Moderate Deviations for Longest Increasing Subsequences: The Lower Tail

We derive a moderate deviation principle for the lower tail probabilities of the length of a longest increasing subsequence in a random permutation. It refers to the regime between the lower tail large deviation regime and the central limit regime. The present article together with the upper tail moderate deviation principle in Ref. 12 yields a complete picture for the whole moderate deviation regime. Other than in Ref. 12, we can directly apply estimates by Baik, Deift, and Johansson, who obtained a (non-standard) Central Limit Theorem for the same quantity.     

Diastereomer-differentiating hydrolysis of 1,3-diol-acetonides: a simplified procedure for the separation of syn- and anti-1,3-diols

[reaction: see text] A new method to facilitate the separation of diastereomeric syn- and anti-1,3-diols is described. The method relies on the different hydrolysis rates of the corresponding diastereomeric acetonides. Treatment of a dichloromethane solution of syn- and anti-1,3-diol-acetonide with a catalytic amount of diluted aqueous hydrochloric acid leads to the selective cleavage of the anti diastereomer. The resulting anti-1,3-diol can be easily separated from the unchanged syn-1,3-diol-acetonide.     

The Structure of Tetrakis(pentafluorophenyl)tellurium(IV), Te(C6F5)4

Tetrakis(pentafluorophenyl)tellurium(IV), Te(C₆F₅)₄, was prepared from the reaction of TeCl₄ and Mg(C₆F₅)Br. Crystallization of the crude product from n‐pentane at ?25 °C gave suitable single crystals. The title compound crystallizes in the monoclinic space group P2₁/c (Z = 8) with two independent molecules per unit cell.     

Anthracene Based Bulky Diol Hosts. Crystal Structures of a Free Host and of Inclusion Compounds with Dipolar Guests

X-ray crystal structures are reported of a free host compound 1, comprising two diphenylmethanol terminal groups attached to a central 9,10-ethynyl substituted anthracene unit, and of three inclusion compounds of a fluoren-9-ol substituted analogous host 2 with acetone, dimethyl sulphoxide (DMSO) and dimethylformamide (DMF) as guest, respectively. Despite the presence of two hydroxyl groups in 1, there is no O–H...O hydrogen bond between the molecules in the guest free crystal – only weaker C–H...O interactions and van der Waals' type connections. In the inclusion compounds of 2, H-bonded 1:2 host–guest associates are formed, where each of the host hydroxyl groups binds to a guest oxygen atom. The orientations of the host–guest connections in these complexes vary, being E for acetone and Z for both DMSO and DMF guests, relative to the host anthracene unit. The DMSO and DMF inclusion compounds of 2 proved to be isostructural.     

Tetraaryl-methane analogues in group 14—V. Distortion of tetrahedral geometryin terms of through-space π–π and π–σ interactions andNMR sagging in terms of π–σcharge transfer

44 members of thecompound series Ph_4−nMR_n (M=Si, Ge, Sn, Pb; R=o-, m-, p-Tol; n=0–4) were synthesized (15 newcompounds). The crystal structures of Ph₃Sn (o-Tol) and PhSn (o-Tol)₃ were determined and compared to 16 known structures. Subject to the distanced (M–C), an interplay between through-space π–π repulsion and π–σ attraction leads to either elongated or compressed tetrahedral geometry. ²⁹ Si-, ¹¹⁹ Sn- and ²⁰⁷ Pb-NMR chemical shifts were determined in solution and in the solid state. ⁷³ Ge chemical shifts were measured only in solution. Anupfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a π–σcharge transfer which is constrained by torsion of the aromatic groups.     

Charge carrier mobility,photovoltaic, and electroluminescent properties of anthracene‐based conjugated polymers bearing randomly distributed side chains

This article reports on the synthesis, characterization, and properties of various anthracene‐containing poly (p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) polymers (AnE‐PVs) bearing statistical distributions of various side chains. Primarily, the ratio of linear octyloxy and branched 2‐ethylhexyloxy side chains at the poly(p‐phenylene vinylene) (PPV) parts was varied, leading to the polymers stat, stat1, and stat2. Furthermore, polymers also containing asymmetric substituted PPV and poly(p‐phenylene ethynylene) units (bearing methoxy and 2‐ethylhexyloxy side chains) were prepared yielding stat3, stat4, and stat5. These materials exhibit a broad variation in their photovoltaic properties. It is once more shown that side chains and their distribution can crucially affect the photovoltaic device performance. The introduction of units with asymmetric substitution into these systems seems to be harmful for their utilization in photovoltaic applications. Organic field‐effect transistors were fabricated to investigate hole mobilities in these new materials. Large variance was observed, falling in the range of almost two orders of magnitude, indicating rather different π–π stacking behavior of the polymer backbones owing to side‐chain modifications. Moreover, a selection of the new polymeric systems was investigated regarding their potential for light‐emitting diode (LED) applications. Polymer LEDs using the polymers AnE‐PVstat, ‐stat3, ‐stat4, and ‐stat5, as the active layer showed turn‐on voltage of ～2 V and exhibited red light emission. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012