Correlation structure-energy

With the advent of modem instrumentation that furnish all pertinent thermodynamic data from a single experiment within a few hours calorimetry can help to tackle problems in host-guest binding that are inaccessible (principally or on a quantitative basis) to any other method. The power of enthalpic measurements, however, is unleashed only if put in a well-defined structural context. As a corollary, the benefit of sound structure-energy correlation on this basis calls for a more intense synthetic input. 

However, whether or not a molecular interaction rests on one dominant configuration in solution cannot be deduced easily. The problem touches on the fundamental issue of structure-energy correlation, and is heavily loaded with justified and/or completely arbitrary presumptions that in many cases reflect a traditional bias rather than a well-balanced appreciation of scientific arguments. 

A fundamental understanding of structure-reactivity and structure-energy correlations in heteroaromatic compounds is of central importance in chemistry and biochemistry. The classical approach to this subject normally... 

CT complex formation from excited states is a widespread phenomenon and consequently has been very extensively studied. 0 A structure-energy correlation of intramolecular CT state formation in a series of (N,N-diethylanilino) amines indicates that high polar excited states are involved (pg values range between 13.4-... 

Both types of correlation analysis, structure-structure and structure-energy correlations, have much in common with FER s or energy-energy correlations [65]. The three types of correlation are analogous in the sense that they all uncover relationships between observables for which there is no a priori reason to be related. They are thus providing genuine, new information, which needs to be interpreted. 

Structure correlations and FER s are well established by now. The same is not true for structure-energy correlations, possibly because in most cases either only kinetic or only structural data are available for a given compound possibly also, because structure-energy correlations require expertise in different experimental techniques. These difficulties should not be serious obstacles, however, to further development of such correlations X-ray facilities are available in many chemical laboratories, and the X-ray crystallographer will usually be more than willing to collaborate with the chemist. 

In the following sections a number of examples are summarized with an emphasis on the chemical information that can be obtained from them. Some have already been mentioned in previous chapters to illustrate specific methodological aspects of structure-structure and of structure-energy correlation. Others will merely be mentioned to provide a reference to the primary literature for the interested reader. 

Seiders, X J., Baldridge, K. K., Grube, G. H., 8c Siegel, J. S. (2001). Structure/energy correlation of bowl depth and inversion barrier in corannulene derivatives Combined experimental and quantum mechanical analysis. Journal of the American Chemical Society, 123, 517-525. 

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