Supramolecular architecture of crown-containing styryl dyes: Part I. Crystal and molecular structures of the acetonitrile solvate monohydrate of the potassium iodide complex with benzo-15-crown-5 ether dye based on methylquinoline iodide

The structure of a single crystal of the acetonitrile solvate monohydrate of the potassium iodide complex with benzo-15-crown-5 ether dye based on methylquinoline iodide (I) is determined by X-ray diffraction. It is established that the single crystal contains positively charged molecules of benzocrown ether photodye (D), K⁺ cations, I^? anions, and water and acetonitrile solvate molecules in the ratio 1: 0.5: 1.5: 1: 1, respectively. The K⁺ cation and one of the I^? anions occupy special positions along the twofold axis. The K⁺ cation is coordinated by ten oxygen atoms of the crown ether fragments of two D molecules to form the [D ₂K]³⁺ complex. Inside the complex, two aromatic quinoline fragments are involved in a stacking interaction. The crossed mutual arrangement of the ethylene fragments and the considerable distance between them exclude the occurrence of intramolecular photochemical [2 + 2]cycloaddition reactions. In the crystal, the [D ₂K]³⁺ cationic complexes form stacks along the b axis. The adjacent complexes in a stack are related through the center of symmetry and, therefore, are arranged in a head-to-tail manner. The double bonds of the neighboring molecular cations D in a stack are strictly parallel to each other and are separated by a distance of 3.754 Å. This geometry is favorable to the intermolecular cycloaddition reaction that should result in the formation of the syn head-to-tail isomer.     

Specific features of the crystal packing that enable styryl dyes of the pyridine series to undergo the solid-phase [2 + 2] photocycloaddition including the process with single crystal retention

The crystal packing of a number of styryl dyes of the pyridine series is analyzed. The structures of three dyes and three [2 + 2] photocycloaddition (PCA) products, 1,2,3,4-tetrasubstituted cyclobutanes, obtained in single crystals are determined by X-ray diffraction. Stacks of planar organic cations are characteristic of styryl dye packings. The proceeding of the PCA reaction as a single crystal-to-single crystal transformation in the syn head-to-head stacks is in principle impossible. The syn head-to-tail stacking packings are favorable for the PCA reactions resulting in the centrosymmetric rctt isomers of cyclobutane. The stacking packings, in which molecules are related by the twofold axes (the anti arrangement of molecules), are also favorable for PCA in single crystals. In this case, the products are the rtct isomers of cyclobutane. The presence of the I^? counterions in a packing is a factor impeding the PCA reaction, because the secondary I…H-C bonds increase the rigidity of the crystal lattice. The conditions necessary for proceeding the PCA reactions in styryl dyes as single crystal-to-single crystal processes are as follows: (1) the stacks split into pairs of organic cations (dimers) with the d distances within 4.2 Å in a dimer and d exceeding 4.2 Å between the dimers; and (2) the dimers are surrounded by flexible shells consisting of anions, solvate molecules, or flexible moieties of the organic cations themselves.     

Pharmaceutical Salts of Fluoroquinolone Antibacterial Drugs with Acesulfame Sweetener

Novel organic salts of norfloxacin and ciprofloxacin with artificial sweeteners such as saccharin and acesulfame were prepared. The two salts 1 and 2 were characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Finally, the crystal structures were solved by single crystal X-ray diffraction data and the structures were analyzed in terms of supramolecular synthons. In norfloxacin acesulfamate 1, two norfloxacin cations and two acesulfame anions form an eight membered cyclic tetramer supramolecular synthon. The salt, ciprofloxacin acesulfamate 2, has a similar structure as salt 1. This study contributes the importance of crystal engineering and supramolecular chemistry to the pharmaceutical applications in terms of interactions and structural correlations in the design of new solid phases.

Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.     

The Charge-Transfer Properties of Rare Earth Complexes

Two new Y Cu complexes and some other rare earth complexes crystals are synthesized. The results of elemental analysis, IR, GTA are corresponding to their formula. The PA spectra of all these complexes and the charge-transfer spectra are studied. The strong conjugate π system makes the charge-transfer spectra of rare earth complexes occur in low energy positions with strong intensity. The charge-transfer effect is also existing in the yttrium(III) complex coordinated by some ligands with the conjugate π system.     

Crystal and molecular structure of a series of 15-crown-5-containing styryl heterocycles and their dimethoxy substituted analogues

A comparative study of the molecular geometry and crystal packing of crown-containing styryl heterocycles and their dimethoxy substituted analogues is performed. It is established that all the compounds exhibit an identical type of distortions of the geometry of the central styryl fragment. These are the localization of the π-electron density at the ethylene bond and the bond alternation in a half of the phenyl ring due to the conjugation of lone electron pairs of the oxygen substituents with the chromophore system of the molecule. A comparative analysis of the crystal packings of the compounds reveals extended separate hydrophilic and hydrophobic regions. The hydrophilic regions are built of crown ether fragments, and the hydrophobic regions consist of π-conjugated and aromatic molecular fragments. The hydrophobic regions are characterized by a wide variety of packing motifs, among which stacking packing is absent. For two compounds, the formation of sandwich dimers that are preorganized to enter into the photochemical [2 + 2]cycloaddition reaction is observed.     

Properties of liquid crystals and Cu2+ recognition based on Schiff bases

Two series of new Schiff base compounds were synthesized. For Schiff base compounds with a pyridine nitrogen atom in 4-position (7a–e), their supramolecular hydrogen bonding complexes show good liquid crystal properties. However, no liquid crystal property is observed for 8a–e. Results of theoretical calculations demonstrate that it is the intermolecular hydrogen bond of Schiff base compounds (8a–e) that prevents the formation of supramolecular hydrogen bonding. The Schiff base compounds, with terminal alkoxy chains, can recognize Cu²⁺ selectively with a color change. Nevertheless, others cannot recognize Cu²⁺.     

RE-Halobenzoic Acid-Terpyridine Complexes,Part V: Synthesis and Supramolecular Assembly of Rare-Earth-3,5-Dihalobenzoic Acid-Terpyridine Materials and Subsequent Comparison of Non-covalent Interactions

The synthesis and crystal structures of 48 new rare-earth (RE?=?La³⁺—Y³⁺)-3,5-dihalogenated benzoic acid (3,5-dibromobenzoic acid [3,5-dBrBA] and 3-bromo-5-iodobenzoic acid [3,5-BrIBA])-terpyridine [TPY] complexes are reported. Ligand based supramolecular assembly drives the formation of five distinct structure types across the lanthanide series. Featured in these structures are multiple significant halogen bonding interactions occurring at the terminal halide substituents in the form of halogen–halogen, halogen–oxygen, and halogen–π interactions. This series complements previous efforts to synthesize and evaluate a catalogue of Ln-halobenzoic acid-TPY materials. With these data, a comparison of the influence of halogen interactions on supramolecular assembly is provided. As one might expect, the frequency with which halogen bonding occurs and the displacement of other assembly mechanisms, depends on the number and polarizability of the halogen species. Structures across these series fall into multiple distinct structure types, as defined by tecton geometry. Since these tectons are isostructural across each respective series, trends in halogen bond propensity can be derived. In this comparison, the likelihood of halogen bonding and disruption of π–π stacking is shown to increase as halogen size increases.

Graphic Abstract

Two new series of rare-earth (RE = La³⁺–Y³⁺)-3,5-dihalogenated benzoic acid (3,5-dibromobenzoic acid and 3-bromo-5-iodobenzoic acid)-terpyridine complexes are synthesized and compared, with respect to supramolecular assembly, to each other and previously reported RE-halogenated benzoic acid-terpyridine series in order to study the role of halogen bonding in this system.

     

Crystal and molecular structure of adduct of 6-benzylaminopurine and 5-sulfosalicylic acid

The crystal structure of adduct of 6-benzylaminopurine and 5-sulfosalicylic acid C₁₉H₂₅N₅O₁₀S 1 is studied using single-crystal diffraction (R = 0.0482 for 2852 reflections with I > 2σ(I)). The asymmetric unit of 1 contains one 6-benzylaminopurine molecule and one 5-sulfosalicylic acid molecule, as well as four lattice water molecules. Hydrogen bonds, formed by 6-benzylaminopurine and 5-sulfosalicylic acid, link the two molecules into one-dimensional chain (omitting four water molecules), further joined to two-dimensional layer network. Short ring-interactions with intra-chain π-π stacking are observed. The data of IR spectroscopy confirm the formation of the two-dimensional supramolecular layer structure. At last, a 3D supramolecular network constructs via hydrogen bonds.     

Some physicochemical studies on organic eutectics

The phase diagrams of phenothiazine with each of m-nitrobenzoic acid (m-NBA) and m-dinitrobenzene (m-DNB) have been studied by thaw-melt method. These materials have been characterized by X-ray diffraction. Growth behavior of the parent components, eutectic and charge transfer complex (CTC) studied by measuring the rate of movement of the growth front in a capillary suggests the applicability of Hillig–Turnbull equation for the system. Microstructure and electrical conductivities of congruent melting complexes and eutectics have been determined. The low electrical conductivities of these materials have been due to weak interaction and mixed stacking of donor and acceptor. Excess thermodynamics functions of the charge-transfer (CT) materials and eutectics have been determined.     

Crystal growth,characterization and Density functional theory computations of supramolecular N‐carbamothioyl acetamide

Single crystals of N‐carbamothioylacetamide (NCTA) were grown by slow evaporation technique at constant temperature. The structure is elucidated by single crystal XRD analysis. The studies reveal that the molecule is associated with accommodating weak C–O···H, N–H···O, N–H···S, C–H···N, C···C and H···H stacking interactions which are responsible for the formation and strengthening of supramolecular assembly. Inter‐ and intramolecular hydrogen bonding interactions exhibit supramolecular architecture in the crystal packing. Two different types of architecture, i.e., a column like packing, and cluster network type of infrastructure are observed. Hirshfeld surfaces and Fingerprint plots were used to locate and analyze the percentage of hydrogen bonding interactions. The various functional groups present in the molecule are confirmed by FT‐IR analysis. Density functional theory computations of the vibrational spectrum, molecular geometry, HOMO‐LUMO energy gaps, NBO and hyperpolarizability (β) were successfully evaluated. Facts concerning with the size, shape, charge density distribution and site of chemical reactivity of the molecule have been obtained by mapping electron density with electrostatic potential (ESP).     

Co-crystal structures of 2,4-diamino-6-phenyl-1,3,5-triazine – 4-chlorobenzoic acid/4-methoxybenzoic acid: Synthesis,structural and Hirshfeld surface analysis

The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid molecules are explain the link between the dimension and shape of their hydrogen-bonded assembly. The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid forming a cyclic R₂²(8) ring motif via N–H?O and O–H?N hydrogen bonding interactions, to form a supramolecular heterosynthon. In both the co-crystal structures, self-association of 2,4-diamino-6-phenyl-1,3,5-triazine moieties are connected via N-H^….N base pairs with cyclic R₂²(8) motif form a supramolecular homosynthon. In co-crystal II, the centrosymmetrically paired methoxy group of 4-methoxy benzoic acid form a supramolecular homosynthon via weak intermolecular C-H^….O hydrogen bonds, generating R₂²(6) ring motif. Both the co-crystal structures are stabilized by weak aromatic π-π and C—Cl???π stacking interactions. Hirshfeld surface and fingerprint plots were used to study the intermolecular interactions both of the crystal structures.     

X-ray diffraction study of fluorene, 9-fluorenone, and 9-dicyanomethylenefluorene derivatives

The results of a single-crystal X-ray diffraction analysis of fluorene, 9-fluorenone, and 9-dicyanomethylenefluorene derivatives as individual compounds, as well as their crystal solvates, molecular complexes, and charge-transfer complexes, are generalized. The most interesting features of the molecular geometry and conformation and the molecular packing in the crystals are discussed. The structural formula of 95 compounds and the R factors for X-ray diffraction analysis, which characterize the reliability of determining the structure, are summarized in three tables.     

苯并[d]咪唑基Ni(Ⅱ)配合物的合成、晶体结构与荧光性质研究

以3-(4-羧苯基)-7-甲基-2-丙基-3H-苯并[d]咪唑-5-羧酸和六水合氯化镍为原料,采用混合溶剂加热回流方法合成出了一例具有三维超分子结构的镍配合物,并通过X射线单晶衍射、元素分析、红外光谱、紫外-可见光光谱和荧光光谱表征方法对其进行了结构解析和性质表征。X-射线单晶衍射结果表明,配合物属于三斜晶系,P1空间群;其晶胞参数为a=0.778 5(16) nm,b=1.126 6(2) nm,c=1.175 6(2) nm, α=113.63(3)°,β=93.24(3)°,γ=101.00(3)°,V=0.917 1(3) nm³。标题配合物为单核配合物,由4个配体阴离子连接中心Ni(II)离子形成了一维环形链,并进一步通过氢键和π-π堆积作用形成了三维超分子结构。荧光光谱分析结果表明配体和标题配合物均具有良好的荧光性质,且配合物的荧光性质优于配体。     

Conformational variability exhibited by mellitic acid anions (MA?n) with organic amine cations: Structures with an abundance of NH ?s OC hydrogen bonds and a paucity of hydrogen bonds

Benzenehexacarboxylic acid (mellitic acid) is an ideal substrate for the study of radially arranged ionic interactions with organic bases. Earlier work has shown that the net charge in MA (−4, −3, or −2) influences its assembly, respectively, either as ribbons or sheets. In the former case the cations intersperse the ribbons forming a tight network. In the MA sheets from the latter, the cations are arranged in orthogonal stacks. In the MA-phenanthroline complex such stacks are arranged exactly parallel resulting in significant π–π interactions. The present work relates to the modification of the phenanthroline motif to flexible structures. The reported ability of 2,3-bis-(2′-pyridyl) pyrazine (P2), prepared from 2,2′-pyridyl by reaction with ethylenediamine (EDA) followed by dehydrogenation of the resulting 2,3-bis-(2′-pyridyl)-5,6-dihydropyrazine, to form helical structures made it an obvious choice for complexation studies with MA. These resulted not only in the formation of the desired 7 MAP2 complex but also, surprisingly, with the dihydroprecursor complex with EDA 3 (MAEDA), a compound that eluded direct preparation with MA and EDA. The crystal structure of MAEDA reports the first complex of MA where MA⁻⁵ ions are encountered. The 15 hydrogen bonds, three for each N, result in hard packing. The complex with P2 7 (MAP2) showed the common features of MA⁻² sheets. Unlike phenanthroline, the nonplanar disposition of the pyridine rings made it possible for both pyridine protons to be available for salt formation, resulting in the arrangement of the cations in layers interposed between the sheets of MA⁻² ions. The pyrazine ring does not participate in hydrogen bonding or stacking in the crystal.     

Liquid Crystal ordering of DNA Dickerson Dodecamer duplexes with different 5’- Phosphate terminations

Abstract

The onset of liquid crystal (LC) phases in concentrated aqueous solutions of DNA oligomers crucially depends on the end-to-end interaction between the DNA duplexes, which can be provided by the aromatic stacking of the terminal base-pairs or by the pairing of complementary dangling-ends. Here we investigated the LC behavior of three blunt-end 12-base-long DNA duplexes synthesized with hydroxyl, phosphate and triphosphate 5’-termini. We experimentally characterized the concentration-temperature phase diagrams and we quantitatively estimated the end-to-end stacking free energy, by comparing the empirical data with the predictions of coarse-grained linear aggregation models.

The preservation of LC ordering, even in presence of the bulky and highly charged triphosphate group, indicates that attractive stacking interactions are still present and capable of induce linear aggregation of the DNA duplexes. This finding strengthens the potential role of chromonic like self-assembly for the prebiotic formation of linear polymeric nucleic acids.     

Theoretical Calculations on Hydroxybutyl 4-aroyloxybenzoates: Synthesis and Mesomorphic Properties of their H-bonded Complexes with Poly(4-vinylpyridine)

Important parameters of hydroxybutyl 4-aroyloxybenzoate ligands were calculated and correlations were made between theoretical and experimental results. In addition, supramolecular side-chain liquid crystalline polymers of the ligands with poly(4-vinylpyridine) were synthesized. Hydrogen bond formation was ascertained by Fourier tranform infra-red spectroscopy. The stabilities of the complexes were determined by thermogravimetric analysis. The mesomorphic behavior was investigated using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction analysis. Semiempirical study revealed that a ratio of ～1.2 in the lengths of flexible and rigid parts of the molecules is the most favorable for a wider liquid crystal (LC) temperature range.     

超分子化合物(C_(12)H_(10)N_4)(C_7H_6O_3)_2的合成、晶体结构及荧光性质

合成了超分子化合物(C_(12)H_(10)N_4)(C_7H_6O_3)_2,并进行了元素分析、红外光谱、紫外光谱表征和单晶X射线衍射分析.构筑单元之间通过多重氢键和π-π堆积作用的协同效应形成超分子化合物,并研究了化合物的固体荧光性能.研究表明:该晶体属于单斜晶系P2_1/c空间群,晶胞参数为:a=0.3974(1) nm,b=2.0330(2) nm,c=1.4343(1) nm, β=94.892(2)°,V=1.15440(19) nm~3,d_c=1.400 g/cm~3,Z = 2,μ= 0.102 mm~(-1),F_((000))=508,R_1=0.0359,wR_2=0.0893 [I>2σ(I)].     

Supramolecular Network via Hydrogen Bonding and π–π Stacking in 4,4′-Bipyridin-1-ium Perchlorate Dihydrate

Abstract The crystal structure of 4,4′-bipyridin-1-ium perchlorate dihydrate, [C₁₀H₉N₂](ClO₄) · 2H₂O, is determined by room temperature X-ray diffraction. The compound crystallizes in the triclinic space group P-1 with a = 8.122(3) ?, b = 9.726(3) ?, c = 17.648(6) ?, α = 78.181(4)°, β = 82.797(5)°, γ = 67.439(4)°, Z = 2, V = 1258.4(7) ?³. In the compound, monoprotonated 4,4′-bipyridin-1-ium cations are self-assembled into supramolecular chains along the a-axis through N–H···N hydrogen bonds in a head-to-tail fashion. The chains are stacked via π–π stacking interactions to create two-dimensional sheets. The interlayer space is occupied by the hydrogen-bonded water chains that are linked to the organic sheets via C–H···O interactions and the perchlorate anions that are linked to the water chains and the organic sheets via O–H···O and C–H···O hydrogen bonds, respectively, thus generating a three-dimensional supramolecular architecture. Index Abstract Supramolecular Network via Hydrogen Bonding and π–π Stacking in 4,4′-Bipyridin-1-ium perchlorate dihydrate Jian-Yong Zhang, Ai-Ling Cheng and En-Qing Gao* Monoprotonated 4,4′-bipyridin-1-ium cations are self-assembled into supramolecular chains along the a-axis through N–H···N hydrogen bonds, and these chains are stacked via π–π stacking and hydrogen bond interactions involving water molecules and perchlorate anions.      

Preparation and Photoluminescent Properties of Hydrogen-bonded Discotic Liquid Crystals

Photoluminescent discotic liquid crystals (DLCs) have been prepared through intermolecular hydrogen bonding between core and peripheral units. 1,3,5-Trihydroxybenzene was employed as core molecule and peripheral stilbazole derivatives containing linearly conjugated moieties were complexed to form hydrogen-bonded DLCs. Their structures, mesophases, and optical properties were investigated. The complexation of core and peripherals made some discotic complexes form photoluminescent DLCs. The prepared luminescent DLCs exhibited columnar mesophases with strong blue or sea green photoluminescence. These findings may contribute to the development of luminescent supramolecular liquid crystals for emitting materials in light emitting devices.     

之字链配合物Cu(phth)2(H2O)2的合成、表征及晶体结构

用Cu(NO3)2·3H2O和phth(邻苯二甲酸)混合反应得到了配合物Cu(phth)2(H2O)2(1).通过元素分析、红外光谱对配合物进行了表征,用X射线单晶衍射仪测定了配合物的晶体结构.配合物为单斜晶系,P2(1)/c空间群.晶胞参数a=0.83895(17)nm,b=1.4441(3)nm,c=0.70992(14)nm,β=112.14(3)°,V=0.7967(3)nm3,Z=2,Dc=1.792 g/cm3,F(000)=438.0,S=1.100,R1=0.0376,wR2=0.0998.铜原子为四配位,呈畸变正方形构型,通过邻苯二甲酸根的π-π堆积作用形成了一维之字型链,相邻的链之间靠氢键和π-π堆积作用形成三维分子结构.