New Base-Doped Polyfluorene Derivatives

A series of new well-defined acidic poly(2,7-fluorene) derivatives have been synthesized by palladium-catalyzed Suzuki couplings. Upon deprotonation (i.e., base doping), these conjugated polymers generate stable polymeric anions counterbalanced by alkali metal cations. The resulting polymeric salts exhibit interesting conducting properties. For instance, base-doped poly[2,7-(9,9-dioctylfluorene)-alt-2,7-((4-hexylphenyl)fluorene-9-carbonyl)] exhibits an electrical conductivity of 10-2−10-3 S/cm in air, at room temperature. In all these polymeric systems, a strong polarization of the electrical conduction is observed which seems to indicate a significant ionic transport. These electrical properties confirm the good potential of these novel acidic fluorene-based π-conjugated polymers for the development of various electrical and electrochemical solid-state devices

Novel Dual Photochromism in Polythiophene Derivatives

The synthesis of azobenzene-substituted polythiophenes (poly[3-(2-(4-((4‘-ethoxyphenyl)azo)phenoxy)ethoxy)-4-methylthiophene] (P3A), poly[3-((6-(4-((4‘-ethoxyphenyl)azo)phenoxy)hexyl)oxy)-4-methylthiophene] (P3B)) and poly[3-(((6-(4-((4-ethoxyphenyl)azo)phenoxy)ethyl)tri(ethoxy)oxy)-4-methylthiophene] (P3C) has led to the development of novel photochromic polymers where the isomerization of the photoactive side chains not only modifies their own UV−visible absorption but also induces a modification of the optical features associated with the conjugated backbone. These results seem to indicate that any perturbation of the side-chain organization in poly(3-alkoxy-4-methylthiophenes) could lead to a modification of the conformation of the main chain and, consequently, to chromic effects both in solution and in the solid state

New Colorimetric and Fluorometric Chemosensor Based on a Cationic Polythiophene Derivative for Iodide-Specific Detection

Electrostatic interactions between anions and a new water-soluble, cationic, affinitychromic poly(3-alkoxy-4-methylthiophene) derivative provide a new tool for a selective optical detection method (colorimetric or fluorometric) for iodide ions

Ionochromic and Thermochromic Phenomena in a Regioregular Polythiophene Derivative Bearing Oligo(oxyethylene) Side Chains

Structural, thermal, and optical studies on regioregular poly[3-oligo(oxyethylene)-4-methylthiophene] have revealed interesting thermochromic and ionochromic effects related to a planar/nonplanar transition of the conjugated backbone. This first-order-like conformational transition (formation of twistons) seems driven by side-chain disordering induced by an increase of temperature or through noncovalent interactions with specific cations. The twisting of one repeat unit of this regioregular polythiophene derivative provokes the twisting of a large number of adjacent thiophene units (a domino effect) which leads to an amplification of the resulting optical (i.e., absorption or emission band) signal. These features are particularly promising for the development of novel affinitychromic and photochromic sensors based on new regioregular poly(3-alkoxy-4-methylthiophene)s

Syntheses of Conjugated Polymers Derived from <i>N</i>-Alkyl-2,7-carbazoles

Syntheses of Conjugated Polymers Derived from N-Alkyl-2,7-carbazole

Synthesis of Diindolocarbazoles by Cadogan Reaction: Route to Ladder Oligo(<i>p</i>-aniline)s

Symmetric and nonsymmetric diindolocarbazoles were successfully synthesized for the first time by a Cadogan ring closure using N-alkyl-2,7-disubstituted carbazole precursors. Cyclization reaction on N-alkyl-2,7-di(2‘-nitrophenyl) carbazole derivatives is not regioselective and produced a separable mixture of symmetric and nonsymmetric diindolocarbazoles. A carbazole derivative with methyl protective groups at the 1- and 8-positions was therefore used to obtain a symmetric ladder oligo(p-aniline) (compound 22). Optical and electrochemical properties of compound 22 indicate that its neutral semiconducting form is stable in air. This novel class of electroactive ladder oligomers should create new opportunities in micro- and nanoelectronics

Toward the Development of New Textile/Plastic Electrochromic Cells Using Triphenylamine-Based Copolymers

We report the preparation and characterization of new electrochromic polymers containing a 4-butyltriphenylamine (BuTPA) unit on the main chain. All polymers were obtained through the Suzuki−Miyaura cross-coupling reaction between 4-butyl-N,N-bis((4,4,5,5-tetramethyl-1,3,2-dioxaborolan-4-phenyl)aniline) and several aryl dibromide molecules to modulate the electronic properties of the resulting copolymers. 2,5-Dibromothiophene, 2,5-dibromo(3,4-ethylenedioxythiophene), 3,6-dibromo-N-octylcarbazole, bis(6-bromo-N-octylcarbazol-3-yl), and 2,7-dibromo-3,6-dimethoxy-9,9-dihexylfluorene were used as comonomers and led to five new copolymers, PT(BuTPA), PE(BuTPA), PC(BuTPA), PCC(BuTPA), and PF(BuTPA). These polymers are readily soluble in many common organic solvents, which make them suitable for spray-coating film deposition. Electrochromic cells with the following configuration were assembled:  ITO-coated glass or plastic/electrochromic polymer/gel electrolyte/ITO-coated glass or plastic or conducting textile. These copolymers exhibit good optical and electrochemical properties for military camouflage needs with color transition from pale yellow to green, transparent to khaki, or pale green to reddish-brown. Electrochemistry, spectroelectrochemistry, and colorimetric measurements of the devices were examined

Robust Direct (Hetero)arylation Polymerization in Biphasic Conditions

The synthesis of conjugated polymers from direct (hetero)­arylation polymerization (DHAP) has been achieved for the first time using biphasic water/toluene conditions. This protocol is robust enough to form polymers even when air is introduced in the system. General reactivity is demonstrated for a single set of polymerization conditions with thienyl- or phenyl-based substrates, whether they are electron-rich or electron-poor. Complete characterization from differential scanning calorimetry and ¹H NMR and UV–vis–NIR spectroscopies is presented, demonstrating this DHAP protocol offers comparable or better properties than the very best values published thus far. High molecular weights are obtained, showcasing the perfect equilibrium of reactivity and selectivity attained with this method. Moreover, this efficient and versatile methodology, which also uses low-cost, “wet” reagents, is scalable and done at ambient pressure

Toward Defect Suppression in Polythiophenes Synthesized by Direct (Hetero)Arylation Polymerization

In this study, we have investigated different reaction conditions for defect suppression in polythiophene derivatives synthesized by direct (hetero)arylation polymerization (DHAP). The well-known PQT12 polymer was used as a model due to its simple structure which facilitated analysis. 2-Bromo-3,4′-didodecyl-2:2′,5′:2″,5″:2‴-quaterthiophene and 2-bromo-3″,4‴-didodecyl-2:2′,5′:2″,5″-2‴-quaterthiophene monomers allowed the analysis of both homocoupling defects and β-branching defects due to their asymmetric structure as well as the effect of β-protection. The properties of the resulting polymers were analyzed using size-exclusion chromatography, differential scanning calorimetry, UV–visible absorption spectroscopy, and 1H NMR spectrometry. Some model compounds were synthesized to help with end-groups analysis, revealing debromination as the main obstacle to chain growth. The highest quality polymer was obtained when using toluene as a solvent, Pd2dba3 as a palladium(0) catalyst, neo-decanoic acid (NDA) as a carboxylic acid additive, and a dual-ligand system with diamine TMEDA and phosphine P(o-OMePh)3. This study also revealed the importance of the choice of the monomers for the preparation of well-defined conjugated polymers

En Route to Defect-Free Polythiophene Derivatives by Direct Heteroarylation Polymerization

We report the synthesis of well-defined poly­(3,3‴-didodecyl-2,2′:5′,2″:5″,2‴-quaterthiophene) (PQT12) from a direct heteroarylation polymerization (DHAP) of 5-bromo-3,3‴-didodecyl-2,2′:5′,2″:5″,2‴-quaterthiophene (monomer <b>A</b>) and 5-bromo-3′,4″-didodecyl-2,2′:5′,2″:5″,2‴-quaterthiophene (monomer <b>B</b>). Experiments with different catalysts, ligands, additives, and solvents have revealed that the utilization of Herrmann–Beller catalyst and P­(<i>o</i>-NMe₂Ph)₃ can lead to selective thiophene–thiophene couplings. In this regard, solid-state optical and thermal measurements were particularly useful to detect the presence of β-branching and indicate that minor molecular defects can induce important changes within the supramolecular organization. We also highlight the fact that steric protection around unsubstituted β-positions of α-bromothiophene units is needed to obtain a good selectivity of the cross-couplings at the α-positions. This can be achieved by the presence of a substituent at an adjacent β-position or the utilization of a bulky acidic additive (<i>i.e</i>., neodecanoic acid) in the catalytic system. These synthetic procedures applied to both monomers have led to PQT12 samples showing essentially the same optical and thermal properties and are comparable to those observed with their analogues prepared from chemical oxidation or Stille coupling