Describes and discusses the use of theoretical models as an alternative to experiment in making accurate predictions of chemical phenomena. Addresses the formulation of theoretical molecular orbital models starting from quantum mechanics, and compares them to experimental results. Draws on a series of models that have already received widespread application and are available for new applications. A new and powerful research tool for the practicing experimental chemist.

AB INITIO Molecular Orbital Theory

We present a new integral equation formulation of the polarizable continuum model (PCM) which allows one to treat in a single approach dielectrics of different nature: standard isotropic liquids, intrinsically anisotropic medialike liquid crystals and solid matrices, or ionic solutions. The present work shows that integral equation methods may be used with success also for the latter cases, which are usually studied with three-dimensional methods, by far less competitive in terms of computational effort. We present the theoretical bases which underlie the method and some numerical tests which show both a complete equivalence with standard PCM versions for isotropic solvents, and a good efficiency for calculations with anisotropic dielectrics.

A new integral equation formalism for the polarizable continuum model: Theoretical background and applications to isotropic and anisotropic dielectrics

This review compiles positively and negatively solvatochromic compounds which have been used to establish empirical scales of solvent polarity by means of UV/vis/near-IR spectroscopic measurements in solution-with particular emphasis on the E ~ ( 3 0 ) scale derived from negatively solvatochromic pyridinium N-phenolate betaine dyes. This requires a short discussion of the concept of solvent polarity and how empirical parameters of solvent polarity can be derived and understood in the framework of linear free-energy relationships. The preconditions for the occurrence of solvatochromism, and further requirements of solvatochromic compounds for them to be useful as solvent polarity indicators will be discussed. In addition to spectroscopically based single parameters of solvent polarity, multiparameter treatments of solvent effects by means of solvatochromic parameters will also be mentioned. The mutual interrelation between some of the more important W/vis/near-IR spectroscopically derived solvent scales, and their correlations with solvatochromic multiparameter equations will be exemplarily given.

Solvatochromic Dyes as Solvent Polarity Indicators

Inhibition of anaerobic digestion process: A review

I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

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Conceptual density functional theory.

Les coefficients de partage octanol/eau de 245 composes aliphatiques et aromatiques sont bien correles par la relation d'energie de solvatation lineaire: logK ow =0,35+5,35V I /100-1,04(π*−0,35δ)-3,84 β m +0,10α m (r=0,9959, SD=0,131) ou V I est le volume molaire intrinseque, π*, β m et α m sont des parametres solvatochromiques

Linear solvation energy relationship. 46. An improved equation for correlation and prediction of octanol/water partition coefficients of organic nonelectrolytes (including strong hydrogen bond donor solutes)

Polar and Steric Substituent Constants for Aliphatic and o-Benzoate Groups from Rates of Esterification and Hydrolysis of Esters1

The Gas-Phase Acidities of Very Strong Neutral Bronsted Acids

The General Nature of the Proportionality of Polar Effects of Substituent Groups in Organic Chemistry

: The F-19 NMR shielding parameters for 21 meta substituted fluorobenzenes relative to a fixed external standard and relative to fluorobenzene as an internal standard were obtained at room temperature at high dilution in 20 widely varying pure solvents. Extensive measurements with 24 additional substituent groups in non-polar and in hydroxylic solvents, both pure and mixed, wereALSO MADE. In spite of a variation over 9.2 ppm in shielding for a given fluorobenzene relative to the fixed external standard, the shielding parameters for seven compounds with chemically inert meta substituents relative to internal fluorobenzene are solvent invariant to a precision of the same order as experimental error. This result offers critical evidence that intermolecular shielding resulting from interaction of the F atom with solvent makes little or no contribution to the shielding parameter of a meta substituted fluorobenzene relative to fluorobenzene as the internal standard. A further conclusion is that the field effect makes no practical contribution to the variation in shielding due to meta (and presumably para) substituents. It is further implied that the bond dipole moments of groups are independent to good precision of this variation in dielectric constant for many nonprotonic solvents at room temperatures. The effects of solvent on the shielding parameter of meta substituted fluorobenzenes with chemically active substituents is attributed to charge-transfer solvent-substituent interactions. (Author)

Robert W. Taft

Papers

Linear solvation energy relationship. 46. An improved equation for correlation and prediction of octanol/water partition coefficients of organic nonelectrolytes (including strong hydrogen bond donor solutes)

Polar and Steric Substituent Constants for Aliphatic and o-Benzoate Groups from Rates of Esterification and Hydrolysis of Esters1

The Gas-Phase Acidities of Very Strong Neutral Bronsted Acids

The General Nature of the Proportionality of Polar Effects of Substituent Groups in Organic Chemistry

Fluorine Nuclear Magnetic Resonance Shielding in meta-Substituted Fluorobenzenes. The Effect of Solvent on the Inductive Order