Temperature effects on the hydrogen-bond patterns in 4-piperidinecarboxylic acid

Abstract

A temperature-controlled X-ray powder diffraction experiment, complemented with TGA and DSC analysis, allowed us to follow changes in the molecular conformation and hydrogen-bond patterns of 4-piperidinecarboxylic acid. The presence of three phases is confirmed. Phase 1 represents the monohydrated form of 4-piperidinecarboxylic acid, which exists from room temperature to 359 K, where dehydration occurs. Phase 2 measured at 363 K corresponds to an anhydrous form of the acid. At ca 458 K the onset of a second, more gradual transition is observed, which ends at around 543 K. Phase 3 measured at 543 K is a high-temperature anhydrous form of the acid. The structures of phases 2 and 3 were solved from synchrotron powder diffraction data by simulated annealing using the DASH program and refined by the Rietveld method. The phase changes are accompanied by modification of the hydrogen-bond patterns and of the torsional orientation of the terminal carboxylate group. This group makes a 49 degrees rotation about the C1-C2 bond during the first transition.

Structures of (S)-(−)-4-oxo-2-azetidinecarboxylic acid and 3-azetidinecarboxylic acid from powder synchrotron diffraction data

“…Additional N1-H4Á Á ÁO3 hydrogen bonds link neighboring chains laterally forming ribbons also running parallel to [010]. As observed in previous studies (Mora et al, 2005), the four hydrogen-bond acceptor capacity of the carboxylic acid is completed by means of two weak C2-H2Á Á ÁO3 and C2-H3Á Á ÁO1 hydrogen bonds. Hydrogen bonding in the 3-azetidinecarboxylic acid (II) is markedly different because of its zwitterionic characters, which makes the amine group in the ring a double donor of H atoms.…”

Hydrogen-bonding in the structures of the 1 : 1 salts of isonipecotamide with a set of four polyfunctional monocyclic heteroaromatic carboxylic acids

“…This prompted our investigation of the possible use of this Lewis base as a synthon for the formation of crystalline materials through the formation of stable hydrogen-bonding systems involving the trans-related associative functional groups of INIPA. This possibility was supported by known structures of both the parent acid [2] and its monohydrate [3] which show the presence of piperidinium-carboxylate zwitterions. The structure of the hydrochloride of this acid is also known [4][5][6].…”

Molecular structure characterization of asphaltene in the presence of inhibitors with nanoemulsions

“…The residue at the highest temperature for asphaltene with DBSA is very low about 4.71%, suggesting that formation of multiple intermolecular interactions like hydrogen bond, acid-base interaction, and p-p interaction between the adjacent molecules of DBSA NEs with asphaltene molecules, which give rise to the high temperature. 54 The formation of coke from asphaltene decreased when DBSA NEs were added to asphaltene, indicating that DBSA NEs tended to stabilize a proportion of asphaltene. The DBSA NEs can promote the loss of labile points of long alkyl chains in DBSA NEs components which linked with asphaltene molecules, releasing more volatile compounds for example gases.…”