Supramolecular Motifs Research Articles

Supramolecular Reinforcement of Polymer–Nanoparticle Hydrogels for Modular Materials Design

AbstractMoldable hydrogels are increasingly used as injectable or extrudable materials in biomedical and industrial applications owing to their ability to flow under applied stress (shear‐thin) and reform a stable network (self‐heal). Nanoscale components can be added to dynamic polymer networks to modify their mechanical properties and broaden the scope of applications. Viscoelastic polymer–nanoparticle (PNP) hydrogels comprise a versatile and tunable class of dynamic nanocomposite materials that form via reversible interactions between polymer chains and nanoparticles. However, PNP hydrogel formation is restricted to specific interactions between select polymers and nanoparticles, resulting in a limited range of mechanical properties and constraining their utility. Here, a facile strategy to reinforce PNP hydrogels through the simple addition of α‐cyclodextrin (αCD) to the formulation is introduced. The formation of polypseudorotoxanes between αCD and the hydrogel components resulted in a drastic enhancement of the mechanical properties. Furthermore, supramolecular reinforcement of CD–PNP hydrogels enabled decoupling of the mechanical properties and material functionality. This allows for modular exchange of structural components from a library of functional polymers and nanoparticles. αCD supramolecular binding motifs are leveraged to form CD–PNP hydrogels with biopolymers for high‐fidelity 3D (bio)printing and drug delivery as well as with inorganic NPs to engineer magnetic or conductive materials.

Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations.

Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π‐stacking and hydrogen‐bonding interactions. The realized supramolecular motifs include hydrogen‐bonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.

Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations

AbstractExciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π‐stacking and hydrogen‐bonding interactions. The realized supramolecular motifs include hydrogen‐bonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.

Multicomponent crystals of p-coumaric acid and trans-ferulic acid: structures and physicochemical properties

• P -coumaric and trans-ferulic acids co-crystallised with 4,4’-bipyridine and dioxane. • Only p -coumaric acid co-crystallised with pyridine. • Persistence of carboxylic acid homosynthon for dioxane and pyridine compounds. • Formation of heterosynthons for 4,4’-bipyridine co-crystals. • Greater thermal stability of trans-ferulic acid compounds. p -coumaric acid ( p CA) and trans -ferulic acid (TFA) formed multicomponent crystals with 4,4’-bipyridine (BIPY) and 1,4-dioxane (DX). p CA also co-crystallised with pyridine (PYR). The crystal structures, thermal analysis, Hirshfeld surfaces and Fourier transform infrared spectroscopy of the compounds are presented. Both ( p CA)·(BIPY) and (TFA)·(BIPY) displayed the supramolecular heterosynthons, COOH···N pyr and OH···N pyr . The ( p CA)·(DX), (TFA)·(DX) and ( p CA)·(PYR) crystal structures featured the carboxylic acid homosynthon and the (phenol)OH···O/N heterosynthon. The observed supramolecular synthons can be related to the molecular sizes of the co-crystal formers thus allowing for the design of specific supramolecular motifs. Differential scanning calorimetry (DSC) results showed that (TFA)·(BIPY) has a higher thermal stability than ( p CA)·(BIPY) . The thermal stability of the dioxane and pyridine compounds followed the trend, (TFA)·(DX) > ( p CA)·(DX) > ( p CA)·(PYR) . The greater thermal stability of the TFA co-crystals can be related to the presence of the methoxy group which formed an intramolecular hydrogen bond with the hydroxyl group.

Supramolecular architectures of mononuclear nickel(II) and homobinuclear copper(II) complexes with the 5,5′-dimethyl-2,2′-bipyridine ligand: Syntheses, crystal structures and Hirshfeld surface analyses

Two new compounds based on one mononuclear nickel(II) and one homobinuclear copper(II) complexes respectively and of general formula [Ni(dmbpy)2(CH3COO)]ClO4 (1) and [Cu2(dmbpy)2(CH3COO)3]ClO4 (2) with dmbpy = 5,5′-dimethyl-2,2′-bipyridine, were synthesized by hydrothermal treatment. Both were influenced by the coordinated acetate ion molecule. The crystal and molecular structures of (1) and (2) were determined by single crystal X-ray diffraction method and both compounds were additionally characterized by means of elemental and thermogravimetric analysis, FT-IR spectroscopy, powder X-ray diffraction and UV–visible. The mononuclear complex (1) shows a distorted octahedral geometry around the metal ion. On the other hand, the copper(II) compound crystallizes as an homobinuclear system, in which each of the metal ions is located into the N2O3 coordination spheres adopting a distorted square pyramidal geometry. In (2) the intramolecular distance between two copper atoms is of the order of Cu1-Cu2 = 3.38 (2) Å. In both crystals packing of these two complexes, H-bonding, π⋯π, and C-H⋯π interactions are operative in forming supramolecular motifs. Complex (1) displays two 1D chains that lead to form R88(42) ring motifs, repetition of which generates a 2D supramolecular network. These chains interacts with the neighbouring ones via intermolecular C-H···π and π···π stacking interactions, leading to the formation of a 3D-stacking network (2D+1D→3D). Formation of a 2D supramolecular sheet in the solid state structure of (2) is facilitated by the C–H⋯O, C–H⋯π and π⋯π interactions (1D+1D→2D). Hirshfeld surface analysis and theoretical calculations were carried out on the two compounds. The results clearly show that C–H···O, C–H··· π and π···π stacking interactions play a paramount role in the stabilization of the supramolecular architecture of (1) and (2). In addition, absorption spectra reveal their semi-conductive nature (4.19 eV for (1)·and 4.43 eV for (2)).

Structure and photocatalytic performance of a metallacycle complex based on flexible carboxylic acid ligand

A new compound of {[Cu2(L)2(2,2′-bipy)2(H2O)2]·2H2O}n (1) (H2L = 1,3-bis(4′-carboxylatophenoxy)benzene, 2,2′-bipy = 2,2′-bipyridine), was prepared and full characterized. 1 shows a metallacycle unit, which was further extended into 3D supramolecular motif through the π-π packing and H-bonded interactions. 1 obtained effectively photocatalytic performance to the disintegration of Rhodamine B (Rh B) compared to the dyes of basic green (BG), methyl violet (MV) and methylene blue (MB). In addition, the plausible mechanism displayed by 1 for the catalytic degradation toward Rh B was proposed using the trapping method and LC-MS studies.

Crystal structure of 9,9-di-ethyl-9H-fluorene-2,4,7-tricarbaldehyde.

The title compound, C20H18O3, crystallizes in the space group P21/c with one mol-ecule in the asymmetric unit of the cell. The fluorene skeleton is nearly planar and the crystal structure is composed of mol-ecular layers extending parallel to the (302) plane. Within a layer, one formyl oxygen atom participates in the formation of a Carene-H⋯O bond, which is responsible for the formation of an inversion symmetric supra-molecular motif of graph set R 2 2(10). A second oxygen atom is involved in an intra-molecular Carene-H⋯O hydrogen bond and is further connected with a formyl hydrogen atom of an adjacent mol-ecule. A Hirshfeld surface analysis indicated that the most important contributions to the overall surface are from H⋯H (46.9%), O⋯H (27.9%) and C⋯H (17.8%) inter-actions.

Supramolecular "Click Chemistry" for Targeting in the Body.

The fields of precision imaging and drug delivery have revealed a number of tools to improve target specificity and increase efficacy in diagnosing and treating disease. Biological molecules, such as antibodies, continue to be the primary means of assuring active targeting of various payloads. However, molecular-scale recognition motifs have emerged in recent decades to achieve specificity through the design of interacting chemical motifs. In this regard, an assortment of bioorthogonal covalent conjugations offer possibilities for in situ complexation under physiological conditions. Herein, a related concept is discussed that leverages interactions from noncovalent or supramolecular motifs to facilitate in situ recognition and complex formation in the body. Classic supramolecular motifs based on host-guest complexation offer one such means of facilitating recognition. In addition, synthetic bioinspired motifs based on oligonucleotide hybridization and coiled-coil peptide bundles afford other routes to form complexes in situ. The architectures to include recognition of these various motifs for targeting enable both monovalent and multivalent presentation, seeking high affinity or engineered avidity to facilitate conjugation even under dilute conditions of the body. Accordingly, supramolecular "click chemistry" offers a complementary tool in the growing arsenal targeting improved healthcare efficacy.

Nanoparticles exploring the macroscopic world

Nanoparticles exploring the macroscopic world

Multifunctional Polysiloxane with coordinative ligand for ion recognition, reprocessable elastomer, and reconfigurable shape memory

Incorporating supramolecular motifs into polysiloxanes has been attracting interest to thrive advanced materials with unprecedented properties, such as enhanced stiffness, high stretchability, self-healing ability, and interfacial adhesion. Herein, we designed and synthesized a novel coordinative polysiloxane functionalized with the 2-hydroxy-1-naphthyl imine group, featuring in the synergistic coordination of N and O atoms towards various metal ions. By making full use of its coordination ability, this novel polysiloxane has been utilized for multipurpose applications. Firstly, remarkable ion recognition ability for Fe3+, Zn2+ and Al3+ ions was demonstrated. Secondly, supramolecular elastomers with thermoplasticity and self-healing ability were prepared by coordinating this polysiloxane with various metal ions. Especially the P1-10%-Fe3+ elastomer exhibits unprecedented mechanical strength (8.8 MPa) and fracture toughness (33.22 MJ/m3) among the reported thermoplastic polysiloxane-based elastomers. Thirdly, reprocessable shape-memory materials were developed by combination of glass transition and topological rearrangement induced by temperature, expanding their potential for complex reversible shape shifting. This new type of polymer could open the door for wider applications of supramolecular polysiloxane materials.

Fluorene Derivatives Bearing Two to Seven Phthalimidomethyl Groups: Syntheses, Crystal Structures and Conversion to Amines

AbstractFluorene derivatives containing four to seven phthalimidomethyl groups (1,3‐dioxo‐1,3‐dihydro‐2H‐isoindol‐2‐yl‐methyl groups) were prepared from 9H‐fluorene, 9,9‐diethyl‐9H‐fluorene as well as from 2,7‐ and 2,4,7‐functionalized 9,9‐diethyl‐9H‐fluorenes by using the conditions of the Tscherniac‐Einhorn reaction. By reacting the 9,9‐diethyl substituted fluorenes with N‐(hydroxymethyl)phthalimide the 2,4,6,7‐ and 2,3,4,6,7‐substituted derivatives were obtained. In the absence of the ethyl groups, as in the case of 9H‐fluorene, the formation of the sixfold and sevenfold substituted compounds was observed (1,2,3,5,7,8‐ and 1,2,3,4,6,7,8‐substituted fluorenes). It should be noted that one position in the bay region of the fluorene skeleton (position 4 or 5) remains unsubstituted in each of the prepared four‐ to sevenfold substituted 9H‐fluorenes. The conversion of the phthalimidomethyl substituted 9,9‐diethyl‐9H‐fluorenes into the corresponding amines takes place with excellent yields. The solid‐state structures of the compounds bearing phthalimidomethyl groups were determined by single‐crystal X‐ray diffraction analysis. The crystal structures are characterized by the presence of C−H⋅⋅⋅O, C−H⋅⋅⋅π and π⋅⋅⋅π interactions as well as C=O⋅⋅⋅π contacts. In the case of the chloroform and dichloromethane solvates the Cl⋅⋅⋅O=C, Cl⋅⋅⋅Cl, and Cl⋅⋅⋅π halogen bonds as well as the C−H⋅⋅⋅Cl hydrogen bonds influence furthermore the crystal packing. Ten‐membered supramolecular motifs of the graph set (10), which are created by the C−H⋅⋅⋅O bonds, can be recognized in some crystal structures. The manuscript provides information about the synthetic routes to new fluorene derivatives and their molecular structures as well as the patterns of noncovalent interactions in the crystalline state.

Defining the Landscape of the Pauling-Corey Rippled Sheet: An Orphaned Motif Finding New Homes.

ConspectusWhen peptides are mixed with their mirror images in an equimolar ratio, two-dimensional periodic structural folds can form, in which extended peptide strands are arrayed with alternating chirality. The resultant topography class, termed the rippled β-sheet, was introduced as a theoretical concept by Pauling and Corey in 1953. Unlike other fundamental protein structural motifs identified around that time, including the α-helix and the pleated β-sheet, it took several decades before conclusive experimental data supporting the proposed rippled β-sheet motif were gained. Much of the key experimental evidence was provided over the course of the past decade through the concurrent efforts of our three laboratories. Studies that focused on developing new self-assembling hydrogel materials have shown that certain amphiphilic peptides form fibrils and hydrogel networks that are more rigid and have a higher thermodynamic stability when made from racemic peptide mixtures as opposed to pure enantiomers. Related interrogation of assemblies composed of mixtures of l- and d-amphiphilic peptides confirmed that the resulting fibrils were composed of alternating l/d peptides consistent with rippled β-sheets. It was also demonstrated that mirror-image amyloid beta (Aβ) could act as a molecular chaperone to promote oligomer-to-fibril conversion of the natural Aβ enantiomer, which was found to reduce Aβ neurotoxicity against different neuronal cell models. With a cross-disciplinary approach that combines experiment and theory, our three laboratories have demonstrated the unique biophysical, biochemical, and biological properties that arise upon mixing of peptide enantiomers, in consequence of rippled β-sheet formation. In this Account, we give an overview of the early history of the rippled β-sheet and provide a detailed structural description/definition of this motif relative to the pleated β-sheet. We then summarize the key findings, obtained on three unique sets of aggregating mirror-image peptide pairs through independent efforts of our three laboratories, and use these results to delineate the landscape of the rippled β-sheet structural motif to inspire future studies. Peptide sequence parameters that favor rippled β-sheet assembly are described, along with the accompanying kinetic and thermodynamic properties, as well as the resulting emergent physical properties of the assemblies. The Account then concludes with a brief overview of some key unresolved challenges in this nascent field. There is much potential for future applications of this unique supramolecular motif in the realm of materials design and biomedical research. We hope this Account will stimulate much-needed discussion of this fascinating structural class to eventually produce a fully quantitative, rational framework for the molecular engineering of rippled β-sheets in the future.

Chirality, Gelation Ability and Crystal Structure: Together or Apart? Alkyl Phenyl Ethers of Glycerol as Simple LMWGs

Chiral recognition plays an important role in the self-assembly of soft materials, in particular supramolecular organogels formed by low molecular weight gelators (LMWGs). Out of 14 pairs of the studied racemic and enantiopure samples of alkyl-substituted phenyl ethers of glycerol, only eight enantiopure diols form the stable gels in nonane. The formation of gels from solutions was studied by polarimetry, and their degradation with the formation of xerogels was studied by the PXRD method. The revealed crystalline characteristics of all studied xerogels corresponded to those for crystalline samples of the parent gelators. In addition to those previously investigated, crystalline samples of enantiopure para-n-alkylphenyl glycerol ethers [alkyl = pentyl (5), hexyl (6), heptyl (7), octyl (8), nonyl (9)] and racemic 3-(3,5-dimethylphenoxy)propane-1,2-diol (rac-14) have been examined by single crystal X-ray diffraction analysis. Among 22 samples of compounds 1–14 studied by SC-XRD, seven different types of supramolecular motifs are identified, of which only two are realized in crystals of supramolecular gelators. An attempt was made to relate the ability to gel formation with the characteristics of the supramolecular motif of a potential gelling agent, and the frequency of formation of the motif, required for gelation, with the chiral characteristics of the sample.

(3aS,4R,5R,6S,7aR)-4,5-Di-bromo-2-[4-(tri-fluoro-meth-yl)phen-yl]-2,3,3a,4,5,6,7,7a-octa-hydro-3a,6-ep-oxy-1H-isoindol-1-one: crystal structure and Hirshfeld surface analysis.

The asymmetric unit of the title compound, C15H12Br2F3NO2, consists of two crystallographically independent mol-ecules. In both mol-ecules, the pyrrolidine and tetra-hydro-furan rings adopt an envelope conformation. In the crystal, mol-ecule pairs generate centrosymmetric rings with R 2 2(8) motifs linked by C-H⋯O hydrogen bonds. These pairs of mol-ecules form a tetra-meric supra-molecular motif, leading to mol-ecular layers parallel to the (100) plane by C-H⋯π and C-Br⋯π inter-actions. Inter-layer van der Waals and inter-halogen inter-actions stabilize mol-ecular packing. The F atoms of the CF3 groups of both mol-ecules are disordered over two sets of sites with refined site occupancies of 0.60 (3)/0.40 (3) and 0.640 (15)/0.360 (15). The most important contributions to the surface contacts of both mol-ecules are from H⋯H (23.8 and 22.4%), Br⋯H/H⋯Br (18.3 and 12.3%), O⋯H/H⋯O (14.3 and 9.7%) and F⋯H/H⋯F (10.4 and 19.1%) inter-actions, as concluded from a Hirshfeld surface analysis.

Fe(II)-driven self-assembly of enzyme-like coordination polymer nanoparticles for cascade catalysis and wound disinfection applications

A kind of coordination polymer nanoparticles was facily prepared using Fe(II) and GMP as the motifs through a coordination-driven self-assembly process. The resultant Fe-GMP CPNs show excellent peroxidase-like activity via the conversion of H 2 O 2 into OH, accompanied by high antibacterial efficiency. GOX could be adaptively encapsulated into Fe-GMP CPNs, and the proposed GOX@Fe-GMP CPNs functioned as an enzyme cascade model with a glucose-responsive property in OH production, with excellent antibacterial and wound disinfection efficiency under physiological conditions. • Self-assemblied coordination polymer nanoparticles were prepared using Fe(II) and GMP. • The Fe-GMP CPNs show excellent peroxidase-like activity through OH production. • The Fe-GMP CPNs indicated high antibacterial efficiency for E. coli and S. aureus . • The prepared GOX@Fe-GMP CPNs functioned as an enzyme cascade model in OH production. • GOX@Fe-GMP CPNs have excellent antibacterial and wound disinfection efficiency. The intelligent regulation of reactive oxygen species by nanozymes and the corresponding cascade catalysis hold great potential as a promising next-generation therapeutic methodology. However, the preparation of nanozymes usually involves high material consumption and tedious multistep processes, especially during the packaging of several functional components to realize the enzyme cascade. Here, we propose a facile strategy to prepare the coordination polymer nanoparticles (CPNs) using ferrous ions as the iron source and guanosine monophosphate (GMP) as the supramolecular motif. The resultant Fe-GMP CPNs show excellent peroxidase-like activity via the conversion of H 2 O 2 into highly active OH, accompanied by high antibacterial efficiency, as well as high encapsulation capacity to simultaneously immobilize guest components through an adaptive self-assembly process. Typically, glucose oxidase (GOX) encapsulation endows as-prepared GOX@Fe-GMP CPNs with glucose-responsive properties, so that glucose can be ultimately converted into OH via intermediate H 2 O 2 . This convenient cascade catalysis system not only possesses excellent antibacterial efficiencies, inhibiting the growth of Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) by 99% and significantly promoting wound healing in the absence of additional H 2 O 2 , but also has great application potential in the fields of biocatalysis and biomedicine.

Preparation of Artificial Hexaplex Composed of Non-Natural Nucleic Acid.

This article describes synthetic procedures for acyclic D-threoninol nucleic acid tethering of bifacial nucleobases. Because these nucleobases have complementary hydrogen bonding sites on both sides, their oligomers can form a hexaplex. These hexaplexes are suitable for use as metal or pH sensors and as supramolecular motifs. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Synthesis of D-threoninol backbone Basic Protocol 2: Synthesis of D-aTNA tethering cyanuric acid Basic Protocol 3: Synthesis of D-aTNA tethering a 2-aminopyrimidine moiety Basic Protocol 4: Synthesis of D-aTNA tethering a 2,4,6-triaminopyrimidine moiety Basic Protocol 5: Synthesis of D-aTNA oligomer tethering cyanuric acid, 2-aminopyrimidine, or 2,4,6-triaminopyrimidine.

Multifunctionality-assisted supramolecular architecture formation in tert-butyl phosphonic acid adducts with cytosine and adenine

Studies on interaction of phosphorus acids with N-heterocycles/nucleobases can unravel supramolecular architectures which can have implications in understanding similar interactions in biological systems. Interaction of tert-butyl phosphonic acid (tBuPO3H2) with nucleobases cytosine (cyt) and adenine (aden) leads to the isolation of hydrogen-bonded supramolecular motifs [(tBuPO3H)(cyt-H)] (1) and [(tBuPO3H)(aden-H)] (2). Solid-state structures of these two adducts established by single-crystal X-ray diffraction studies were found to contain a 1:1 ratio of the phosphorus acid and the nucleobase. Presence of hydrophobic t-butyl groups on phosphorous in compounds 1 and 2 aids the isolation of water-free acid-base complexes. Adducts 1 and 2 exist as hydrogen-bonded ion pair, each possessing eight-membered hydrogen-bonded rings involving nucleobase molecules and PO3H units of the phosphonate anions. A number of N–H···O, C–H···O, and O–H···O hydrogen bonds apart from weak C–H···O interactions are prevalent in the structures of these supramolecular architectures.

Effectiveness of cell adhesive additives in different supramolecular polymers.

Supramolecular motifs in elastomeric biomaterials facilitate the modular incorporation of additives with corresponding motifs. The influence of the elastomeric supramolecular base polymer on the presentation of additives has been sparsely examined, limiting the knowledge of transferability of effective functionalization between polymers. Here it was investigated if the polymer backbone and the additive influence biomaterial modification in two different types of hydrogen bonding supramolecular systems, that is, based on ureido‐pyrimidinone or bis‐urea units. Two different cell‐adhesive additives, that is, catechol or cyclic RGD, were incorporated into different elastomeric polymers, that is, polycaprolactone, priplast or polycarbonate. The additive effectiveness was evaluated with three different cell types. AFM measurements showed modest alterations on nano‐scale assembly in ureido‐pyrimidinone materials modified with additives. On the contrary, additive addition was highly intrusive in bis‐urea materials. Detailed cell adhesive studies revealed additive effectiveness varied between base polymers and the supramolecular platform, with bis‐urea materials more potently affecting cell behavior. This research highlights that additive transposition might not always be as evident. Therefore, additive effectiveness requires re‐evaluation in supramolecular biomaterials when altering the polymer backbone to suit the biomaterial application.

Supramolecular architectures, Hirshfeld surface analysis of 2-Amino 4-methyl pyridinium 4 amino salicylate and 2-Amino 4-methyl pyridinium 5 chloro salicylate

In the present study, crystals of two salts were grown by mixing of 2-Amino 4-methyl pyridine(2AMP) with 4-amino salicylic acid(4ASA) (C 6 H 9 N 2 + C 7 H 6 NO 3 − Salt-I) and 5‑chloro salicylic acid(5ClSA) (C 6 H 9 N 2 + C 7 H 4 O 3 Cl − Salt-II). In the crystal structure of both salts the 2-amino-4methyl pyridinium cations are protonated at N-atom of pyridine. The 4-aminosalicylate and 5-chlorosalicylate anions interact with the protonated cations through N H⋅⋅O hydrogen bonds form R 2 2 ( 8 ) ring motifs. The crystal structure of both (I) and (II) salts are stabilized by N‒H⋅⋅⋅O, C‒H⋅⋅⋅O hydrogen bonding interactions. Hirshfeld surfaces and fingerprint plots facilitate to compare the intermolecular interactions and visualize different supramolecular motifs in the crystal structure.

A SUPRAMOLECULAR STRUCTURE OF PHOSPHORYLATED N-PHENYL-1,2,4-TRIAZOLE- 3-THIONE AND ITS CRYSTAL SOLVATE

A comparative analysis of the molecular and crystal structures is performed for 5-[(diphenylphosphoryl) methyl]-4-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (1) in individual crystal (1a) and a crystal solvate with dimethylformamide (DMF) in the 1:1 ratio (1b). The crystals of both modifications have the identical geometries of the molecule of the key compound, and the crystals (despite their different crystal systems and unit cells parameters) are characterized by the formation of an identical one-dimensional supramolecular motif in them due to classical N–H...O hydrogen bonds and weaker noncovalent – C-H ... S interactions in crystal 1a and CH ... N in crystal 1b. A tetragonal packing of one-dimensional motifs oriented along the smallest unit cell parameter are observed in both cases. Solvate molecules are localized in zero-dimensional cavities in crystal 1b. Despite a denser molecular packing in crystal 1b, the solid-state phase transformation is observed for its polycrystalline sample, and the powder X-ray diffraction method shows that it partially transforms into form 1a with time. The latter form is characterized by a less dense molecular packing in the crystal.