Reactions In Molecular Crystals Research Articles

(Invited) A Soft-Crystal Chemiluminescence System: Luminescence Property of Adamantylideneadamantane 1,2-Dioxetanes Conjugated with a Fluorophore

Chemiluminescence (CL) produces photon by a chemical reaction of a CL substrate to give a product in the excited state. Because emitted photons are readily detectable, CL is a powerful tool to monitor a chemical event in an analyte. In the materials science, CL will be useful to analyze an event at the molecular level in a solid material for developing functional devises. For instance, CL has been used to measure mechanical forces applied to polymers.1 In this study, we have investigated CL reactions in molecular crystals, to create the chemistry of “soft crystals”2 as reaction fields. For this purpose, we investigated CL properties of adamantylideneadamantane 1,2-dioxetanes (Adox) conjugated with a fluorophore in the crystalline state. We report here characteristic CL properties of the Adox derivatives and talk about the molecular mechanism of the crystalline-state CL.3 Adox is one of stable 1,2-dioxetanes, and its thermal decomposition partially gives the excited singlet (S1) or triplet (T1) state of 2-adamantanone (AdCO).4 The S1 state of AdCO can fluoresce weakly with the maximum at 420 nm. A designed Adox derivative 1 has a non-π-conjugatively linked phthahlimide as a crystal structure modulator and the emitting moiety by accepting energy from the excited AdCO. We first prepared syn- and anti-isomers of the Adox derivative 1 and investigated their CL properties in crystals. The isomers showed contrastive CL properties by heating their crystal samples at 160 °C. Each crystal structure of the isomers has its own distinctive packing pattern of the Adox and phthalimide moieties, and the clear differences in CL intensities, emission maxima and reaction kinetics of the isomers are well correlated to the packing patterns. Thus, CL emission properties and reaction kinetics in the crystalline-state were precisely manipulated by the crystal structures. To understand the crystalline-state CL reactions in detail, we further investigated CL of modified Adox derivatives along with thermoanalytical studies. The results provide information on the origins of the characteristic CL behaviors and the reaction mechanism in soft crystals.1) Chen, Y.; Spiering, A. J. H.; Karthikeyan, S.; Peters, G. W. M.; Meijer, E. W.; Sijbesma, R. P., Nat. Chem., 2012, 4, 559.2) Kato, M.; Ito, H.; Hasegawa, M.; Ishii, K., Chem. Eur. J., 2019, 25, 5105.3) Matsuhashi, C.; Ueno, T.; Uekusa, H.; Sato-Tomita, A.; Ichiyanagi, K.; Maki, S.; Hirano, T., Chem. Commun., 2020, 56, 3369.4) Hummelen, J. C.; Luider, T. M.; Wynberg, H., Pure Appl. Chem., 1987, 59, 639. Figure 1

Recent Researches of Physical Properties and Reactions in Molecular Crystals Using Neutron Diffraction Technique

Recent Researches of Physical Properties and Reactions in Molecular Crystals Using Neutron Diffraction Technique

Intermolecular Acyl-Transfer Reactions in Molecular Crystals

It is far more difficult to recognize and predict the chemical reactions that a molecule of an organic compound can undergo in crystalline (solid) state as compared to the solution state (the "organic functional group" approach), since the published data on solid-state structure-reactivity investigations and correlations are scant. The discovery of the first intermolecular acyl-transfer reaction in molecular crystals of racemic 2,4-di- O-benzoyl- myo-inositol-1,3,5-orthoformate (DiBz) during our attempts to develop methods for the synthesis of phosphoinositols, motivated us to find other molecular crystals capable of supporting similar reactions. Small changes to the molecular structure of DiBz yielded analogues with different crystal structures which showed varying degrees of acyl transfer reactivity as compared to the crystals of DiBz. A systematic investigation of the structures, polymorphism, cocrystallization behavior, and the corresponding reactivity of these crystals allowed us to correlate the acyl transfer reactivity with their structures and inherent noncovalent interactions and provided crucial insights into the mechanism of these reactions. Polymorphs or cocrystals of these compounds exhibited dissimilar reactivities due to differences in the molecular conformation and/or arrangements in their crystals. The knowledge of phase transitions between polymorphs enabled us to control and tune the reactivity in the solid state. We could identify three conditions essential for intermolecular acyl transfer: (i) favorable relative geometry of the electrophile (ester C═O) and the nucleophile (OH), (ii) noncovalent interactions (C-H···π) between the reacting molecules which help in maintaining the facility and specificity of the reaction, and (iii) the presence of channels in the lattice which enable propagation of the reaction in the crystal. Based on this supramolecular structure-reactivity correlation, we identified other molecular crystals (composed of molecules of widely different molecular structure from that of DiBz) from a survey of the Cambridge Structural Database (CSD) and predicted their acyl transfer reactivity. The increased availability of user-friendly modern X-ray diffractometers and related software has enabled efficient collection, analysis and interpretation of single crystal X-ray diffraction data, essential for such studies. The rapidly expanding CSD facilitates the identification of crystals with similar structures and reactivity patterns. In a wider perspective, facile reactions in molecular crystals fascinate chemists because these reactions usually exhibit unique product selectivity and have the potential to be developed as sustainable green reactions. We are optimistic that similar approaches for the study of other group transfer reactions in molecular crystals would augment and widen the scope of chemical reactions in molecular crystals in particular and the solid state in general. The ability to predict the reactivity of molecules in their crystals could find applications in organic synthesis, material science and industry. Realization of the involvement of inositol derivatives in cellular processes led to the discovery of cellular signal transduction mechanisms. The ability of inositol derivatives to support facile acyl-transfer reactions in the crystalline state might well have opened a new avenue for research in the area of organic solid-state reactions.

QM/MM Approach to Isomerization of Ruthenium(II) Sulfur Dioxide Complex in Crystal; Comparison with Solution and Gas Phases

The theoretical study of chemical reactions in molecular crystals is a challenging research target. To optimize the transition state in a crystal, we have improved the crystal model and modified the quantum mechanics/molecular mechanics (QM/MM) method based on the periodic MM crystal model. We applied this method to the ruthenium(II) sulfur dioxide complex [RuII(NH3)4(SO2)Py]2+ 1Py which is potentially useful for optical data storage systems in crystal because this Ru complex has two isolable metastable structures, η1-O-bound MS1 and η2-S,O-bound MS2, in addition to η1-S-bound ground state GS in crystal. MS2 and MS1 are formed from GS by photoirradiation at low temperature (10–100 K) and thermal isomerization occurs from MS2 to MS1 and from MS2 to GS by raising the temperature. For comparison, the thermal isomerization of [RuII(NH3)4(SO2)L]n+ (L = Cl–, W, and Py) was investigated in gas and aqueous phases, where the three-regions 3D reference site interaction model self-consistent field (RISM-SCF) method ...

Phase changes and chemical reactions in molecular crystals

Phase changes and chemical reactions in molecular crystals

Acyl-transfer reactions in molecular crystals: reactivity correlation with crystal structure

Acyl-transfer reactions in molecular crystals: reactivity correlation with crystal structure

Intramolecular Cyclization of Carbonate and Thiocarbonate Derivatives of myo-Inositol in the Solid State: Implications for Acyl Group Transfer Reactions in Molecular Crystals.

Racemic 4-O-phenoxycarbonyl and 4-O-phenoxythiocarbonyl derivatives of myo-inositol orthoformate undergo thermal intramolecular cyclization in the solid state to yield the corresponding 4,6-bridged carbonates and thiocarbonates, respectively. The thermal cyclization also occurs in the solution and molten states, but less efficiently, suggesting that these cyclization reactions are aided by molecular pre-organization, although not strictly topochemically controlled. Crystal structures of two carbonates and a thiocarbonate clearly revealed that the relative orientation of the electrophile and the nucleophile in the crystal lattice facilitates the intramolecular cyclization reaction and forbids the intermolecular reaction. The correlation observed between the chemical reactivity and the non-covalent interactions in the crystal of the reactants provides a way to estimate the chemical stability of analogous molecules in the solid state.

Thermal decomposition of solid azobisisobutyronitrile

The rate of the thermal decomposition of solid azobisisobutyronitrile was measured under conditions such that the side processes, such as gas-phase decomposition, the formation of liquid products, crystal cracking, and polymorphic transitions, had no effect on the process rate. The reaction occurs on the inner crystal surface, and its rate depends on the method of crystallization. The sample crystallized under conditions of low supersaturation is the most stable. The kinetic parameters of the reaction are E = 134.9 ± 3.5 kJ/mol and log A = 14.12 ± 1.5 [s−1]. The decomposition rate constant of solid azobisisobutyronitrile is 50 times lower than that of azobisisobutyronitrile in benzene solution. The low reaction rate in the solid phase is explained in terms of the additional-volume model proposed for unimolecular reactions in molecular crystals.

Thermal decomposition of cis-2, 4, 6, 8-tetranitro-1H, 5H-2, 4, 6, 8-tetraazabicyclo[3.3.0]octane

The thermal decomposition kinetics of cis-2, 4, 6, 8-tetranitro-1H, 5H-2, 4, 6, 8-tetraazabicyclo[3.3.0]octane was measured in various solvents and in the solid phase by the manometric method. The general regularities for cyclic nitramines concerning the possibility of chain decomposition in hydrocarbon solvents, the kinetic display of cell effect in viscous media, a decrease in the decomposition rate in the solid state, and the quantitative description of this effect in terms of the model of monomolecular reactions in molecular crystals are supplemented and discussed. The dependence of the decomposition rate constants in solutions on the N-N bond lengths in a series of secondary nitramines was shown using the correct values of decomposition rate constants.

Designing permeable molecular crystals that react with external agents to give crystalline products.

Designing permeable molecular crystals that react with external agents to give crystalline products.

Monte-Carlo simulations of chemical reactions in molecular crystals

Chemical reactions in molecular crystals, yielding new entities (dimers, trimers,…, polymers) in the original structure, are simulated for the first time by stochastic Monte Carlo methods. The results are compared with those obtained by deterministic methods. They show that numerical simulation is a tool for understanding the evolution of these mixed systems. They are in kinetic and not in thermodynamic control. Reactive site distributions, x-ray diffuse scattering, and chain length distributions can be simulated. Comparisons are made with deterministic models and experimental results obtained in the case of the solid state dimerization of cinnamic acid in the beta phase and in the case of the solid state polymerization of diacetylenes.

水素結合における構造物性と機能 固相光異性化反応における分子間水素結合の役割

The hydrogen bond plays important roles in the reactions of molecular crystals. If the reactive group of the molecule is hydrogen bonded with the neighboring molecules in the crystal, the hydrogen bond severely influences the reactivity of the molecule, because it (1) changes the electronic state of the reactive group and/or (2) inhibits the migration of the group in the process of reaction. Even if the hydrogen bond has no connection with the reactive group, it strengthens the crystal lattice and accelerates the photoreactions since not only the energy to destroy the crystalline lattice is unnecessary but also light can easily penetrate into the crystal. The hydrogen migration in the solid-state reactions can be directly observed by neutron diffraction when only the peculiar hydrogen atom considered can be replaced with the deuterium atom.

Phase changes and chemical reactions in molecular crystals

Phase changes and chemical reactions in molecular crystals

The theory of fission of a singlet frenkel exciton into two localised triplet excitations

The non-radiative rate of singlet exciton fission into two localised triplet excitations is calculated for molecular crystals. An energy gap law is obtained. Strong coupling limit between the singlet-triplet and the ground state-triplet vibrational states of the molecules is found more suitable for such reactions in molecular crystals. The rate of decay ( W) calculated for tetracene lies in the range 10 9–10 11 sec −1. W is also calculated for naphthalene and anthracene crystals.

Reactions of Organic Crystals with Gases

Although reactions of molecular crystals are much more widespread than has been generally appreciated (53), the great sensitivity of their rates to seemingly trivial changes in molecular structure clearly provides a major stumbling block to the general utilization of such processes. A key to understanding the effects of structural changes has been provided by the demonstration of anisotropy of such reactions discussed in this article. It is recognized, however, that many factors in addition to those aspects of the crystal structure utilized in the discussion above may play a part in determining reactivity of crystalline solids with gases. The recent ready availability of crystal structure data for molecular crystals should lead to a more rapid development of the principles governing the packing of such crystals and their reactivity. The resulting control of such reactions should not only provide the means of causing them when they are desired, as, for example, for synthesis, but also the means of preventing them when they are to be avoided, as in the stabilization of pharmaceuticals. Finally, it appears that we have only just begun to exploit the potential reaction specificity and the exciting possibilities resulting from the unique symmetry properties of the crystalline state.

Reactions of molecular crystals with gases. II. X-ray structure of crystalline 4-chlorobenzoic acid and the anisotropy of its reaction with ammonia gas

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of molecular crystals with gases. II. X-ray structure of crystalline 4-chlorobenzoic acid and the anisotropy of its reaction with ammonia gasRodger S. Miller, Iain C. Paul, and David Y. CurtinCite this: J. Am. Chem. Soc. 1974, 96, 20, 6334–6339Publication Date (Print):October 1, 1974Publication History Published online1 May 2002Published inissue 1 October 1974https://doi.org/10.1021/ja00827a015RIGHTS & PERMISSIONSArticle Views162Altmetric-Citations45LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Reactions of molecular crystals with gases. III. Relation of anisotropy to crystal structure in reactions of carboxylic acids and anhydrides with ammonia gas

Reactions of molecular crystals with gases. III. Relation of anisotropy to crystal structure in reactions of carboxylic acids and anhydrides with ammonia gas

Reactions of molecular crystals with gases. I. Reactions of solid aromatic carboxylic acids and related compounds with ammonia and amines

Reactions of molecular crystals with gases. I. Reactions of solid aromatic carboxylic acids and related compounds with ammonia and amines