Effects of Ionizing Radiation on Halogen-Bonded Dipyridyl-Naphthalenediimide Cocrystals.

Cocrystals are promising modular materials that can contain aromatics as coformers with the ability to fluoresce upon radiation exposure for use in scintillation and dosimetry. The materials must be able to endure significant exposures to ionizing radiation, and there is currently a minimal understanding of atomistic criteria to enhance the structural stabilities of organic materials for such applications. The current study examines four cocrystals with a common molecular component as a naphthalene backbone-dipyridyl-naphthalenediimide () that interact with the halogen-bond (XB) donors , diiodobenzene (), and diiodotetrafluorobenzene ().

Light-Induced Disruption of 1D Wire-Like Arrays of Monoatomic Ag(I) Ions: Single-Crystal Reaction with Crystal Softening.

The exploitation of noncovalent bonding in the solid state is attractive to generate one-dimensional (1D) wire-like assemblies of metals and uncover dynamic and physical properties of such intriguing structures. Herein, we describe a metal-organic crystal based on Ag(I) ions that assemble to be organized into 1D wire-like assemblies maintained by argentophilic interactions. UV-light irradiation of the crystal composed of the 1D structures results in a single-crystal-to-single-crystal (SCSC) photodimerization that transforms the 1D periodic metal arrays to isolated metal dimers.

Supramolecular Matter Through Crystal Engineering: Covalent Bond Formation to Postsynthetic Modification.

Supramolecular chemistry can transform organic synthesis by revealing that crystalline materials are not static but rather dynamic environments for controlled covalent bond formations and manipulations. This review focuses on how supramolecular chemistry can be developed to direct molecular synthesis in the organic solid state, directing reliable C─C bond formations to enable transformations difficult or impossible in solution. Special attention is given to postsynthetic modifications that serve to broaden the functional scope of solid-state reactivity allowing organic crystals to be developed as molecular flasks and a form of supramolecular matter.

Structural Integrities of Symmetric and Unsymmetric -Bis-pyridyl Ethylene Powders Exposed to Gamma Radiation: Packing and Electronic Considerations Assisted by Electron Diffraction.

Radiation detection (dosimetry) most commonly uses scintillating materials in a wide array of fields, ranging from energy to medicine. Scintillators must be able to not only fluoresce owing to the presence of a suitable chromophore but also withstand damage from radiation over prolonged periods of time. While it is inevitable that radiation will cause damage to the physical and chemical properties of materials, there is limited understanding of features within solid-state scintillators that afford increased structural integrity upon exposure to gamma (γ) radiation.

Assessing Structures and Solution Behaviors of Molecular and Ionic Cocrystals with a Common Bioactive Molecule: 2,4-Pyridinedicarboxylic Acid with Tranexamic Acid and Nicotinamide.

Cocrystals of 2,4-pyridinedicarboxylic acid () with either nicotinamide () or tranexamic acid () as ( and , respectively, are reported, with the former being a molecular cocrystal and the latter being an ionic cocrystal. Single-crystal structure analyses showed that and its coformers are sustained by neutral and ionic hydrogen bonds. Suspensions of resulted in complete conversion to monohydrate after 48 h, while was thermodynamically stable at a lower pH and showed a 2-fold increase in the concentration, relative to pure monohydrate under similar conditions.

Nanoscale Dodecahedral and Fullerene-Type Organoboroxine and Borazine Cages from Planar Building Units.

Boroxine- and borazine-cage analogs to C, C, and C were calculated and compared in terms of structure, strain indicators, and physical properties relevant to nanoscale applications. The results show C and C type cages are less strained than the smaller congener, primarily due to minimized bending in the B-arylene-B segments. The smallest cage calculated has a diameter of 2.

DDX3X and Stress Granules: Emerging Players in Cancer and Drug Resistance.

The DEAD (Asp-Glu-Ala-Asp)-box helicase 3 X-linked (DDX3X) protein participates in many aspects of mRNA metabolism and stress granule (SG) formation. DDX3X has also been associated with signal transduction and cell cycle regulation that are important in maintaining cellular homeostasis. Malfunctions of DDX3X have been implicated in multiple cancers, including brain cancer, leukemia, prostate cancer, and head and neck cancer.

A molecular T-pentomino for separating BTEX hydrocarbons.

Methods to separate molecules (e.g., petrochemicals) are exceedingly important industrially.

Atomistic-Level Effects of Noncovalent Interactions and Crystalline Packing for Organic Material Structural Integrity upon Exposure to Gamma Radiation.

Developing an atomistic understanding of ionizing radiation induced changes to organic materials is necessary for intentional design of greener and more sustainable materials for radiation shielding and detection. Cocrystals are promising for these purposes, but a detailed understanding of how the specific intermolecular interactions within the lattice upon exposure to radiation affect the structural stability of the organic crystalline material is unknown. This study evaluates atomistic-level effects of γ radiation on both single- and multicomponent organic crystalline materials and how specific noncovalent interactions and packing within the crystalline lattice enhance structural stability.

Mechanochemical Mediated Coexistence of B←N Coordination and Hydrogen Bonding.

Mechanochemistry afforded a photoactive cocrystal via coexisting (B)O-H⋅⋅⋅N hydrogen bonds and B←N coordination. Specifically, solvent-free mechanochemical ball mill grinding and liquid-assisted grinding of a boronic acid and an alkene resulted in mixtures of hydrogen-bonded and coordinated complexes akin to mixtures of noncovalent complexes that can be obtained in solution in equilibria processes. The alkenes of the hydrogen-bonded assembly undergo an intermolecular [2+2] photodimerization in quantitative conversion, effectively reporting the outcome of the self-assembly processes.

Effects of Gamma Radiation on Single- and Multicomponent Organic Crystalline Materials.

Exploration of highly ionizing radiation damage to organic materials has mainly been limited to polymers and single-component organic crystals due to their use in coatings and scintillation detection. Additional efforts are needed to create new tunable organic systems with stability in highly ionizing radiation to rationally design novel materials with controllable chemical and physical properties. Cocrystals are a promising class of compounds in this area because of the ability to rationally design bonding and molecular interactions that could lead to novel material properties.

Mechanochemistry Facilitates a Single-Crystal X-ray Structure Determination of Free Base Naloxone Anhydrate.

A method to obtain single crystals of the opioid antagonist naloxone in the free base form is facilitated using mechanochemistry. The application of mechanochemistry reduces the number of steps and makes single crystals readily available from solution compared to using an approach based exclusively on solution or the reported method based on sublimation. The X-ray structure confirms the structure determined using powder diffraction and provides details of hydrogen bonding.

Inhibiting Sublimation of Thymol by Cocrystallization.

A thymol:4,4'-dipyridyl (2:1) cocrystal (Form I) is reported to suppress thymol sublimation. The cocrystal was prepared via solution-mediated phase transformation and its structure is sustained by O-H (phenol) ··· N (pyridyl) hydrogen bonds between two individual components. A cocrystal polymorph (Form II) was formed via solid state transformation or via vapor phase upon heating.

Programming Rapid Functional Group Diversification into a Solid-State Reaction: Aryl Nitriles for Self-Assembly, Click Reactivity, and Discovery of Coexisting Supramolecular Synthons.

A method to rapidly diversify the molecules formed in organic crystals is introduced, with aryl nitriles playing a novel dual role as both hydrogen-bond acceptors and modifiable organic groups. The discovery of coexisting supramolecular synthons in the same crystal is also described. The general concept is demonstrated by using a bis(aryl nitrile) alkene that undergoes a hydrogen-bond-directed intermolecular [2+2] photodimerization to form a tetra(aryl nitrile)cyclobutane.

Structures and Reactivities of Cocrystals Involving Diboronic Acids and Bipyridines: In Situ Linker Reaction and 1D-to-2D Dimensionality Change via Crystal-to-Crystal Photodimerization.

Cocrystallizations of diboronic acids [1,3-benzenediboronic acid (1,3-bdba), 1,4-benzenediboronic acid (1,4-bdba) and 4,4'-biphenyldiboronic acid (4,4'-bphdba)] and bipyridines [1,2-bis(4-pyridyl)ethylene (bpe) and 1,2-bis(4-pyridyl)ethane (bpeta)] generated the hydrogen-bonded 1 : 2 cocrystals [(1,4-bdba)(bpe) ] (1), [(1,4-bdba)(bpeta) ] (2), [(1,3-bdba)(bpe) (H O) ] (3) and [(1,3-bdba)(bpeta) (H O)] (4), wherein 1,3-bdba involved hydrated assemblies. The linear extended 4,4'-bphdba exhibited the formation of 1 : 1 cocrystals [(4,4'-bphdba)(bpe)] (5) and [(4,4'-bphdba-me)(bpeta)] (6). For 6, a hemiester was generated by an in-situ linker transformation.

Halogen-Bond Mediated [2+2] Photodimerizations: À la Carte Access to Unsymmetrical Cyclobutanes in the Solid State.

The ditopic halogen-bond (X-bond) donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene (, , and , respectively) form binary cocrystals with the unsymmetrical ditopic X-bond acceptor -1-(2-pyridyl)-2-(4-pyridyl)ethylene (). The components of each cocrystal ()·(), ()·(), and ()·() assemble via N···I X-bonds. For ()·() and ()·(), the X-bond donor supports the C=C bonds of to undergo a topochemical [2+2] photodimerization in the solid state: UV-irradiation of each solid resulted in stereospecific, regiospecific, and quantitative photodimerization of to the corresponding head-to-tail () or head-to-head () cyclobutane photoproduct, respectively.

Self-Assembly of Diboronic Esters with U-Shaped Bipyridines: "Plug-in-Socket" Assemblies.

Self-assembled complexes utilizing the ditopic dative bond acceptor 1,3-diboronic acid with catechol and complementary U-shaped donors in the form of 1,8-dipyridylnaphthalenes (1,8-bis(4-pyridyl)naphthalene (), 1,8-bis(4-ethylenylpyridyl)naphthalene (), and 1,8-bis(4-ethynylpyridyl)naphthalene ()) yielded discrete two-component structures. The assemblies exhibit "plug-in-socket" geometries. DFT calculations are consistent with the donor pyridyl and acceptor catecholate being electron poor and rich, respectively.

Cubane-forming cyclic dienes that exhibit orthogonal reactivities in the solid state.

Photoirradiation of a binary cocrystal composed of two different cyclic dienes generates a highly-symmetric cubane-like tetraacid cage regioselectively and in quantitative yield. The cage forms by a double [2+2] photodimerization of one of the diene cocrystal components. The second diene while photostable in the cocrystal reacts in a double [2+2] photodimerization as a pure form quantitatively to form a tetramethyl cubane-like cage.

Supramolecular construction of a cyclobutane ring system with four different substituents in the solid state.

Methods to form cyclobutane rings by an intermolecular [2 + 2] cross-photoreaction (CPR) with four different substituents are rare. These reactions are typically performed in the liquid phase, involve multiple steps, and generate product mixtures. Here, we report a CPR that generates a cyclobutane ring with four different aryl substituents.

Clues from cocrystals: a ternary solid, polymorphism, and rare supramolecular isomerism involving resveratrol and 5-fluorouracil.

We describe a supramolecular synthesis of a ternary cocrystal involving resveratrol and 5-fluorouracil (5-fu) with trans-bis(4-pyridyl)ethylene (bpe). We also have discovered a polymorph of a binary cocrystal involving 5-fu and bpe that originates from rare supramolecular isomerism.

Correction: Mechanical rigidity of a shape-memory metal-organic framework increases by crystal downsizing.

Correction for 'Mechanical rigidity of a shape-memory metal-organic framework increases by crystal downsizing' by Al A. Tiba et al., Chem.

X-ray crystal structure of -bis-(pyridin-3-yl)ethyl-ene: comparing the supra-molecular structural features among the symmetrical bis-(-pyrid-yl)ethyl-enes ( = 2, 3, or 4) constitutional isomers.

The mol-ecular structure of -bis-(pyridin-3-yl)ethyl-ene (), CHN, as determined by single-crystal X-ray diffraction is reported. The mol-ecule self-assembles into two dimensional arrays by a combination of C-H⋯N hydrogen bonds and edge-to-face C-H⋯ inter-actions that stack in a herringbone arrangement perpendicular to the crystallographic -axis. The supra-molecular forces that direct the packing of as well as its packing assembly within the crystal are also compared to those observed within the structures of the other symmetrical isomers -1,2-bis-(-pyrid-yl)ethyl-ene ( , , where = ' = 2 or 4).

Mechanical rigidity of a shape-memory metal-organic framework increases by crystal downsizing.

Soft porous nanocrystals with a pronounced shape-memory effect exhibit two- to three-fold increase in elastic modulus compared to the microcrystalline counterpart as determined by atomic force microscopy nanoindentation. The increase in rigidity is consistent with the known shape-memory effect displayed by the framework solid at the nanoscale. Crystal downsizing can offer new avenues for tailoring the mechanical properties of metal-organic frameworks.

Phototriggered Guest Release from a Nonporous Organic Crystal: Remarkable Single-Crystal-to-Single-Crystal Transformation of a Binary Cocrystal Solvate to a Ternary Cocrystal.

The development of organic solids for applications in materials science requires a fundamental understanding of how close packing of molecules can affect structure and function. We report here nonporous organic crystals that release entrapped guest molecules upon application of UV light. We show components of binary cocrystal solvates to undergo an intermolecular photoreaction to generate ternary cocrystals that results in release of entrapped solvent molecules.

Superstructural diversity in salt-cocrystals: higher-order hydrogen-bonded assemblies formed using U-shaped dications and with assistance of π-π stacking.

Salt cocrystals with components that assemble by hydrogen bonds and aromatic anion-molecule stacks (π--π stacks) are reported. U-shaped bipyridines and an isocoumarin carboxylic acid self-assemble to form 5-, 6-, and 10-component aggregates with components in double and quadruple face-to-face stacks. DFT calculations support the π--π stacks to help stabilize the salt cocrystals.