Structure of the 1:1 complex of resorcinol and urea

Pickering, Michael V.; Small, R. W. H.

doi:10.1107/s0567740882011200

Cited by 14 publications

(14 citation statements)

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“…Its unusual crystal growth patterns have remained a mystery for more than 100 years. 22,23 In individual monocrystals of resorcinol and of urea, resorcinol has several different polymorphs corresponding to different relative orientations of the hydroxyl groups (see refs 24−27), and for urea, a number of polymorphs have also been reported (see refs 28−30 for urea); however, only one structure is reported for the cocrystal, 31,32 and indeed, only one structure was observed for the 1:1 cocrystal in our own experimental crystallization attempts. Here, we show that a d-AFED trajectory generates a new structure in <25 ps that is confirmed as a low-energy polymorph in a standard (independent) random-search CSP approach.…”

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confidence: 88%

“…The simulations (see Computational Methods) start from the reported orthorhombic structure (space group P 2 1 2 1 2 1 ) shown in Figure a, which was previously determined experimentally, , observed in our own crystallization experiments (see Experimental Methods and the Supporting Information), and confirmed by us as the lowest-energy polymorph using standard zero-temperature crystal structure prediction protocols. (See Computational Methods.…”

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confidence: 99%

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Generating Cocrystal Polymorphs with Information Entropy Driven by Molecular Dynamics-Based Enhanced Sampling

Song

Vogt-Maranto

Wiscons

et al. 2020

J. Phys. Chem. Lett.

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Predicting structures of organic molecular cocrystals is a challenging task when considering the immense number of possible intermolecular orientations. Use of the Shannon information entropy, constructed from an intermolecular orientational spatial distribution function, to drive a search for crystal structures via enhanced molecular dynamics can be an efficient way to map out a landscape of putative polymorphs. Here, the Shannon entropy is used to generate a set of collective variables for differentiating polymorphs of a 1:1 cocrystal of resorcinol and urea. We show that driven adiabatic free energy dynamics, a particular enhanced-sampling approach, combined with these entropy variables, can transform the stable phase into alternate polymorphs. Density functional theory calculations confirm that a structure obtained from the enhanced molecular dynamics is stable at pressures above 1 GPa. We thus show that enhanced sampling should be considered an integral component of crystal structure searching protocols for systems with multiple independent molecules.

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confidence: 88%

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confidence: 99%

Generating Cocrystal Polymorphs with Information Entropy Driven by Molecular Dynamics-Based Enhanced Sampling

Song

Vogt-Maranto

Wiscons

et al. 2020

J. Phys. Chem. Lett.

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“…The choice of coformers is explained on one hand by the presence in all of them the strong H-donor in the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 form of hydroxy group capable to generate the robust OH … N(pyridine) heterosynthon [23], and on the other hand by the fact that the crystals of the pure forms of 1,3-benzene-diol III [24], 2,4-dinitrophenol IV [25][26][27], and several of their adducts are acentric solids [28,29] studied as NLO materials [30]. By changing the position of the pyridine nitrogen atom, N-substituents, and bridge in chromophores on one hand, and the coformers on the other hand, we tried to understand the outcome of these changes along with influence of functional groups on the acentric crystal packing.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

New organic binary solids with phenolic coformers for NLO applications

Draguta

Fonarı

Leonova

et al. 2015

Journal of Molecular Structure

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Five binary adducts between N,N-dimethyl-4-[(E)-2-(pyridin-4-yl)ethenyl]aniline) 1, N,N-diethyl-4-[(E)-2-(pyridin-4-yl)ethenyl]aniline) 2, N,N-dimethyl-4-[(E)-pyridin-3-yldiazenyl]aniline 3, and coformers that include 4-nitrophenol I, 4-nitrobenzoic acid II, benzene-1,3-diol III, and 2,4-dinitrophenol IV were synthesized to follow the factors influencing the formation of polar crystals. New solids were characterized by melting points and absorption spectra, while their structures were proven by single crystal X-ray diffraction. Adducts differ by the components' ratio and position of the acidic hydrogen atom, thus giving examples of four new cocrystals and one salt. The single crystal X-ray analysis revealed the acentric packing for two compounds, 1 . (I) and 3(3) . (III) that crystallize in the Pca2 1and P1 space groups. The melting point data and the cut-off wavelength from absorption spectra show that these materials are stable till relatively high temperatures and transparent in a wide range of spectrum.

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“…Because of its special H bond donor and acceptor capabilities, a large number of urea co-crystals have been described, e.g. with carboxylic acids, [37][38][39][40][41][42][43][44][45][46] amides, 47 ,-dihydroxyalkanes, 48-50 phenols 51 and carbohydrates, 52 various of which were obtained by mechanochemical techniques. Honer et al, for example, reported the mechanochemical synthesis of urea ionic co-crystals with Mg and Ca salts 53 and Casali et al prepared two polymorphs of the ionic co-crystal urea .…”

Section: Introductionmentioning

confidence: 99%

Spontaneous Solid-State Cocrystallization of Caffeine and Urea

MacFhionnghaile

Crowley

McArdle

et al. 2020

Crystal Growth & Design

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The co-crystallization of caffeine and urea was monitored and analyzed using infrared spectroscopy, Raman microscopy, scanning electron microscopy, differential scanning calorimetry and X-ray diffraction. The caffeine-urea co-crystal was shown to form spontaneously over several weeks under low energy mixing of the solids at room temperature and low relative humidity (<30%). Pre-milling the two coformers separately accelerated the process and the co-crystal formation could be detected within three days. When caffeine and urea were milled together, the physical mixture that was confirmed by X-ray powder diffraction immediately after milling transformed to the co-crystal within hours of storage at room temperature and 30 % relative humidity. The scanning electron microscopy images of the milled sample indicated the role of inter-particle surface contact in the spontaneous solidstate reaction. Multivariate data analysis was used to find the optimum cooling crystallization conditions for obtaining co-crystals suitable for single crystal X-ray analysis.

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Structure of the 1:1 complex of resorcinol and urea

Cited by 14 publications

References 1 publication

Generating Cocrystal Polymorphs with Information Entropy Driven by Molecular Dynamics-Based Enhanced Sampling

Generating Cocrystal Polymorphs with Information Entropy Driven by Molecular Dynamics-Based Enhanced Sampling

New organic binary solids with phenolic coformers for NLO applications

Spontaneous Solid-State Cocrystallization of Caffeine and Urea

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