Tandem Suzuki Polymerization/Heck Cyclization Reaction to Form Ladder-Type 9,9'-Bifluorenylidene-Based Conjugated Polymer

The synthesis of ladder-type 9,9'-bifluorenylidene-based conjugated polymer is reported. Unlike the typical synthetic strategy, the new designed ladder-type conjugated polymer is achieved via tandem Suzuki polymerization/Heck cyclization reaction in one-pot. In the preparation process, Suzuki polymerization reaction occurred first and then the intramolecular Heck cyclization followed smoothly under the same catalyst Pd(PPh3)4. The model reaction proved that the introduction of iodine (I) for this tandem reaction can effectively control the sequential bond-forming process and inhibit the additional competitive side reactions. Thus, small-molecule model compounds could be obtained in high yields. The successes of the synthesized small molecule and polymer compounds indicate that the Pd-catalyzed tandem reaction may be an effective strategy for improving extended π-conjugated materials.

Synthesis of Ladder-Type 9,9'-Bifluorenylidene-Based Conjugated Oligomers via a Pd-Catalyzed Tandem Suzuki Coupling/Heck Cyclization Approach

For new ladder-type oligomers and polymers with versatile and robust synthetic strategies, in this study, four fully conjugated ladder-type overcrowded 9,9'-bifluorenylidene-based compounds and oligomers (BFY1, BFY2, BFY3, and BFY4) were synthesized via a Pd-catalyzed tandem Suzuki coupling/Heck cyclization reaction. By monomer screening and route optimization, the target products were obtained in high yields and characterized by ¹H and ¹³C NMR spectroscopy and high resolution mass spectroscopy.

Fulvalene-Based Polycyclic Aromatic Hydrocarbon Ladder-Type Structures: Synthesis and Properties

Polycyclic aromatic hydrocarbons (PAHs) have found strong interest for their electronic properties and as model systems for graphene. While PAHs have been studied intensively as single units, here PAHs were constructed in ladder-type arrangements using cross-conjugated fulvalene and dithiafulvalene motifs as connecting units and moving forward a convenient synthetic approach for dimerizing (thio)ketones into olefins by the action of Lawesson's reagent. Some of the PAHs can also be regarded as "super-extended" tetrathiafulvalenes (TTFs) with some of the largest cores ever explored, being multi-redox systems that exhibit both reversible oxidations and reductions. Concomitant absorption redshifts were observed when expanding the ladder-type structures from one to two to three indenofluorene units, and optical and electrochemical HOMO-LUMO gaps were found to correlate linearly. Various conformations (and solid-state packing arrangements) were studied by X-ray crystallography and computations.

Zwitterionic liquid crystalline polythiophene as an antibiofouling biomaterial

To address a key challenge of conjugated polymers in biomedical applications having poor antifouling properties that eventually leads to the failure and reduced lifetime of bioelectronics in the body, herein we describe the design, synthesis, and evaluation of our newly designed multifunctional zwitterionic liquid crystalline polymer PCBTh-C8C10, which is facilely synthesized using oxidative polymerization. A conjugated polythiophene backbone, a multifunctional zwitterionic side chain, and a mesogenic unit are integrated into one segment. By DSC and POM characterization, we verify that the introduction of 3,5-bis(2-octyl-1-dodecyloxy)benzene as a mesogenic unit into the polythiophene backbone allows the formation of the liquid crystalline mesophase of the resulting polymer. We also demonstrate that the PCBTh-C8C10 coated surface exhibits good conductivity, stability, hydrophilicity, and remarkable antibiofouling properties against protein adsorption, cell growth, and bacteria attachment. This new zwitterionic liquid crystalline polymer having good antibiofouling features will be widely recognized as a promising biomaterial that is applicable in implantable organic bioelectronics via inhibiting the foreign body response. A deep understanding of structure-property relationships of zwitterionic conjugated polymers has also been provided in this study.