Thiophene Groups Research Articles

Overcoming the trade-off between Voc and Jsc: Asymmetric chloro-substituted two-dimensional benzo[1,2-b:4,5-b′]dithiophene-based polymer solar cells

To achieve the high PCE and simultaneously overcome the trade-off between open circuit voltage (VOC) and short-circuit current density (JSC), the reasonable design of the donor material is still a great challenge in non-fullerene polymer solar cells (PSCs). Herein, a pair of asymmetric 2D BDT-based wide band gap polymers, named PBPTBz-1Cl and PBPTBz-2Cl, respectively, were designed and synthesized through simultaneously introducing a chloro-substituted thiophene and another alkoxylphenyl groups as side chains onto the same BDT unit. As expected, the polymers PBPTBz-1Cl and PBPTBz-2Cl exhibit the deeper HOMO levels of −5.32 and −5.41 eV, respectively, compared with the HOMO value of −5.27 eV for chlorine-free substituted polymer PBPTBz-0Cl. Therefore, the PBPTBz-2Cl:IT-M based PSCs exhibited a higher Voc of 0.99 V, with an enhanced Jsc of 14.92 mA cm−2 and PCE of 7.18%. The Voc, Jsc and PCE were simultaneously enhanced from PBPTBz-0Cl:IT-M to PBPTBz-1Cl:IT-M, then to PBPTBz-2Cl:IT-M based PSCs successively. These results demonstrate that the challenge of the trade-off between Voc and Jsc could be overcome through the asymmetric strategy of the chloro-substituted thiophene and alkylphenyl groups as different side chains onto the same BDT unit. Hence, considering the low cost of starting materials and convenient introduction of chlorine atoms, the asymmetric chlorination of the side chain of BDT unit would be the great potential for achieving the high-performance PSCs.

Enhancement of molecular-level ordering of isoindigo based organic materials through deprotecting of cleavable carbamate groups with long alkyl chains

A new highly soluble isoindigo based organic material with both cleavable carbamate protecting groups bearing long alkyl chains and thiophene groups was successfully synthesized. The carbamate protecting groups were easily removed by solvent-vapor thermal annealing using a mixture of trifluoroacetic acid and chloroform. Deprotection of the NH functional groups in the isoindigo backbone in situ facilitated H-bonding that dramatically improved the strength of the intermolecular interactions. X-ray diffraction and high-voltage electron microscopy studies of the resulting organic material showed long-range ordered crystalline structure. High crystallinity due to enhanced π-π stacking and hydrogen bonding significantly improved the charge carrier mobility. The hole mobilities of isoindigo based organic material measured by SCLC method improved from 3.46 x 10−6 cm2 V−1 s−1 to 1.13 x 10-3 cm2 V−1 s−1 upon deprotection of the NH functional groups.

Flash vacuum pyrolysis of oxo-stabilised phosphonium ylides containing methoxythiophene and methylthiophene groups

Ten new oxo-stabilised phosphonium ylides containing substituted thiophene groups, as well as two deuterium-labelled analogues, are prepared and fully characterised. Upon flash vacuum pyrolysis at 800 °C, the simpler examples undergo extrusion of Ph3PO coupled with domino cyclisation to give thieno[3,2-b]furan and thieno[3,4-b]furan products but the corresponding approach to a thieno[2,3-b]furan fails. One ylide designed to give a thieno[3,4-b]furan instead gives phenylbutadiyne and 2-phenyl-3-vinylthiophene at 725 °C and the mechanism of this unusual process is elucidated by deuterium labelling. Attempts to access more complex heterocyclic products from extended methoxythienyl ylides failed. Two ylides bearing a 3-methyl-2-thienylacryloyl group gave 5-benzylbenzothiophene, 5-(α-methylbenzyl)benzothiophene and fluoreno[3,4-b]thiophene upon FVP at 800 °C and the mechanism was again elucidated by deuterium labelling.

Principles of Design for Substrate-Supported Molecular Switches Based on Physisorbed and Chemisorbed States.

The physisorbed (precursor) and chemisorbed states of a molecule on metal surfaces can be utilized to build a logic switch at the single-molecule level, enabling further microminiaturization of electronic devices beyond the silicon limits. However, a serious drawback of this design is easy lateral diffusion of the molecule in the physisorbed state, which may destroy the normal switch operation. Here, we demonstrate that anchoring engineering can be an effective way to enhance the stability of molecular switches without degrading switching functionality. As exemplified by trans-ADT on Cu(111), we show that the lateral diffusion of such molecular switch can be obstructed by the anchoring of the ending thiophene groups, along with a rotation of the adsorbate during the switching process. More general, our results also suggest that when searching for molecular switches with reversible physisorbed and chemisorbed states with excellent bistability and lateral stability, the focus should be on finding molecules with a moderate HOMO-LUMO energy gap and anchoring atoms with positive charge that can then be deposited on substrates with which they interact moderately. This allows further improvement of the lateral and vertical stability of such a molecular switch by substituting the thiophene groups with selenophene, thus establishing trans-ADS on Cu(111) as a promising switch.

Enhanced Organic Solar Cell Performance by Lateral Side Chain Engineering on Benzodithiophene-Based Small Molecules

The three novel acceptor–donor–acceptor (A–D–A) conjugated small molecules were synthesized, each featuring a benzodithiophene (BDT) core presenting lateral flexible side chains: TB-BDT6T substituted with 2-ethynyl-5-octylthiophene, TS-BDT6T substituted with 2-(octylthio)thiophene, and TT-BDT6T substituted with 2-(2-ethylhexyl)thieno[3,2-b]thiophene groups. The lateral incorporation of functionalized π-conjugated flexible side chains, without altering the end-capped acceptor (cyanoacetate) moieties, amended the optoelectronic properties of these BDT-based small molecules. X-ray diffraction spectroscopy revealed that these small molecules possess high crystallinity; moreover, the optimized blend film morphologies, recorded using atomic force microscopy, revealed miscibility with PC61BM, and turn out nanoscale phase separations. The energy levels of the highest occupied and lowest unoccupied molecular orbitals of these small molecules were allowed, leading to high open-circuit voltages (Voc) for their solar...

Physical Insight on Mechanism of Photoinduced Charge Transfer in Multipolar Photoactive Molecules

Two series of novel dyes were designed based on the multipolar structures of the red dye D35 and blue dye DB, by introducing the furan (F), benzene ring (B) and benzo[c]thiophene (BT) groups into the conjugated bridge of D35 in proper order and adjusting the position of diketopyrrolopyrrole(DPP) unit and the incorporation of fluorine in the conjugated bridge of DB, respectively. We performed the quantum chemistry calculation to investigate the ground state and excited properties in a direct correlation with the spectra properties and abilities of losing or accepting electron for the original and designed molecules. Furthermore, the absorption spectra characteristics in consideration of the aggregation of dyes on the TiO2 layer and intermolecular charge transfer rate of the dimers were calculated. The obtained results indicate that the larger intermolecular charge transfer rate leads to the poor photoelectrical properties of the dyes, and the designed dyes D35-3 and DB-2 would exhibit the best photoelectrical properties among the investigated dyes due to their lower energy gaps, widened absorption spectra and prominent charge transfer properties.

Guest-Induced Switchable Breathing Behavior in a Flexible Metal-Organic Framework with Pronounced Negative Gas Pressure.

Flexible metal-organic frameworks (MOFs) have attracted great interest for their dynamically structural transformability in response to external stimuli. Herein, we report a switchable "breathing" or "gate-opening" behavior associated with the phase transformation between a narrow pore (np) and a large pore (lp) in a flexible pillared-layered MOF, denoted as MOF-1 as, which is also confirmed by SCXRD and PXRD. The desolvated phase (MOF-1 des) features a unique stepwise adsorption isotherm for N2 coupled with a pronounced negative gas adsorption pressure. For comparison, however, no appreciable CO2 adsorption and gate-opening phenomenon with stepwise sorption can be observed. Furthermore, the polar micropore walls decorated with thiophene groups in MOF-1 des reveals the selective sorption of toluene over benzene and p-xylene associated with self-structural adjustment in spite of the markedly similar physicochemical properties of these vapor molecules.

Effect of the Polyketone Aromatic Pendent Groups on the Electrical Conductivity of the Derived MWCNTs-Based Nanocomposites.

Electrically conductive plastics with a stable electric response within a wide temperature range are promising substitutes of conventional inorganic conductive materials. This study examines the preparation of thermoplastic polyketones (PK30) functionalized by the Paal–Knorr process with phenyl (PEA), thiophene (TMA), and pyrene (PMA) pendent groups with the aim of optimizing the non-covalent functionalization of multiwalled carbon nanotubes (MWCNTs) through π–π interactions. Among all the aromatic functionalities grafted to the PK30 backbone, the extended aromatic nuclei of PMA were found to be particularly effective in preparing well exfoliated and undamaged MWCNTs dispersions with a well-defined conductive percolative network above the 2 wt % of loading and in freshly prepared nanocomposites as well. The efficient and superior π–π interactions between PK30PMA and MWCNTs consistently supported the formation of nanocomposites with a highly stable electrical response after thermal solicitations such as temperature annealing at the softening point, IR radiation exposure, as well as several heating/cooling cycles from room temperature to 75 °C.

Regioregular polymers containing benzodithiophene and thienothiophene segments with different electron donating side chains for high-performance polymer solar cells

This study describes a systematic study on side chain effect in the poly(thieno[3,4-b]thiophene)benzo[1,2-b:4,5-b′]dithiophene (PTB) polymer series based regioregular polymers with D1-A-D2-A configuration, denoted as PTT-BDT(R1)-TT-BDT(R2). The synthesized three regioregular polymers employ the same conjugated backbone but with different side chains (R1, R2), P1; hexyldecyl thiophene (HD, R1) and ethylhexyl thiophene (EH, R2), P2; hexyldecyl thiophene (HD, R1) and ethylhexylthio thiophene (S-EH, R2), P3; hexyldecylthio thiophene (S-HD, R1) and ethylhexylthio thiophene (S-EH, R2). Introduction of different side chains influenced optical, electrochemical, molecular packing properties, and device performance. The P3 polymer with alkylthio thiophene groups as R1 and R2 showed much broader light absorption and lower HOMO level than other polymers with relatively less alkylthio thiophene groups. Furthermore, the P3 polymer exhibited favorable polymer orientation and short π-π stacking distance for efficient charge transport in the BHJ PSCs. The P3 based bulk-heterojunction (BHJ) polymer solar cell (PSC) showed an improved PCE of 7.20% while the P1 and P2 based BHJ PSC devices showed PCEs of 5.27% and 6.45%, respectively. This result, within our knowledge, is the highest record among BHJ PSCs based PTB polymer series composed of benzo[1,2-b:4,5-b’]dithiophene (BDT) segment and non-fluorinated alkyl ester (COOR) side chain substituted thieno[3,4-b]thiophene (TT) segment.

Enhancement of CO2 Uptake and Selectivity in a Metal-Organic Framework by the Incorporation of Thiophene Functionality.

The complex [Zn2(tdc)2dabco] (H2tdc = thiophene-2,5-dicarboxylic acid; dabco = 1,4-diazabicyclooctane) shows a remarkable increase in carbon dioxide (CO2) uptake and CO2/dinitrogen (N2) selectivity compared to the nonthiophene analogue [Zn2(bdc)2dabco] (H2bdc = benzene-1,4-dicarboxylic acid; terephthalic acid). CO2 adsorption at 1 bar for [Zn2(tdc)2dabco] is 67.4 cm3·g–1 (13.2 wt %) at 298 K and 153 cm3·g–1 (30.0 wt %) at 273 K. For [Zn2(bdc)2dabco], the equivalent values are 46 cm3·g–1 (9.0 wt %) and 122 cm3·g–1 (23.9 wt %), respectively. The isosteric heat of adsorption for CO2 in [Zn2(tdc)2dabco] at zero coverage is low (23.65 kJ·mol–1), ensuring facile regeneration of the porous material. Enhancement by the thiophene group on the separation of CO2/N2 gas mixtures has been confirmed by both ideal adsorbate solution theory calculations and dynamic breakthrough experiments. The preferred binding sites of adsorbed CO2 in [Zn2(tdc)2dabco] have been unambiguously determined by in situ single-crystal diffraction studies on CO2-loaded [Zn2(tdc)2dabco], coupled with quantum-chemical calculations. These studies unveil the role of the thiophene moieties in the specific CO2 binding via an induced dipole interaction between CO2 and the sulfur center, confirming that an enhanced CO2 capacity in [Zn2(tdc)2dabco] is achieved without the presence of open metal sites. The experimental data and theoretical insight suggest a viable strategy for improvement of the adsorption properties of already known materials through the incorporation of sulfur-based heterocycles within their porous structures.

Toward Asymmetric Synthesis of Pentaorganosilicates

Introducing chiral silicon centers was explored for the asymmetric Rh-catalyzed cyclization of dihydrosilanes to enantiomerically enriched spirosilanes as targets to enable access to enantiostable pentacoordinate silicates. The steric rigidity required in such systems demands the presence of two naphthyl or benzo[b]thiophene groups. The synthetic approach to the expanded spirosilanes extends Takai’s method (Kuninobu et al. in Angew Chem Int Ed 52(5):1520–1522, 2013) for the synthesis of spirosilabifluorenes in which both a Si–H and a C–H bond of a dihydrosilane are activated by a rhodium catalyst. The expanded dihydrosilanes were obtained from halogenated aromatic precursors. Their asymmetric cyclization to the spirosilanes were conducted with [Rh(cod)Cl]2 in the presence of the chiral bidentate phosphane ligands (R)-BINAP, (R)-MeO-BIPHEP, and (R)-SEGPHOS, including derivatives with P-(3,5-t-Bu-4-MeO)-phenyl (DTBM) groups. The highest enantiomeric excess of 84% was obtained for 11,11′-spirobi[benzo[b]-naphtho[2,1-d]silole] with the DTBM-SEGPHOS ligand.

Hg2+ chromogenic and fluorescence indicators based on rhodamine derivatives bearing thiophene group

In this paper, chromogenic and fluorescent indicators have been prepared that can be used to detect Hg2+ in aqueous solutions. Through amide condensation reaction and primary amine-aldehyde reaction, sulfur containing thiophene group was connected to rhodamine B with diethylene triamine as bridge molecule, and rhodamine B-diethylene triamine sulfide was prepared and characterized. The prepared indicator can accurately detect Hg2+ in the environment without being interfered by other common metal ions such as ions of Na+, K+, Mg2+, Zn2+, Fe3+, Cu2+, Zn2+ and Cr3+. As the concentration of Hg2+ increases, the UV–vis absorbance at 560 nm grows. According to the Benesi-Hildebrand equation, combined with the UV–vis characterization, the stoichiometry between Hg2+ and the prepared indicator proved to be 1:1. The detection limit of detection of Hg2+ was equal to 1.95 × 10−7 mol/L, and the response of the solution turned to red after adding the indicator can be displayed within 2 min. This indicator applies to weakly acidic to neutral environments.

Design and synthesis of a novel tripod rhodamine derivative for trivalent metal ions detection

A tripod rhodamine derivative (L) with flexible chains was synthesized through linking tris(2-aminoethyl)amine appended rhodamine and two thiophene groups. Based on the synergetic action of the acidic medium provided by trivalent metal ions and stability complex came from trivalent metal ions and probe L, the probe displayed higher selectivity and sensitivity in CH3OH/H2O (1/3) solution. The formation of these complexes caused a new absorption peak appearance at 555 nm along with color changes of the solution. Meanwhile, a drive fluorescence behaviors of probe L by the trivalent metal ions were observed with a dramatical enhancement of the fluorescence at 585 nm, respectively. Interestingly, introducing EDTA to the probe L/Fe(III) complex, the fluorescence intensity of the complex was further enhanced. Based on the high throughput analysis strategy, the probe L was designed as a logic gate for detecting trivalent metal ions. Typically, the combination ratio of the probe L with Fe(III) was 1/1 (mole), which was obtained by Job-plot experiment and further confirmed by DFT calculations. Moreover, the tripod rhodamine derivative as a “turn-on” fluorescence switch was applied to detect Fe(III) in actual sample.

Effects of Single Atom N-Substitution in the Molecular Skeleton on Fabricated Film Quality and Memory Device Performance

In this paper, two conjugated organic small molecules, NITP and NITZ, were designed and synthesized. NITZ is just altered by single atom N-substitution from the NITP thiophene group to the thiazole group in the heterocyclic aryl ring of the skeleton. The morphology and intermolecular stacking style of the fabricated nanofilms were analyzed by atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), and X-ray diffraction (XRD). It demonstrates that both molecules prefer highly ordered packing after annealing, and the crystallite orientation is even more superior by N-substitution. As a result, both memory devices exhibit ternary memory performance. This study highlights that the thiazole group also constitutes a good candidate for a π-bridge of organic semiconducting molecules, and it really provides a simple and refined strategy for designing multilevel memory materials by single atom substitution.

Development and Characterization of Novel Conductive Nanofiller Based on Multi-Walled Carbon Nanotubes Grafted with Poly(3,4-Ethylenedioxythiophene)

In the present study, an approach for the graft polymerization of multi-walled carbon nanotubes (MWCNTs) with 3,4-ethylenedioxythiophene (EDOT) has been evaluated. The surface of the MWCNTs was activated with thiophene groups through the amide linker followed by oxidative polymerization of EDOT monomer resulted in the development of PEDOT-g-MWCNTs. The methods of thermal gravimetric analysis (TGA), X-ray fluorescence, and Raman spectroscopy were used for characterization of functionalization efficiency. The TGA data indicated of 21% functionalization attached to MWCNTs. X-ray fluorescence confirmed the presence of Cl, and S atoms in functionalized fillers. The study of Raman spectra confirmed the presence of PEDOT groups attributed to most characteristic signal at 1400-1500 cm-1 region. The electrical conductivity for both pristine MWCNT and PEDOT-g-MWCNT powder materials was compared.

Study on 2-thiophenecarbonyl chloride-quenched olefin polymerization with α-diimine nickel catalysts

The number of active centers in α-diimine nickel-catalyzed olefin homogeneous polymerization system is rarely studied before. A systemic study on quenching method with 2-thiophenecarbonyl chloride (TPCC) in homogeneous catalytic system is presented. Ethylene and propylene polymerizations catalyzed with homogeneous α-diimine nickel catalysts (ArN=C(An)–C(An)=NAr)NiBr2 (cat.1, Ar=2,6-C6H3(i-Pr)2) and (ArN=C(C12H8)C=NAr)NiBr2 (cat.2, Ar=2,6-C6H3(i-Pr)2, C12H8=acenaphthene-1,8-diyl) were quenched by TPCC. The potential side reaction between TPCC and alkyl aluminum-terminated polymer chain caused by chain transfer to cocatalyst under different quenching conditions was investigated. Samples were obtained with different TPCC/AlMAO molar ratios and had similar sulfur contents; a confirmation that the excess TPCC in the system did not cause obvious side reactions which could lead to place more thiophene groups to the polymer chains. Moreover, when the quenching time was in the range of 3–20 min, the sulfur contents remained stable and the value of Npol (number of moles of polymer chains) was not obviously changed, supporting that sufficient quenching reaction had already accomplished within the first 3 min. We claimed that the side reaction could be ignored under controllable conditions. TPCC was confirmed to be an effective quenching agent in homogeneous catalytic system. The quenching method with TPCC was also established.

Polybrominated BOPHY Dyes: Synthesis, Reactivity, and Properties.

A series of mono- to hexabrominated BOPHY dyes have been regioselectively synthesized in 41-96% yields from bromination of parent bis(difluoroboron)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (BOPHY), bromination of hydrazine-linked bispyrrole intermediate, or brominated 2-formylpyrrole precursors in moderate to excellent yields. The reactivities of these polybrominated BOPHY dyes were further studied via regioselective nucleophilic substitution or Suzuki/Stille cross-coupling reactions from which a series of 5- or 5,5'-substituted BOPHYs with amine, pyrrole, thiophene, and phenyl groups were obtained in moderate to high yields of 37-94%. The regioselectivities of both the bromination and nucleophilic substitution reaction, and these resultant BOPHY dyes, are confirmed by NMR, HRMS, and crystal structures. The spectroscopic properties of these resultant BOPHYs were studied, and most of them showed strong absorbance and bright fluorescence with maximum wavelengths centered at between the range of 430 and 660 nm. Their absorption and emission spectra were red-shifted for each bromine atom incorporated. The positions in which bromines or substituents are attached modulate the photophysical properties of the resulting BOPHY dyes.

A novel hydrophilic pyridinium salt polymer/SWCNTs composite film for high thermoelectric performance

Polymer/carbon nanotube composites have gained great progress in the past decade. However, the lack of scalability of production due to the relatively high volatility and strong toxicity of the dispersion solvent have created a great need for environmental friendly process for expanding TE applications. In this work, organic-inorganic composite films composed of a novel hydrophilic pyridinium salt polymer (noted as P2) and SWCNTs were prepared for thermoelectric application. The novel hydrophilic pyridinium salt polymer was designed and synthesized containing the pyridinium salt for aqueous dissolution and thiophenes as the conjugation group to make the polymer/CNT composite film electrical connecting, therefore improving the thermoelectric performance. Another pyridinium salt polymer (noted as P1) without thiophene group was also synthesized for the purpose of comparison. The polymers attach on the surface of CNTs through π-π conjugation interaction between conjugation groups and π-electrons of CNTs. The P2/CNT composites were homogeneously dispersed in the aqueous solution, revealing better dispersion behavior than P1/CNT, which is probably because of the stronger contact interaction between P2/CNT than P1/CNT due to the higher electron delocalization of polymer P2 than P1. The electrical conductivity of P2/CNT composite film reached the maximum value of 159 S/cm with 50% CNT content. Consequently, a high power factor of 46.4 μW/mK2 was obtained for the P2/50%CNT composite film.

The effect of different π-bridge configuration on bi-anchored triphenylamine and phenyl modified triphenylamine based dyes for dye sensitized solar cell (DSSC) application: A theoretical approach

Twenty eight bi-anchored triphenylamine (TH-1 to TH-14) and phenyl modified triphenylamine (PH-TH-1 to PH-TH-14) based metal free organic dyes are designed for DSSC application. The electronic effect of different π-bridge configurations in donor-π-bridge-acceptor (D-π-A)2 structure was theoretically simulated and verified using density functional theory (DFT) and time dependent density functional theory (TD-DFT). The triphenylamine and phenyl modified triphenylamine groups are used as donor and cyanoacrylic acid group is used as acceptor. Thiophene and cyanovinyl groups are used as π-bridge. The ground state molecular structure was optimized by density functional theory and the electronic absorption spectra were calculated by time dependent density functional theory. The light harvesting efficiency (LHE), dye regeneration energy (ΔGreg) and electron injection energy (ΔGinject) are determined by computational examination. It is observed that, when the number of π-bridge increases, the band gap of the dye decreases. Also the absorption maximum and molar extinction coefficient of the dyes are increased. Theoretical result shows that the thiophene-cyanovinyl and thiophene-thiophene-cyanovinyl–cyanovinyl configurations give broader and red shifted absorption spectrum compared to other configurations. Also the results of phenyl modified triphenylamine (PH-TH) dyes clearly show better absorption and dye regeneration energy compared to TH dyes.

A Gold-Catalyzed Domino Cyclization Enabling Rapid Construction of Diverse Polyheterocyclic Frameworks.

We report herein an efficient gold(I)-catalyzed post-Ugi domino dearomatization/ipso-cyclization/Michael sequence that enables access to libraries of diverse (hetero)arene-annulated tricyclic heterocycles. This process affords novel complex polycyclic scaffolds in moderate to good yields from readily available acyclic precursors with excellent chemo-, regio-, and diastereoselectivity. The power of this strategy has been demonstrated by the rapid synthesis of 40 highly functionalized polyheterocycles bearing indole, pyrrole, (benzo)furan, (benzo)thiophene, pyrazole, and electron-rich arene groups in two operational steps.