Exploring the hydrogen-bond preference of N–H moieties in co-crystals assembled via O–H(acid)⋯N(py) intermolecular interactions

Aakeröy, Christer B.; Hussain, Izhar; Forbes, Safiyyah; Desper, John

doi:10.1039/b614984g

Cited by 71 publications

(42 citation statements)

References 47 publications

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“…The C−O bond length for the carboxylic acid of pNBA was significantly different (1.224, 1.328 Å) indicating no proton transfer has occurred and that the cocrystal is neutral and is not a salt. The observed hydrogen bonding pattern is consistent with Etter's Rules 12,13 of hydrogen bonding and Aakeroÿ's findings 14 where the strongest hydrogen bond donor hydrogen bonds to the strongest hydrogen bond acceptor (acid··· pyrazine), and the second best donor hydrogen bonds to the second best acceptor (amide···amide). Short CH···O and NH··· O contacts (<3.5 Å) and secondary π-stacking interactions sustain the crystal structure.…”

supporting

confidence: 90%

A Tale of Two Stoichiometrically Diverse Cocrystals

Abourahma

Shah

Melendez

et al. 2015

Crystal Growth & Design

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Liquid-assisted grinding of an equimolar amount of pyrazinamide and p-nitrobenzoic acid yields two stoichiometric cocrystals in a 1:1 and 2:1 ratio, respectively. The 2:1 cocrystal was found to be the thermodynamically stable cocrystal based on solid stoichiometric interconversion, solvent-mediated conversion, and solubility studies. M echanochemistry 1,2 is one of the go-to methods for the synthesis and screening of cocrystals. A technique that goes back to the early 19th Century 3 was pioneered in the context of engineering cocrystals by the late Margaret Etter. 4−6 She demonstrated through a series of studies that cocrystals can be formed by grinding two components together in the solid state. Since then, synthesis of cocrystals by mechanochemistry has become widely popular. Mechanochemistry is particularly attractive because it can produce cocrystals not readily accessible by solution or melt synthesis. Moreover, it has been shown to afford control over the polymorphic outcome and stoichiometric composition of cocrystals. 7,8 The technique produces microcrystalline materials, which are primarily characterized by powder X-ray diffraction (PXRD). A unique PXRD pattern that is different from the starting materials generally indicates the formation of a new product. However, unlike in the case of a single component system where variation in the PXRD pattern of the product can be attributed to polymorphism, in a two-component system stoichiometric variation is an additional possibility that has to be taken into consideration. Differentiating between polymorphs and stoichiometrically diverse cocrystals by PXRD alone is not an easy task, and misinterpreting PXRD data can easily confuse polymorphs and stoichiometric cocrystals. A case in point is presented herein with a pair of pyrazinamide (PZA)·p-nitrobenzoic acid (pNBA) cocrystals. The relative thermodynamic stability based on solvent-mediated conversion, solid state stoichiometric interconversion and solubility studies is also discussed.pNBA is a suitable coformer for PZA that was selected to complement our previous study 9 on the effect of electronwithdrawing/-donating substituents on cocrystal formation. Figure 1 depicts the molecular structure of PZA and pNBA and the supramolecular synthons 10 likely to sustain the resulting cocrystal.Equimolar amounts of PZA and pNBA were reacted by liquid-assisted grinding (LAG) in the presence of various solvents. The resulting microcrystalline product was analyzed by PXRD and differential scanning calorimetry (DSC). PXRD data revealed the formation of a new phase, as indicated by a unique PXRD pattern that is different from either of the starting materials. DSC data showed two endotherms at ca. 171 and 183°C suggesting that two phases existed. Influenced by Figure 1. Molecular structures of pyrazinamide (PZA) and pnitrobenzoic acid (pNBA) and the possible supramolecular synthons that could sustain the two in a cocrystal.Communication pubs.acs.org/crystal

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supporting

confidence: 90%

A Tale of Two Stoichiometrically Diverse Cocrystals

Abourahma

Shah

Melendez

et al. 2015

Crystal Growth & Design

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“…There is a simple method to determine if pyridine rings are neutral or ionized. If the C‐N‐C bond angle of the pyridine ring is in the range of 117–118°, a neutral pyridine is indicated; meanwhile, an obtuse angle in the range of 120–122° indicates the ionization and formation of a pyridinium cation . For compounds 3QBA‐1NP and 5IQBA‐1NP , the C‐N‐C bond angles are 122.60(11)° and 121.87(17)°, indicating that the nitrogen atoms of 3QBA and 5IQBA are indeed protonated.…”

Section: Resultsmentioning

confidence: 99%

Exploration of the Luminescence Properties of Organic Phosphate Salts of 3‐Quinoline‐ and 5‐Isoquinolineboronic Acid

et al. 2019

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3-Quinoline-and 5-isoquinolineboronic acids (3QBA and 5IQBA) were combined with 1-naphthyl and diphenyl phosphate (1NP and DPP) to give three crystalline molecular salts of 1:1 stoichiometric composition, viz., 3QBA-1NP, 5IQBA-1NP and 3QBA-DPP. The products were characterized by elemental analysis, single-crystal X-ray diffraction studies, IR spectroscopy, luminescence spectroscopy and TG-DSC measurements. The analysis of the solid-state structures revealed that the molecular components are linked by strong charge-assisted hydrogen bonds forming heterodimeric synthons of the type B(OH) 2 ··· -O 2 P and N + -H···O(P). In addition, the hydrogen phos- [a] Crystalline solids of compounds 3QBA-1NP, 5IQBA-1NP and 3QBA-DPP were isolated upon combination of the starting reagents in absolute ethanol. The products were characterized by elemental analysis, single-crystal X-ray diffraction (SCXRD) analysis, IR spectroscopy and TG-DSC analysis. In addition, the luminescence properties were explored. 2708 Scheme 1. List of compounds employed for the formation of the molecular salts described in this contribution.

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“…It is known that the broad peaks derived from O-H···N stretching appear around 1950 and 2450 cm −1 when strong hydrogen bonds are present in the crystal [20]. However, the peak around 1950 cm −1 shifts toward 2150 cm −1 if the proton is located on the N side of the hydrogen bond, i.e., O···H-N [21]. Furthermore, C=O stretching in the carboxyl group has been utilized to differentiate between the protonated and deprotonated state of the carboxyl group; for example, in terephthalic acid, C=O stretching appeared at 1692 cm −1 , whereas in disodium terephthalate, C=O stretching appeared at 1567 cm The IR spectra of 1-Cl and 1-Br also support the proposal that both compounds are co-crystals (Figure 3a,b).…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Structure, and Magnetic Properties of New Spin Crossover Fe(II) Complexes Forming Short Hydrogen Bonds with Substituted Dicarboxylic Acids

Nakanishi

Sato

2016

Crystals

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Abstract:We synthesized new Fe(II) compounds consisting of [Fe(L) 2 ] (HL: 2-Acetylpyridine isonicotinoylhydrazone) and dicarboxylic acids. Single crystal analysis shows that short hydrogen bonds are formed between [Fe(L) 2 ] and dicarboxylic acids. The hydrogen bonding interactions between metal complexes and dicarboxylic acids are complemented by π-π interactions, forming two-dimensional network structures. Magnetic properties show that the Fe(II) compounds exhibit gradual spin crossover behavior around room temperature and a T 1/2 value is dependent on the halogen substituent on the dicarboxylic acids.

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Exploring the hydrogen-bond preference of N–H moieties in co-crystals assembled via O–H(acid)⋯N(py) intermolecular interactions

Cited by 71 publications

References 47 publications

A Tale of Two Stoichiometrically Diverse Cocrystals

A Tale of Two Stoichiometrically Diverse Cocrystals

Exploration of the Luminescence Properties of Organic Phosphate Salts of 3‐Quinoline‐ and 5‐Isoquinolineboronic Acid

Synthesis, Structure, and Magnetic Properties of New Spin Crossover Fe(II) Complexes Forming Short Hydrogen Bonds with Substituted Dicarboxylic Acids

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