Thiadiazolo[3,4-c]pyridine as an Acceptor toward Fast-Switching Green Donor–Acceptor-Type Electrochromic Polymer with Low Bandgap

Abstract

Thiadiazolo[3,4-c]pyridine (PT), an important analog of benzothiadiazole (BT), has most recently been explored as a novel electron acceptor. It exhibits more electron-accepting ability and other unique properties and potential advantages over BT, thus inspiring us to investigate PT-based donor-acceptor-type (D-A) conjugated polymer in electrochromics. Herein, PT was employed for the rational design of novel donor-acceptor-type systems to yield a neutral green electrochromic polymer poly(4,7-di(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-[1,2,5] thiadiazolo[3,4-c]pyridine) (PEPTE). PEPTE revealed a lower bandgap (Eg,ele=0.85 eV, Eg,opt=1.12 eV) than its BT analog and also favorable redox activity and stability. Furthermore, electrochromic kinetic studies demonstrated that PEPTE displayed higher coloration efficiency than BT analog, good optical memory, and very fast switching time (0.3 s at all three wavelengths), indicating that PT would probably be a promising choice for developing novel neutral green electrochromic polymers by matching with various donor units.

Aqueous electrosynthesis of an electrochromic material based water-soluble EDOT-MeNH2 hydrochloride

“…It's worth noting that most electropolymerization systems are limited to organic solvents [11,[20][21][22][23][24], which exhibit some shortcomings such as environmental pollution, insecurity, energy shortage etc. Aqueous solution, as a promising "green" alternative solvent medium to traditional volatile and toxic solvents, is beneficial from a cost, handling, environmentally friendly, and safety point of view.…”

Furan and pyridinechalcogenodiazole-based π-conjugated systems via a donor-acceptor approach

“…1 H NMR (400 MHz, DMSO-d 6 , ppm), δ 7.52 (s, 1H), 6.00 (s, 2H), 5.06 (s, 2H). [1,2,5]thiadiazolo [3,4-c]pyridine [34] To a solution of anhydrous chloroform (10 mL) containing 2, 5-dibromo-3,4-diaminopyridine (1.00 g, 3.74 mmol) with surrounding temperature of 0°C, thionyl bromide (2.25 g, 18.9 mmol) was added dropwise, followed by stirring of the mixture at the same temperature under nitrogen atmosphere for 0.5 h. Then the reaction was stirred at room temperature for 0.5 h. This was followed by reflux at 75°C. After 8 h of heating, thionyl bromide (2.25 g, 18.9 mmol) was added dropwise again and the mixture was refluxed for 4 h. The reaction mixture was allowed to cool to room temperature, and poured into ice-water.…”

“…The reagent 2,5-dibromo-3,4-diaminopyridine [28] and tributyl(furan-2-yl)stannane [36] were synthesized according to literature procedures. 4,7-Dibromo [1,2,5]thiadiazolo [3,4-c]pyridine [34] and 4,7-dibromo- [1,2,5]selenadiazolo [3,4-c] pyridine [34] were synthesized through ring closure reaction with thionyl bromide and selenium dioxide, respectively. Lastly, two monomers, Fu-S-Fu and Fu-Se-Fu, were Scheme 1 Synthetic routes of Fu-S-Fu and Fu-Se-Fu synthesized via Stille coupling reaction in satisfactory yields.…”

“…Recently, we developed several typical furan-based and thiadiazolo [3,4-c]pyridine-based polymers [32][33][34], such as polyfurans, polybifurans, polytrifurans [32], furan-EDOT polymers [33], and PEPTE [34], leading to the availability of promising furan-based polymer electrochromic materials. Considering advantages of furan-based copolymers, furan was employed as a building block for the design of donor-acceptor system.…”

A Camouflage Material: p- and n-Type Dopable Furan Based Low Band Gap Electrochromic Polymer and Its EDOT Based Copolymer

“…In order to overcome this problem, electrocopolymerization of 1 was carried out with 3,4-ethylenedioxythiophene (EDOT). There were two reasons behind this co-monomer (EDOT) selection: (1) Due to the excellent stability of homopolymer of EDOT (PEDOT) 24 and EDOT containing hibrit polymers [25][26][27] , it is apparent that stability of copolymer increases when compared to homo-polymer; (2) 1 and EDOT have similar oxidation potentials, which is an important parameter for electrocopolymerization. Electrochromic and electrochemical properties of P1 changed and, as expected, the stability of this polymer increased by the addition of the EDOT group.…”