot)2, which indicates the variability of the potential on the surface; upsilon, a measure of the balance between positive and negative regions. In the applications discussed, these quantities and the area are obtained through ab initio computations. The various specific relationships can be summarized through a general interaction properties function (GIPF), property = f(area, PI, sigma(tot)2, upsilon), the functional form of which depends upon the property of interest.
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| 8. |
- POLITZER, P, et al.
(författare)
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ANALYTICAL REPRESENTATION AND PREDICTION OF MACROSCOPIC PROPERTIES - A GENERAL INTERACTION PROPERTIES FUNCTION
- 1995
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Ingår i: IMMUNOANALYSIS OF AGROCHEMICALS: EMERGING TECHNOLOGIES. - : AMER CHEMICAL SOC. - 0841231494 ; , s. 109-118
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Forskningsöversikt (refereegranskat)abstract
- We present a procedure whereby quantities computed for an isolated molecule can be used to represent and predict macroscopic properties that reflect molecular interactions. Such representations are all special cases of a General Interaction Properties Function (GIPF). The molecular quantities are evaluated on the surface of the molecule, defined as the 0.001 au contour of its electronic density; most of them are related to its electrostatic potential. Among the macroscopic properties for which GIPF expressions have been developed are aqueous acidities, boiling points, critical constants, partition coefficients, heats of vaporization, solubilities in supercritical fluids and hydrogen bonding parameters. The GIPF approach is expected to facilitate the design of molecules for specific purposes such as haptens in immunochemistry, since it identifies the key factors that determine particular properties and provides a means for evaluating proposed compounds prior to their syntheses.
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| 9. |
- POLITZER, P, et al.
(författare)
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INVESTIGATION OF RELATIONSHIPS BETWEEN SOLUTE MOLECULE SURFACE ELECTROSTATIC POTENTIALS AND SOLUBILITIES IN SUPERCRITICAL FLUIDS
- 1992
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 96:20, s. 7938-7943
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Tidskriftsartikel (refereegranskat)abstract
- We have sought to relate the electrostatic potentials of naphthalene and some indole derivatives, computed at the ab initio Hartree-Fock STO-5G//STO-3G level, to their experimentally determined solubilities in four supercritical fluids (C2H6, C2H4, CO2, and CHF3). Very good correlations were found between solubility and the sum of the variances of the positive and negative potentials on the solute molecular surfaces; these relationships are quantitatively similar for all four solvents. For oxindole, we conclude that the enol tautomer predominates in these solutions. The inclusion of solute molecule surface areas and volumes did not improve our correlations.
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| 10. |
- POLITZER, P, et al.
(författare)
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RELATIONSHIPS BETWEEN SOLUTE MOLECULAR-PROPERTIES AND SOLUBILITY IN SUPERCRITICAL CO2
- 1993
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : AMER CHEMICAL SOC. - 0022-3654 .- 1541-5740. ; 97:3, s. 729-732
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Tidskriftsartikel (refereegranskat)abstract
- For 21 organic compounds, we have investigated the dependence of solubility in supercritical C02 upon several properties of the solute molecules, which were calculated at the ab initio SCF STO-5G*//STO-3G* level. Good double-variable linear regressions were found that relate solubility to (a) the total variance of the electrostatic potential on the molecular surface and (b) the molecular volume. Solubility varies inversely with the variance of the surface potential, consistent with solute-solute interactions dominating over solute-solvent interactions in determining solubility in low-density supercritical solutions.
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