Lomeridine dihydrochloride

Lomeridine dihydrochloride (l-[bis(4-fluorophenyl)methyl]-4-(2,3,4-trimethoxygenzyl)-piperazine dihydrochloride) has been shown to be capable of existing in two polymorphic forms, for which the structures have been reported [39]. Form I was obtained from acetonitrile solution, while Form II was crystallized from methanol, ethanol, w-propanol, /-propanol, n-butanol, or methyl ethyl ketone. Crystallographic data reported for the two forms are found in Table 16. 

Views of the molecular conformations adopted by lomeridine dihydrochloride in its two polymorphic forms. (The figure is adapted from data presented... 

Not all instances of conformational polymorphism are as dramatic as that just described, and often different conformers of a single side chain are able to pack into different crystalline arrangements. For instance, the two polymorphs of/>-(li ,3 S)-3-thioanisoyl-l,2,2-trimethyl-cyclopentane carboxylic acid were found to be associated with different conformations of the carboxylate group [15], Torsion about a single C-N bond was shown to be the origin of the polymorphism detected for lomeridine dihydrochloride [16], Finally, relatively small differences in molecular conformation were detected for the two polymorphic and four solvated crystalline forms of spironlactone [17],... 

The solid-state FTIR spectra of many polymorphic systems often are found to be only slightly different, indicating that the pattern of molecular vibrations is not grossly affected by differences in crystal structure. Examples of this type of behavior are typified in studies conducted on etoposide [113], tegafur [114], lomeridine dihydrochloride [115], and carbamazepine [116]. In other instances, the FTIR spectra... 

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