PCPP derivatives containing carbazole pendant as hole transporting moiety for efficient blue electroluminescence

The syntheses and characterization of poly((2,6‐(4,4‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))‐co‐(2,6‐(4,4‐bis(4‐(((9‐carbazolyl)hexyl)oxy)phenyl))‐4H‐cyclopenta[def]phenanthrene)) (BCzPh‐PCPPs) and poly((2,6‐(4,4‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))‐co‐(2,6‐(4‐(4‐(((9‐carbazolyl)hexyl)oxy)phenyl)‐4‐(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))) (CzPh‐PCPPs), with carbazole unit as pendants, are presented. The carbazole moiety, which can improve the hole injection ability, was introduced as a pendant on the PCPP backbone. The devices of the polymers with the configurations of ITO/PEDOT:PSS/polymers/Ca/Al generate EL emission with maximum peaks at 400–450 nm, CIE coordinates of (x = 0.11–0.29, y = 0.11–0.33), low turn‐on voltages of 4–6 V, maximum brightness of 60–810 cd/m², and luminescence efficiencies of 0.04–0.22 cd/A. The PL spectra of CzPh‐PCPPs films did not show any peak at around 550 nm, which corresponds to keto defect or aggregate/excimer formation, even after annealing for 30 h at 150 °C in air. Out of the series, CzPh‐PCPP1 (PCPP derivative with 10% of carbazole moiety as pendant) shows blue emission with the maximum brightness of 810 cd/m² at 9 V, and the highest luminescence efficiency of 0.22 cd/A at 395 mA/cm². © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1327–1342, 2009     

Analysis of Linear Viscous Flow with a Free Surface in a Circular Cylinder Subjected to Small-Amplitude Circular Oscillations

A fluid flow with a free surface inside a circular cylinder subjected to horizontal, circular oscillation was analyzed theoretically and numerically under the assumption of small-amplitude oscillation and high Reynolds number. It was shown that the nature of the oscillatory flow is of a standing-wave type when projected onto the axial plane and of a progressive-wave type when projected onto the azimuthal plane. The Stokes drift motion in the azimuthal direction and the steady streaming velocity at the edge of the bottom- and side-wall boundary layers are then used in the numerical computation for the steady axisymmetric recirculatory flow outside the boundary layers. We have found that the solutions can be well predicted by asymptotic analysis for the full Navier–Stokes equations in the low streaming-Reynolds-number limit. A simple experiment on flow visualization revealed a good agreement in the surface flow pattern on the bottom wall. It also provided steady recirculatory flows that were not much different from the numerical results on the whole. Received 16 August 1999 and accepted 14 January 2000     

Complete harmonic stable minimal hypersurfaces in a Riemannian manifold

In this paper, we will introduce the notion of harmonic stability for complete minimal hypersurfaces in a complete Riemannian manifold. The first result we prove, is that a complete harmonic stable minimal surface in a Riemannian manifold with non-negative Ricci curvature is conformally equivalent to either a plane R ² or a cylinder R × S ¹, which generalizes a theorem due to Fischer-Colbrie and Schoen [12]. The second one is that an n ≥ 2-dimensional, complete harmonic stable minimal, hypersurface M in a complete Riemannian manifold with non-negative sectional curvature has only one end if M is non-parabolic. The third one, which we prove, is that there exist no non-trivial L ²-harmonic one forms on a complete harmonic stable minimal hypersurface in a complete Riemannian manifold with non-negative sectional curvature. Since the harmonic stability is weaker than stability, we obtain a generalization of a theorem due to Miyaoka [20] and Palmer [21]. Research partially Supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan. The author’s research was supported by grant Proj. No. KRF-2007-313-C00058 from Korea Research Foundation, Korea. Authors’ addresses: Qing-Ming Cheng, Department of Mathematics, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan; Young Jin Suh, Department of Mathematics, Kyungpook National University, Taegu 702-701, South Korea     

Bis[3,6-bis(6-methyl-2-pyridyl)pyridazine-κ2N2,N3]chlorocopper(II) perchlorate

The title compound, [CuCl(C₁₆H₁₄N₄)₂]ClO₄, consists of a mononuclear complex cation and a perchlorate anion. The coordination of the copper(II) ion exhibits a trigonal bipyramidal geometry, where the equatorial plane is composed of the Cl atom and two N atoms of the two pyridazine rings, and the axial positions are occupied by the N atoms of two methyl­pyridine rings.     

Real hypersurfaces in complex two-plane Grassmannians whose structure Jacobi operator is of Codazzi type

We give a non-existence theorem for Hopf hypersurfaces in complex two-plane Grassmannians G ₂(? ^m+2) whose structure Jacobi operator R _ξ is of Codazzi type.     

Some Conditions on Real Hypersurfaces in Quaternionic Projective Spaces in Terms of Lie Derivatives

The purpose of this paper is to give a non-existence property with the Lie derivative of the structure tensors φ _i and some characterizations of real hypersurfaces of type A ₁, A ₂ in a quaternionic projective space QP ^m in terms of the Lie derivatives of the second fundamental tensor A and the induced Riemannian metric g on the distribution D ^⊥ = Span {U ₂, U ₂, U ₃}. This revised version was published online in June 2006 with corrections to the Cover Date.     

On the short carbonyl bond in bis[μ‐1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxido‐κ2N:O]bis{[1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxido‐κN]bis(imidazole)copper(II)}

The short carbonyl bond in the title compound, [Cu₂(C₇H₄­NO₃S)₄(C₃H₄N₂)₄] [Liu, Huang, Li & Lin (1991). Acta Cryst. C 47 , 41–43], is an artifact of disorder in the iso­thia­zol‐3(2H)‐one 1,1‐dioxide part of the 1,2‐benziso­thia­zol‐3(2H)‐one entity. In the present redetermination, all bond dimensions in the centrosymmetric dinuclear mol­ecule are normal. The five‐coordinate Cu atom shows trigonal–bipyramidal coordination. Hydro­gen bonds from the imidazole donor ligand link adjacent mol­ecules into a two‐dimensional layer structure.