Position Of Thiophene Research Articles

In-depth quantitative and theoretical study of ambident electrophilies of 2-bromo-3-X-5-nitrothiophenes

As part of our continuing studies into the electron deficient nature of five-membered ring heterocycles, specifically 2‑methoxy-3-X-5-nitrothiophenes and 3-X-5-nitrothiophene, we report here a kinetic study of σ-complexation reactions involving 2‑bromo-3,5-dinitrothiophene 1 and various nitroalkyl anions in aqueous solution at 20 °C. Theoretical calculations at the density functional theory (DFT) level were performed to confirm the proposed mechanism. From the previously reported nucleophilicity parameters N and sN for the nucleophiles 2 and the derived second-order rate constants, the electrophilicity parameter (E) at the C-4 position of thiophene 1 was quantified according to the linear free enthalpy relationship log k (20 °C) = sN (E + N). Mayr's approach accurately predicted the rate constants for the reactions of this thiophene 1 with a series of para-substituted phenoxide anions in water at 20 °C. A reasonable correlation between calculated global electrophilicity index ω values and experimental electrophilic reactivities was observed and discussed.

Molecular-Docking Study of Thiophene analogues against GABAa Receptor used to design New Antiepileptic agents

Heterocyclic compounds are widely spread in nature and have diversified application in design of new drug molecule. This approach is used to design new antiepileptic agents. Based on various findings, one of the target protein for antiepileptic molecule is selective gamma amino butyric acid (GABA). Selective GABA is the controller of CNS activity. In this study, thiophene derivatives were used to design the new antiepileptic agents through a selective GABA activation. The probable activity of thiophene derivatives could be increased by substitution in all position of thiophene except 1st. Molecular docking of selective GABA activation was required to predict their antiepileptic activity. The molecular docking of thiophene analogues was carried out using AutoDock viva Ver.1.1.2. Twenty thiophene analogues were docked into GABAa with Protein data bank (PDB) code 4cof. The interaction was assessed based on the docking score. Diazepam was used as the standard for this study. Twenty thiophene analogues showed the approximate docking score -6.3 to -9.6 kcal/mol. Thirteen thiophene analogues which value that have greater docking score compared to diazepam used as a standard. Compound T-15 had higher binding energy than other thiophene analogue because it has the lowest docking score. All new thiophene analogues are possible to be synthesize and performed their pre-clinical evaluation.

The isotope effect on charge transport for bithiophene and di(n-hexyl)-bithiophene: impacts of deuteration position, deuteration number and side chain substitution position

The isotope effect on charge transport had been proposed to judge the transport mechanism in organic semiconductors. By using quantum nuclear tunneling model, we found that isotopic substitution could reduce mobility. For deeply understanding the impacts of the isotopic substitution position, substitution number and even molecular structure on the isotope effect, we take 2,2′-bithiophene and its dihexyl substitutions as examples to study the deuteration effect on hole transport. For deuterated–bithiophene, the isotope effect is linearly increasing with deuteration number. However, when the number is identical, deuteration on 5(5′)-position of thiophene will lead to stronger isotope effect than 3(3′)- or 4(4′)-position, since the reorganization energy contributed by 5-position hydrogen atoms is larger. For di(n-hexyl)-bithiophene isomers, 5,5′-dihexyl substitution also exhibits the strongest isotope effect after hexyl-deuteration or all-deuteration, due to the larger reorganization energy contributed by hexyl group in 5(5′)-position rather than 3(3′)- and 4(4′)-positions. Our calculation indicates that for identical system, the isotope effect is closely related to the number and position of isotopic atoms, while for isomers, the isotope effect is also related to the molecular configuration, such as the position of side chain substitution.

Rhodanine side-chained thiophene and indacenodithiophene copolymer for solar cell applications

In this work, 2-(3-ethyl-4-oxothiazolidin-2-ylidene)malononitrile is connected on the β position of thiophene, and this monomer is copolymerized with indacenodithiophene (IDT) to build one novel photovoltaic polymer (PIDTPCR). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) level of the polymer is −5.26 eV and −3.45 eV, respectively. Compared with reference polymer without rhodanine side chain, PIDTPCR polymer shows low band gap and low energy level which contribute to the Jsc and Voc of the PSCs devices. The best performance parameters of the solar cells devices are Voc (0.91 V), Jsc (10.1 mA/cm2), FF (52.4%) and PCE (5.18%).

ChemInform Abstract: Pd(OAc)2/AgOAc Catalytic System Based Bidentate Ligand Directed Regiocontrolled C—H Arylation and Alkylation of the C‐3 Position of Thiophene‐ and Furan‐2‐carboxamides.

AbstractThe title procedure is investigated for various educts bearing different ligands at the amide nitrogen.

Pd(OAc)2/AgOAc Catalytic System Based Bidentate Ligand Directed Regiocontrolled C–H Arylation and Alkylation of the C‐3 Position of Thiophene‐ and Furan‐2‐carboxamides

AbstractA contemporary method is reported for the Pd(OAc)2/AgOAc catalytic system based bidentate ligand directed, regioselective C–H activation and C–C bond formation at the C‐3 position of thiophene‐ and furan‐2‐carboxamides, which are derived from 8‐aminoquinoline or 2‐(methylthio)aniline. The Pd‐catalyzed C–H arylation of thiophene‐ and furan‐2‐carboxamides with a variety of aryl iodides and heteroaryl iodides was highly regioselective and afforded C‐3‐arylated thiophene‐2‐carboxamides and furan‐2‐carboxamides in good to very good yields. The bidentate ligand directed Pd(OAc)2/AgOAc based strategy was also successfully employed for benzylation and alkylation reactions of the thiophene‐2‐carboxamides. These reactions occurred with high regioselectivity to afford the C‐3‐benzylated and C‐3‐alkylated thiophene‐2‐carboxamides in good yields. The observed regioselectivity of these reactions was confirmed by X‐ray crystal structure analyses of compounds 3e, 5a, and 6a.

Influence of thiophene and benzene unit in triphenylamine dyes on the performance of dye-sensitized solar cells

Five triphenylamine dyes (WR1-5) featuring thiophene and benzene unit as the π-conjugated spacers or the substitutes attached to the triphenylamine core were synthesized for investigating the influence of thiophene and benzene unit on the performance of dye-sensitized solar cells (DSSCs). Apart from the alteration of the thiophene and benzene, the position of thiophene or benzene in triphenylamine dyes also has a major impact on some important electro-optical properties such as molar extinction coefficient, maximum absorption peaks and the ground-state oxidation behavior of these dyes. How the thiophene and benzene unit affect the charge recombination is discussed in terms of dye surface blocking and intermolecular interactions between dyes and electrolyte acceptor species. Among these dyes, WR2 containing thiophene unit as the π-conjugated spacer and thiophene donor group attached to the triphenylamine core yield the best photovoltaic performance: a short-circuit photocurrent density (JSC) of 10.8mAcm−2, an open-circuit photovoltage (VOC) of 860mV, and a fill factor (FF) of 0.66, corresponding to an overall conversion efficiency of 6.13% under standard global AM1.5 solar light conditions.

Effect of shifting of aromatic rings on charge carrier mobility and photovoltaic response of anthracene and thiophene-containing MEH-PPE-PPVs

We have investigated the charge carrier mobility and photovoltaic response of two thiophene-[ P1 (MEH-PPE 1-PThV 2) and P2 (MEH-PThE 1-PPV 2)] as well as two anthracene-containing poly (phenylene-ethynylene) family of polymers [ P3 (MEH-PPE 1-PAnV 2) and P4 (MEH-PAnE 1-PPV 2)], whereby the position of thiophene or anthracene has been shifted from between two double bonds ( P1 and P3) to the bridge between triple bond and double bond ( P2 and P4). P2 shows better photovoltaic performance than P1, whereas similar photovoltaic characteristics were found for P3 and P4. The devices using the blends of P2 as donor and PCBM as acceptor (1:3 weight ratio) exhibited a short-circuit current density of J SC=5.2 mA/cm 2, an open-circuit voltage of V OC=800 mV, fill factor FF=0.44 and resulting power conversion efficiency η AM 1.5 =1.8%.

Understanding Selectivity in the Oxidative Addition of the Carbon−Sulfur Bonds of 2-Cyanothiophene to Pt(0)

The reaction of 2-cyanothiophene with a zerovalent platinum bisalkylphosphine fragment yields two thiaplatinacycles derived from the cleavage of the substituted and unsubstituted C-S bonds. While cleavage away from the cyano group is preferred kinetically, cleavage adjacent to the cyano group is preferred thermodynamically. Density functional theory using B3LYP level of theory on a model of this system is consistent with experimental results in that the transition state energy leading to the formation of the kinetically favored C-S bond cleavage product is lower by 5.3 kcal mol(-1) than the barrier leading to the thermodynamically favored product. There is a 6.7 kcal mol(-1) difference between these two products. The cyano substituent at the 2- position of thiophene did not substantially change the mechanism involved in the C-S bond cleavage of thiophene previously reported.

Intramolecular rhodium carbenoid insertions into aromatic C—H bonds. Preparation of 1,3-dihydrothiophene 2,2-dioxides fused onto aromatic rings

The preparation of 1-carboalkoxy-1,3-dihydrobenzo[b]thiophene 2,2-dioxides via rhodium acetate or rhodium trifiuoro-acetate catalyzed decomposition of α-diazo-β-arylmethanesulfonyl esters is described. The reaction has been extended to yield 1,3-dihydrothiophene 2,2-dioxides fused to the 2,3 position of thiophene and indole, but not of furans. In the latter case products derived from the opening of the furan ring were obtained. Keywords: synthesis, 1-carboalkoxy-1,3-dihydrobenzo[b]thiophene 2,2-dioxides, intramolecular carbenoid insertions, rhodium acetate catalysis.