Mary W. Creese

Structure—frequency correlations. Analysing non-additive data patterns of saturated aliphatic alcohols — an example

Abstract The OH stretching frequencies, νmax values, for a series of 22 monohydric, saturated, aliphatic alcohols have been examined, and a structure—frequency correlation pattern is presented. A formal procedure is offered for analyzing frequency differences (and contrasts), and it is shown that the frequency pattern for the majority of the compounds is well described by a simple, non-linear formula. It is concluded that the substituent effects are non-additive.

Statistical methods for combining and improving chemical data taken from several independent sources

Abstract Statistical methods are used to analyze and reduce contradictions among published data lists. As an example a coherent and precise list of the OH stretching frequencies of a series of 32 saturated alcohols is assembled from overlapping and conflicting source lists, using the least-squares approximation. The data lists are recalibrated, and precision and accuracy questions are examined.

The energy well connection graph: a use of curvilinear coordinates to achieve dimension reduction for graph representation of molecular conformation energy data

In the conformation space of a flexible molecule, curvilinear coordinate paths connecting conformations of segments of the given molecule are used to reduce the number of variables required for describing barriers between preferred conformations of the molecule as a whole. The technique is applied to a hypothetical example, then to m-trinuoromethyl-N-ethyl-amphetamine (fenfluramine), and to N-methyl-3-phenyl-3-(o-methoxyphenoxy)-propylamine (nisoxetine). In the latter example, the number of variables is thus reduced from six to three. In all three examples, a graph representation of low-energy well connection is achieved. The limit of easy comprehension has thus been moved back from about three torsion angles to three effective segments. Within this limit the procedure leads to a quantitative diagram, which is no harder to read than a contour map, showing the barriers to low-energy interconnection among the favorable conformations of a moderately complex molecule.