Supramolecular Control over Tautomerism in Organic Solids

Užarević, Krunoslav; Stilinović, Vladimir; Rubčić, Mirta

doi:10.1002/9783527695713.ch13

Cited by 2 publications

(3 citation statements)

References 117 publications

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“…8,9 The solid-state separation of the tautomers of some tautomeric molecules has been achieved using this method. 10–15 New strategies should be developed to realize the solid-state separation of the tautomers of more tautomeric molecules. We proposed that the solid-state separation of the tautomers of the same molecules can be realized by doping the tautomeric molecules in an existing tautomeric polymorph or amorphous phase of their similar molecules with a definite tautomeric form which would induce them to dope with a certain tautomeric form.…”

Section: Introductionmentioning

confidence: 99%

Solid-state separation of hypoxanthine tautomers through a doping strategy

Xue

Liang

et al. 2022

CrystEngComm

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Section: Introductionmentioning

confidence: 99%

Solid-state separation of hypoxanthine tautomers through a doping strategy

Xue

Liang

et al. 2022

CrystEngComm

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“…The amidine–imidine forms equilibrate through a shift of acidic proton from one site to another site with structural changes to generate two structures of relatively comparable energies. 41 Among them, a good number of examples yield polymorphs. 42−44 The weak interactions such as anion−π interactions are dependent on the tautomeric form with which the anion can interact.…”

Section: Introductionmentioning

confidence: 99%

“…Although amidine or imidine forms of a number of drugs are stabilized, there are also certain studies dealing with base-pairs of nucleo-bases relating the coexistence of the two forms in charge-assisted hydrogen-bonded dimers. The amidine–imidine forms equilibrate through a shift of acidic proton from one site to another site with structural changes to generate two structures of relatively comparable energies . Among them, a good number of examples yield polymorphs. − The weak interactions such as anion−π interactions are dependent on the tautomeric form with which the anion can interact .…”

Section: Introductionmentioning

confidence: 99%

Combinations of Tautomeric Forms and Neutral-Cationic Forms in the Cocrystals of Sulfamethazine with Carboxylic Acids

Singh

Baruah

2019

ACS Omega

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The cocrystals of sulfamethazine with different acids, namely, 2-mercaptophenylcarboxylic acid, 2,6-pyridinedicarboxylic acid, 4-(4-hydroxyphenylazo)phenylcarboxylic acid, 3-(4-hydroxyphenyl)propanoic acid, and 4-(phenyl)phenylcarboxylic acid, are studied here. Each has distinct notable supramolecular features. The pyrimidin-2-amine unit of the sulfamethazine provided unique examples of cocrystals in which amidine and imidine forms or neutral and protonated forms of sulfamethazine are observed in 2:2 ratios. Hence, this study provides avenues to explore cocrystals with tautomeric forms together in a cocrystal and also neutral and protonated cocrystal partners as apparent multicomponents in cocrystals. Among the cocrystals, three of them have the amidine form of the sulfamethazine in respective self-assembly. The cocrystal of 2-mercapto-phenylcarboxylic acid with sulfamethazine has the amidine form and it has the distinction of having S–H···π interactions. The cocrystal of sulfamethazine with 2,6-pyridinecarboxylic acid is a rare example of a 1:1 cocrystal of sulfmethazine with dicarboxylic acid. It has methanol molecules as a solvent of crystallization. Sulfamethazine forms a hydrated cocrystal with 4-(4-hydroxyphenylazo)-phenylcarboxylic acid that has conventional R 2 2 (8) synthons of amidine hydrogen-bonding with carboxylic acid. The phenolic part of the acid component is anchored to the water molecule and provides a robust self-assembly. The hydrated cocrystal of sulfamethazine with 3-(4-hydroxyphenyl)propanoic acid (2:2 cocrystal) has two independent molecules of sulfamethazine, one in amidine form and the other in imidine form. It has two neutral carboxylic acids anchored through complementary hydrogen bonds and also has two water molecules of crystallization. The cocrystal of sulfamethazine with 4-(phenyl)phenylcarboxylic acid is also a 2:2 cocrystal. It is a di-hydrate, which has a neutral and protonated form of sulfamethazine. The neutral form is hydrogen-bonded to a neutral carboxylic acid, whereas the protonated form is charge-assisted hydrogen-bonded to the corresponding carboxylate anion.

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Supramolecular Control over Tautomerism in Organic Solids

Cited by 2 publications

References 117 publications

Solid-state separation of hypoxanthine tautomers through a doping strategy

Solid-state separation of hypoxanthine tautomers through a doping strategy

Combinations of Tautomeric Forms and Neutral-Cationic Forms in the Cocrystals of Sulfamethazine with Carboxylic Acids

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