Poly-3-thienylboronic acid: a chemosensitive derivative of polythiophene

Abstract

Poly-3-thiopheneboronic acid was synthesized by electrochemical polymerization from 3-thienylboronic acid dissolved in the mixture of boron trifluoride diethyl etherate and acetonitrile. Cyclic voltammetry during electropolymerization shows oxidative and reductive peaks growing in each next cycle. An investigation by scanning electron microscopy displayed the polymer layer like a highly flexible film of 110 nm thick with grains of 60–120 nm in size. Strong negative solvatochromic effect was observed. Optical spectra of poly-3-thienylboronic acid at different potentials and pH were studied. Potential cycling leads to a well reversible electrochromic effect. At pH 7.4, the increase of potential leads to the decrease in the absorption band at 480 nm and to the rise in the absorption band at 810 nm with an isosbestic point at 585 nm. Spectroelectrochemical behavior of poly-3-thienylboronic acid and polythiophene was compared. Binding of sorbitol at fixed electrode potential leads to an increase in the absorbance in the shortwave band and to the decrease in the longwave band; the effect depends on the electrode potential and pH. Perspectives of application of poly-3-thienylboronic acid as new chemosensitive material are discussed.

3-Thienylboronic Acid as a Receptor for Diol-Containing Compounds: A Study by Isothermal Titration Calorimetry

“…One can observe an increase in the absolute value of the binding energy for potential change between 0.13 V and 0.23 V and a decrease of this value for further potential increase till ~0.4 V. The potential value 0.23 V corresponds to the maximal value of the binding constant. Unfortunately, the used method of potential variation did not allow us to study higher potential values at which the main electrochemical activity of this compound is observed [38]. The maximal change in the binding constant between TBA and sorbitol in the studied potential range was 2.75; for the earlier studied electrochemical transistor based on polyaniline and its interaction with trimethylamine this value was 2.47 at the much wider potential range [52].…”

“…The main feature of TBA in comparison with other similar compounds is its electrochemical activity. Due to this activity, TBA can be electrochemically polymerized forming highly conducting polymer films [38]. It allows us to consider TBA as a promising material for applications in chemical sensors with electrically controlled affinity or in virtual sensor arrays with electrochemical switching of chemosensitive properties [49].…”

“…The common problem of this polymer is the pH sensitivity of its backbone [37]; in the case of analytical applications, it leads to pH interference and requires using of strong buffers. In [38] we have mentioned an unsuccessful attempt to develop a conductometric sensor based on such polymers: the pH interference was so high that it was impossible to get a reliable response to the saccharides.…”

“…This advantage makes thiophene with boronic acid moieties a promising chemosensitive material for recognizing diol-containing compounds. Recently, we have already reported the preparation of poly-3-thienylboronic acid by electrochemical polymerization of 3-thienylboronic acid (TBA) and discussed the optical, electrochromic, and chemosensitive properties of this new material [38].…”

Poly-3-thienylboronic Acid Nanoparticles: Synthesis, Characterization, and Interaction with Saccharides Studied at the Level of Individual Nanoparticles

“…In contrast to BA-containing polymers with a polyaniline backbone, the polythiophene backbone of PThBA has no inherent pH sensitivity. At the same time, the absorption spectra of PThBA changes in the presence of saccharides …”