Wireless electrochemical actuation of soft materials towards chiral stimuli

Different areas of modern chemistry, require wireless systems able to transfer chirality from the molecular to the macroscopic event. The ability to recognize the enantiomers of a chiral analyte is highly desired, since in the majority of cases such molecules present different physico-chemical properties that could lead, eventually, to dangerous or harmful interactions with the environment or the human body. From an electrochemical point of view, enantiomers have the same electrochemical behavior except when they interact in a chiral environment. In this Feature Article, different approaches for the electrochemical recognition of chiral information based on the actuation of conducting polymers are described. Such a dynamic behavior of π-conjugated materials is based on an electrochemically induced shrinking/swelling transition of the polymeric matrix. Since all the systems, described so far in the literature, are achiral and require a direct connection to a power supply, new strategies will be presented in the manuscript, concerning the implementation of chirality in electrochemical actuators and their use in a wireless manner through bipolar electrochemistry. Herein, the synergy between the wireless unconventional actuation and the outstanding enantiorecognition of inherent chiral oligomers is presented as an easy and straightforward read out of chiral information in solution. This approach presents different advantages in comparison to classic electrochemical systems such as its wireless nature and the possible real-time data acquisition.

Enabling Conducting Polymer Applications: Methods for Achieving High Molecular Weight in Chemical Oxidative Polymerization in Alkyl- and Ether-Substituted Thiophenes

Polythiophenes (PTs) constitute a diverse array of promising materials for conducting polymer applications. However, many of the synthetic methods to produce PTs have been optimized only for the prototypical alkyl-substituted example poly(3-hexylthiophene) (P3HT). Improvement of these methods beyond P3HT is key to enabling the widespread application of PTs. In this work, P3HT and two ether-substituted PTs poly(2-dodecyl-2H,3H-thieno[3,4-b][1,4]dioxine) (PEDOT-C12) and poly(3,4-bis(hexyloxy)thiophene) (PBHOT) are synthesized by the FeCl₃-initiated oxidative method under different conditions. Polymerization was carried out according to a common literature procedure (“reverse addition”) and a modified method (“standard addition”), which differ by the solvent system and the order of addition of reagents to the reaction mixture. Gel-permeation chromatography (GPC) was performed to determine the impact of the different methods on the molecular weights (M_w) and degree of polymerization (X_w) of the polymers relative to polystyrene standards. The standard addition method produced ether-substituted PTs with higher M_w and X_w than those produced using the reverse addition method for sterically unhindered monomers. For P3HT, the highest M_w and X_w were obtained using the reverse addition method. The results show the oxidation potential of the monomer and solution has the greatest impact on the yield and X_w obtained and should be carefully considered when optimizing the reaction conditions for different monomers.