A versatile approach to affinitychromic polythiophenes

The preparation of both postfunctionalizable and chromic poly[3-(N-succinimido-p-phenylcarboxylate(tetraethoxy)oxy)-4-methylthiophene] is reported. The N-hydroxysuccinimide ester side group can easily react with different amine-bearing molecules in the solid state to yield a library of new polythiophene derivatives. The resulting polymers can be dissolved in various solvents, and interactions between the side chains (ligands) and different analytes (targets) can be detected from modifications of both the side-chain and the backbone conformations resulting in important color changes (i.e., affinitychromism). This colorimetric polymeric transducer could therefore lead to highly valuable, versatile, and inexpensive tools for highthroughput screening and drug discovery.     

Incompressible Elastic Bodies with Non-Convex Energy under Dead-Load Surface Tractions

In this paper we study the equilibrium deformations of an incompressible elastic body with a non-convex strain energy function which is subjected to a homogeneous distribution of dead-load tractions. To determine the stable solutions we consider the mixtures of the phases which minimize the total energy density. In the special case of a trilinear material we discuss the stability of the equilibrium phases in detail. Finally, we show that multiphase solutions are possible when the surface loads correspond to a critical simple shear and we sketch their possible forms. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of dihydrolysergol analogues

As a part of a search for novel biological active ergoline derivatives, the indole ring present in the ergoline skeleton (indole[4,3‐f,g]quinoline) was converted into different heterocyclic ring systems such as quinazoline 2 , benzofurane 3 and benzoxazole 4 . Due to the paramount importance of chirality to attain biological activity, natural dihydrolysergic acid 1 was chosen as starting material and a synthetic pathway conservative in term of chirality was followed.     

A New Poly(2,7‐Dibenzosilole) Derivative in Polymer Solar Cells

A new soluble conjugated copolymer based on 2,7‐dibenzosilole and 4,7‐dithien‐2‐yl‐2,1,3‐benzothiadiazole units has been synthesized (PBSDTBT). Bulk heterojunction solar cell devices are fabricated using this material as the donor and [6,6]‐phenyl‐C₆₁ butyric acid methyl ester (PCBM) as the acceptor. The power conversion efficiency is 1.6% under AM1.5 illumination. This material also shows a good V_OC (0.97 V). The results are quite promising considering the relatively large bandgap (1.9 eV) of this polymer.

     

A Zoom-In Approach to Design SDH Mesh Restorable Networks

Mesh restorable networks based on SONET (Synchronous Optical Network, standard optical transmission technology widely accepted and implemented in North America) or SDH (Synchronous Digital Hierarchy, the European standard currently adopted by the major European telecom operators) are an economically attractive solution in areas where high demand and high connectivity are involved (Wu, 1995). In these networks, the reconfiguration capability of the digital cross connect systems (DCS) allows to reroute the demand affected by network failures. The degree of sharing of spare capacity in networks based on this architecture is high.This paper presents a heuristic algorithm for solving the near-optimal design of SDH mesh-type link restorable networks, i.e. determining the network topology and assigning the capacity to transport the demand in normal situations and to allow full link restorability in case of single link failures. The algorithm is based on a Zoom-In technique, a novel approach which forms a compromise between sequential and integrated techniques. The different building blocks of the algorithm are tested extensively and compared with other results mentioned in literature. Comparison of the simulation results for the overall design problem with other solution techniques indicates that the Zoom-In method is a quite promising approach, able to combine the accuracy of integrated approaches with the calculation speed of sequential approaches.     

A Convenient A2 + B3 Approach to Hyperbranched Poly(arylene oxindole)s

Summary: We developed a facile approach to hyperbranched polymers by applying a superelectrophilic reaction within an A₂ + B₃ strategy. A significant reactivity difference between the intermediate and the starting material was utilized to avoid gelation in the A₂ + B₃ polymerization. A number of hyperbranched poly(arylene oxindole)s were achieved in a one‐step polymerization and characterized by NMR spectroscopy and gel permeation chromatography. Moreover, further modifications at the interior and exterior of the resulting polymers were explored as well.

Structure of the hyperbranched polymers produced using the A₂ + B₃ approach.     

Large‐scale synthesis of arborescent polystyrenes

A method was developed for the large (100 g) scale synthesis of arborescent polystyrenes using acetyl coupling sites. Successive generations of dendritic graft polymers were obtained from cycles of polystyrene substrate acetylation with acetyl chloride and coupling in the presence of LiCl with “living” polystyryllithium chains capped with 2‐vinylpyridine units. The grafting yield for the synthesis of a generation zero (G0 or comb‐branched) arborescent polystyrene under the conditions previously reported for the 10 g scale reactions decreased from 95 to 75% when scaled up to 100 g. The lowered yield was linked to side chain dimerization and deactivation of the macroanions. The modified 100 g scale procedure, using end‐capping of the polystyryllithium with 1,1‐diphenylethylene and the addition of 3–6 equivalents per living end of 2‐vinylpyridine as a dilute solution, eliminated side chain dimerization and provided grafting yields of up to 95%. The large‐scale procedure developed was applied to the synthesis of arborescent polystyrenes of generations up to G2 with low polydispersity indices (M_w/M_n ≤ 1.04) and molecular weights increasing in an approximately geometric fashion for each cycle. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5742–5751, 2008     

Estimates for Commutators of Orthogonal Fourier Series

In this paper we study weighted norm inequalities for the commutators[b, S_n] where b is a BMO function and S_n denotes the nth partialsum of the Fourier series relative to a system of orthogonalpolynomials on [–1, 1] with respect to general weights.Results about generalized Jacobi and Bessel Fourier series areobtained.