Hydrophilic and hydrophobic pockets at surfaces of strychninium self-assemblies in pseudopolymorphous crystals of strychninium salts

Białońska, Agata; Ciunik, Zbigniew

doi:10.1039/b605203g

Cited by 6 publications

(9 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Strychnine models were based on a recent crystal structure (Cambridge Structural Database entry b605203) and were visualized with the PyMOL Molecular Graphics System version 1.3 (Schrödinger, LLC).…”

Section: Methodsmentioning

confidence: 99%

Counterion influence on chemical shifts in strychnine salts

Metaxas

Cort

2013

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

The highly toxic plant alkaloid strychnine is often isolated in the form of the anion salt of its protonated tertiary amine. Here, we characterize the relative influence of different counterions on (1)H and (13)C chemical shifts in several strychnine salts in D2O, methanol-d4 (CD3OD), and chloroform-d (CDCl3) solvents. In organic solvents but not in water, substantial variation in chemical shifts of protons near the tertiary amine was observed among different salts. These secondary shifts reveal differences in the way each anion influences electronic structure within the protonated amine. The distributions of secondary shifts allow salts to be easily distinguished from each other as well as from the free base form. Slight concentration dependence in chemical shifts of some protons near the amine was observed for two salts in CDCl3, but this effect is small compared with the influence of the counterion. Distinct chemical shifts in different salt forms of the same compound may be useful as chemical forensic signatures for source attribution and sample matching of alkaloids such as strychnine and possibly other organic acid and base salts.

show abstract

Section: Methodsmentioning

confidence: 99%

Counterion influence on chemical shifts in strychnine salts

Metaxas

Cort

2013

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…The previously mentioned high percentage of solvated brucinium salts (89%) mainly results from a strong tendency of the amide O atom of the common brucinium corrugated layers to participate in hydrogen bonds, in which solvent molecules are their donors. , Also, in B4NBDA(1) and in B4NBLA(2) , methanol molecules and the 17-membered water cluster, respectively, form hydrogen bonds with the amide O atom of the corrugated layers. Recognition of the anions together with their closest solvation sphere, as observed in B4NBLA(2) , may contribute to the high percentage of solvated brucinium salts.…”

Section: Discussionmentioning

confidence: 99%

Seventeen-Membered Water Cluster Resulting from Recognition of Solvated Anions on Brucinium Corrugated Layers

Białońska

Ciunik

2014

Crystal Growth & Design

Self Cite

View full text Add to dashboard Cite

Formation of diastereomeric salts remains the most important method for the separation of racemic acids and bases. Selection of a suitable resolving agent in this method is a key for successful resolution. There are primary, secondary, and tertiary chiral amines among frequently used resolving agents for the separation of racemic acids. Cations of most of them and anions of resolved acids are linked to each other by a characteristic system of hydrogen bonds resulting in common cationic–anionic self-assemblies. In this respect, brucine and strychnine are unique, because incorporation of anionic species into a crystal lattice of their salts usually does not affect common cationic self-assembly. The uniqueness of both resolving agents is also reflected in a high frequency of solvated salt formation. In this paper, we show that the presence of water molecules incorporated into the crystal lattice of the brucinium salt may result from recognition of the resolved compound together with its closest aqueous environment on the common brucinium corrugated layers. Performing racemic resolution of model compounds and studying structural relations between succeeding crystalline fractions, we also point out factors responsible for the successful separation of N-(4-nitrobenzoyl)alanine by fractional crystallization of brucinium diastereomeric salts.

show abstract

“…Crystals of distrychninium N-(4-nitrobenzoyl)-D-glutamate hydrates are one such example where the 4-nitrobenzoyl group of the anions is directed outward in a surface of the strychninium selfassembly (in the product of crystallization) or is hidden in a deep row in a surface of the strychninium self-assembly (in the product of recrystallization). 24 Sakai et al 25,26 showed that a change of dielectric constant of solvent can affect fractional crystallization order during racemic resolution of some amines in which N-tosyl-(S)-phenylalanine, (S)-mandelic acid, or (R,R)-tartaric acid were used as the resolving agents. A less soluble diastereomeric salt that crystallizes from one solvent/ mixture of solvents is more soluble than diastereomeric salt that crystallizes from another solvent/mixture of solvents.…”

Section: ■ Discussionmentioning

confidence: 99%

“…Dependent on dielectric constants, a change of molecular recognition nature also has been manifested in crystals as the results of crystallization from solution prepared by dissolvation of anhydrous components and of recrystallization of resulted hydrate. Crystals of distrychninium N -(4-nitrobenzoyl)- d -glutamate hydrates are one such example where the 4-nitrobenzoyl group of the anions is directed outward in a surface of the strychninium self-assembly (in the product of crystallization) or is hidden in a deep row in a surface of the strychninium self-assembly (in the product of recrystallization) . Sakai et al , showed that a change of dielectric constant of solvent can affect fractional crystallization order during racemic resolution of some amines in which N -tosyl-( S )-phenylalanine, ( S )-mandelic acid, or ( R,R )-tartaric acid were used as the resolving agents.…”

Section: Discussionmentioning

confidence: 99%

Dielectrically Controlled Priority of Interactions in Molecular Recognition

Białońska

Ciunik

2014

Crystal Growth & Design

Self Cite

View full text Add to dashboard Cite

It was shown previously that formation of brucinium double salts during attempts of racemic resolution of N-(3,5-dinitrobenzoyl)amino acid (alanine or serine) by fractional crystallization of brucinium diastereomeric salts is related to the self-recognition of anions of the amino acid derivatives into dimeric units stabilized by a set of hydrogen bonds (Białonśka, A. and Ciunik, A. Why Is the Resolution of Certain Racemic Modifications Inefficient? Formation of Diastereomeric Double Salts of Brucinium. Cryst. Growth Des. 2013, 13, 111−120). Similar dimeric units were observed in brucinium diastereomeric salts precipitated from methanol solutions containing brucine and one enantiomer of the amino acid derivative. To test if the ability of the anions to form dimeric units can be weakened, an increase of dielectric constant of solutions from which the brucinium salts precipitated was applied. In this approach, three new crystalline forms of brucinium salts with enantiomeric N-(3,5-dinitrobenzoyl)serine were obtained. Two of them belong to Z' > 1 structure, and occurrence of the Z' > 1 structures is discussed. In the new crystalline forms, a set of hydrogen bonds that stabilizes the dimeric units is replaced by interactions of the anions with solvent molecules, and the anions are linked to each other at most by lone hydrogen bonds. Recognition between cationic and anionic species by ionic N−H + ···O − hydrogen bonds, observed in the previously reported crystal structures of brucinium N-(3,5-dinitrobenzoyl)-L-serinate 3.88-hydrate and in the new form, brucinium N-(3,5-dinitrobenzoyl)-L-serinate brucine 11.5-hydrate, is precluded by formation of π···π stacking interactions between the anions and brucine molecules as well as by separation of the anions and cations by the extended net of hydrogen-bonded water molecules.

show abstract

Hydrophilic and hydrophobic pockets at surfaces of strychninium self-assemblies in pseudopolymorphous crystals of strychninium salts

Cited by 6 publications

References 31 publications

Counterion influence on chemical shifts in strychnine salts

Counterion influence on chemical shifts in strychnine salts

Seventeen-Membered Water Cluster Resulting from Recognition of Solvated Anions on Brucinium Corrugated Layers

Dielectrically Controlled Priority of Interactions in Molecular Recognition

Contact Info

Product

Resources

About