Redox-State Dependent Spectroscopic Properties of Porous Organic Polymers Containing Furan, Thiophene, and Selenophene (original) (raw)
Related papers
Redox-active porous organic polymers (POPs) have enormous potential in applications ranging from electrocatalysis to solar energy conversion. Exploiting the different electronic states offers exciting prospects for controlling host-guest chemistry, however, this aspect of multifunctionality has to date, remained largely unexplored. Here, we present a strategy for the development of multifunctional materials with industrially sought-after properties. A series of hydrophobic POPs containing redox-active triarylamines linked by ethynyl (POP-1), 1,4-diethynylphenyl (POP-2) and 4,4 0 -diethynylbiphenyl (POP-3) bridges have been synthesised and characterised by NMR and EPR spectroscopy, as well as spectroelectrochemistry and computational modelling. The facile electrochemical or chemical oxidation of the POPs generate mixed-valence radical cation states with markedly enhanced adsorption properties relative to their neutral analogues, including a 3-fold improvement in the H 2 uptake at 77 K and 1 bar, and an increase in the isosteric heat of adsorption for CO 2 .
A new p- and n-dopable selenophene derivative and its electrochromic properties
Organic Electronics, 2009
A novel electrically conducting polymer, poly(2-dodecyl-4,7-di(selenophen-2-yl)benzotriazole) (PSBT), containing selenophene as the strong donor and benzotriazole as the strong acceptor groups was synthesized by electrochemical polymerization. Homopolymerization and copolymerization (in the presence of 3,4-ethylenedioxythiophene (EDOT)) were achieved in acetonitrile/dichloromethane(95/5 v/v) with 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF 6 ). The electrochemical and optical properties of homopolymer and copolymer were investigated by cyclic voltammetry, UV-Vis, near IR Spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that homopolymer can be reversibly reduced and oxidized (both n-and p-doped) between À1.9 V and +1.4 V, at a scan rate of 100 mV/s. The homopolymer revealed a transmissive light blue color in the oxidized state, and a red-purple color in the neutral state. A transmissive light blue color was also observed in the reduced state. Homopolymer films could be fully switched between their reduced and oxidized forms in 2.4 s and 0.4 s with a percent transmittance of 32% and 56% at 511 and 1200 nm, respectively. Poly(SBT) exhibits a k max value of 511 nm and a band gap of 1.67 eV which is quite low among the selenophene-containing polymers reported so far except for poly(1,2-bis(2-seleninyl)ethane).
Journal of The Electrochemical Society, 2015
Herein, we report the synthesis of two donor-acceptor-donor polymers (P1 and P2) based on thiophene (M1) and thieno [3,2-b]thiophene (M2) as the donor and 2,5-bis(dodecyloxy)benzene as the acceptor unit. The effects of different donor units on the polymers' electrochemical and optical properties were examined by cyclic voltammetry and spectroelectrochemical analysis. Introducing thieno[3,2-b]thiophene unit as the donor unit enhances π-stacking and consequently lowering the bandgap of the resulting polymer. The electronic band gaps, defined as the onset of the π-π * transition, were found to be 2.0 eV for P1 and 1.7 eV for P2. Both P1 and P2 films revealed multi-colored electrochromism. A dual-type complementary colored electrochromic device (ECD) using P2/PEDOT in sandwich configuration was constructed. Spectroelectrochemistry, switching ability and open circuit memory of the ECD were investigated. During the past decade, the field of organic electronics has progressed enormously as a result of growing interest in materials chemistry. The first generation of conducting organic materials were composed of predominantly carbon-based molecular structures such as linear acenes, poly acetylene, and poly(p-phenylene viny-lene) derivatives (PPV). 1-3 The following generation involved the widespread incorporation of heterocycles into the conjugated backbone such as thiophene, pyrrole and their derivatives. 4-6 Currently, conjugated polymers and small organic molecules have been designed using "donor-acceptor" strategy. 7-10 This method involves synthesizing monomers and polymers with a delocalized π-electron system that consists of alternating electron-rich (donor) and electron-deficient (acceptor) units. The combination of high-lying HOMO levels (residing on the donor units) and low-lying LUMO levels (residing on the acceptor units) results in a local electron density gradient along the backbone, creating a lower energy charge-transfer transition. 11,12 The presence of this lower energy transition leads to smaller optical band gaps. A low bandgap leads to absorption in the visible region. Low bandgap, stability, solubility (which is crucial for their processability), planarity (which is important for obtaining good π-orbital overlap and effective electron delocalization) are the main requirements for organic electronic materials. In an attempt to manipulate relevant parameters to fulfill these requirements through synthetic expertise, numerous organic heterocyclic and pendant groups have been incorporated into the backbones of donor-acceptor conjugated polymers and small molecules. Thiophene based materials have demonstrated great potential as donor units due to their desirable properties such as stability , ease of synthesis, and modification. In recent years, thiophene moiety was coupled with benzoselenadiazole, 13 benzotriazole, 14,15 carbazole, 16 benzothiadiazole, 17,18 ethylenedioxythiophene, 19 diketopyrrolopyrrole, 20 3-alkylthiophene, 21 quinoxaline, 22 and benzimidazole. 23 The study of the opto-electronic properties of conjugated polymers and small organic molecules designed based on D-A approach provides valuable information for understanding the structure-property relationship. And also it allows designing materials with an enhanced opto-electronic property. These materials have been used in organic light-emitting diodes, 24-27 organic solar cells, 28-31 field effect transistors, 32-34 sensors, 35-37 and electrochromic devices (ECDs). 38-43 Conjugated polymers have gained great attention for ECDs due to the z fact that they are more processable than inorganic electrochromic materials and offer the advantage of a high degree of color tailorability. Electrochromism is defined as the reversible change in transmittance and/ or reflectance of the material upon applied voltage. The color changes between a transparent state and a colored state or between the two colored states are associated with electrochemically induced oxidation-reduction reactions. In this paper, we report two new donor-acceptor-donor conjugated polymers which were synthesized by combining electron-accepting 2,5-bis(dodecyloxy)benzene with electron-donating thiophene and thieno[3,2-b]thiophene. The influence of the structural differences of the electron-donating units on the electrochemical and optical properties of the resulting polymers was investigated. Experimental General.-All reagents and chemicals were obtained from commercial sources and used without further purification unless otherwise mentioned. 1,4-Bis(dodecyloxy)benzene, 44 1,4-dibromo-2,5-bis(dodecyloxy)benzene, 44 tributyl(thiophen-2-yl)stannane, 45 tributyl(thieno[3,2-b]thiophen-2-yl)stannane 46 were synthesized according to previously published procedures. Tetrahydrofuran (THF) was dried over sodium and benzophenone. Bruker Spectrospin Avance DPX-400 Spectrometer was used to record 1 H NMR and 13 C NMR spectra of synthesized materials in CDCl 3. Chemical shifts were recorded in ppm downfield from tetramethylsilane. Elec-tropolymerization of monomers were achieved in a three-electrode electrochemical cell. Indium Tin Oxide doped glass slide (ITO) as the working electrode, platinum wire as the counter electrode, and Ag wire as the pseudo reference electrode were used under ambient conditions using a Gamry potentiostat. Spectroelectrochemical studies of polymers were performed on a Varian Cary 5000 UV-Vis-NIR spectrophotometer. Minolta CS-100 colorimeter was used to perform colorimetry studies. Synthesis.-1,4-bis(dodecyloxy)benzene (2).-To a solution of hy-droquinone (4.00 g, 36.3 mmol) in dry DMF (50.0 ml), K 2 CO 3 (20.8 g, 83.6 mmol) was added and the solution was stirred under inert atmosphere at 100 • C for 1 hour. Then 1-bromododecane (15.1 g, 109 mmol) was added to the mixture. After 42 hours, the mixture was cooled to room temperature and poured onto distilled water. The product was extracted with CH 2 Cl 2 , and dried over anhydrous MgSO 4. After) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.132.123.28 Downloaded on 2015-06-30 to IP
Dyes and Pigments, 2019
Here we report the fabrication of a novel three-dimensional conjugated porous polymer (CPP-P1) developed by a palladium-catalyzed Sonogashira poly-condensation reaction. The solid polymer was thoroughly characterized by 13 C cross-polarization solid-state NMR and X-ray photoelectron spectroscopy (XPS). The pristine nitrogen-containing CPP was explored as an electrocatalyst for the oxygen reduction reaction (ORR) in alkaline media 0.1 M KOH. We observed that in the case of pristine polymer CPP-P1 oxygen reduction occurs through four electron transfer pathway with excellent stability and good tolerance to methanol. The detailed molecular-level structure for oxygen reduction and mode of oxygen binding site to the polymer was explained by density functional theory (DFT) calculation.
Synthetic metals, 2012
Two thiophene monomers: 3-methyltetra(oxyethylene)oxy-4-methylthiophene (MT) and a monomer containing a meso-3,5-ditert-butyl-tetraphenylporphyrin unit linked via a tetra(ethylene glycol) spacer (MTP) were synthesized and characterized. Both monomers were copolymerized in different ratios MT:MTP (2:1 and 4:1), using FeCl 3 as oxidizing agent, to give the corresponding copolymers (CTP-1 and CTP-2). MTP was also homopolymerized under the same reaction conditions to give the homopolymer (PTP). The obtained monomers and polymers were characterized by FTIR, 1 H and 13 C NMR spectroscopies. On the other hand, the optical properties of the polymers were studied by absorption and fluorescence spectroscopy in THF solution. All polymers exhibited the typical absorption bands of the porphyrin units: a Soret band at = 422 nm and four Q-bands between = 500 and 700 nm, as well as an additional band at = 451 nm, due to the polythiophene backbone. PTP, CTP-1 and CTP-2 showed fluorescence in the region between = 500 and 800 nm. Finally, the electrochemical properties of MTP and the obtained polymers were studied by cyclic voltammetry. Tetraphenylporphyrin (TPP) was used as model compound for comparative purposes. The obtained electrochemical data revealed the presence of the redox processes due to the porphyrin and the thiophene units. The reactivity of MTP toward electrochemical polymerization was studied.
Journal of Applied Polymer Science, 2016
A new series of extended-conjugated and thermally stable thiophene-containing imine-linked polymers were synthesized via a Schiff-base condensation reaction between aryl aldehydes and 2,6-diaminopyridine building blocks. The backbones of the polymers were functionalized with phenyl, fluorosubstituted phenyl, thienyl, and pyridyl aromatic rings. The successful synthesis was confirmed with spectrochemical characterization techniques, including IR, 1 H-NMR, 13 C-NMR, and elemental analyses. The electronic properties of the polymers were investigated with ultraviolet-visible (UV-vis) absorption spectroscopy; the properties were collected experimentally and calculated with density functional theory (DFT) in the gas phase. The maximum absorption calculated from DFT was higher than the experimental values by about 60 nm; this was attributed to the absence of the solvent effect in the DFT case. The frontier molecular orbital ((HOMO) highest occupied molecular orbital and (LUMO) lowest unoccupied molecular orbital), optical band gap (E g ), and total energy (E T ) values of the optimized structures were calculated. Apparently, there was a significant relation between the number of thiophene rings and the resulting E g and E T values. As the number of thiophene rings in the polymer chain increased, E g and E T decreased, and the thermal stability of the polymers increased. E g and the absorption band edges were determined experimentally from the UV-vis and transmittance spectra, respectively. Poly(terthienyl-azomethine-pyridine-azomethine), with the highest thiophene content, had the lowest experimental and calculated E g values (2.10 and 2.63 eV, respectively). In contrast, upon fluorination, poly[(2,5dithienyl-1,4-difluorobenzene)-azomethine-pyridine-azomethine] exhibited the highest E g (2.81 eV) and absorption band edges (2.94 eV), whereas the thermal stability decreased to 250 8C.
Journal of Polymer Science Part A: Polymer Chemistry, 2010
Novel bi-triphenylamine-containing aromatic dibromide M3, N,N-bis(4-bromophenyl)-N 0 ,N 0 -dipheny-l,4-phenylenediamine, was successfully synthesized. The novel conjugated polymer P1 having number-average molecular weight of 1.31 Â 10 4 was prepared via Suzuki coupling from the dibromide M3 and 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester. Polymer P1 had excellent thermal stability associated with a high glass-transition temperature (T g ¼ 141 C). The hole-transporting and UV-vis-near-infrared electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the conjugated polymer films cast onto indium-tin oxide-coated glass substrates exhibited two reversible oxidation redox couples at E 1/2 values of 0.73 and 1.13 V versus Ag/Ag þ in acetonitrile solution. The hole mobility of the conjugated polymer P1 revealed $10 À3 cm 2 V À1 s À1 , which is much higher than that of other conjugated polymer systems. The observed UV-vis-nearinfrared absorption change in the conjugated polymer film P1 at applied potentials ranging from 0.00 to 1.23 V are fully reversible and associated with strong color changes from pale yellowish in its neutral form to green and blue in its oxidized form. Using a combination of experimental study and theoretical investigation, we proposed an oxidation mechanism based on molecular orbital theory, which explains the cyclic voltammetry experimental results well. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4654][4655][4656][4657][4658][4659][4660][4661][4662][4663][4664][4665][4666][4667] 2010
Electrochem, 2022
Ferrocene-based porous organic polymers (FPOPs) were prepared from phenol-formaldehyde polymer (Bakelite) and phenol as starting materials; and two possible mechanisms for polymerization were discussed. Solid-state 13C CP-MAS NMR, FTIR, powder XRD, elemental analysis and ICP (Fe, Na, B) were performed to characterize the prepared materials. The two synthetic approaches produced polymers with different pore sizes: the FPOP synthesized through Bakelite presented a higher surface area (52 m2 g−1) when compared to the one obtained by the bottom-up polymerization from phenol (only 5 m2 g−1). Thermogravimetric analysis confirmed the thermal stability of the material, which decomposed at 350 °C. Furthermore, cyclic voltammetry (CV) of the new FPOP on modified electrodes, in ACN and 0.1 M TBAP as an electrolyte, showed fully reversible electron transfer, which is similar to that observed for the ferrocene probe dissolved in the same electrolyte. As a proof-of-concept for an electrochromic d...
Synthetic Metals, 2009
Up to date there are few studies reporting the use of selenophene derivatives as electrochromic polymers. This report highlights the synthesis of a selenophene containing multi-ring aromatic polymer which possesses reasonable optical contrasts at both visible and near-IR regions. Electrochemical synthesis of a conducting polymer from a multi-ring aromatic monomer, 2-(2,5-bis(hexyloxy)-4-(selenophen-2yl)phenyl)selenophene (BSB(OC 6 H 13 ) 2 ), was achieved at a lower potential than its corresponding parent, selenophene. The strong absorption band for the undoped polymer was 474 nm and the onset energy for the -* transition (Eg) was 1.9 eV (645 nm).