Infrared intensities of N-methylacetamide associates

Kuznetsova, L. M.; Furer, V.L.; Maklakov, L. I.

doi:10.1016/0022-2860(95)09209-9

Cited by 22 publications

(28 citation statements)

References 6 publications

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“…It was believed that NMA molecules form hydrogen-bonded chains in aprotic solutions by analogy with the crystal structure. 2 The formation of hydrogen bonds of NHÁ Á ÁO=C is evident from a large red shift of the NH stretching vibrational frequency observed by infrared and Raman spectroscopies, [2][3][4][5][6] whatever structures other than the chain type exist for larger aggregates. In the contrary sense, the chain-like association does not necessarily continue for building large clusters.…”

Section: Introductionmentioning

confidence: 99%

Characteristic distributions of negatively charged N-monosubstituted amide clusters generated by electron attachment in supersonic expansions

Maeyama

Mikami

2004

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

Characteristic distributions of negatively charged N-monosubstituted amide clusters generated by electron attachment in supersonic expansions

Maeyama

Mikami

2004

Phys. Chem. Chem. Phys.

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“…With ATR-FTIR spectroscopy the type of hydrogen bonding of the amide group of INA in solutions could be identified. 14 15 The shift can thus be due to the presence of dimers, the hydrogen bonding of INA and methanol or both interactions. A similar but more substantial peak shift was observed in the spectrum of form II solids (dimers) compared to that of form I and form IV solids (chains) (ESIw).…”

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confidence: 99%

“…14 Fig. 3 15 The shift can thus be due to the presence of dimers, the hydrogen bonding of INA and methanol or both interactions.…”

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confidence: 99%

Isonicotinamide self-association: the link between solvent and polymorph nucleation

et al. 2012

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We show that, in a controlled and reproducible way, specific solvents lead to specific polymorphic forms of isonicotinamide. We argue on the basis of Raman and FTIR spectroscopy that the hydrogen bonding in solution kinetically drives the nucleation towards a specific form. This generally may lead to good understanding and control of polymorphism and crystal nucleation.The ability to control and predict crystal nucleation is of paramount importance from the viewpoint of crystal engineering, materials synthesis and crystalline product quality. [1][2][3] In this communication we demonstrate the reproducible effect of solvents on the formation of isonicotinamide (INA) polymorphs. We establish that in solvents with strong hydrogen bond acceptors, the dominant configuration of the INA molecules with respect to each other is that of amide-pyridine heterosynthons (headto-tail chains) (Fig. 1). Similarly, solvents with strong hydrogen bond donors lead to dominancy of amide-amide homosynthons (head-to-head dimers). This self-association in solution controls the polymorph nucleation of INA by controlling the building unit attaching to the nucleus.Polymorphism can be defined as the ability of a single chemical compound to form more than one crystal structure. 4 Polymorphism of active pharmaceutical ingredients is the subject of intense interest in both science and industry. 4,5 On the one hand, this is because crystalline product quality aspects such as drug efficacy, bioavailability and safety are affected by the polymorphic form present. On the other hand, polymorphs have economic and intellectual property implications.Often through empirical research, effects of solvent, supersaturation and impurities are observed on polymorph formation. 6 Recently, next to the two known forms of INA, 7 a third form was reported which incidentally and irreproducibly formed during a co-crystal screen from a multicomponent solution. 8 More recently, the difficult to control evaporative crystallization process yielded two new forms of INA.9 Form IV was obtained only as a mixture together with form II and/or V. For form V yields were often poor, typically 10%, and in some cases it could not be obtained.The crystal nucleation of INA is a most interesting process because of the strongly differing packing of form II and the other forms (ESIw). Isonicotinamide form II has been reported to be the most stable form at room temperature. 8 In the structure of form II the amide groups form homosynthons (dimers), 8 which in turn are hydrogen bonded through the oxygen atom and the remaining hydrogen of the amide group. Interestingly, the pyridine group does not participate in hydrogen bonding in the crystal structure of form II, contrary to all other currently known forms of INA. These consist of differently packed head-to-tail chains connected through heterosynthons of the amide and the pyridine group.The classical view of crystal nucleation is that building units attach to and detach from clusters of molecules.10 This attaching building unit could be...

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“…In order to avoid self-association, amide concentration in carbon tetrachloride solutions was below 0.003 mol dm 3 . Concentration of the aromatic hydrocarbons varied between 0.2 and 1 mol dm -3 .…”

Section: Methodsmentioning

confidence: 99%

Chemometric characterization of the hydrogen bonding complexes of secondary amides and aromatic hydrocarbons

Jović

Nikolić

Petrović³

2012

Hem Ind

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The paper reports the results of the study of hydrogen bonding complexes between secondary amides and various aromatic hydrocarbons. The possibility of using chemometric methods was investigated in order to characterize N-H•••π hydrogen bonded complexes. Hierarchical clustering and Principal Component Analysis (PCA) have been applied on infrared spectroscopic and Taft parameters of 43 N-substituted amide complexes with different aromatic hydrocarbons. Results obtained in this report are in good agreement with conclusions of other spectroscopic and thermodynamic analysis

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Infrared intensities of N-methylacetamide associates

Cited by 22 publications

References 6 publications

Characteristic distributions of negatively charged N-monosubstituted amide clusters generated by electron attachment in supersonic expansions

Characteristic distributions of negatively charged N-monosubstituted amide clusters generated by electron attachment in supersonic expansions

Isonicotinamide self-association: the link between solvent and polymorph nucleation

Chemometric characterization of the hydrogen bonding complexes of secondary amides and aromatic hydrocarbons

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