A simple and sensitive method is described for the electrochemical determination of shikonin, a widely used anti‐tumoral agent, based on its electrochemical oxidation at a nanostructured poly(hydroxymethylated‐3,4‐ethylenedioxy‐thiophene) (PEDOT‐MeOH) electrode, which was fabricated by a facile electropolymerization method. Compared with bare and poly(3,4‐ethylenedioxythiophene) (PEDOT) electrodes, the PEDOT‐MeOH film exhibited a distinctly higher activity for the electrooxidation of shikonin. The PEDOT‐MeOH electrode showed a wide linear response for shikonin in the concentration range from 1.0 nM to 10.0 µM with detection limit of 0.3 nM. Furthermore, the PEDOT‐MeOH electrode displayed high stability, good reproducibility and high sensitivity for the detection of shikonin. 相似文献
The ring‐fused thiophene derivatives benzo[c]thiophene and its precursor bicyclo[2.2.2]octadiene (BCOD) have been introduced as π‐conjugated spacers for organic push–pull sensitizers with dihexyloxy‐substituted triphenylamine as donor and cyanoacrylic acid as acceptor ( OL1 , OL2 , OL3 , OL4 , OL5 , OL6 ). The effects of the fused ring on the spectroscopic and electrochemical properties of these sensitizers and their photovoltaic performance in dye‐sensitized solar cells have been evaluated. Introduction of a binary benzo[c]thiophene and ethylenedioxy thiophene as π bridge caused a significant red shift of the characteristic intramolecular charge‐transfer band to 642 nm. It is found that the sensitizer OL3 , which contains one benzo[c]thiophene unit as π linker, gives the highest overall conversion efficiency of 5.03 % among all these dyes. 相似文献
The present study describes the synthesis of phenanthro[3,4‐b]thiophene (3) , phenanthro[4,3‐b]thiophene (4) and its potential dihydrodiol metabolites, trans‐6,7‐dihydroxy‐6,7‐dihydrophenanthro[3,4‐b]thiophene (5) and trans‐8,9‐dihydroxy‐8,9‐dihydrophenanthro[3,4‐b]thiophene (6) , trans–6,7‐dihydroxy‐6,7‐dihydro‐phenanthro[4,3‐b]thiophene (7) and trans‐8,9‐dihydroxy‐8,9‐dihydrophenanthro[4,3‐b]thiophene (8) from Suzuki coupled intermediates. The UV spectra of these dihydrodiols are presented. These spectra are useful tools for identifying these dihydrodiols among unknown metabolites of 1 and 2 produced in vitro or in vivo.相似文献
In the present paper we report direct experimental evidence of the existence of hydrogen bonds between poly(3,4-(ethylenedioxy)thiophene) (PEDOT) and DNA complexes and bring deeper knowledge about how such interactions can take place in such species. To this end, we used both experimental and theoretical methodologies to examine the interactions between the building blocks composing these two macromolecules. The specific interaction natures between 3,4-(ethylenedioxy)thiophene (EDOT, E) and doubly protonated guanine (GH(2)(2+)) monomers have been investigated using UV-vis spectroscopy. Quantum mechanical calculations in the density functional theory (DFT) and time-dependent density functional theory (TDDFT) frameworks have been used to identify the structures of the possible complexes. These differ in the interaction pattern, and it was possible to interpret the absorption spectra in terms of intermolecular interactions. Our results allow verification of the previous hypothesis about the formation of specific N-H···O interactions between G-containing nucleotide sequences and PEDOT. Clearly, DFT calculations indicate that E:GH(2)(2+) complexes are stabilized by N-H···O interactions, which involve an E oxygen and the -NH and -NH(2) moieties of GH(2)(2+). Furthermore, TDDFT calculations are able to reproduce the absorption spectra (both energy gaps and relative oscillator strength magnitudes) of E and GH(2)(2+), as well as the complex. 相似文献
5,15-Bis[acetylene-4-(ethylenedioxy)thiophene]-10,20-bis(4-carboxyphenyl)porphyrin was synthesized by a Sonogashira coupling and polymerized to fibres; TEM and AFM images show uniform porphyrin wires with a length of several micrometers and a thickness of less than 4 nm. 相似文献
All isomers of the parent phenanthro[b]thiophenes, namely, phenanthro[1,2-b]thiophene, phenanthro-[2,1-b]thiophene, phenanthro[2,3-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[4,3-b]thiophene and phenanthro[9,10-b]thiophene have been synthesized. 相似文献
An efficient multi‐component synthesis of highly functionalized 2,2′‐bifurans and 2‐(thiophen‐2‐yl)furans is described. A mixture of furan‐ or thiophene‐2‐carbonyl chloride, an isocyanide, and a dialkyl acetylenedicarboxylate undergoes a smooth addition reaction in dry CH2Cl2 at ambient temperature to produce 2‐amino‐5‐(4‐chlorofuran‐2‐yl)furan‐3,4‐dicarboxylates and 2‐amino‐5‐(4‐chlorothiophen‐2‐yl)furan‐3,4‐dicarboxylates. A single‐crystal X‐ray‐analysis of a derivative conclusively confirms the structure of these 2,2′‐bifurans and 2‐(thiophen‐2‐yl)furans. A novel electrophilic aromatic substitution reaction can justify the formation of the Cl‐substituted furan or thiophene rings. 相似文献
3,4: 3′,4′-Bis(ethylenedioxy)biphenyl undergoes bromination, nitration, and cyclopropylcarbonylation only at the 2-position.
Analogous reactions with 2-substituted bis(ethylenedioxy)biphenyls occur regioselectively at the 2′-position. The reactions
of 2-cyclopropylcarbonyl- and 2,2′-bis(cyclopropylcarbonyl)bis(ethylenedioxy)biphenyls with complex metal hydrides afforded
the corresponding arylcyclopropylcarbinols which tended to undergo intramolecular alkylation of the aromatic ring with conservation
of the cyclopropane fragment (monosubstituted derivatives) and formation of cyclopropyl-containing cyclic ethers (disubstituted
ethylenedioxybiphenyls). The reduction of the nitro group in 2′-cyclopropylcarbonyl-2-nitro-4,5: 4′,5′-bis(ethylenedioxy)biphenyl
was accompanied by intramolecular cyclization involving spatially close functional groups, the cyclopropane fragment remaining
intact. 相似文献
Summary: Due to its capability of dispensing very small volumes of different liquids in a controlled manner, ink‐jet printing is well suited for combinatorial experiments. The multi‐nozzle ink‐jet delivery system is especially advantageous for parallel chemical synthesis of different materials. We have used ink‐jet printing of an oxidizing agent to pattern a pre‐coated conducting polymer, poly(3,4‐ethylenedioxy)‐thiophene‐poly(styrene sulfonate) (PEDOT‐PSS), yielding electrodes with predefined shapes and a controlled degree of sheet resistivity for use in gray‐scale organic light‐emitting devices (OLEDs). The electrical and optical properties of the PEDOT‐PSS layer are modified via chemical interaction using the oxidizing agent. These experiments were performed using a desktop ink‐jet printer in conjunction with common graphic software which employed color functions such as CMY (cyan, magenta and yellow), HSL (hue, saturation and luminosity) and RGB (red, green and blue).
Photographs of gray‐scale OLEDs patterned on PEDOT‐PSS surfaces by an ink‐jet printer on plastic substrates. 相似文献
We have developed a catalytic asymmetric synthesis of (S)‐4‐ethyl‐6,6‐(ethylenedioxy)‐7,8‐dihydro‐4‐hydroxy‐1H‐pyrano[3,4‐f]indolizine‐3,10(4H)dione ( 5 a ), a synthetic intermediate for (20S)‐camptothecin analogues. A key step in this synthesis is an asymmetric α‐hydroxylation of a lactone with a vinylogous pyridone structure ( 8 a ) by using a guanidine–urea bifunctional organocatalyst. The present oxidation was successfully applied to the synthesis of C20‐modified derivatives of (+)‐C20‐desethylbenzylcamptothecin ( 13 ). 相似文献
From methyl pyropheophorbide‐a (MPPa) (1), methyl 2‐formylmethyl‐2‐devinyl‐9‐ethylenedioxy‐9‐deoxopyropheophorbide‐a (2) and methyl 3‐acetyl‐9‐ethylenedioxy‐2‐devinyl‐9‐deoxopyropheophorbide‐a (3) were prepared. The Grignard reactions of 2 and 3 were performed using cycloalkyl magnesium bromides to afford cycloalkyl‐substituted sec‐alcohol 4 and tert‐alcohols 9a‐c, respectively. By the deprotection of the ethylenedioxy group, these alcohols were respectively converted to exocyclic ketones 5 and 10a‐c, which were dehydrated to give chlorins 6 and 11a‐c having an alkenyl function at the 2‐position. On the other hand, the oxidation and deprotection of the alcohol 4 gave a diketo chlorin 8. 相似文献
The 3‐heteroaryl‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones 6a‐e were synthesized by the oxidative‐hydrolytic ring transformation of the 3‐heteroaryl‐1,2‐diazepino[3,4‐b]]quinoxaline‐5‐carbonitriles 9a‐c , which were obtained by the 1,3‐dipolar cycloaddition reaction of the 2‐(2‐heteroarylmethylene‐1‐methylhydrazino)quinoxaline 4‐oxides with 2‐chloroacrylonitrile. The assignment of the thiophene and furan ring protons was carried out through the data of the NOE, decoupling, and coupling constants. 相似文献
Two heterocyclic compounds based on the thieno[3,4-c]thiophene structure with four aryl substituents were prepared and their behavior in electrooxidation studied. These tetraarylthieno[3,4-c]thiophenes were synthesized in three steps starting from 1,3-dibenzoylmethane in the case of 1,3,4,6-tetraphenyl-2 u 4 i 2 -thieno[3,4-c]thiophene 1a and from 1,3-bis(4'-methoxyphenyl)propane-1,3-dione in the case of 1,3,4,6-tetrakis(4'-methoxyphenyl)-2 u 4 i 2 -thieno[3,4-c]thiophene 1b , a new compound. Both cyclic and hydrodynamic voltamperometric analyses indicate two reversible one-electron oxidation stages for compound 1b , while for compound 1a only the first stage is reversible. The preparative electrooxidation of the two compounds results in the opening of one thiophene ring giving rise to n -keto-thioketones. 相似文献
The hexane extract of the aerial parts and roots of Limnophila indica yielded a new flavone, 3′,4′‐ethylenedioxy‐5‐hydroxy‐3‐(1‐hydroxy‐1‐methylethyl)‐6,7‐dimethyl‐5′‐methoxyflavone‐8‐carboxylic acid ( 1 ), characterized by spectral studies. 相似文献