Generation of crystal structures of acetic acid and its halogenated analogs

Abstract

The approach of Karfunkel and Gdanitz has been used to predict possible crystal structures of acetic acid and three of its monohalogenated analogs starting with the molecular structure alone. The results demonstrate that this approach is capable of finding many, if not all, of the possible packing arrangements of molecules of this size, but that it is not currently capable of correctly ranking these structures in terms of their enthalpy. This deficiency is probably due to inadequacies in the force field used to minimize the structures. The inadequacies relate to the description of acidic hydrogen bonds and halogen–halogen interactions. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1–20, 1998

Crystal structure prediction of organic pigments: quinacridone as an example

“…It models hydrogen bonds in crystal structures reasonably well. In certain cases, for example hydrogen bonds in acids, limitations have been reported (Payne et al, 1998). The force-field description of the structures in the present case appears to be quite adequate, since all three polymorphs were found within 3 kcal mol À1 .…”

A theoretical investigation of conformational aspects of polymorphism. Part 2. Diarylamines

“…This contradicts the other calculations, and it is likely that this is a consequence of a failing of the Dreiding force field, which has problems in the treatment of carboxylic acid dimers. 24 Variations in the results mean that it is not evident which form of BIXGIY has the most stable lattice. Differential thermal analysis of the polymorphs indicates that forms III and IV are transformed into form I at 156 and 144 ЊC, respectively, which then melts at 242 ЊC.…”

“…These minimisations were performed to overcome the particular sensitivity of the Dreiding FF to hydrogen bond lengths in carboxylic acids. 24…”

Pressure-controlled aggregation in carboxylic acids. A case study on the polymorphism of bromochlorofluoroacetic acid

“…The monochloroacetic acid is known to form three polymorphs, 12 16 Some of the crystal structures of halogenated analogues of acetic acid have already been predicted using computational methods. 17 Most recently it was found that the dimer-catemer phase transitions can be induced by temperature in the hydrogen bonds between amide groups of cyheptamide molecules. 18 Also previous research on tetrolic acid has already shown such activated phase transition from a dimer to catemer motif.…”