Formation of racemic compound crystals by mixing of two enantiomeric crystals in the solid state. Liquid transport of molecules from crystal to crystal

Toda, Fumio; Tanaka, Kōichi; Miyamoto, Hisakazu; Koshima, Hideko; Miyahara, Ikuko; Hirotsu, Ken

doi:10.1039/a606561i

Cited by 77 publications

(64 citation statements)

References 30 publications

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“…This does not lead to single crystals but the melting point and the spectroscopic and photochromic properties are identical to those found for the crystallized material. It is not uncommon that bimolecular solid state reactions of this kind take place [9].…”

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confidence: 99%

Phenazine andmeso-1,2-Diphenyl-1,2-ethanediol - Partners in Photochromic Cocrystals

Smolka¹,

Sustmann²,

Boese³

1999

J. prakt. Chem.

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The formation of hydrogen-bonded networks by cocrystallisation of 1,4-bisimines and 1,2-diols [1] has led to the discovery of a new type of photochromism [2]. Excitation of the charge-transfer (CT) band of a cocrystal in which suitably placed phenyl groups were substituted by a dimethylamino group as donor and a cyano group as acceptor resulted in electron transfer followed by proton migration. The stabilization of the excited CT state by proton transfer proved to be thermally reversible. Hydrogen bridges between lone-pair electrons of imines and the protons of hydroxy groups of diols are the supramolecular building blocks of the cocrystals.One of the goals of crystal engineering [3] is the attempt to influence or even predict the arrangement of molecules in a lattice in order to induce new properties in supramolecular structures, properties which are not present in the isolated components or in solution. Here, we describe an extension of the concept of forming cocrystals from 1,4-bisimines and 1,2-diols. Phenazine is considered as a 1,4-bisimine which is forced into a synperiplanar arrangement by ring formation. The nitrogen atoms provide the two lone pairs of electrons as acceptors of hydrogen atoms from the hydroxy groups of 1,2-diols. ResultsPhenazine and meso-1,2-diphenyl-1,2-ethanediol were dissolved in ethyl acetate in a 1:1 ratio, and the solvent was allowed to evaporate slowly. From this solution when it was kept in the dark crystals were obtained which showed the yellow colour of phenazine. Keywords: Crystal engineering, Electron transfer, Supramolecular chemistry, Photochromism, Phenazine Abstract. A hydrogen-bonded network in a 1:1 cocrystal of phenazine and meso-1,2-diphenyl-1,2-ethandiol places phenazine and diol in such a way that a thermally reversible photochromism is produced. The structure of the cocrystal is determined by X-ray crystallography. Thermally reversible changes in the UV/Vis and IR spectrum on irradiation, in cocrystals were analyzed by single crystal X-ray diffraction which yielded the crystal packing in the centrosymmetric space group P 1. Figure 1a shows a projection of the arrangement of phenazine and the 1,2-diol which gives insight in the packing pattern of the crystal. The two nitrogen atoms of each phenazine molecule form hydrogen bonds to neighbouring meso-1,2-diphenyl-1,2-ethanediol molecules. The O-H ... N bridges are almost linear (165°), the oxygen-nitrogen distance is 285 pm. The projection along [1 0 0] in Fig. 1a shows the centrosymmetric molecules arranged in chains, so that additional C-H ... π edge to face interactions [4] between CH bonds of phenazine and the π-electrons of the phenyl groups of meso-1,2-diphenyl-1,2-ethanediol exist, as indicated by dotted lines at one pair of molecules in Fig. 1b. One of these interactions characterized by a CH .. (centroid phenyl ring) distance of 289 pm is significant and due to the lattice symmetry occurs alternately on each side of the phenyl groups along the chains. The other interaction showing a distance of 357 pm is exp...

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confidence: 99%

Phenazine andmeso-1,2-Diphenyl-1,2-ethanediol - Partners in Photochromic Cocrystals

Smolka¹,

Sustmann²,

Boese³

1999

J. prakt. Chem.

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“…However, it is most likely that there are hydrogen bonds between the OH groups of neighboring BN derivatives, as is found in the case of unsubstituted BN crystals. 2 On mixing/grinding with BQ crystals, BN derivatives changed their hydrogen bond partners from naphthol hydroxyl to carbonyl groups of BQ. In the adduct crystal I, (R)-6,6Ј-diBrBN molecules are hydrogen bonded to the neighboring (R)-6,6Ј-diBrBN molecules as well as the carbonyl oxygen atoms of BQ.…”

Section: Adduct Crystal Formationmentioning

confidence: 99%

“…However, recent reports have shown that, even inside crystals, molecules are not necessarily strictly constrained. [1][2][3] Previously, we reported formation of a red adduct crystal of the charge-transfer type (X-I) by grinding crystals of racemic bis-␤-naphthol (rac-BN) and benzoquinone (BQ) in an agate mortar. 4 Evidence for the formation of a new crystal was obtained by X-ray powder diffractometry, which revealed the induction of a new set of peaks with time and the concurrent disappearance of the original peaks.…”

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confidence: 99%

Chirality recognition in solvent‐free solid‐state crystallization: Chiral adduct formation by bis‐β‐naphthol derivatives and benzoquinone crystals

2001

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New adduct crystals were obtained by simply mixing/grinding component crystals of bis-beta-naphthol (BN) derivatives with benzoquinone (BQ) under solvent-free conditions. Chiral recognition was found to operate during this process and either a racemic or a chiral crystal of a BN derivative produced an adduct crystal with BQ by solid-state crystallization. The chirality preference changed subtly according to the molecular structure of the BN derivative. Even in circumstances in which no adduct was formed, addition of a third component, such as crystals of naphthalene, to the grinding mixture yielded an adduct crystal. Remarkably, these adduct crystals were found to decompose spontaneously with time and revert to the starting crystal of the BN derivative by losing BQ molecules from the crystal lattice. Local melting of crystals by the grinding pressure was found unlikely to be the mechanism of adduct formation. Overall, these results demonstrate that molecules in the solid state could change their relative location and hydrogen bonding partners, thereby exerting chiral discrimination.

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“…(2) and - [4,5]decane (3) and interpret the experimental results in the light of the crystallographic data for neat 2 and 3. 7 We chose the systems 1-2 and 1-3 for the first mechanistic AFh4 investigation of a solid-solid clathration. The data indicate that large-scale resolution of solid volatile racemates can be achieved conveniently even in the case of surface passivation.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of solid-solid resolution of pantolactone

Kaupp

Schmeyers

Toda

et al. 1996

J. Phys. Org. Chem.

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The enantioselective solid-solid clathration of (S)-pantolactone ( I ) into (R,R)-trans-2,3-bis(diphenylhydroxymethyl)-l,4-dioxaspiro[4~4]nonane (2) and -[4.5]decane (3) was studied preparatively and mechanistically using atomic force microscopy (AFM) measurements and crystal packing data. Shortdistance solid-to-solid sublimation mechanisms occur in both cases with initial formation of epitaxial floes along the b-axis in 2 and random craters in 3. The bulk control in the phase rebuilding stage is understood from the particular crystal packings. Bulk control was largely lost in the phase transformation stage when passivation of the surfaces occurred in both cases. The host lattices of 2 and 3 exhibit closed molecular double layers with all hydroxyl groups inside and lacking access for intercalation of I. The reaction has to start at isolated surface defects. Once started, new doors for further entrance of guest molecules (S)-I are opened in the double layer. For practical use, both the crystallographic difficulties and the passivation have to be overcome. A slurry technique involving addition of stoichiometric amounts of water to the solids provided useful conditions for the preparative resolution of (R/S)-I or further racemates exhibiting passivation, whereas heating alone speeded up the resolution of 2-methylpiperwine with 2.

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Formation of racemic compound crystals by mixing of two enantiomeric crystals in the solid state. Liquid transport of molecules from crystal to crystal

Cited by 77 publications

References 30 publications

Phenazine andmeso-1,2-Diphenyl-1,2-ethanediol - Partners in Photochromic Cocrystals

Phenazine andmeso-1,2-Diphenyl-1,2-ethanediol - Partners in Photochromic Cocrystals

Chirality recognition in solvent‐free solid‐state crystallization: Chiral adduct formation by bis‐β‐naphthol derivatives and benzoquinone crystals

Mechanism of solid-solid resolution of pantolactone

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