Aromatic Thiophene Research Articles

Pre-screening of an eco-friendly solvent for separating industrial mixtures: A useful tool for solvent selection

In this work, gas liquid chromatography was used to obtain the retention data of volatile organic solvents (here referred as solutes) at different temperatures, T = (313.15 - 353.15) K and at atmospheric pressure. The retention data obtained was used to compute the activity coefficients at infinite dilution. The solvent was prepared by the combination of 1‑butyl‑2,3-dimethylimidazolium chloride and diethylene glycol at 1:2 molar ratio and was used as a stationary phase to evaluate intermolecular interactions of various volatile organic solvents, including (aromatic hydrocarbons, ketones, alkanes, alkenes, alkynes, alcohols, thiophene, acetonitrile and tetrahydrofuran). Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy were utilized to determine any possible shifts when the two compounds were assorted. TGA/DSC 1 was also utilized to determine the thermal stability of the investigated solvent and to confirm that there will be no bleeding on the column loading when operated at T = (313.15 - 353.15) K. The excess thermodynamic properties at infinite dilution including enthalpies, Gibbs free energies and entropy term were computed to further explain the types of interactions occurring between the systems. The activity coefficients at infinite dilution data were used to calculate the separation parameters (selectivity and capacity) to evaluate the feasibility of the solvent in separating the industrial mixtures. Values pertaining to selectiveness and capacity were evaluated and compared to other extracting solvents found in literature for the separation of azeotropic mixtures. The attained activity coefficients at infinite dilution data reveals that the investigated solvent better separate solutes at low temperatures and this is an added advantage when using 1‑butyl‑2,3-dimethylimidazolium chloride to diethylene glycol. In addition, the investigated solvent was found suitable for the extraction of azeotropic mixtures comprising alkanes and alcohols.

Effect of different side chains on alternating copolymers of benzodithiophene and thiophene in organic solar cells

AbstractPolymeric semiconductors offer the dual advantages of lightness and flexibility, facilitating the large‐scale production of organic electronic devices. In the present research, electron donor polymers were synthesized incorporating high electron density aromatic units, specifically benzodithiophene (BDT) and thiophene (Th), to explore their efficacy in organic electronics. This systematic study focused on evaluating the impact of varying side chains on the material properties of these polymers. It was found that polymers with Th side chains exhibited significantly enhanced thermal stability, approximately 100°C higher than their alkoxide side chain counterparts. For the polymer PEHO‐BDT3HT, a bandgap value of around 1.6 eV was obtained. Furthermore, binary devices were developed using these novel copolymers, among which PDT‐BDT3HT demonstrated superior photovoltaic performance, achieving a power conversion efficiency of 1.56% without any optimization. This work not only sheds light on the influence of side chain variations in polymer properties but also showcases the potential of BDT and Th‐based copolymers in the field of organic electronics.

Intramolecular Donor–Acceptor Design in Porous Organic Framework for Liquid Fuels Adsorption Desulfurization

AbstractA porous organic framework containing well‐defined donor–acceptor units, named donor–acceptor porous organic framework (D–A‐POF), is successfully synthesized. The localized electric field gradient at the pore surface induced by the intramolecular donor–acceptor (D–A) interactions endows D–A‐POF with excellent desulfurization capabilities. D–A‐POF exhibits high adsorption capacity of 3‐methylthiophene (12.26 mmol g−1, 392.32 mg S g−1) and 1‐benzothiophene (793.65 mg g−1, 189.25 mg S g−1) with impressive adsorption selectivity. Density functional theory calculations provide compelling evidence of the preferential selective adsorption of aromatic thiophene sulfides in D–A‐POF. In fixed‐bed breakthrough experiments, D–A‐POF demonstrates its ability to selectively capture thiophene sulfides from model gasoline, resulting in fuel with sulfide content below 10 ppb. The high stability and high desulfurization efficiency of D–A‐POF make it promising as a new porous adsorbent for ultra‐depth adsorption desulfurization.

Non-target and target analysis to identify and characterize thiophenes in soil from an abandoned coking plant

There is concern about the large amounts of aromatic compounds emitted during coking. Previous studies of coking emissions have been focused on polycyclic aromatic hydrocarbons, dioxin-like compounds, phenols, and volatile organic compounds, but previously unidentified compounds produced during coking may also harm human health. Here, the main pollutants in 69 soil samples from an abandoned coking plant were identified by non-target screening using two-dimensional gas chromatography time-of-flight mass spectrometry. Polycyclic aromatic hydrocarbons, long-chain alkanes, and thiophenes were dominant. High concentrations of thiophenes (benzothiophenes, dibenzothiophenes, and benzonaphtholthiophenes) were found. Quantitative analysis of 12 thiophenes (selected because of their concentrations and detection frequencies) was performed, and the concentrations were 0.03–647 μg/g dry weight, which were extremely high compared with concentrations in soil from uncontaminated sites and other industrial sites. Dibenzothiophene and benzo[b]naphtho[2,1-d]thiophene were dominant, accounting for 69% of the total thiophene concentration. Thiophene profiles in very contaminated areas were different from the profile in coal but similar to the profile in tar. Thiophenes in soil at the coking plant may have been supplied in tar leaks, wastewater, coke oven gases, and exhaust gases. A toxicity assessment indicated a strong likelihood of oxidative stress being induced by exposure to multiple thiophenes at the coking plant. The results suggest that thiophene emissions from coking plants should attract more attention than currently.

Theoretical and experimental investigation of bridging atom effect on the fluorene and silafluorene based trimeric monomers and their corresponding polymers

A series of monomers bearing fluorene and silafluorene with different bridging atoms and 3,4-ethylenedioxythiophene (EDOT) and 3,4-propylenedioxythiophene (ProDOT) as the donor units were synthesized via Stille coupling. To investigate the effect of different donor units and different bridging atoms, the optical and electrochemical behaviors of the monomers and their corresponding polymers were investigated by some electroanalytical and spectroscopic techniques. Electropolymerization of monomers was carried out potentiodynamically via repetitive cycling. Electrochemical investigations revealed that silafluorene bearing monomers and their corresponding polymers were found to exhibit slightly lower oxidation potentials and lower band gap (Eg) values as compared to their fluorene-containing analogs. Moreover, a comparison between two different donor groups revealed that the Eg of polymers bearing EDOT units was found to be lower (about 0.30 eV) as compared to ProDOT bearing ones due to the twist structure of ProDOT that reduces the overlap between the oxygen lone pairs and the aromatic thiophene ring. The results were further confirmed by DFT calculations.

A comprehensive method of ionic liquid screening and experimental verification for simultaneous separation of multiple sulfides from oil

Ionic liquid (IL) as the extractant has shown an excellent performance in oil desulfurization. However, it is still a great challenge to select an appropriate IL that can simultaneously remove multiple sulfides from oils due to enormous ILs' quantities. In this work, an ILs' screening method based on the fuzzy comprehensive evaluation function and COSMO-RS method was developed for oil extraction desulfurization. Four typical aromatic thiophene sulfides – thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) were considered as the removal targets, and n-heptane was chosen as the model oil. By this method, a single IL – 1-butyl-3-methylpyridinium dicyanamide ([BMPy][DCA]) was selected from 702 ILs for removing the four sulfides from n-heptane. Liquid-liquid equilibrium (LLE) data of n-heptane + TS/BT/DBT/4,6-DMDBT + [BMPy][DCA] systems at 298.15 K were measured and then correlated by the NRTL equation. A data processing method for LLE experimental indices, distribution coefficient and selectivity, was proposed for their crossed curves and different measuring ranges to facilitate the comparison of ILs' extraction performance. The comprehensive experimental indices based on this processing method were compared with the comprehensive predicted indices obtained by screening. The results showed a consistent trend between the two, and the excellent desulfurization performance of [BMPy][DCA] was confirmed. The separation mechanism was then analyzed through the quantum chemistry method. The results showed that the interactions of four sulfides with either n-heptane or [BMPy][DCA] both were the van der Waals interaction and steric effect. The [BMPy][DCA] could attract the sulfides more potently than the n-heptane, demonstrating the extraction's mechanism and characteristics. The stronger itself interactions of BT, DBT and 4,6-DMDBT as solid sulfides limited their solubility in liquid–liquid two phases. In addition, the decomposition of interaction energy showed that the attraction between the sulfides and the [BMPy][DCA] was dominated by dispersion, assisted by electrostatics, and equipped with a small amount of induction. The essence of repulsion between them was the exchange-repulsion.

Recent Advances in Selenophene-Based Materials for Organic Solar Cells.

Due to the low cost, light weight, semitransparency, good flexibility, and large manufacturing area of organic solar cells (OSCs), OSCs have the opportunity to become the next generation of solar cells in some specific applications. So far, the efficiency of the OSC device has been improved by more than 20%. The optical band gap between the lowest unoccupied molecular orbital (LUMO) level and the highest occupied molecular orbital (HOMO) level is an important factor affecting the performance of the device. Selenophene, a derivative of aromatic pentacyclic thiophene, is easy to polarize, its LUMO energy level is very low, and hence the optical band gap can be reduced. In addition, the selenium atoms in selenophene and other oxygen atoms or sulfur atoms can form an intermolecular interaction, so as to improve the stacking order of the active layer blend film and improve the carrier transport efficiency. This paper introduces the organic solar active layer materials containing selenium benzene in recent years, which can be simply divided into donor materials and acceptor materials. Replacing sulfur atoms with selenium atoms in these materials can effectively reduce the corresponding optical band gap of materials, improve the mutual solubility of donor recipient materials, and ultimately improve the device efficiency. Therefore, the sulfur in thiophene can be completely replaced by selenium or oxygen of the same family, which can be used in the active layer materials of organic solar cells. This article mainly describes the application of selenium instead of sulfur in OSCs.

Novel thiophene derivatives as eco-friendly corrosion inhibitors for mild steel in 1 M HCl solution: Characterization, electrochemical and computational (DFT and MC simulations) methods

Two novel organic aromatic thiophene derivatives, 5-(thiophen-2-yl)− 1 H-tetrazole (TET) and thiophene-2-carbaldehyde oxime (OXM) were investigated for their anticorrosion properties on the mild steel (M-S) in a 1 M HCl media. The two organic inhibitors have significant resistance to the effect of time of immersion, for example, the effectiveness of the molecule TET increases with the increase in time until 12 h and the molecule OXM effectiveness remains almost stable. The adsorption mechanism of OXM and TET was evaluated by electrochemical measurements (polarization and impedance spectroscopy), ultraviolet-visible spectrophotometry (UV–Vis), scanning electron microscopy (SEM) joint with energy dispersive analysis of X-rays (EDAX). The effectiveness of these molecules was significantly influenced by temperature, immersed time, and concentration [10−6 M − 10−3 M], reaching a maximum of 94 %, and 95 % for OXM and TET, respectively, at 10−3 M. In addition, the maximum shift in Ecorr values is 10–17 mV, which implies that the investigated thiophene compounds are mixed-type (anodic/cathodic) inhibitors. SEM micrographs confirmed the formation of a protective layer adsorbed on the M-S surface. The Electrophilic/nucleophilic attacks (Fukui indices) on M-S are theoretically determined. Strong consistency of findings obtained by computational (DFT and MC simulations) and electrochemical tests were demonstrated.

Complete Set of Diketopyrrolopyrrole Centrosymmetrical Cofacial Stacked Pairs.

Stacked centrosymmetrical dimers and simultaneously H-bonded and stacked hexamers of thiophene-substituted diketopyrrolopyrrole (ThDPP) were studied using DFT as models for crystals with slipped-stacked molecules in 1D columns. Eight stacked dimer arrangements were found, six of which are driven by the minimisation of electron repulsion and realised by placing the partially negatively charged atoms of the diketopyrrolopyrrole rings below the centre of an adjacent thiophene ring. Four of these stacks are related to N,N'-dialkylated derivatives of ThDPP found in the literature, while a further one is related to an N,N'-diacylated derivative. An analogous set of eight stacks was discovered computationally for phenyl-substituted DPP (PhDPP), four of which are known among H-bonded DPP pigments, and one more among N,N'-dialkylated PhDPP derivatives. The results shed more light on the mechanisms that drive the formation of stacks between nonaromatic (DPP) and aromatic (Th, Ph) rings. The excitation energies of the lowest four singlet states computed by TD DFT enabled excitonic coupling and energy separation between Frenkel-resonance-type and charge-transfer states to be established, depending on the equilibrium stack geometry.

Noncovalent Interactions between Aromatic Heterocycles and Carboxylic Acids: Rotational Spectroscopy of the Furan-Formic Acid and Thiophene-Formic Acid Complexes.

The binary molecular complexes formed between the aromatic heterocycles furan and thiophene with formic acid were investigated using pulsed-jet Fourier transform microwave spectroscopy and quantum chemical computations. For both of the complexes, rotational spectra of the lowest energy isomer were detected and assigned. Rotational spectroscopic results and density functional theory calculations support that the preferred conformation of the furan-formic acid complex is characterized by a relatively strong O-H···O and a weak C-H···O hydrogen bonds while the O-H···π and C-H···O hydrogen bonds stabilize the thiophene-formic acid complex. Natural bond orbital analysis further proves the experimental observation, suggesting that the strength of the O-H···O(furan) interaction is about two times stronger than that of O-H···π(thiophene). The symmetry adapted perturbation theory analysis reveals that electrostatic interaction is dominant in stabilizing the two complexes and that dispersion becomes significant in the thiophene-formic acid complex compared to furan-formic acid.

Molecular Dynamic Insights into the Distinct Solvation Structures of Aromatic and Aliphatic Compounds in Monoethanolamine-Based Deep Eutectic Solvents.

Deep eutectic solvents (DESs) are developing as an alternate medium for aromatic extraction, especially benzene and thiophene from aliphatic hydrocarbon mixtures. In this work, molecular dynamics (MD) simulations were first used to investigate the solvation structure of benzene, thiophene, and n-hexane in monoethanolamine-based DESs. It reveals the liquid structures in the adjacent neighbor shells, which is a function of electron-withdrawing sulfur attached to thiophene and the π-electron cloud of benzene. The intermolecular forces between aromatic, aliphatic, and DES components are analyzed in van der Waals and hydrogen bond interactions. The chloride ions serve as a charge carrier bridge between choline and monoethanolamine precursors. The solvation of benzene, thiophene, and n-hexane in the DESs depends on volume expansion and minor solvent structural changes. Density functional theory results provided information on the mechanism of short-range interactions between organic solutes and studied DES. It aids in understanding the structural orientations of a DES with the addition of solutes, essential to the formation of DES. The solvation shell structure and characteristics were investigated in tandem with the possibility of benzene and thiophene clustering. The 1H NMR and 2D 1H-1H-NOESY were used to investigate the intermolecular interactions between benzene, thiophene, and n-hexane with monoethanolamine-based solvents. It concludes that high-ordered DES1 is more inclined to higher solubility than lower-ordered ones with a higher molar ratio of monoethanolamine. The solvation was reduced because the entropy gain was not maximized in the lower ordered DESs.

Rhodium-Catalyzed Ring Expansion Reactions for the Concise Construction of Densely Functionalized Oxathionines and Oxathiocines

Ring expansion reactions have been proven to be efficient tools for building medium-sized rings with broad applications in synthetic and medicinal chemistry. However, the strategy involving pericyclic or pseudopericyclic pathways via sulfur ylide-initiated [1,4]-sigmatropic rearrangement remains an under-exploited area. Herein, we disclose an interesting ring expansion of thiochromenes and aromatic thiophenes via rhodium catalysis, which enables the straightforward assembly of polyaromatic oxathionines and oxathiocines with diverse functionalities. The mechanistic investigation via DFT calculations revealed this ring expansion transformation to be a [1,4]-sigmatropic rearrangement via a metal-free sulfur-based ylide.

Removing ionic and organic mercury from light hydrocarbon liquids by ordered zeolite-templated carbon doped with sulphur

Sulphur-doped, β-zeolite-templated carbons (S-β-ZTCs) were synthesized by chemical vapor co-deposition of hydrogen sulfide (H2S) and acetylene (C2H2) to remove ionic (Hg2+) and organic mercury (Hgorg) from gasoline. In situ doping of sulphur introduced aromatic thiols and thiophenes into the ZTC's framework that removed the mercury by forming Hg–S bonds. Notably, these covalently bonded sulphur groups exhibited better stability than physically deposited elemental sulphur, yielding less than 10% material loss after repeated adsorption-desorption tests. Thanks to these unique chemical properties, the adsorption capacity of S-β-ZTCs for Hg2+ in the gasoline (2660 μg/g) was at least an order of magnitude larger than that of common adsorbents. Moreover, simultaneous adsorption of Hg2+ and Hgorg on S-β-ZTCs proceeded independently when the total mercury concentration was in the range applicable to most natural gas condensate samples. Finally, Grand Canonical Monte Carlo (GCMC) method and Density Functional Theory (DFT) study were used to reveal the adsorption mechanism of ZTCs on Hg2+ and Hgorg. These findings provided a better understanding of the mercury sorption mechanism of S-β-ZTCs and have important practical significance for the clean production of the condensate processing industry.

All are aromatic: A 3D globally aromatic cage containing five types of 2D aromatic macrocycles

All are aromatic: A 3D globally aromatic cage containing five types of 2D aromatic macrocycles

Theoretical assessment of the influences of aromatic bridges on molecular second order nonlinear optical responses of Donor-Bridge-Acceptor types of molecular organic chromophores

Push-pull types Donor-Bridge-Acceptor (D-B-A) organic molecules have been reported as efficient functional materials for various technological applications. Often their interesting properties were reported to be directly linked to their nature of intramolecular charge transfers (ICT). Bridge that connects the D with A, plays the vital role in the ICT processes. A recent report of comparative experimental and computational nonlinear optical (NLO) study, shows many interesting behaviours exhibited by aromatic (diazine, thiophene and benzene rings) bridges. Many earlier studies also exist, where effects of one or more of aromatic bridges were investigated for NLO applications. But no systematic comparative study with well-known aromatic bridges at one place exist in literature. Inspired by those earlier works, this computational work reports the influences of a set of mono-aromatic ring bridges on NLO properties for a set of D-B-A types of organic molecules. This work can be expected to serve as a reference for many researchers working in the search of new and efficient functional materials.

Terminal π-group engineering of organic co-sensitizers for thiourea dye based dye-sensitized solar cells

To enhance the conversion efficiency of organic dye sensitized solar cells (DSSCs) via the co-sensitization strategy, a series of organic co-sensitizers (CS1–3) for thiourea dye D8 were designed and synthesized. They take carbazole as the donor unit and 2-cyanoacrylic acid as the anchoring group. Their π-bridges contain a thiophene primary spacer and a different terminal aromatic linker, i.e., thiophene, furan, and benzene for CS1–3, respectively. The effects of different terminal spacer group on the optical, electrochemical, and photovoltaic properties of carbazole-based co-sensitizers were investigated comprehensively. Moreover, the roles of CS1–3 as co-sensitizers for D8 are further examined. The co-sensitized cells based on D8 and CS3 exhibited the highest power conversion efficiency (PCE) of 8.53%, which was superior to that of devices with D8 (PCE = 7.92%). Theoretical calculation investigation revealed that CS3 incorporating a benzene terminal group possessed the most twisty configuration, which may be beneficial to the prevention of aggregation and electron recombination. Furthermore, incident photon to current efficiency (IPCE) spectra and electrochemical impedance spectroscopy (EIS) investigations were performed to clarify the mechanism of the co-sensitization behavior.

Deciphering Benzene–Heterocycle Stacking Interaction Impact on the Electronic Structures and Photophysical Properties of Tetraphenylethene-Cored Foldamers

Deciphering Benzene–Heterocycle Stacking Interaction Impact on the Electronic Structures and Photophysical Properties of Tetraphenylethene-Cored Foldamers

Crystal structure and Hirshfeld surface analysis of 2-methyl-3-nitro-N-[(E)-(5-nitro-thio-phen-2-yl)methyl-idene]aniline.

The title compound, C12H9N3O4S, synthesized by condensation of 5-nitro-thio-phene-2-carbaldehyde and 2-methyl-3-nitro-aniline, crystallizes in the ortho-rhom-bic space group P212121. In the mol-ecule, the aromatic benzene and thio-phene rings are twisted with respect to each other, making a dihedral angle of 23.16 (7)°. In the crystal, mol-ecules are linked by inter-molecular C-H⋯O hydrogen bonds into chains extending along the c-axis direction. Weak π-π stacking inter-actions along the a-axis direction provide additional stabilization of the crystal structure. The roles of the various inter-molecular inter-actions were clarified by Hirshfeld surface analysis, which reveals that the crystal packing is dominated by O⋯H (39%) and H⋯H (21.3%) contacts. The crystal studied was refined as a two-component inversion twin.

First deep eutectic solvent-based (DES) stationary phase for gas chromatography and future perspectives for DES application in separation techniques

The paper presents the first application of deep eutectic solvents (DES) as stationary phases for gas chromatography. DES obtained by mixing tetrabutylammonium chloride (TBAC) as a hydrogen bond acceptor (HBA) with heptadecanoic acid being a hydrogen bond donor (HBD) in a mole ratio of HBA:HBD equal to 1:2 was characterized by its ability to separate volatile organic compounds (VOCs). The Rohrschneider – McReynolds constants determined reveal that the synthesized DES is a stationary phase of medium polarity. A detailed retention characteristic was determined for a number of groups of chemical compounds, including aromatic hydrocarbons, alcohols, ketones, sulfides and thiophene derivatives. The synthesized DES was found to have a high selectivity towards alcohols. At the same time, the investigated stationary phase was found to have specific interactions with some analytes. For example, a stronger retention was observed for 1-hexanol and 1-heptanol compared to other alcohols. Retention times of these two alcohols are longer by 191% and 300%, respectively, relative to the expected value based on their boiling point. Such an increased retention is caused by a synergistic effect of various kinds of interactions – the possibility of formation of hydrogen bonds between the DES and the hydroxyl group of alcohols and hydrophobic interactions of alkyl chains of the DES with the alkyl chain of alcohols. The ability to modify properties of DESs by replacement of HBA or HBD with a different chemical compound or by dissolving in DES macromolecular substances makes the proposed stationary phase highly flexible. In addition to using the developed DES in chromatographic techniques, the retention data collected indicate the possibility of its application to other separation techniques, i.e. extractive distillation.

Design of novel conjugated microporous polymers for efficient adsorptive desulfurization of small aromatic sulfur molecules

This paper presents a computational study of the adsorptive desulfurization of small aromatic sulfur compounds by conjugated microporous polymers (CMPs). The density-functional tight-binding method augmented with an R−6 dispersion correction is employed to investigate the physisorption binding mechanism and electronic properties of the CMP-aromatic sulfur complexes. We show that the widely extended π conjugation in the CMP skeletons is favorable for the non-covalent adsorption of aromatic thiophene and dibenzothiophene via π–π, H–π, and S–π interactions. The average binding energies are calculated to be −6.2 ∼ −15.2 kcal/mol for CMP- thiophene/dibenzothiophene systems. For the dibenzothiophene molecule with larger size and more extended conjugation, it binds more than twice stronger to CMP than the thiophene molecule. We show that the replacement of quinoline unit to the phenylene group in the network linker effectively enhances the average binding capacities by around 0.8–1.8 kcal/mol. Our calculations theoretically demonstrate that CMPs materials are kind of promising candidates for the adsorptive desulfurization of small aromatic sulfur compounds. This paper provides useful theoretical guidance for design of novel carbon-based adsorbents for adsorptive desulfurization.