Conjugated polymers with carbazole, fluorene, and ethylene dioxythiophene in the main chain and a pendant cyano group: Synthesis, photophysical, and electrochemical studies

Room Temperature Hydrogen Gas Sensing via Reversible Hydrogenation of Electrochemically Deposited Polycarbazole on Interdigitated Pt Transducers

In this study, polycarbazole (PCz) is presented as a receptor structure for chemoresistive hydrogen sensors. The fabrication of the proposed sensors via electropolymerisation of PCz on interdigitated Pt electrodes is an inexpensive, cost-efficient, and repeatable method. Preliminary results presented in this work show that PCz-based sensors are sensitive to hydrogen gas in the range of 1–4% in air at room temperature. Notably, responses are both relatively high (from approximately 280% for 1% of H₂) and rapid (response and recovery times for 1% H₂ from 5 s and up to 32 s, respectively). Results of PCz structures on Pt and Au electrodes prove that the application of Pt electrodes is crucial for observation of sensing effect. A sensing mechanism based on reversible hydrogenation of PCz is proposed to explain the sensor operating principles.

The Different Outcomes of Electrochemical Copolymerisation: 3-Hexylthiophene with Indole, Carbazole or Fluorene

Electrochemical polymerisation is reported to be a method for readily producing copolymers of various conjugated molecules. We employed this method for mixtures of indole, carbazole or fluorene with 3-hexylthiophene (HT), in order to obtain their soluble copolymers. Although polymer films were obtained, infrared (IR) and Raman investigations showed that instead of the expected linear copolymers, polyindole and polycarbazole N-substituted with HT, as well as a poly(3-hexylthiophene) (PHT)/polyfluorene blend were produced instead. Boron trifluoride diethyl etherate was also used in an attempt to promote copolymerisation, but the produced deposits were found to be highly degraded.

Π-Stacking Signature in NMR Solution Spectra of Thiophene-Based Conjugated Polymers

Studies on conjugated polymers seldom report on their NMR characterization in solution. This paper shows how NMR experiments, both ¹H NMR and routine 2D NMR spectra, can help in gaining a further insight into the aggregation behavior of conjugated polymers and could be used to flank the more employed solid-state NMR and other spectroscopy and microscopy techniques in the understanding of the aggregation processes. NMR spectroscopy allows distinguishing, within the class of poorly solvatochromic conjugated polymers, those highly prone to form π-stacked aggregates from the ones that have a low tendency toward π-stacking.

White light emission from fluorene-EDOT and phenothiazine-hydroquinone based D–π–A conjugated systems in solution, gel and film forms

The appropriate composition of two new D–π–A conjugated organic molecules in combination with rhodamine B is observed to emit cool white light in solution and solid states.