Selenophene‐Flanked Diketopyrrolopyrrole Based Conjugated Polymers for Ambipolar Field‐Effect Transistors

The development of selenophene‐flanked DPP (SeDPP) based copolymers, especially for the ambipolar ones, lags behind other aromatic group flanked DPP‐based polymers. Herein, we report two new ambipolar SeDPP‐based conjugated polymers. One is the alternating polymer PSeDPPFT with normal SeDPP and 3,4‐difluorothiophene units. The other is PSeFDFT , in which the electron acceptor unit is replaced by a new SeDPP derivative, referred as to half‐fused SeDPP. The more planar structure of half‐fused SeDPP endows the backbone of PSeFDFT with good rigidity and planarity. Both polymers exhibit ambipolar transporting properties in air. The PSeFDFT based field‐effect transistors (FETs) display higher and more balanced ambipolar properties with μ_h^ave of 0.27 cm²·V^–1·s^–1, μ_e^ave of 0.18 cm²·V^–1·s^–1, and μ_h^ave/μ_e^ave of 1.5 than those of PSeDPPFT (μ_h^ave = 0.11 cm²·V^–1·s^–1, μ_e^ave = 0.042 cm²·V^–1·s^–1, and μ_h/μ_e = 2.6). This is attributed to the more planar structure, lower LUMO level, higher HOMO level, and better interchain packing orientations of PSeFDFT by comparing with PSeDPPFT . Therefore, a new molecular design strategy to modulate the hole and electron transporting properties is proposed for conjugated D‐A polymers.     

Progress in hydrogels for sensing applications: a review

There are several developments taking place in the field of sensors driven by the world today requirements. One of the most important novelties of the last two decades in the field is represented by the hydrogel-based sensors which constitute a wide family of innovative smart sensing devices relevant for many different applications. Hydrogels in fact are hydrophilic, biocompatible and highly water swellable polymer networks able to convert chemical energy into mechanical energy, with the great peculiarity to be able to respond to external stimuli. These characteristics have ensured them considerable recognition as valuable tool for smart sensing and diagnostics. The aim of this review is to focus on the advances obtained in the field in the last ten years.     

Raman Optical Activity (ROA) as a New Tool to Elucidate the Helical Structure of Poly(phenylacetylene)s

Poly(phenylacetylene)s are a family of helical polymers constituted by conjugated double bonds. Raman spectra of these polymers show a structural fingerprint of the polyene backbone which, in combination with its helical orientation, makes them good candidates to be studied by Raman optical activity (ROA). Four different well‐known poly(phenylacetylene)s adopting different scaffolds and ten different helical senses have been prepared. Raman and ROA spectra were recorded and allowed to establish ROA‐spectrum/helical‐sense relationships: a left/right‐handed orientation of the polyene backbone (M_helix/P_helix) produces a triplet of positive/negative ROA bands. Raman and ROA spectra of each polymer exhibited the same profile, and the sign of the ROA spectrum was opposite to the lowest‐energy electronic circular dichroism (ECD) band, indicating a resonance effect. Resonance ROA appears then as an indicator of the helical sense of poly(phenylacetylene)s, especially for those with an extra Cotton band in the ECD spectrum, where a wrong helical sense is assigned based on ECD, while ROA alerts of this misassignment.     

Syntheses and Crystal Structures of Two Coordination Polymers with Aromatic Dioxide as Bridge Ligands

Two coordination polymers, namely, two-dimensional complex 1 {[Cu(μ- L)1.5(ClO4)2(H2O)].(H2O)0.5}n (L = pyrazine-1,4-dioxide) and one-dimensional complex 2 [Co(μ-L)Br2(H2O)2]n, have been synthesized with pyrazine-1,4-dioxide as bridging ligands, and their crystal structures were determined by X-ray crystallography. Crystal data for complex 1: monoclinic system, space group C2/c, with a = 23.310(3), b = 12.2338(17), c = 10.6075(15) , β = 110.487(2)°, V = 2833.6(7) 3, Z = 8, C6H9Cl2CuN3O12.5, Mr = 457.60, Dc = 2.145 g/cm3, F(000) = 1832 and μ = 1.998 mm-1; and those for 2: monoclinic system, space group C2/c, with a = 11.012(3), b = 7.483(2), c = 11.451(3) , β = 101.654(4)°, V = 924.2(4) 3, Z = 4, C4H8Br2CoN2O4, Mr = 366.87, Dc = 2.637 g/cm3, F(000) = 700 and μ = 10.487 mm-1. 1 shows a two-dimensional sheet structure on the ac plane through the coordination of μ-L bridging ligands with Cu(II) ions, while 2 displays a zigzag one-dimensional chain along the c axis via the coordination of μ-L bridging ligand with Co(II) ions. Hydrogen bonds in 1 and 2 make the sheets (or chains) connect each other to form a three-dimensional structure.     

Syntheses, Crystal Structures and Magnetism of Two New Coordination Polymers [Ni（bix）2Cl2]n and [Co（bix）Cl2]n

The self-assembly reactions of MIICl2 (M = Ni, Co) with the flexible bix ligand [bix = 1,4-bis(imidazole-1-ylmethyl)benzene] yielded a 2D network [NiII(bix)2Cl2]n 1 and a 1D chain [CoII(bix)Cl2]n 2. Their crystal structures have been determined by X-ray single-crystal diffraction analysis. Complex 1 characters a two-dimensional grid-type structure and crystallizes in monoclinic, space group P21/c with a = 7.7231(7), b = 12.7787(9), c = 13.9374(13) , β = 105.419(4)o, C28H28Cl2N8Ni, Mr = 606.19, Ζ = 2, V = 1326.0(2) 3, Dc = 1.518 g/cm3, μ = 0.969 mm-1, F(000) = 628, R = 0.0429 and wR = 0.0783 for 2503 observed reflections (I > 2σ(I)). Compound 2 is a one-dimensional chain and crystallizes in orthorhombic, space group Pbca with a = 11.3696(6), b = 10.2128(6), c = 14.4943(9) , C14H14Cl2CoN4, Mr = 368.12, Z = 4, V = 1683.01(17) 3, Dc = 1.453 g/cm3, μ = 1.334 mm-1, F(000) = 748, R = 0.0317 and wR = 0.0800 for 1778 observed reflections (I > 2σ(I)). Magnetic properties of the title complexes were also investigated.     

Fluorinated organic chemicals: Prospects in New Electrochemical Energy Technologies

This contribution has been partly adapted from a special lecture intended to commemorate the Nobel prize, awarded one century ago, to Henri Moissan. It, is focused on fluorinated and perfluorinated molecules and macromolecules used in electrochemical energy sources, i.e. storage and conversion of energy. The latter, which figure indisputably among New Energy Technologies, include lithium batteries and fuel cells based on polymeric membranes both of which have tremendous development potential in terms of performances, safety and cost reductions. The advantages inherent in fluorine, in particular its electron-withdrawing effect and the oxidation stability that it provides to the carbon-fluorine bond, make it an asset in the search for new organic molecular and macromolecular anions with extensive delocalization of the negative charge, usable both in lithium batteries and fuel cells. As for fluorinated and perfluorinated macromolecule backbones, they are currently the reference material in fuel cell ionomeric membranes but some of them are also good candidates for use in lithium-ion batteries. This paper, far from being exhaustive, also emphasizes the economic aspects that influence material selection and also govern the future of basic research.     

On the calculation of a limit for infinite systems from data on finite systems

We propose a mathematical model for the calculation of physical or chemical properties of infinite polymers, based on data for structurally closely related finite molecules. The modelling is phenomenological but permits a physical interpretation of the parameters involved in the equations. Received: 11 June 1996 / Accepted: 5 June 1997     

分子印迹膜的制备研究进展

将分子印迹技术与膜分离技术相结合的分子印迹膜,由于其高选择性,近年来受到了国内外研究者的广泛关注.本文初步探讨了分子印迹膜(MIM) 的两种分离机理以及目前主要的制备方法:同步法和复合法.     

Determination of P-Cresol (and Other Phenolics) Using a Conducting Polymer Based Electro-Immunological Sensing System

Abstract

Antibodies to a p-cresol bovine serum albumin conjugate have been produced and incorporated into a conducting polymer to form an electro-immunological sensing system. Using flow injection analysis and pulsed electrochemical detection sensitive, reproducible and rapid responses to p-cresol and other phenolics can be obtained. The sensor is reusable.     

Synthesis,Characterization and Fluorescent Properties of Three One‐Dimensional Coordination Polymers Derived from Polypyridyl Ligands

Three one‐dimensional coordination polymers, [MnCl₂(4‐pyterpy)]∙2CHCl₃ ( 1 ), [Mn(NO₃)₂(4‐pyterpy)]∙CHCl₃ ( 2 ) and [Ag(NO₃)(3‐pyterpy)]∙H₂O ( 3 ) (4‐pyterpy = 4′‐(4‐pyridyl)‐2,2′:6′,2″‐terpyridine and 3‐pyterpy = 4′‐(3‐pyridyl)‐2,2′:6′,2″‐terpyridine) were synthesized and characterized by X‐ray diffraction. All three compounds exhibit a rare “head‐to‐tail” coordination of the multidentate ligand, but differ significantly in their polymer chain conformations. Additionally, the fluorescent properties of all three compounds were investigated and show a weak, ligand‐centered fluorescence at 416–418 nm.