Redetermination of 2-methyl-4-nitro-pyridine N-oxide.

An improved crystal structure of the title compound, C6H6N2O3, is reported. The structure, previously solved [Li et al. (1987 ▶). Jiegou Huaxue (Chin. J. Struct. Chem.), 6, 20-24] in the ortho-rhom-bic space group Pca21 and refined to R = 0.067, has been solved in the ortho-rhom-bic space group Pbcm with data of enhanced quality, giving an improved structure (R = 0.0485). The mol-ecule adopts a planar conformation with all atoms lying on a mirror plane. The crystal structure is composed of mol-ecular sheets extending parallel to the ab plane and connected via C-H⋯O contacts involving ring H atoms and O atoms of the N-oxide and nitro groups, while van der Waals forces consolidate the stacking of the layers.

5-(Naphthalen-1-yl)isophthalic acid-dimethyl sulfoxide-water (2/1/2).

The asymmetric unit of the title compound, 2C18H12O4·C2H6OS·2H2O, consists of four crystallographically independent mol-ecules of 5-(naphthalen-1-yl)isophthalic acid, two dimethyl sulfoxide and four water mol-ecules. The dihedral angles formed by the the planes of the aromatic fragments of the organic mol-ecules range from 57.4 (1) to 59.1 (1)°. In the crystal, multiple O-H⋯O hydrogen bonds link the water mol-ecules with the carbonyl and sulfoxide groups, giving rise to double ribbons along the b-axis direction.

4-(Naphthalen-1-yl)pyridine.

In the title compound, C15H11N, the mean planes of the aromatic moieties are inclined to one another by 72.9 (1)°. The crystal is stabilized by π-π stacking inter-actions between the pyridine rings of inversion-related mol-ecules, with a centroid-centroid distance of 3.772 (2) Å. In addition, C-H⋯π contacts involving an α-C-H group of the pyridine ring and the nonsubstituted ring of the naphthalene unit are observed, giving rise to a herringbone-type supramolecular architecture of the naphthalene moiety being contained in the molecule.

(E)-2-[2-(3-Nitro-phen-yl)ethen-yl]quinolin-8-ol.

In the title compound, C17H12N2O3, the mean planes of the benzene ring and the quinoline moiety are inclined to one another by 11.0 (1)°. The nitro substituent is twisted at an angle of 7.9 (2)° with respect to the attached benzene ring. Intra-molecular O-H⋯N and C-H⋯N hydrogen bonds occur. The crystal is constructed of mol-ecular stacks without involvement of π-stacking inter-actions, but showing inter-stack association via O-H⋯O and C-H⋯O hydrogen bonding. Thus, the supramolecular architecture of the crystal results from stacked molecules stabilized by hydrogen bonding between the stacks.

5-Bromo-benzene-1,3-dicarbo-nitrile.

The asymmetric unit of the title compound, C8H3BrN2, consists of two mol-ecules. The crystal structure features undulating mol-ecular sheets with the mol-ecules linked by C-H⋯N hydrogen bonds with one N atom acting as a bifurcated acceptor. N⋯Br inter-actions also occur [N⋯Br = 2.991 (3) and 3.099 (3) Å]. Inter-layer association is accomplished by offset face-to-face arene inter-actions [centroid-centroid distance = 3.768 (4) Å].

1,3-Diiodo-azulene-2-carbonitrile.

In the title compound, C11H5I2N, the two iodine-atom substitutents with their large atomic sizes lead to short intra-molecular I⋯H distances (3.01 Å). In the crystal, the tris-ubstituted azulene system forms π-stacks [centroid-centroid distance = 3.6343 (11) Å] along the a-axis direction, showing the characteristic azulene inter-action mode between the electron-rich five-membered ring and the electron-deficient seven-membered ring. I⋯I [3.9129 (2) Å] non-covalent contacts are observed along with weak C-H⋯N and C-H⋯π. bonds.

(E)-2-[2-(4-Carb-oxy-phen-yl)ethen-yl]-8-hydroxy-quinolin-1-ium chloride ethanol monosolvate.

In the title compound, C18H14NO3 (+)·Cl(-)·CH3CH2OH, the dihedral angle formed by the mean planes of the quinolinium and benzene rings is 3.4 (1)°, while the carb-oxy substituent is tilted at an angle of 4.8 (1)° with respect to the benzene ring. There is a short N-H⋯O contact in the cation. In the crystal, due to the planar mol-ecular geometry, two-dimensional aggregates are formed parallel to (221) via C-H⋯O, C-H⋯Cl, O-H⋯Cl and N-H⋯Cl hydrogen bonds. Inter-layer association is accomplished by O-Hethanol⋯Cl and O-H⋯Oethanol hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances vary from 3.6477 (12) to 3.8381 (11) Å]. A supra-molecular three-dimensional architecture results from a stacked arrangement of layers comprising the ionic and hydrogen-bonded components.

5,5'-(Ethyne-1,2-di-yl)diisophthalic acid dimethyl sulfoxide tetra-solvate.

In the title compound, C18H10O8·4C2H6OS, the mid-point of the triple bond of the main mol-ecule is located on a special position, i.e. about an inversion center. The carboxyl groups are twisted slightly out of the planes of the aromatic rings to which they are attached, making dihedral angles of 24.89 (1) and 7.40 (2)°. The cystal packing features strong O-H⋯O hydrogen bonds, weaker C-H⋯O inter-actions and O⋯S contacts [3.0981 (11) Å] and displays channel-like voids extending along the a-axis direction which contain the dimethyl sulfoxide solvent mol-ecules.

3,3''-Bis(9-hy-droxy-fluoren-9-yl)-1,1':3',1''-terphen-yl.

The asymmetric unit of the title compound, C44H30O2, contains two independent mol-ecules in which the terminal rings of the terphenyl element are inclined at angles of 36.3 (1) and 22.5 (1)° with respect to the central ring and the dihedral angles between the fluorenyl units are 72.3 (1) and 62.8 (1)°. In the crystal, pairs of O-H⋯O hydrogen bonds link the mol-ecules into inversion dimers. The hy-droxy H atoms not involved in these hydrogen bonds form O-H⋯π inter-actions in which the central terphenyl rings act as acceptors. Weak C-H⋯O contacts and π-π [centroid-centroid distance = 4.088 (2) Å] stacking inter-actions also occur. Taking into account directed non-covalent bonding between the molecules, the crystal is constructed of supramolecular strands extending along the a-axis direction.

All organic host-guest crystals based on a dumb-bell-shaped conjugated host for light harvesting through resonant energy transfer.

Together we glow: Fully organic host-guest crystals with two dyes inserted in their parallel nanochannels display broad emission in the visible range thanks to resonant energy transfer. The conjugated host crystal provides light harvesting in the UV region.

Organic fluorine compounds: a great opportunity for enhanced materials properties.

Interactions of "organic fluorine" have gained great interest not only in the context of crystal engineering, but also in the systematic design of functional materials. The first part of this tutorial review presents an overview on interactions known by organic fluorine. This involves π-π(F), C-F···H, F···F, C-F···π(F), C-F···π, C-F···M(+), C-F···C=O and anion-π(F) interactions, as well as other halogen bonds. The effect of the exchange of H vs. F is discussed by means of several examples and a short introduction to the young field of "fluorous" chemistry is given. The second part is dedicated to numerous applications of fluorine and fluorous interactions. It is shown how application of fluorination is used to enable a number of reactions, to improve materials properties and even open up new fields of research.

Redetermination of tetra-methyl tetra-thia-fulvalene-2,3,6,7-tetra-carboxyl-ate.

An improved crystal structure of the title compound, C(14)H(12)O(8)S(4), is reported. The structure, previously solved using the heavy-atom method (R = 7.1%), has now been solved using direct methods. Due to the improved quality of the data set an R value of 2.06% could be achieved. In the crystal, C-H⋯S and C-H⋯O contacts link the mol-ecules.

1,4-Bis[4-(tert-butyl-sulfan-yl)phen-yl]buta-1,3-diyne.

The asymmetric unit of the title compound, C(24)H(26)S(2), consits of one half-mol-ecule, which is located on a center of inversion. The two benzene rings are exactly coplanar while the tert-butyl group is oriented nearly perpendicular to the ring plane [C-S-C-C = -81.14 (11)°].

2-Amino-terephthalic acid N,N-dimethyl-formamide disolvate.

The asymmetric unit of the title structure, C(8)H(7)NO(4)·2C(3)H(7)NO, contains one 2-amino-terephthalic acid and two N,N-dimethyl-formamide mol-ecules. Strong O-H⋯O hydrogen bonds between the acidic carb-oxy H atoms of 2-am-ino-terephthalic acid and the O atoms of both solvent mol-ecules form linear 1:2 complex units. One H atom of the amine group is involved in intra-molecular N-H⋯O hydrogen bonding, whereas the second one takes part in an inter-molecular N-H⋯O connection. Furthermore, the crystal is stabilized by weak C-H⋯O hydrogen bonds.

1,5-Diamino-2,6-dibromo-9,10-anthraquinone.

In the title compound, C(14)H(8)Br(2)N(2)O(2), the mol-ecular structure features intra-molecular N-H⋯O [2.639 (2) Šand 130°] and N-H⋯Br [3.053 (2) Šand 114°] hydrogen bonding. Due to inversion symmetry, the asymmetric part of the unit cell consits of one half-mol-ecule. In the crystal, inversion dimers linked by pairs of N-H⋯O [2.955 (2) Šand 135°] hydrogen bonds occur. The structure also features C=O⋯π [3.228 (2) Å] and Br⋯Br [3.569 (1) Å] contacts.

High-separation performance of chromatographic capillaries coated with MOF-5 by the controlled SBU approach.

Recently developed MOF surface-coating techniques, the controlled SBU approach (CSA) for the generation of MOF-5, and the use of self-assembled monolayers have been combined to generate a wall-bonded, crosslinked stationary phase for gas chromatographic capillary columns displaying excellent performance in the separation of natural gas components. The chromatographic performance of this new type of column has been compared to the state-of-the-art solution for this separation problem, namely a coated silica column of the porous layer open tubular (PLOT) type. Chromatographic parameters such as separation, resolution, and tailing factors, as well as plate numbers and heights in the case of isothermal operation, have been determined. Kinetic and thermodynamic parameters characterizing the analyte-stationary phase interaction have been determined for various C1-C4 analytes.

Bridge-substituted calix[4]arenes: syntheses, conformations and application.

The bridge-substituted calix[4]arene carboxylic acid, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetramethoxy-calix[4]arene-2-carboxylic acid (1), can be readily converted to various esters 2-4 and reduced to the alcohol 5, which reacts with methyl iodide to give the ether 6. The alcohol can be dansylated to give 7, the fluorescence of which is selectively quenched by Cu(II) in acetonitrile. An attempt to convert the acid 1 to an amide resulted unexpectedly in the formation of a lactone 8. The conformational characteristics of 1-8 have been studied in solution and, in the cases of 2 and 4, in the solid state by determination of their single-crystal X-ray structures. With the exception of 8, in all these compounds the bridge substituent adopts an equatorial (lateral) orientation.

Three new fluorinated N-phenyl-substituted pentacyclic ethanoanthracenedicarboximides.

Diels-Alder reaction between maleimides featuring 3,5-di-, 2,4,6-tri- and pentafluorinated N-phenyl substituents and anthracene yields the corresponding pentacyclic ethanoanthracenedicarboximide compounds, namely N-(3,5-difluorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximide, C(24)H(15)F(2)NO(2), (IIa), N-(2,4,6-trifluorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximide, C(24)H(14)F(3)NO(2), (IIb), N-(2,3,4,5,6-pentafluorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximide, C(24)H(12)F(5)NO(2), (IIc). The crystal structures of (IIa)-(IIc) reveal an expected molecular geometry with a `V'-shape of the anthracene-derived tricyclic moiety. The crystal packings of (IIa) and (IIb) are dominated by π-π and C-H···O/F interactions, while F···F and C-H···π contacts are absent. In contrast, (IIc) shows F···F and C-H···O/F contacts, but no π-involved contacts of relevance.

Poly[(µ4-2,5-dimethoxybenzene-1,4-dicarboxylato)manganese(II)] and its zinc(II) analogue: three-dimensional coordination polymers containing unusually coordinated metal centres.

The title compounds, [Mn(C(10)H(8)O(6))](n) and [Zn(C(10)H(8)O(6))](n), are isomorphous coordination polymers prepared from 2,5-dimethoxyterephthalic acid (H(2)dmt) and the respective metal(II) salts. Both complexes form three-dimensional metal-organic frameworks with each M(II) centre bridged by four 2,5-dimethoxyterephthalate (dmt(2-)) anions, resulting in the same type of network topology. The asymmetric unit consists of one M(II) cation on a twofold axis and one half of a dmt(2-) anion (located on a centre of inversion). In the crystal structure, the M(II) centres are coordinated in a rather unusual way, as there is a distorted tetrahedral inner coordination sphere formed by four carboxylate O atoms of four different dmt(2-) anions, and an additional outer coordination sphere formed by two methoxy and two carboxylate O atoms, with each of the O atoms belonging to one of the four different dmt(2-) anions forming the inner coordination sphere. Consideration of both coordination spheres results in a super-dodecahedral coordination geometry for the M(II) centres. Besides the numerous M(II)···O interactions, both structures are further stabilized by weak C-H···O contacts.

Little change but great effect: varying supramolecular interactions in 2,5-dimethoxyterephthalic acid and 2,5-diethoxyterephthalic acid.

The title terephthalic acid derivatives, namely 2,5-dimethoxyterephthalic acid, C(10)H(10)O(6), (I), and 2,5-diethoxyterephthalic acid, C(12)H(14)O(6), (II), exhibit nearly planar molecular structures, with maximum deviations from the least-squares planes calculated for all non-H atoms of 0.0418 (6) and 0.0902 (10) Å for (I) and (II), respectively. The molecules of both title compounds contain an inversion centre and thus the asymmetric unit of both crystal structures consists of only half a molecule. It is a remarkable fact that a comparatively small change in the substitution of the terephthalic acid [dimethoxy in (I) versus diethoxy in (II)] causes major differences in the dominating supramolecular interactions. While in (II) the packing structure is stabilized by typical intermolecular hydrogen-bonded carboxylic acid dimer interactions, the carboxyl group in (I) forms an unusual intramolecular hydrogen bond with the O atom of the neighbouring methoxy group.