Probing atomic level structural transformation in O–H⋯N heterosynthon crystal

Khan, Mujeeb; Enkelmann, Volker; Brunklaus, Gunther

doi:10.1039/b820732a

Cited by 15 publications

(12 citation statements)

References 21 publications

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“…1,2‐Bis(4’‐ pyridyl)ethylene (bpe) is a commonly used spacer which has been employed in a number of studies for the construction of metal organic frameworks (MOFs) and coordination polymers, in which the juxtaposed two C=C double bonds tended to convert into cyclobutane rings under UV irradiation conditions . Discrete hydrogen‐bonded supramolecular assemblies obtained from cocrystallization of resorcinol and olefin‐containing carboxylic acids have also been found to facilitate [2 + 2] photodimerization . The C=C double bonds in such hydrogen‐bonded supramolecular assemblies are arranged in a parallel fashion with an appropriate π…π stacking.…”

Section: Background and Originality Contentmentioning

confidence: 99%

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

Jin

et al. 2019

Chin. J. Chem.

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Summary of main observation and conclusion A series of dicarbene‐bridged metallacycles [Ag2(1)2](PF6)2, [Ag2(2)2](BF4)2, [Ag2(3)2](PF6)2, [Ag2(7)2](BF4)2, [Ag2(8)2](BF4)2 and [Ag2(11)2](PF6)2 were obtained in high yields via the reactions of 1,2,4‐triazole‐, 1,2,3‐triazole‐ and imidazo[1,5‐a]pyridine‐based ligands with Ag2O in CH3CN. The C=C double bonds in all of the newly synthesized metallacycles went through [2 + 2] photodimerization under UV irradiation condition (λ = 365 nm, T = 298 K) yielding the dinuclear rctt‐cyclobutane‐silver(I) complexes [Ag2(4)](PF6)2, [Ag2(5)](BF4)2, [Ag2(6)](PF6)2, [Ag2(9)](BF4)2, [Ag2(10)](BF4)2 and [Ag2(12)](PF6)2, respectively with quantitative yields. Treatment of the these cyclobutane‐bridged silver(I) complexes with NH4Cl resulted in the exclusive formation of cyclobutane derivatives after removal of the silver(I) metal ions.

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Section: Background and Originality Contentmentioning

confidence: 99%

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

Jin

et al. 2019

Chin. J. Chem.

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“…The co-crystals were designed according to the availability of specific supramolecular synthons − and are mainly based on the robust {OH···O} synthon though in case of p -amino-benzoic acid the {OH···NH 2 } synthon was identified. Since nicotinamide and its stereoisomer isonicotinamide contain CONH 2 and N aromatic functional groups, the likely resulting co-crystals may exhibit {OH···O}, {OH···NH 2 }, or {OH···N aromatic } synthons where the latter is a particularly versatile supramolecular unit for crystal engineering applications. − In addition, salt co-crystals with concomitant presence of NCL both as neutral component and as salt co-former (derived from salification of NCL with inorganic salts) as well as mixed solvate/hydrate salts of NCL were very recently reported . The latter partially included the solvent dimethyl sulfoxide (DMSO), which in view of the identified brain degeneration due to apoptosis in the central nervous system induced by DMSO already at low doses of 0.3 mL/kg appears pharmaceutically questionable .…”

Section: Introductionmentioning

confidence: 99%

Crystal Engineering of Pharmaceutical Co-crystals: “NMR Crystallography” of Niclosamide Co-crystals

Luedeker

Gossmann

Langer

et al. 2016

Crystal Growth & Design

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Niclosamide is a Biopharmaceutics Classification System (BCS) class II taeniacide currently reconsidered for new promising applications including treatment of rheumatoid arthritis, prevention of protein degeneration in neurodegenerative diseases, or even multi-targeted therapy of cancer and cancer stem cells. Its efficacy in medical treatments, however, is currently limited by its insufficient solubility or bioavailability. Thus, we have further explored the potential of hydrogen-bond-mediated co-crystal formation of niclosamide with suitable co-formers selected from either the “Generally Regarded as Safe” (GRAS) or United States Food and Drug Administration (U.S. FDA) “Everything Added to Food in the United States” (EAFUS) list, respectively. Solvent-assisted solid grinding and/or slow solvent evaporation yielded four new co-crystals: (i) niclosamide–2-aminothiazole (NCL-AT), (ii) niclosamide–benzamide (NCL-BA), (iii) niclosamide–isoniazide (NCL-IN), and (iv) niclosamide–acetamide I and II (NCL-AA-I/NCL-AA-II). The crystal structures of NCL-AA-I/II, NCL-AT were solved from white microcrystalline powder samples on the basis of the combined application of powder X-ray diffraction (PXRD), solid-state NMR, and Density Functional Theory (DFT) chemical shift computation. In addition, the crystal structure of the monohydrate NCL-HA was reconsidered for comparison. Finally an improvement of the equilibrium solubility of the 1:1 co-crystal NCL-AT could be determined (2.8 times that of pristine NCL and 1.4 times that of NCL-UREA co-crystal), suggesting NCL-AT as a candidate for future medical treatment.

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“…Co-crystallization of res with 4,4′-AP or 4,4′-BPE was achieved by dissolving the two components (1:1 molar ratio) separately in ethanol, combining the solutions into one vial, and allowing the solution to evaporate slowly. Similar methods have been used to produce hydrogen-bonded co-crystals involving these components; − however, the pedal motion at various temperatures and the thermal expansion parameters were not investigated. Crystals suitable for X-ray diffraction formed within 2 days.…”

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confidence: 99%

Molecular Pedal Motion Influences Thermal Expansion Properties within Isostructural Hydrogen-Bonded Co-crystals

Hutchins

Unruh

Verdu

et al. 2018

Crystal Growth & Design

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The influence of molecular pedal motion on the thermal expansion properties of three isostructural hydrogen-bonded co-crystals based upon resorcinol is reported. The resulting co-crystals all exhibit discrete four-component assemblies held together by O–H···N hydrogen bonds and comprise resorcinol (res) with a series of isosteric bipyridines, namely, 4,4′-azopyridine (4,4′-AP), trans-1,2-bis(4-pyridyl)ethylene (4,4′-BPE), and 1,2-bis(4-pyridyl)acetylene (4,4′-BPA). The ability to change the core of the hydrogen bond acceptor molecules from an azo (NN) to an ethylene (CC) and finally an acetylene (CC) group affords co-crystals that differ in their tendency to undergo dynamic pedal motion in the organic solid state. All three co-crystals, 2(res)•2(4,4′-AP), 2(res)•2(4,4′-BPE), and 2(res)•2(4,4′-BPA), exhibit thermal expansions that correlate with the strength of the noncovalent interactions, as well as the propensity of the core to undergo pedal motion.

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Probing atomic level structural transformation in O–H⋯N heterosynthon crystal

Cited by 15 publications

References 21 publications

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

Crystal Engineering of Pharmaceutical Co-crystals: “NMR Crystallography” of Niclosamide Co-crystals

Molecular Pedal Motion Influences Thermal Expansion Properties within Isostructural Hydrogen-Bonded Co-crystals

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