Keita Tani

In the title compound, [Na(C₂₂H₁₉N₄O₄S)(CH₃CN)]_n, the Na^I atom adopts a distorted square-pyramidal coordination geometry, formed by one N and one O atom of the qunolinol moiety in the ligand, two O atoms of sulfonate moieties of two adjacent ligands and the N atom of the coordinated acetonitrile solvent. The Na^I atom is located well above the mean basal plane of the square-based pyramid. The apical position is occupied by a sulfonate O atom of a neighboring ligand. Three N atoms of the bis(pyridin-2-ylmethyl)amine moiety in the ligand are not coordinated by the sodium atom. The molecule forms an intramolecular bifurcated O—H...[N(tertiary amine),N(pyridine)] hydrogen bond, generating S(6) and S(5) rings. In the crystal, four molecules are linked by four Na—O(sulfonato) bridged coordination bonds, forming a supramolecular centrosymmetric tetramer unit comprising an eight-membered ring, and generating a two-dimensional network sheet. The molecules of different sheets form intermolecular C—H...O hydrogen bonds, and thereby a three-dimensional network structure.

The title compound, C₃₃H₃₃N₃, is a carbazolophane, which is a cyclophane composed of two carbazole fragments. It has a planar chirality but crystallizes as a racemate in the space group P-1. The molecule adopts an anti-configuration, in which two carbazole fragments are partially overlapped. Both carbazole ring systems are slightly bent, with the C atoms at 3-positions showing the largest deviations from the mean planes. The dihedral angle between two carbazole fragments is 5.19 (3)°, allowing an intramolecular slipped π–π interaction [Cg...Cg = 3.2514 (8) Å]. In the crystal, the molecules are linked via intermolecular C—H...N hydrogen bonds and C—H...π interactions into a network sheet parallel to the ab plane. The molecules of different sheets form other C—H...π interactions, thus forming a three-dimensional network.

A series of novel mono- and bis[(9-alkylcarbazol-3-yl) methyl]acrylamides were synthesized and their radical polymerization was investigated. Emissions of bis(carbazolyl) acrylamide polymers were extended to longer wavelengths compared with those of the corresponding mono(carbazolyl) polymers, indicating the existence of interchromophoric interaction between carbazole moieties. Ionization potentials of the polymers by photoelectron yield spectroscopy showed that donor ability of the biscarbazolyl polymer was higher than that of the monocarbazolyl polymer.

Diarylethene derivatives, 1c and 1d, having carrier mobilization sites have been synthesized. Their photochromic properties are examined both in solution and in thin film. Current voltage characteristics at photostationary state of 1c and 1d showed drastic current increase compared with the corresponding open-ring isomers 1c and 1d, respectively.

The title compound, C43H32F6N2S2, is a new symmetrical photochromic diarylethene derivative with 9-ethylcarbazol-3-yl substituents. The molecule adopts a photoactive antiparallel conformation [Irie (2000). Chem. Rev. 100, 1685-1716; Kobatake et al. (2002). Chem. Commun. pp. 2804-2805], with a dihedral angle between the mean planes of the two thiophene rings of 56.23 (6)degrees. The distance between the two reactive C atoms is 3.497 (3) angstrom. In the crystal, two molecules are associated through a pair of C-H center dot center dot center dot F intermolecular hydrogen bonds, forming a centrosymmetric dimer. Dimers are linked by weak pi-pi interactions [centroid-centroid distance = 3.8872 (13) angstrom], forming chains along the c axis.

In the title compound, [Cu(C18H16F4N2O2)(H2O)], the Cu-II atom shows a distorted square-pyramidal coordination geometry with the N,N',O,O'-tetradentate piperazine-diphenolate ligand forming the basal plane. The apical site is occupied by the O atom of a coordinated water molecule. Neighbouring complexes are associated through intermolecular O-H center dot center dot center dot O and O-H center dot center dot center dot F hydrogen bonds between the water molecule and a phenolate O atom or an F atom from an adjacent ligand, respectively, forming a centrosymmetric dimer. Dimers are linked by additional intermolecular C-H center dot center dot center dot O and C-H center dot center dot center dot F hydrogen bonds, giving infinite chains propagating along the a axis.

Electrical carrier separation from a photoexcited photochromic molecule could be a promising method for controlling the photosensitivity of such a molecule. We report an efficient carrier separation from a photochromic diarylethene (DAE) molecule by adopting a device structure with a heterojunction consisting of an n-type diarylethene layer and a p-type layer of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB). A photocurrent originating from carrier separation for the colored photostationary state was observed, even at zero applied voltage. The efficient carrier separation occurred at the interface between the DAE and NPB layers and was the result of the internal electrical field induced by the pn heterojunction.

In the centrosymmetric dinuclear Cu(II) title complex, [Cu(2)(C(18)H(16)Cl(4)N(2)O(2))(2)], the Cu(II) atom adopts a square-pyramidal geometry with a tetradentate ligand in the basal plane. The apical site is occupied by a phenolate O atom from an adjacent ligand, forming a dimer. The molecular structure is stabilized by intramolecular C-H center dot center dot center dot O and C-H center dot center dot center dot Cl hydrogen bonds.

Inter-moiety electronic interactions in the singlet and triplet excimer states of triply bridged [3.3.n](3,6,9)-carbazolophanes ([3.3.n]Cz, n = 3-6) were studied by emission and transient absorption measurements. In these [3.3.n]Cz molecules, the dihedral angle and the separation distance r between fully overlapped two arbazole rings change systematically from nearly parallel (n = 3, r = 3.35 A) to oblique (n = 6, r = 4.03 angstrom). In rigid glass at 77 K, [3.3.n]Cz (n = 3, 4) (r < 4 angstrom) exhibited red-shifted and structureless excimer fluorescence and phosphorescence while [3.3.n]Cz (n = 5, 6) (r > 4 angstrom) exhibited monomer-like vibrational fluorescence and phosphorescence. In solution at 130 K, all [3.3.n]Cz molecules exhibited an excimeric fluorescence band while [3.3.5]Cz still exhibited monomer-like phosphorescence. Transient absorption spectra measured at 294 K exhibited local excitation and charge-transfer bands for all [3.3.n]Cz molecules in the excited singlet and triplet states, suggesting that not only singlet but also triplet excimers of carbazole are formed at room temperature. Furthermore, the singlet-triplet energy gap decreased with the decrease in n, suggesting that electrons are effectively delocalized over the two carbazole moieties. These findings showed that both singlet and triplet excimers of carbazole are formed with a separation distance shorter than about 4 angstrom and are most stable in the parallel-sandwich structure and that the configurational mixing between exciton resonance and charge resonance states plays an essential role in the formation of singlet and triplet excimers of carbazole.

Novel fluorine-containing macrocyclic molecules have been synthesized in order to clarify the interaction or coordination ability of the C-F unit towards metal ions. The cage compounds 1 and 2 were prepared by direct coupling reactions between the appropriate diamines and dibromides, while bond isomers of the cage compounds were synthesized via fluorinated diaza[3.3]metacyclophanes. Complex formation with alkali metal cations, NH4+, and Ag+ ions has been assessed by picrate extraction experiments. Comparison of the cation affinities of hosts 1, 2, and 4, shows that the spatial arrangement of the fluorine atoms strongly affects the donor ability of the host molecules. The hexafluoro cage compound 1, with six fluorine atoms in an ability of the C-F unit compounds 1 and 2 wt octahedral geometry, exhibits relatively strong coordination ability towards K+, NH4+, and Ag+ ions, while compound 2, with four fluorine atoms in a structure similar to that of 1 shows only poor affinity for these ions. Compound 4, which has six fluorine atoms arranged in a quasi planar fashion, was found to show weak affinity towards NH4+ and Ag+ ions. Thus, octahedrally arranged fluorine atoms evidently provide the best fit for spherical cations. Compound 1 shows characteristic H-1-,C-13-, and F-19-NMR-spectral changes upon complexation. The crystal structure of 1 has been elucidated and compared to that of the K+ complex. The C-F bonds are found to be slightly elongated in the K+ complex, which is clearly indicative of coordination of the fluorine atom to K+.

Successive additions of 3,5-dinitro-2-pyridone (1) with three molecules of ethyl vinyl ether (EVE) were investigated. The first addition is the first example of reverse electron-demand Diels-Alder (REDA) cyclization of 2-pyridone which acts as a diene to give an unstable bicyclic intermediate 9. Meisenheimer complexes 2a and 2b are isolated as a quenched intermediate of 9. The second addition is a REDA cyclization between the nitroalkene moiety of 9 and EVE to afford a six-membered nitronate 4, which are characterized by some chemical reactions. The third step is 1,3-dipolar addition of the nitronate with EVE to give a 1:3 adduct 3.