ProTOT: Synthesis of the missing member of the 3,4-chalcogen substituted bridged thiophenes and its utilization in donor-acceptor polymers

Abstract

Synthesis of sulfur containing derivatives of bridged dioxythiophene based polymers (PEDOT and PProDOT) and their applications in electrochromism have been pursued in recent years with promising results. Interestingly, synthesis of 3,4-dihydro-2H-thieno [3,4-b] [1,4]oxathiepine (ProTOT) has not been pursued.. Here, we describe the synthesis of this novel electron rich monomer and D-A-D type monomer that contain ProTOT as the donor and benzo lc] [1,2,5]thiadiazole as the acceptor. ProTOT cannot be electrochemically polymerized to yield the corresponding polymer PProTOT. However, the D-A-D monomer utilizing ProTOT as the donor unit was electropolymerized successfully to yield P(ProTThia) and its electrochromic properties and performance in amperometric biosensors have been investigated. P(ProTThia) was shown to be both p and n-dopable with 4 distinctly different colors at different redox states. P(ProTThia) showed a promising optical contrast of 35% in the visible region and excellent optical contrast of 80% in the NIR region. A novel amperometric biosensor for the detection of glucose consisting of P(ProTThia), chitosan (CHIT) and multi-walled carbon nanotubes (MWCNT) was also constructed. Herein, for the first time, we propose that a specific combination of this trio can be used as an inexpensive alternative and effective way to fabricate highly sensitive and fast response glucose biosensors. The proposed glucose sensing system possessed superior properties with K-M(app) value of 0.05 mM, 32 mu M limit of detection and 63.76 mu A mM(-1) cm(-2) sensitivity which was also tested with a commercial beverage sample to ratify the feasibility of the proposed sensor.