Thiophene Analogues Research Articles

Dithiolodithiole as a building block for conjugated materials.

The development of new conjugated organic materials for dyes, sensors, imaging, and flexible light emitting diodes, field-effect transistors, and photovoltaics has largely relied upon assembling π-conjugated molecules and polymers from a limited number of building blocks. The use of the dithiolodithiole heterocycle as a conjugated building block for organic materials is described. The resulting materials exhibit complimentary properties to widely used thiophene analogues, such as stronger donor characteristics, high crystallinity, and a decreased HOMO-LUMO gap. The dithiolodithiole (C4S4) motif is readily synthetically accessible using catalytic processes, and both the molecular and bulk properties of materials based on this building block can be tuned by judicious choice of substituents.

Dithiolodithiole as a Building Block for Conjugated Materials

The development of new conjugated organic materials for dyes, sensors, imaging, and flexible light emitting diodes, field-effect transistors, and photovoltaics has largely relied upon assembling π-conjugated molecules and polymers from a limited number of building blocks. The use of the dithiolodithiole heterocycle as a conjugated building block for organic materials is described. The resulting materials exhibit complimentary properties to widely used thiophene analogues, such as stronger donor characteristics, high crystallinity, and a decreased HOMO–LUMO gap. The dithiolodithiole (C4S4) motif is readily synthetically accessible using catalytic processes, and both the molecular and bulk properties of materials based on this building block can be tuned by judicious choice of substituents.

In vitro Biological Activity of Some Synthesized Monoazo Heterocycles Based On Thiophene and Thiazolyl-Thiophene Analogue

In vitro Biological Activity of Some Synthesized Monoazo Heterocycles Based On Thiophene and Thiazolyl-Thiophene Analogue

Triarylborane-terminalized branched π-conjugative dyes: Synthesis, structure and optoelectronic properties

Organic optoelectronic materials with high fluorescence quantum yield, both in solution and in the solid state, have attracted considerable interest in recent years. In this work, we designed and synthesized three triarylborane-terminalized branched π-conjugative compounds, including two C3-symmetric π-3A(acceptor) triarylboron dyes: 2,7,12-tri(5-(dimesitylboryl)thiophen-2-yl)-5,5′,10,10′,15,15′-hexaethyltruxene and 2,7,12-tri((5-(dimesitylboryl)thiophen-2-yl)ethynyl)-5,5′,10,10′,15,15′-hexaethyltruxene, and a 2D(donor)-π-A asymmetric dye: 2,7-di(N,N-diphenylamino)-12-(5-(dimesitylboryl)thiophen-2-yl)-5,5′,10,10′,15,15′-hexaethyltruxene. The three compounds displayed prominent optical properties. The ethynyl spaced thiophene analogue emitted intense fluorescence both in the THF solution and in the solid state with excellent quantum yields. Interestingly, their solid powders showed a very different fluorescence colour from their respective THF solution. The results of theoretical calculations were in good agreement with the experimental absorption and CV spectra. The high reversibility of the three boron-containing dyes in their redox process indicates substantial stability of the produced species, which make them promising light-emitting materials.

Aromaticity Decreases Single-Molecule Junction Conductance.

We have measured the conductance of single-molecule junctions created with three different molecular wires using the scanning tunneling microscope-based break-junction technique. Each wire contains one of three different cyclic five-membered rings: cyclopentadiene, furan, or thiophene. We find that the single-molecule conductance of these three wires correlates negatively with the resonance energy of the five-membered ring; the nonaromatic cyclopentadiene derivative has the highest conductance, while the most aromatic of this series, thiophene, has the lowest. Furthermore, we show for another wire structure that the conductance of furan-based wires is consistently higher than for analogous thiophene systems, indicating that the negative correlation between conductance and aromaticity is robust. The best conductance would be for a quinoid structure that diminishes aromaticity. The energy penalty for partly adopting the quinoid structure is less with compounds having lower initial aromatic stabilization. An additional effect may reflect the lower HOMOs of aromatic compounds.

Development of Synthetic Method for ^|^pi;-Conjugated Polymers via Direct Arylation Polycondensation

Recent progress in direct arylation polycondensation made by our group is summarized herein. Polycondensation via direct arylation of C-H bonds in fluorinated benzenes or thiophene analogs afforded the corresponding conjugated polymers with high molecular weight in good yield. These protocols enable synthesis of conjugated polymers without prior preparation of organometallic monomers. Optimization of the reaction conditions led to the establishment of a simple catalytic system employing reduced Pd catalyst loading in the absence of a phosphine ligand. Elemental analysis and microanalysis revealed the high purity of the obtained polymer, which is derived from the simple catalytic system. The pure polymer exhibited excellent performance as a material for organic field effect transistors and organic photovoltaics.

Electrochemical Route to Solution-Processable Polymers of Thiophene/Selenophene Capped Didodecyloxybenzo[1,2-b:4,3-b′]dithiophene and Their Optoelectronic Properties

Two new solution-processable polymers P1 and P2 are being reported here, which were prepared by electrochemical polymerization of thiophene and selenophene capped 7,8-didodecyloxybenzo[1,2-b:4,3-b′]dithiophene (BdT-Dod), respectively and characterized by gel permeation chromatography (GPC) and 1H NMR. The selenophene containing polymer possesses lower band gap than the thiophene analogue. Density functional theory (DFT) calculation showed the highly curved structure of the polymers and reproduced the trend in their optical band gaps. P2 showed larger bathochromic shift in the absorption spectrum from solution to film state compared to that of P1, which indicates better π-stacking interaction in the solid state for P2. In spite of having highly curved chains, the polymers successfully exhibited electrochromic switching. The exchange of the end-caps from thiophene to selenophene have manifested with higher electrochromic switching ability and better polaronic and bipolaronic features in spectroelectrochemic...

Biomimetic Synthesis and Analytics of the Human aryl Hydrocarbon Receptor Agonist 1-(furan-2-yl)-2-(1H-indol-3-yl)ethanone, and its 1-(thiophen-2-yl) and 1- (pyrrol-2-yl) Analogues

1-(2-Furanyl)-2-(3-indolyl)ethanone (FIE, 4) is a potent ligand of the human aryl hydrocarbon receptor (AhR), the so-called dioxin receptor, and the estrogen receptors (ERs), with high activities in transactivation assays. Direct synthesis approaches towards 4 have been hampered by the high oxidative instability of both the indole moiety and the furan part. A biomemetic synthetic pathway was devised that provides the compound for the first time in gram amounts sufficient for comprehensive testing. In the first step, ascorbigen (11) - a breakdown product of glucobrassicins in cruciferous vegetables - is formed according to a rare example of direct C-alkylation of non-protected ascorbic acid (vitamin C) by (3-indolyl)-methyl intermediates under physiological conditions. Ascorbigen is then decarboxylated and rearranged to the target compound 4 under similarly mild conditions in the presence of zinc oxide on silica gel, providing 88% overall yield. The same reaction can be carried out without catalyst but at slightly elevated temperatures under carefully profiled microwave heating, though at somewhat decreased yields along this path (60%), i.e. 28% yield penalty. The thiophene analogue and pyrrol analogue of the target were synthesized according to the same protocol. The reaction conditions were thoroughly optimized, and all compounds were comprehensively analytically characterized, including complete NMR resonance assignment in the 1H- and 13C-domains, MS and pyrolysis-GCMS characterization, and X-ray crystal structure analysis of the thiophene derivative. Keywords: AhR, Ascorbate, Ascorbic acid, Ascorbigen, C-alkylation, Decarboxylation, Human aryl hydrocarbon receptor, 3-indolylcarbinol, (3-indolyl)methyl ketones, Rearrangement.

α‐Oligofurans: A Computational Study

Recently, α-oligofurans have emerged as interesting and promising organic electronic materials that have certain advantages over α-oligothiophenes. In this work, α-oligofurans were studied computationally, and their properties were compared systematically with those of the corresponding oligothiophenes. Although the two materials share similar electronic structures, overall, this study revealed important differences between α-oligofurans and α-oligothiophenes. Twisting studies on oligofurans revealed them to be significantly more rigid than oligothiophenes in the ground state and first excited state. Neutral α-oligofurans have more quinoid character, higher frontier orbital energies, and higher HOMO-LUMO gaps than their α-oligothiophene counterparts. The theoretical results suggest that oligofurans (and subsequently polyfuran) have lower ionization potentials than the corresponding oligothiophenes (and polythiophene), which in turn predicts that oligofurans can be lightly doped more easily than oligothiophenes. Oligofuran dications (8 F(2+)-14 F(2+)) of medium-sized and longer chain lengths show a polaron-pair character, and the polycations of α-oligofurans cannot accommodate high positive charges as easily as their thiophene analogues.

Synthesis of Solution-Processable Poly(cyclopenta[c]selenylvinylene) and Its Charge Transport Properties: Comparative Study with the Thiophene Analogue

We report here the synthesis and characterization of 5,5-bis(dodecyloxymethyl)-5,6-dihydro-4H-cyclopenta[c]selenophene (DCPS) and its characterization by single crystal X-ray diffraction technique. In continuation to this, two new solution-processable copolymers PDCPSV and PDCPTV, comprising of DCPS and 5,5-bis(dodecyloxymethyl)-5,6-dihydro-4H-cyclopenta[c]thiophene (DCPT), respectively, in combination with vinylene unit were synthesized, characterized and compared on the basis of their physical, optical and electronic properties. We have successfully introduced vinylene linkage between two consecutive DCPS or DCPT units in the polymer main chain that resulted in low band gap and oxidatively stable polymers. The 3,4-cyclopentane substitution on thiophene and selenophene affords the planarity to the resulting polymers and the question of regioregularity does not arise in the polymer chain in contrast to the 3-alkyl substitution. PDCPSV showed a p-type mobility of 5.6 × 10–3 cm2 V–1 s–1, whereas PDCPTV showed 3.8 × 10–3 cm2 V–1 s–1. The polymers were further characterized by GPC, TGA, DSC, thin-film XRD, and cyclic voltammetry (CV).

IMINE–ENAMINE TAUTOMERISM OF DIHYDROAZOLOPYRIMIDINES. 6. SYNTHESIS AND TAUTOMERISM OF THIENYL DERIVATIVES OF DIHYDRO-1,2,4-TRIAZOLO[1,5- a ]PYRIMIDINES

The cyclocondensation of thiophene analogs of chalcone with 3-amino-1,2,4-triazole gives 5- and 7-(α-thienyl)dihydro-1,2,4-triazolo[1,5-a]pyrimidines. The tautomer composition of synthesized compounds was analyzed. Authors: S. M. Desenko, E. S. Gladkov, N. V. Getmanskii, I. M. Zemlin, and V. D. Orlov. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (5), pp 608-612 http://link.springer.com/article/10.1007/BF02324647

Visible‐Near Infrared Absorbing Polymers Containing Thienoisoindigo and Electron‐Rich Units for Organic Transistors with Tunable Polarity

AbstractSystematic creation of polymeric semiconductors from novel building blocks is critical for improving charge transport properties in organic field‐effect transistors (OFETs). A series of ultralow‐bandgap polymers containing thienoisoindigo (TIIG) as a thiophene analogue of isoindigo (IIG) is synthesized. The UV‐Vis absorptions of the TIIG‐based polymers (PTIIG‐T, PTIIG‐Se, and PTIIG‐DT) exhibit broad bands covering the visible to near‐infrared range of up to 1600 nm. All the polymers exhibit unipolar p‐channel operations with regard to gold contacts. PTIIG‐DT with centrosymmetric donor exhibits a maximum mobility of 0.20 cm2 V−1 s−1 under gold contacts, which is higher than those of the other polymers containing axisymmetric donors. Intriguingly, OFETs fabricated with aluminum electrodes show ambipolar charge transport with hole and electron mobilities of up to 0.28 (PTIIG‐DT) and 0.03 (PTIIG‐T) cm2 V−1 s−1, respectively. This is a record value for the hitherto reported TIIG‐based OFETs. The finding demonstrates that TIIG‐based polymers can potentially function as either unipolar or ambipolar semiconductors without reliance on the degree of electron affinity of the co‐monomers.

Large negative differential resistance and rectifying behaviors in isolated thiophene nanowire devices

We design isolated molecular nanowires composed of thiophene oligomers sandwiched between two one-dimensional gold electrodes. Electronic transport through the molecular junctions with two interface geometries is studied by performing the first principles calculations based on density functional theory and nonequilibrium Green's function. The current-voltage (I-V) curves of the molecular wires display an unexpected negative differential resistance and rectifying behaviors along with the oscillation effects, different from other theoretical and experimental studies about the analogous thiophene devices. The significant difference is attributed to the design of the one-dimensional gold electrodes with large enough vacuum layer in transverse direction in order to suppress the interaction between wires. Such transport behaviors indicate that the thiophene molecular device would be an important candidate in future molecular electronics.

Two new-type cannabimimetic quinolinyl carboxylates, QUPIC and QUCHIC, two new cannabimimetic carboxamide derivatives, ADB-FUBINACA and ADBICA, and five synthetic cannabinoids detected with a thiophene derivative α-PVT and an opioid receptor agonist AH-7921 identified in illegal products

We identified two new-type cannabimimetic quinolinyl carboxylates, quinolin-8-yl 1-pentyl-(1H-indole)-3-carboxylate (QUPIC, 1) and quinolin-8-yl 1-(cyclohexylmethyl)-1H-indole-3-carboxylate (QUCHIC, 2); and two new cannabimimetic carboxamide derivatives, N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-(4-fluorobenzyl)-1H-indazole-3-carboxamide (ADB-FUBINACA, 3) and N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-pentyl-1H-indole-3-carboxamide (ADBICA, 4), as designer drugs in illegal products. Compound 3 was reported to have a potent affinity for cannabinoid CB1 receptor by Pfizer in 2009, but this is the first report of its detection in illegal products. No chemical or pharmacological data for compounds 1, 2, and 4 have appeared until now, making this the first report on these compounds. We also detected synthetic cannabinoids, APICA N-(5-fluoropentyl) analog (5), APINACA N-(5-fluoropentyl) analog (6), UR-144 N-(5-chloropentyl) analog (7), JWH-122 N-(5-chloropentyl) analog (8), and AM-2201 4-methoxynaphthyl analog (4-MeO-AM-2201, 9) herein as newly distributed designer drugs in Japan. It is of interest that compounds 1 and 2 were detected with their synthetic component, 8-quinolinol (10). A stimulant thiophene analog, α-pyrrolidinovalerothiophenone (α-PVT, 11), and an opioid receptor agonist, 3,4-dichloro-N-([1-(dimethylamino)cyclohexyl]methyl)benzamide (AH-7921, 12), were also detected as new types of designer drugs coexisting with several synthetic cannabinoids and cathinone derivatives in illegal products.

2-Methiopropamine, a thiophene analogue of methamphetamine: studies on its metabolism and detectability in the rat and human using GC-MS and LC-(HR)-MS techniques

2-Methiopropamine [1-(thiophen-2-yl)-2-methylaminopropane, 2-MPA], a thiophene analogue of methamphetamine, is available from online vendors selling "research chemicals." The first samples were seized by the German police in 2011. As it is a recreational stimulant, its inclusion in routine drug screening protocols should be required. The aims of this study were to identify the phase I and II metabolites of 2-MPA in rat and human urine and to identify the human cytochrome-P450 (CYP) isoenzymes involved in its phase I metabolism. In addition, the detectability of 2-MPA in urine samples using the authors' well-established gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-linear ion trap-mass spectrometry (LC-MS(n)) screening protocols was also evaluated. The metabolites were isolated from rat and human urine samples by solid-phase extraction without or following enzymatic cleavage of conjugates. The phase I metabolites, following acetylation, were separated and identified by GC-MS and/or liquid chromatography-high-resolution linear ion trap mass spectrometry (LC-HR-MS(n)) and the phase II metabolites by LC-HR-MS(n). The following major metabolic pathways were proposed: N-demethylation, hydroxylation at the side chain and at the thiophene ring, and combination of these transformations followed by glucuronidation and/or sulfation. CYP1A2, CYP2C19, CYP2D6, and CYP3A4 were identified as the major phase I metabolizing enzymes. They were also involved in the N-demethylation of the analogue methamphetamine and CYP2C19, CYP2D6, and CYP3A4 in its ring hydroxylation. Following the administration of a typical user's dose, 2-MPA and its metabolites were identified in rat urine using the authors' GC-MS and the LC-MS(n) screening approaches. Ingestion of 2-MPA could also be detected by both protocols in an authentic human urine sample.

Bis(naphthalene diimide) derivatives with mono- and dicarbonyl-fused tricyclic heterocyclic bridges as electron-transport materials

A series of triads in which two naphthalene diimide (NDI) units are bridged through their 2-positions by cyclopenta[2,1-b; 3,4-b′]dithiophene-4-one, cyclopenta[2,1-b;3,4-b′]dithiazole-4-one, benzo[1,2-b:6,5-b′]dithiophene-4,5-dione, and benzo[1, 2-b:6,5-b′]dithiazole-4,5-dione was synthesised, characterised by cyclic voltammetry and UV–vis absorption spectroscopy, modelled using density functional theory (DFT) calculations, and examined as solution-processed films in n-channel OFETs. The influence of the electron affinity and ionisation potential of the bridging fused heterocycle and of the length and position of alkyl chains in the triads on the electronic properties of the materials in solution and electrical properties in the thin film was explored. The nature of the bridge has a strong effect on the optical and electrochemical properties of materials. Use of increasingly electron-poor bridging groups led to hypsochromic shifts of the low-energy visible absorption (assigned to a transition from a bridge-based HOMO to a LUMO predominantly located on the NDI moieties) and an anodic shift of the first reduction potential from ca.−1.1 V to−0.7 V vs. Cp2Fe+/0. The average electron mobility, μe, varied from 0.17 cm2 V−1 s−1 to 2.3×10−4 cm2 V−1 s−1 with the largest mobility observed for the material with cyclopenta[2,1-b;3,4-b′]dithiophene-4-one bridge. An extension of the N-alkyl chains on the NDI units from n-hexyl to n-dodecyl led to a two-fold decrease in μe for materials with cyclopenta[2,1-b;3,4-b′]dithiophene-4-one bridge, while introduction of alkyl chains to the 3- and 5-positions of the bridge was even more detrimental for the electron transport. Despite the expected increased planarity (based on DFT calculations) and more facile first reduction potential of compounds based on the cyclopenta[2,1-b;3,4-b′]dithiazole-4-one bridge, a three-fold decrease in μe was observed when this bridge was used in place of its thiophene analogue, although the threshold voltage decreased from 11.5 to 7.3 V. Materials containing benzo[1,2-b:6,5-b′]dithiophene(or dithiazole)-4,5-dione bridges, which are easier to reduce than an isolated NDI, exhibited further decrease in μe to 7×10−3 cm2 V−1 s−1 and 2.3×10−4 cm2 V−1 s−1, respectively.

Synthesis of tetraselenophenoporphyrazine and its application in transistor devices

We report the first synthesis of a soluble selenophene containing porphyrazine derivative, tetraselenophenoporphyrazine (SePz). Thin films of SePz exhibit a broad and strong absorption in the visible to near-IR region, which is red shifted compared to the thiophene analogue, and demonstrate p-type carrier mobilities of 10−2 cm2 V−1 s−1 in bottom gate, bottom contact field effect transistors.

Trisubstituted thiophene analogues of 1-thiazolyl-2-pyrazoline, super oxidase inhibitors and free radical scavengers

Xanthine oxidase (XO) generates superoxide anions and H2O2 for the self-defence system of organism. Abnormal production of this superoxide’s (reactive oxygen species) is responsible for a number of complications including inflammation, metabolic disorder, cellular aging, reperfusion damage, atherosclerosis and carcinogenesis. Series of novel trisubstituted thiophenyl-1-thiazolyl-2-pyrazoline libraries are synthesized containing 2,5-dichloro thiophene, 5-chloro-2-(benzylthio) thiophene and 5-chlorothiophene-2-sulphonamide, from chalcones in PEG-400 as green solvent. Superoxide (XO) inhibitory and free radical scavenging activities were also figured out with molecular modeling analysis, bearing in mind their possible future for super oxide inhibitor (Gout) therapeutics, compound 3k shows interesting superoxide inhibitory and free radical scavenger activity with IC50=6.2μM, in comparison with allopurinol.

Synthesis of Annulated Arenes and Heteroarenes Involving Lewis Acid-Mediated Regioselective Annulation of Unsymmetrical 1,2-(Diaryl/diheteroarylmethine)dipivalates

A ZnBr(2)-mediated regioselective annulation of unsymmetrical 1,2-diarylmethinedipivalates in DCM at room temperature led to the formation of annulated arenes and heteroarenes. The annulation of the dipivalate proceeds through the intermediacy of benzylic carbocations followed by intramolecular cyclization and subsequent aromatization to give the annulated products. The annulation methodology is highly efficient for the syntheses of anthracene as well as naphtho[b]thiophene analogues.

Synthesis, solid‐state, and charge‐transport properties of conjugated polythiophene‐S,S‐dioxides

AbstractAn alkylated semiconducting polymer comprising alternating bithiophene‐[all]‐S,S‐dioxide and aromatic monothiophene units in the polymer backbone was synthesized with the intent of modifying the energy gap and lowest unoccupied molecular orbital for use as a stable n‐type semiconductor. Films spun from this semiconducting polymer were characterized utilizing X‐ray scattering, near edge X‐ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy, and thin‐film field effect transistors to determine how oxidation of the thiophene ring systems impacts the structural and electronic properties of the polymer. The thiophene‐S,S‐dioxide polymers have lower optical and electrical band gaps than corresponding thiophene polymers. X‐ray scattering results indicate that the polymers are well ordered with the π–π stacking distances increased by 0.4 Å relative to analogous thiophene polymers. The electrical stability of these polymers is poor in transistors with a drop in the field effect mobility by approximately one order of magnitude upon addition of just 5% of the thiophene‐S,S‐dioxide unit in a copolymer with thiophene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013