Photoinduced control over the self-organized orientation of amorphous molecular materials using polarized light.

Novel chiral amorphous molecular materials containing photoresponsive azobenzene moieties were designed and synthesized. These materials led to the formation of smooth and uniform thin films without grain boundaries. Photoirradiation of the thin film with linearly and elliptically polarized light caused trans-cis photoisomerization of the azobenzene moieties and resulted in an anisotropic orientation of the materials. Maximum change in a value of birefringence, Deltan, after irradiation of the linearly polarized light is about 0.08 with a response time of 10 s. However, when irradiation was ceased after photoinduced orientation, the value of Deltan decreased due to relaxation of the azobenzene moieties. Furthermore, these materials exhibited a high efficiency of a photoinduced polarization rotation over 30 deg mum(-1) after irradiation with the elliptically polarized light for 60 s. We also found that the efficiency depends on ellipticity of the incident light and on the thickness of the sample. The origin of the large change in the molecular orientation is the anisotropic arrangement of the azobenzenes in the terminal groups upon irradiation with the linearly and elliptically polarized light.

Intra-complex energy transfer of europium(III) complexes containing anthracene and phenanthrene moieties.

Laser excitation and luminescence studies were carried out for an ethanol solution of tris(hexafluoroacetylacetonato)europium(III), Eu(hfac)(3)(H(2)O)(2) (1), and n-hexane solutions of tris(hexafluoroacetylacetonato)europium(III) bis(9-diisopropylphosphorylanthracene), Eu(hfac)(3)(DiPAnO)(2) (2), and tris(hexafluoroacetylacetonato)europium(III) bis(2-diisopropylphosphorylphenanthrene), Eu(hfac)(3)(DiPPheO)(2) (3). The absorption spectra of 2 and 3 in n-hexane are interpreted by assuming that the central Eu(III) ion weakly interacts with the DiPAnO and DiPPheO moieties. The emission spectroscopic studies revealed that (1) Eu(hfac)(3)(DiPAnO)(2) emits only fluorescence from the DiPAnO moiety and (2) Eu(hfac)(3)(DiPPheO)(2) gives luminescence from the central Eu(III) ion, and (3) Eu(hfa)(3)(H(2)O)(2) and Eu(hfac)(3)(DiPPheO)(2) afford emission from both the (5)D(1) and (5)D(0) states of the Eu(III) ion upon 355 nm laser excitation. The intracomplex energy transfer processes are presented on the basis of absorption, emission and laser excitation studies.

Surface waves in photorefractive polymer films.

We observed the temporal development of surface waves and investigated their power propagation loss in typical photorefractive polymer films sandwiched between ITO glass substrates. We found that amplified scattered waves generated in a pumped region started to develop into surface waves from a point where they reached the substrate through the self-bending effect. The surface waves propagated over a distance of 1.7 mm, thereby confining the power to a region at a distance of 30 microns from the substrate. Considerable propagation power loss of the surface waves was observed at a low pumping power of the beam; however, the power loss decreased considerably when the beam had high power.

Photoswitching of dextro/levo rotation with axially chiral binaphthyls linked to an azobenzene.

To examine the reversible photoisomerization and subsequent change of asymmetric field, we synthesized optically active 3,3'-disubstituted-1,1'-binaphthyls with an azobenzene moiety. Reflecting the structural change, the specific rotation and circular dichroism underwent significant variations. Under certain conditions, the positive-negative signals were reversible. Furthermore, the magnitude of these changes showed a 3,3'-substituent dependency. Dibenzyloxy or bis(diphenylmethyloxy) derivatives were better suited for sign interconversion of the optical properties. In contrast, the hydroxy group(s) lacked both optical signals and durability.

Light-driven twisting behaviour of chiral cyclic compounds.

Chiral cyclic compounds exhibited light-driven twisting by means of trans-cis photoisomerization in 1,4-dioxane solution, a neat film, and a liquid-crystalline host.

Metal-organic thin-film transistor (MOTFT) based on a bis(o-diiminobenzosemiquinonate) nickel(II) complex.

The semiconducting film based on bis(o-diiminobenzosemiquinonate) nickel(II) complex showed uniaxial orientation structure along the normal to the substrate and good p-type metal-organic thin-film transistor (MOTFT) character.

Synthesis and crystallographic characterization of low-dimensional and porous coordination compounds capable of supramolecular aromatic interaction using the 4,4'-azobis(pyridine) ligand.

Coordination compounds with a 4,4'-azobis(pyridine) (azpy) ligand, {[M2(azpy)6(H2O)5] x 4PF6 x azpy x H2O}n (M = Ni(II) (1) or Co(II) (2)) (0-dimensional (0-D) dimer), {[Zn(azpy)3(H2O)2] x 2PF6 x 2azpy x 4H2O}n (3) (1-dimensional (1-D) fishbone-type chain), {[Ag(azpy)] x PF6}n (4) (1-D linear chain), {[Mn(NCS)2(azpy)2] x azpy}n (5) (2-dimensional (2-D) grid sheet), and {[Ni(NCS)2(azpy)2] x 3toluene}n (6) (2-D grid sheet), were synthesized and structurally characterized. Compounds 1 and 2 have a 0-D dimer motif, in which one M(II) (M(II) = Ni(II) or Co(II)) coordination site is shared by unidentate azpy and H2O ligands, each with half-occupancy, i.e., exhibiting static disorder. Compounds 3 and 4 afford 1-D fishbone-type and 1-D linear chain motifs, respectively. Azpy mediates pi-pi and pi-p interactions between these low-dimensional structures. Compounds 5 and 6 possess a 2-D grid sheet motif. These sheets assemble to form microporous frameworks that incorporate aromatic guests, such as coordination-free azpy (5) and toluene (6). There exist not only pi-pi and pi-p interactions but also CH-pi interactions between the framework azpy ligands and guests. It should be noted that the azpy ligand is a good candidate for the construction of new assembling systems of coordination compounds through its aromatic interactions.

Synthesis and characterization of phenanthrylphosphine gold complex: observation of Au-induced blue-green phosphorescence at room temperature.

A new 9-diphenylphosphinophenanthrene ligand (9DPP, 1), its oxide (9DPPO, 2), and its gold complex [(AuCl(9DPP)] (3) were synthesized. The Au(I) complex 3 was found to exhibit intense blue-green, room-temperature phosphorescence (Phip = 0.06 and tauT = 22.7 micros) originating in the locally excited triplet of the phenanthrene moiety (3LE) in degassed 2-methyltetrahydrofuran solution. On the assumption that PhiST = 1.0 for 3, the radiative rate constant (kr) in the triplet state is calculated to be 2.6 x 10(3) s(-1). This value is 4 orders of magnitude larger than the radiative rate constant of the triplet phenanthrene (0.26 s(-1)). Thus, the coordinated Au(I) atom is concluded to have a markedly large heavy-atom effect on kr of the phenanthrene chromophore in 3.

Framework control by a metalloligand having multicoordination ability: new synthetic approach for crystal structures and magnetic properties.

By utilizing the novel metalloligand l(Cu), [Cu(2,4-pydca)(2)](2)(-) (2,4-pydca(2)(-) = pyridine-2,4-dicarboxylate), which possesses two kinds of coordination groups, selective bond formation with the series of the first-period transition metal ions (Mn(ii), Fe(ii), Co(ii), Cu(ii), and Zn(ii)) has been accomplished. depending on the coordination mode of 4-carboxylate with Co(ii), Cu(ii), and Zn(ii) ions, L(Cu) forms a one-dimensional (1-d) assembly with a repeating motif of [-M-O(2)C-(py)N-Cu-N(py)-Co(2)-]: {[ZnL(Cu)(H(2)O)(3)(DMF)].DMF}(N)() (2), [ZnL(Cu)(H(2)O)(2)(MeOH)(2)](N)() (3), and {[ML(Cu)(H(2)O)(4)].2H(2)O}(N)() (M = Co (4), Cu (5), Zn (6)). the use of a terminal ligand of 2,2'-bipyridine (2,2'-bpy), in addition to the cu(ii) ion, gives a zigzag 1-d assembly with the similar repeating unit as 4-6: {[Cu(2,2'-bpy)L(Cu)].3H(2)O}(N)() (9). on the other hand, for Mn(ii) and Fe(ii) ions, L(Cu) shows a 2-carboxylate bridging mode to form an another 1-d assembly with a repeating motif of [-M-O-C-O-CU-O-C-O-]: [ML(Cu)(H(2)O)(4)](N)() (M = Mn (7), Fe (8)). this selectivity is related to the strength of lewis basicity and the electrostatic effect of L(Cu) and the irving-williams order on the present metal ions. according to their bridging modes, a variety of magnetic properties are obtained: 4, 5, and 9, which have the 4-carboxypyridinate bridge between magnetic centers, have weak antiferromagnetic interaction, whereas 7 and 8 with the carboxylate bridge between magnetic centers reveal 1-d ferromagnetic behavior (Cu(II)-M(II); M(II) = Mn(II), J/k(B) = 0.69 K for 7; M(II) = Fe(II), J/k(B) = 0.71 K for 8).

Photoluminescence properties of vapor deposited films of a bisazomethine dye.

Steady-state and time-resolved photoluminescence (PL) measurements on vapor deposited films of a non-ionic bisazomethine dye have been performed. In the films, it is possible to control the ratio between J-aggregate and crystalline phases of the dye by means of exposure to chloroform vapour, and thus the origin of PL can be determined from comparison between several films. In the films, PL was emitted exclusively from the crystalline phase. Although the origin of PL was not from the J-aggregate phase, some features of the observed PL were very similar to those reported for J-aggregates of ionic dyes. We also found that these features in the vapor deposited films were caused by a competition between free excitons and excitons trapped at defect sites.

J-aggregates in vapor deposited films of a bisazomethine dye.

This is the first report of J-aggregate formation of a non-ionic bisazomethine dye in vapor deposited films; this dye allows us to prepare easily large homogeneous and very stable J-aggregate thin films and to investigate intrinsic properties of low-dimensional Frenkel excitons.

New microporous coordination polymer affording guest-coordination sites at channel walls.

Utilization of a metalloligand, ([Cu(2,4-pydca)2(H2O)].2Et3NH) (1) (2,4-pydca = pyridine-2,4-dicarboxylate), as a building unit provides a novel porous coordination polymer, ([ZnCu(2,4-pydca)2(H2O)3(DMF)].DMF)n (2), in which the Zn(II) ion at the node of the network acts as a linker and the Cu(II) ion in the channel wall is available for guest-coordination.

Effects of Splenectomy on Blood Coagulation and Fibrinolysis in Patients with Liver Cirrhosis: Possible Role of the Spleen in Haemostasis.

Blood coagulation and fibrinolysis before and after splenectomy was studied in 74 cases of liver cirrhosis. A hypocoagulable state was found before splenectomy, but the platelet count, and the levels of fibrinogen, plasminogen, ±2-macroglobulin and antithrombin III increased significantly after splenectomy (p < 0.05 to p < 0.001). A marked improvement was observed on the values of r (reaction time), k (clot formation time) and ma (maximal amplitude) of thrombelastograms (p < 0.05 to p < 0.001). The prothrombin time was reduced after the surgery, but not significantly (0.05 < p < 0.1). The levels of arantitrypsin remained almost unchanged, while serum fibrinogen-fibrin degradation products (FDP) showed a slight decrease postoperatively.The immunohistologic study of the spleen excised from 7 cases with liver cirrhosis, with the use of the direct immunofluorescence technique, demonstrated the deposits of fibrin in the splenic cords in all cases. It was not recognized in the spleens of 4 cases without cirrhosis used as the control.A further study of the spleen weight and plasma fibrinogen level showed that a significant inverse correlation exists between these two parameters (p < 0.01).These findings suggest that localized intravascular coagulation (LIC) occurs in the enlarged spleen associated with liver cirrhosis.