Limits...
Crystal structure resolution of two different chlorhexidine salts

View Article: PubMed Central - PubMed

ABSTRACT

Two salts of the chlorhexidine di-cation (H2CHx2+) – (H2CHx)(SO4)·3H2O and (H2CHx)(CO3)·4H2O – have been synthesised and characterised crystallographically.

No MeSH data available.


The hydrogen bonds between the oxyanions in a) (H2CHx)(SO4)·3H2O and b) (H2CHx)(CO3)·4H2O. Chlorhexidine cations shown in blue, red and gold belong to three different ‘coils’. Oxyanions are shown using green bonds. In b), lighter bond colours have been used to show chlorhexidine and carbonate anions that belong to the second half of the central blue ‘coil’. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4920644&req=5

fig4: The hydrogen bonds between the oxyanions in a) (H2CHx)(SO4)·3H2O and b) (H2CHx)(CO3)·4H2O. Chlorhexidine cations shown in blue, red and gold belong to three different ‘coils’. Oxyanions are shown using green bonds. In b), lighter bond colours have been used to show chlorhexidine and carbonate anions that belong to the second half of the central blue ‘coil’. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Mentions: Each oxyanion participates in hydrogen-bonding interactions with chlorhexidine cations from three different coils. Carbonate anions are involved in hydrogen bonds with two chlorhexidine cations from one coil, in addition to one cation from each of two adjacent coils as shown in Fig. 4. Sulfate anions form hydrogen bonds with three cations from one coil, plus one cation from each of two adjacent coils. Due to the difference in shape of the SO42− and CO32− anions, the hydrogen-bonding interactions within the coils are slightly different. The SO42− anion forms hydrogen bonds to three adjacent chlorhexidine cations of both left- and right-handed conformation. When viewed along the a-axis, the sulfate anions are located towards the centre of the open end of the U-shaped coil and can interact with both halves of the U-shape. This generates a three-dimensional hydrogen-bonded framework of SO42− anions and H2CHx2+ cations. The CO32− anion, however, can participate in intra-chain hydrogen bonds with two non-adjacent chlorhexidine cations that both have the same conformation (either left- or right-handed). When viewed along the a-axis, the carbonate anions sit almost aligned with the two sides of the U-shape, and so are only able to interact with the chlorhexidine cations along one side of the U-shape. This generates a two-dimensional hydrogen-bonded framework of CO32− anions and H2CHx2+ cations that extends parallel to the ac-plane (Fig. 5). Water molecules of crystallisation occupy the remaining space between the coils and form hydrogen bonds with both the oxyanions and the chlorhexidine cations so that both compounds contain a complex three-dimensional hydrogen-bonded network. A list of the hydrogen bonds found in both compounds presented in Supporting Information.


Crystal structure resolution of two different chlorhexidine salts
The hydrogen bonds between the oxyanions in a) (H2CHx)(SO4)·3H2O and b) (H2CHx)(CO3)·4H2O. Chlorhexidine cations shown in blue, red and gold belong to three different ‘coils’. Oxyanions are shown using green bonds. In b), lighter bond colours have been used to show chlorhexidine and carbonate anions that belong to the second half of the central blue ‘coil’. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920644&req=5

fig4: The hydrogen bonds between the oxyanions in a) (H2CHx)(SO4)·3H2O and b) (H2CHx)(CO3)·4H2O. Chlorhexidine cations shown in blue, red and gold belong to three different ‘coils’. Oxyanions are shown using green bonds. In b), lighter bond colours have been used to show chlorhexidine and carbonate anions that belong to the second half of the central blue ‘coil’. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Mentions: Each oxyanion participates in hydrogen-bonding interactions with chlorhexidine cations from three different coils. Carbonate anions are involved in hydrogen bonds with two chlorhexidine cations from one coil, in addition to one cation from each of two adjacent coils as shown in Fig. 4. Sulfate anions form hydrogen bonds with three cations from one coil, plus one cation from each of two adjacent coils. Due to the difference in shape of the SO42− and CO32− anions, the hydrogen-bonding interactions within the coils are slightly different. The SO42− anion forms hydrogen bonds to three adjacent chlorhexidine cations of both left- and right-handed conformation. When viewed along the a-axis, the sulfate anions are located towards the centre of the open end of the U-shaped coil and can interact with both halves of the U-shape. This generates a three-dimensional hydrogen-bonded framework of SO42− anions and H2CHx2+ cations. The CO32− anion, however, can participate in intra-chain hydrogen bonds with two non-adjacent chlorhexidine cations that both have the same conformation (either left- or right-handed). When viewed along the a-axis, the carbonate anions sit almost aligned with the two sides of the U-shape, and so are only able to interact with the chlorhexidine cations along one side of the U-shape. This generates a two-dimensional hydrogen-bonded framework of CO32− anions and H2CHx2+ cations that extends parallel to the ac-plane (Fig. 5). Water molecules of crystallisation occupy the remaining space between the coils and form hydrogen bonds with both the oxyanions and the chlorhexidine cations so that both compounds contain a complex three-dimensional hydrogen-bonded network. A list of the hydrogen bonds found in both compounds presented in Supporting Information.

View Article: PubMed Central - PubMed

ABSTRACT

Two salts of the chlorhexidine di-cation (H2CHx2+) – (H2CHx)(SO4)·3H2O and (H2CHx)(CO3)·4H2O – have been synthesised and characterised crystallographically.

No MeSH data available.