Clean and Efficient Iodination of Thiophene Derivatives
作者:Frédéric Gohier、Jérémie Grolleau、Pierre Frère
DOI:10.1055/s-0035-1560480
日期:——
Abstract Iodination of thiophene derivatives is realized using a simple, fast, and efficient methodology. Iodination of thiophene and 2- or 3-substituted or 3,4-disubstituted thiophenes with N-iodosuccinimide (NIS) activated with 4-toluenesulfonic acid in ethanol gives pure iodinated products that require no further purification. Iodination of thiophene derivatives is realized using a simple, fast
Crown-annelated quater- (4T) and sexithiophenes (6T) with oligooxyethylene chains of various lengths attached at the 3-positions of the terminal thiophene rings have been synthesized. Analysis of the cation-binding properties of the macrocycles by H-1 NMR and UV-vis spectroscopy reveals the formation of a 1:1 complex with Ba2+, Sr2+, or Pb2+ and shows that cation complexation results in a conformational transition in the pi-conjugated system. Theoretical analysis of this process by density functional methods predicts that this conformational transition results in a narrowing of the highest occupied-lowest unoccupied molecular orbital gap of the conjugated system with a decrease of the redox potentials (E-1(0) and E-2(0)) associated with the formation of the 4T cation radical and dication. Cyclic voltarmmetry shows that, depending on the binding constant, the presence of metal cation produces a negative or a positive shift of E-1(0) while E-2(0) always shifts negatively. This unusual behavior is discussed in terms of interplay between electrostatic interactions and conformational changes associated with cation binding.
Electrogenerated poly(thiophenes) derivatized by bipyridine ligands and metal complexes
The synthesis of a series of bithiophenic precursors of electrogenerated conjugated polymers functionalized by bipyridine ligands is described. The precursor structure involves two polymerizable groups attached at both ends of a bipyridine ligand and fixed at an internal beta-position of thiophene via an alkylsulfanyl or alkoxy spacer. Electrochemical and optical data show that the low polymerization potential resulting from the association of 3,4-ethylenedioxythiophene (EDOT) and alkylsulfanyl or alkoxy thiophene combined with the multi-site polymerization approach allows a straightforward electrosynthesis of extensively conjugated and stable functionalized polymers. On the basis of these results, iron and ruthenium complexes of these precursors have been synthesized and electropolymerized. The analysis of the electrochemical behavior of the resulting polymers shows that they exhibit the typical electrochemical signature of both the conjugated polythiophene backbone and the immobilized metal complex.
3- and 3,4-Bis(2-cyanoethylsulfanyl)thiophenes as Building Blocks for Functionalized Thiophene-Based π-Conjugated Systems
The facile access to 3- and 3,4-bis(2-cyanoethyl-sulfanyl)thiophenes allows the straightforward synthesis of 3-alkylsulfanyl and symmetrical or unsymmetrical 3,4-dialkylsulfanylthiophenes by using a methodology based on a highly efficient sequence of deprotection/alkylation reactions of thiolate group(s).
Electroactive polyacrylates bearing linear conjugated systems based on EDOT moieties
New polyacrylates bearing an electropolymerizable bi or terthiophene group have been synthesized via classical radical polymerization and via RAFT process. Polymerizations can be controlled if thiophene moieties have protected a positions; otherwise polymerization is difficult or impossible. Cross-linked polymers can be obtained after film electropolymerizations on different electrodes (gold, carbon and platinum). (C) 2017 Elsevier Ltd. All rights reserved.