Low-Molecular-Weight Organogelators Based on N-dodecanoyl-L-amino Acids-Energy Frameworks and Supramolecular Synthons

Lauric acid was used to synthesize the low-molecular-weight organogelators (LMOGs), derivatives of two endogenous (L)-alanine, (L)-leucine, and three exogenous (L)-valine, (L)-phenylalanine, and (L)-proline amino acids. The nature of processes responsible for the gel formation both in polar and in apolar solvents of such compounds is still under investigation. Knowing that the organization of surfactant molecules affects the properties of nano scale materials and gels, we decided to elucidate this problem using crystallographic diffraction and energy frameworks analysis. The single crystals of the mentioned compounds were produced successfully from heptane/^tBuOMe mixture. The compounds form lamellar self-assemblies in crystals. The energetic landscapes of single crystals of a series of studied amphiphilic gelators have been analyzed to explore the gelling properties. The presented results may be used as model systems to understand which supramolecular interactions observed in the solid state and what energy contributions are desired in the designing of new low-molecular-weight organic gelators.

Long-Range Supramolecular Synthon Isomerism: Insight from a Case Study of Vinylic Tellurium Trihalides Cl(Ph)C=C(Ph)TeX3 (X = Cl, I)

A slight modification of the synthetic procedure resulted in a new (Cc) polymorph of vinylic tellurium-trichloride Z-Cl(Ph)C=C(Ph)TeCl3 (1, β-form) which is stabilized by Te⋯Cl chalcogen bonds, assembling its molecules into the zigzag chains. Such a packing motive is in contrast to the known (Pca21) polymorph of Z-Cl(Ph)C=C(Ph)TeCl3 (1, α-form, CCDC refcode: BESHOW), which is built upon Te⋯π(Ph) chalcogen bonded chains. We noted a similar case of [Te⋯halogen] vs. [Te⋯π(Ph)] supramolecular synthon polymorphism in its triiodide congener Z-Cl(Ph)C=CPh(TeI3) (2, α and β-polymorphic forms). Quantum chemical calculations of the intermolecular interaction and lattice energies for 1α–β and 2α–β supported the assumption that α is thermodynamic while β is a kinetic form. Kinetic forms 1β and 2β are isostructural (Cc), while the thermodynamic forms 1α (Pca21) and 2α (P21/c) are not and feature an unusual example of long-range supramolecular synthon module isomerism. In other words, 1α–2α pairs demonstrate very similarly to isostructural Te⋯πPh ChB stabilized chains, which are further packed differently relative to each other, following different angular geometry of type-I Cl⋯Cl and type-II I⋯I halogen bonding. These structural considerations are backed by quantum chemical calculations that support the proposed hierarchy of primary and secondary supramolecular synthons and the assignment of α and β as thermodynamic and kinetic forms, respectively.

Long-range supramolecular synthon polymorphism: a case study of two new polymorphic cocrystals of Ph2Te2–1,4-C6F4I2

Two new polymorphic forms of Ph2Te2–1,4-C6F4I2 cocrystals feature an unusual packing of Ph2Te2 molecules, which is typical for native Ph2Se2 but not Ph2Te2. This suggests the existence the yet unknown, Ph2Se2-like polymorph of Ph2Te2.

Crystals at a Carrefour on the Way through the Phase Space: A Middle Path

Multiple supramolecular functionalities of cyclic α-alkoxy tellurium-trihalides (including Te---O, Te---X (X = Br, I) and Te---π(C=C) supramolecular synthons) afford rich crystal packing possibilities, which consequently results in polymorphism or Z’ > 1 crystal structures. Example of three crystal forms of cyclohexyl-ethoxy-tellurium-trihalides, one of which combines the packing of two others, affords a unique model to observe the supramolecular synthon evolution at the early stages of crystallization, when crystals on the way find themself at a carrefour between the evolutionally close routes, but fail to choose between two energetically close packing patterns, so taking the “middle path”, which incorporates both of them (and results in two crystallographically independent molecules). In general, this allows a better understanding of the existing structures, and an instrument to search for the new polymorphic forms.

Highly polar stacking interactions wrap inorganics in organics: lone-pair–π-hole interactions between the PdO4 core and electron-deficient arenes

Each PdO4 plane of Pd3(OAc)6 behaved as a 5-center nucleophile (O lone pairs and the dz2-PdII orbital) that interacts with π-donating arenes to afford highly polar circular stacking, where organics wrapped inorganics.

Binding of anionic Pt(ii) complexes in a dedicated organic matrix: towards new binary crystalline composites

Square-planar [PtL₄]²⁻ (L = CN⁻, Cl⁻, Br⁻) anions are bound by π-acidic HAT(CN)₆ in solution and in the solid state to provide the basis for the first epitaxially grown anion–π crystalline composites.

Crystal engineering strategies towards halogen-bonded metal–organic multi-component solids: salts, cocrystals and salt cocrystals

This highlight presents an overview of the current advances in the preparation of halogen bonded metal–organic multi-component solids, including salts and cocrystals comprising neutral and ionic constituents.

Chimeric supramolecular synthons in Ph2Te2(I2)Se

Iodination of Ph₂Te₂Se by molecular iodine is directed towards the Te atom and yields {diiodo[(phenyltellanyl)selanyl]-λ⁴-tellanyl}benzene, PhTeSeTeI₂Ph or C₁₂H₁₀I₂SeTe₂. The molecule can be considered as a chimera of PhTeSeR, PhTeSeTePh and R'TeI₂Ph fragments. The crystal structure features a complex interplay of the supramolecular synthons Te...π(Ph), Se...Te and I...Te, combining molecules into a three-dimensional framework. Their combination affords long-range supramolecular synthons which are fused in a way resembling the mythological chimera and could be defined as chimeric supramolecular synthons. The energies of the intermolecular interactions have also been calculated and analyzed.

A new supramolecular heterosynthon [C–I⋯OC(carboxylate)] at work: engineering copper acetate cocrystals

Carboxylate–iodine supramolecular heterosynthons in combination with energy frameworks can be reliably applied in engineering hybrid metal-carboxylate cocrystals.

Chlorotellurate(iv) supramolecular associates with “trapped” Br2: features of non-covalent halogen⋯halogen interactions in crystalline phases

Reactions of chlorotellurates(iv) and Br₂ afford formation of supramolecular complexes Cat₂{[TeCl₆](Br₂)} (Cat = Me₃N⁺ (1), PyH⁺ (2), 4-MePyH⁺ (3) and 1-MePy⁺ (4)) where dibromine fragments are “trapped” by [TeCl₆]³⁻via Br⋯Cl halogen bonding.

A concerted evolution of supramolecular interactions in a {cation; metal complex; π-acid; solvent} anion-π system

Comprehensive studies on a concerted evolution of supramolecular interactions with multicomponent synthon reproduction provide a new tool to describe the trapping of flat [M(L)₄]²⁻ complexes within π-acidic cavities.

Intermolecular Interactions in Functional Crystalline Materials: From Data to Knowledge

Intermolecular interactions of organic, inorganic, and organometallic compounds are the key to many composition–structure and structure–property networks. In this review, some of these relations and the tools developed by the Cambridge Crystallographic Data Center (CCDC) to analyze them and design solid forms with desired properties are described. The potential of studies supported by the Cambridge Structural Database (CSD)-Materials tools for investigation of dynamic processes in crystals, for analysis of biologically active, high energy, optical, (electro)conductive, and other functional crystalline materials, and for the prediction of novel solid forms (polymorphs, co-crystals, solvates) are discussed. Besides, some unusual applications, the potential for further development and limitations of the CCDC software are reported.

The energy frameworks of aufbau synthon modules in 4-cyanopyridine co-crystals

The supramolecular arrangement of 4-cyanopyridine (4CNpy) in its native crystal form and its co-crystals with halogen bond (XB) donors is discussed in terms of energy frameworks of long-range synthon aufbau modules (LSAMs) energy frameworks.