A Redox‐Dependent Electrochromic Material: Tetri‐EDOT Substituted Thieno[3,2‐b]thiophene

Organic electrochromic materials change color rapidly under applied potential. A butterfly‐shaped compound, 5,5′,‐5″,‐5′″‐(thieno[3,2‐b]thiophene‐2,3,5,6‐tetrayl) tetrakis‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxine) (t‐EDOT‐TT) is synthesized for the first time and polymerized at different potentials via electropolymerization technique. By applying different polymerization potentials, the optical and electrochromic properties of this newly synthesized polymer can be tuned. Owing to the dependence of functional group position in the polymer structure on the redox potential, this polymer can be utilized in very interesting organic optoelectronic applications.

     

An Alternating Copolymer Derived from Indolo[3,2‐b]carbazole and 4,7‐Di(thieno[3,2‐b]thien‐2‐yl)‐2,1,3‐benzothiadiazole for Photovoltaic Cells

An alternating narrow bandgap conjugated copolymer (PICZ‐DTBT, E_g = 1.83 eV) derived from 5,11‐di(9‐heptadecanyl)indolo[3,2‐b]carbazole and 4,7‐di(thieno[3,2‐b]thien‐2‐yl)‐2,1,3‐benzothiadiazole (DTBT), was prepared by the palladium‐catalyzed Suzuki coupling reaction. The resultant polymer absorbs light from 350–690 nm, exhibits two absorbance peaks at around 420 and 570 nm and has good solution processibility and thermal stability. The highest occupied molecular orbital (HOMO) energy level and lowest unoccupied molecular orbital (LUMO) level of the copolymer determined by cyclic voltammetry were about −5.18 and −3.35 eV, respectively. Prototype bulk heterojunction photovoltaic cells from solid‐state composite films based on PICZ‐DTBT and [6,6]‐phenyl‐C₇₁ butyric acid methyl ester (PC₇₁BM), show power conversion efficiencies up to 2.4% under 80 mW · cm⁻² illumination (AM1.5) with an open‐circuit voltage of V_oc = 0.75 V, a short current density of J_sc = 6.02 mA · cm⁻², and a fill factor of 42%. This indicates that the copolymer PICZ‐DTBT is a viable electron donor material for polymeric solar cells.

     

Synthesis and characterization of thieno[3,2‐b]thiophene‐isoindigo‐based copolymers as electron donor and hole transport materials for bulk‐heterojunction polymer solar cells

A novel class of thieno[3,2‐b]thiophene (TT) and isoindigo based copolymers were synthesized and evaluated as electron donor and hole transport materials in bulk‐heterojunction polymer solar cells (BHJ PSCs). These π‐conjugated donor‐acceptor polymers were derived from fused TT and isoindigo structures bridged by thiophene units. The band‐gaps and the highest occupied molecular orbital (HOMO) levels of the polymers were tuned using different conjugating lengths of thiophene units on the main chains, providing band‐gaps from 1.55 to 1.91 eV and HOMO levels from ?5.34 to ?5.71 eV, respectively. The corresponding lowest unoccupied molecular orbital (LUMO) levels were appropriately adjusted with the isoindigo units. Conventional BHJ PSCs (ITO/PEDOT:PSS/active layer/interlayer/Al) with an active layer composed of the polymer and PC₇₁BM were fabricated for evaluation. Power conversion efficiency from a low of 1.25% to a high of 4.69% were achieved with the best performing device provided by the D?π?A polymer with a relatively board absorption spectrum, high absorption coefficient, and more uniform blend morphology. These results demonstrate the potential of this class of thieno[3,2‐b]thiophene‐isoindigo‐based polymers as efficient electron donor and hole transport polymers for BHJ PSCs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Alternating narrow band gap copolymers derived from indeno[1,2‐b]fluorene and thiophene‐cored‐thieno[3,4‐b]pyrazine derivatives—Synthesis,characterization and comparative studies of photochemical stability

Alternating narrow band gap (NBG) conjugated polymers derived from 6,6′,12,12′‐tetraoctylindeno[1,2‐b]fluorene (IF) and 2,3‐dimethyl‐5,7‐dithien‐2‐yl‐thieno[3,4‐b]pyrazine (DTTP), 2,3‐diphenyl‐5,7‐dithien‐2‐yl‐thieno[3,4‐b]pyrazine (DPTP) or 2,3‐dioctyl‐5,7‐dithien‐2‐yl‐thieno[3,4‐b]pyrazine (DOTP), named as PIF‐DTTP, PIF‐DPTP, and PIF‐DOTP, respectively, were synthesized by Suzuki coupling reaction and characterized. The photochemical stabilities of the copolymers and copolymer derived from IF and 5,7‐dithien‐2‐yl‐thieno[3,4‐b]pyrazine (DTP) were investigated by the UV absorptions, PL spectra, FT‐IR spectra, and photovoltaic properties of the copolymers as a function of UV irradiation time. The studies revealed that the degradation of thieno[3,4‐b]pyrazine (TP) ring under UV irradiation can be retarded or eliminated by introducing phenyl group into the 2,3‐positions of TP ring, and indicated that 2,3‐diphenylthieno[3,4‐b]pyrazine could be used as durable electron deficient moiety to achieve donor–acceptor NBG‐conjugated polymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterisation of thieno[3,2-b]thiophene-based linear shaped liquid crystals

A series of thieno[3,2-b]thiophene-based liquid crystalline molecules has been synthesised. To investigate the effects of alkyl substituent groups and structure of mesogenic cores, eight kinds of thieno[3,2-b]thiophene-based molecules containing different alkyl substituent groups and mesogenic cores have been synthesised. These molecules were characterised by differential scanning calorimetry, polarising optical microscopy, ultraviolet–visible absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry and polarised fluorescence spectroscopy. The results indicated that the thieno[3,2-b]thiophene-based donor-acceptor-donor (D-A-D) type molecules showed the presence of a smectic A phase. Changes in the length of alkyl substituents and mesogenic cores affected the phase transitions, optical and electrochemical properties of the molecules.     

Stacking patterns of thieno[3,2‐b]thiophenes functionalized by sequential palladium‐catalyzed Suzuki and Heck cross‐coupling reactions

The crystal structures of three 5‐alkenyl‐2‐arylthieno[3,2‐b]thiophenes, namely 3,6‐dibromo‐5‐(4‐tert‐butylstyryl)‐2‐(naphthalen‐1‐yl)thieno[3,2‐b]thiophene, C₂₈H₂₂Br₂S₂, (I), 3,6‐dibromo‐5‐(4‐methylstyryl)‐2‐(naphthalen‐1‐yl)thieno[3,2‐b]thiophene, C₂₅H₁₆Br₂S₂, (II), and 3,6‐dibromo‐2‐(4‐tert‐butylphenyl)‐5‐(4‐methylstyryl)thieno[3,2‐b]thiophene, C₂₅H₂₂Br₂S₂, (III), have been determined in order to evaluate the geometry of the molecules. The π‐conjugated system containing the thieno[3,2‐b]thiophene skeleton, the ethylene bridge and the phenyl rings is almost planar. The aromatic ring directly attached to the thieno[3,2‐b]thiophene moiety is not coplanar with the thieno[3,2‐b]thiophene moiety itself due to steric hindrance of the bromo substituent. The crystal packings are characterized by π–π stacking [only for (II)] and C—Br...π interactions. The long axes of the molecules in (I) are oriented in two directions; for the two other structures the long axis is oriented in one direction only.     

Synthesis of through‐space conjugated polymers containing [2.2]paracyclophane and thieno[3,4‐b]pyrazine in the main chain

We synthesized through‐space conjugated polymers with [2.2]paracyclophane and thieno[3,4‐b]pyrazine units in the main chain by the Sonogashira–Hagihara coupling reaction. The obtained polymers were soluble in common organic solvents, and homogeneous thin films were readily obtained from the polymer solutions by spin‐coating techniques. The polymers exhibited the extension of the conjugation length via the through‐space interaction. The polymers showed orangish‐red emission with peak maxima of around 610 nm in diluted solutions and their thin films, which were derived from the thieno[3,4‐b]pyrazine moieties. The optical and electrochemical behaviors of the polymers containing pseudo‐para‐ and pseudo‐ortho‐linked [2.2]paracyclophane were identical. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

3,6‐Dialkylthieno[3,2‐b]thiophene moiety as a soluble and electron donating unit preserving the coplanarity of photovoltaic low band gap copolymers

It has been shown recently, that the presence of alkyl side chains at the 3‐positions on the thiophene rings placed next to 2,1,3‐benzothiadiazole core in the backbone of several conjugated polymers results in severe steric hindrance and prevents efficient planarity of the thiophene‐2,1,3‐benzothiadiazole‐thiophene (TBzT) segment. Both properties have a strong influence on the optoelectronic properties of the polymer and need to be considered when the polymer is to be used for organic electronics applications. In this work, we modified a previously synthesized oligothiophene copolymer, consisting of two 3,4′‐dialkyl‐2,2′‐bithiophene units attached to a 2,1,3‐benzothiadiazole unit (TBzT segment) and a thieno[3,2‐b]thiophene unit, by optimizing the lateral alkyl side chains following a density functional theory investigation. It is demonstrated that eliminating the alkyl side chains from the 3‐positions of the TBzT segment and anchoring them onto the thieno[3,2‐b]thiophene, using an efficient synthesis of the 3,6‐dihexylthieno[3,2‐b]thiophene unit, allows us to reduce the energy band gap. In addition, the chemical modification leads to a better charge transport and to an enhanced photovoltaic efficiency of polymer/fullerene blends. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Aromatic Heterocycle 1,3,4‐Oxadiazole‐Substituted Thieno[3,4‐b]thiophene to Build Low‐Bandgap Polymer for Photovoltaic Application

Electron‐deficient heterocycle 1,3,4‐oxadiazole is first introduced to the 2‐position of thieno[3,4‐b]thiophene (TT) to construct a new building block 2‐(thieno[3,4‐b]thiophen‐2‐yl)‐5‐(alkylthio)‐1,3,4‐oxadiazole (TTSO) with alkylthio chain. The polymer PBDT–TTSO based on TTSO and benzodithiophene (BDT) exhibits a deep lying highest occupied molecular orbital (HOMO) energy level of −5.32 eV and low‐bandgap of 1.62 eV. The power conversion efficiency (PCE) of 5.86% is obtained with a relatively high V _OC of 0.74 V, a J _SC of 13.1 mA cm⁻², and FF of 60.5%. Furthermore, as S atom in thioether can be oxidized easily, the optoelectronic properties of PBDT–TTSO treated with different oxidants are preliminary investigated. Interestingly, the oxidation products still maintain high PCE with reduction less than 30%. This work demonstrates a new method to regulate HOMO energy levels by introducing electron‐deficient aromatic heterocyclic moiety.

     

金催化的炔烃羟基化反应: 合成2取代苯并呋喃化合物

本文报道了一种以邻炔基苯酚为原料,通过金催化的炔烃羟基化反应合成2取代苯并呋喃的方法. 该方法可以在温和的条件下快速以高产率得到各种2取代苯并呋喃. 关键前体邻炔基苯酚可以很容易由Sonogashira 反应制备.     

Ru(II) complexes bearing tertiary phosphine ligands: a novel and efficient homogeneous catalyst for one‐pot synthesis of dihydropyrano[3,2‐c]chromene and tetrahydrobenzo[b]pyran derivatives

A number of ruthenium complexes were prepared and their catalytic activities in three‐component one‐pot condensation of aldehydes, malononitrile and 4‐hydroxycoumarin or dimedone was considered to afford dihydropyrano[3,2‐c]chromenes and tetrahydrobenzo[b]pyran derivatives under optimum reaction conditions. We found that a catalytic amount of RuBr₂(PPh₃)₄ efficiently promotes the reaction in a short time (3–15 min) and with high yield (75–88%). Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluation of Neurotropic Activity and Molecular Docking Study of New Derivatives of pyrano[4″,3″:4′,5′]pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidines on the Basis of pyrano[3,4-c]pyridines

Background: Heterocyclic compounds and their fused analogs, which contain pharmacophore fragments such as pyridine, thiophene and pyrimidine rings, are of great interest due to their broad spectrum of biological activity. Chemical compounds containing two or more pharmacophore groups due to additional interactions with active receptor centers usually enhance biological activity and can even lead to a new type of activity. The search for new effective neurotropic drugs in the series of derivatives of heterocycles containing pharmacophore groups in organic, bioorganic and medical chemistry is a serious problem. Methods: Modern methodology of drugs involves synthesis, physicochemical study, molecular modeling and selection of active compounds through virtual screening and experimental evaluation of the biological activity of new chimeric compounds with pharmacophore fragments. For the synthesis of new compounds, classical organic methods were used and developed. For the evaluation of neurotropic activity of new synthesized compounds, some biological methods were used according to indicators characterizing anticonvulsant, sedative and antianxiety activity as well as side effects. For docking analysis, various soft ware packages and methods were used. Results: As a result of multistep reactions, 11 new, tri- and tetracyclic heterocyclic systems were obtained. The studied compounds exhibit protection against pentylenetetrazole (PTZ) seizures as well as some psychotropic effects. The biological assays evidenced that nine of the eleven studied compounds showed a high anticonvulsant activity by antagonism with pentylenetetrazole. The toxicity of the compounds is low, and they do not induce muscle relaxation in the studied doses. According to the study of psychotropic activity, it was found that the selected compounds have an activating behavior and anxiolytic effects on the “open field” and “elevated plus maze” (EPM) models. The data obtained indicate the anxiolytic (antianxiety) activity of the derivatives of tricyclic thieno[2,3-b]pyridines and tetracyclic pyridothieno[3,2-d]pyrimidin-8-ones, especially pronounced in compounds 3b–f and 4e. The studied compounds increase the latent time of first immobilization on the “forced swimming” (FS) model and exhibit antidepressant effects; compounds 3e and 3f especially exhibit these effects, similarly to diazepam. Docking studies revealed that compounds 3c and 4b bound tightly in the active site of γ-aminobutyric acid type A (GABA_A) receptors with a value of the scoring function that estimates free energy of binding (∆G) at −10.0 ± 5 kcal/mol. Compound 4e showed the best affinity ((∆G) at −11.0 ± 0.54 kcal/mol) and seems to be an inhibitor of serotonin (SERT) transporter. Compounds 3c–f and 4e practically bound with the groove of T4L of 5HT_1A and blocked it completely, while the best affinity observed was in compound 3f ((∆G) at −9.3 ± 0.46 kcal/mol). Conclusions: The selected compounds have an anticonvulsant, activating behavior and anxiolytic effects and at the same time exhibit antidepressant effects.     

New copolymers with thieno[3,2‐b]thiophene or dithieno[3,2‐b:2′,3′‐d]thiophene units possessing electron‐withdrawing 4‐cyanophenyl groups: Synthesis and photophysical,electrochemical, and electroluminescent properties

New monomers containing 4‐cyanophenyl (–PhCN) groups attached to a thieno[3,2‐b]thiophene (TT) or dithieno[3,2‐b:2′,3′‐d]thiophene (DTT) structure were synthesized and characterized as 4‐(2,5‐dibromothieno[3,2‐b]thiophen‐3‐yl)benzonitrile (Br–TT–PhCN) or 4,4′‐(2,6‐dibromodithieno[3,2‐b:2′,3′‐d]thiophene‐3,5‐diyl)dibenzonitrile (Br–DTT–PhCN). The Suzuki coupling of 9,9‐dioctylfluorene‐2,7‐diboronic acid bis(1,3‐propanediol)ester and the Br–TT–PhCN or Br–DTT–PhCN monomer was utilized for the syntheses of novel copolymers poly{9,9‐dioctylfluorene‐2,7‐diyl‐alt‐3‐(4′‐cyanophenyl)thieno[3,2‐b]thiophene‐2,5‐diyl} (PFTT–PhCN) and poly{9,9‐dioctylfluorene‐2,7‐diyl‐alt‐3,5‐bis(4′‐cyanophenyl)dithieno[3,2‐b:2′,3′‐d]thiophene‐2,6‐diyl} (PFDTT–PhCN), respectively. The photophysical, electrochemical, and electroluminescent (EL) properties of these novel copolymers were studied. Their photoluminescence (PL) exhibited the same emission maximum for both copolymers in solution. Red‐shifted PL emissions were observed in the thin films. The PL emission maximum of PFTT–PhCN was more significantly redshifted than that of PFDTT–PhCN, indicating more pronounced excimer or aggregate formation in PFTT–PhCN. The ionization potential (HOMO level) and electron affinity (LUMO level) values were 5.54 and 2.81 eV, respectively, for PFTT–PhCN and were 5.57 and 2.92 eV, respectively, for PFDTT–PhCN. Polymer light‐emitting diodes (LEDs) with copolymer active layers were fabricated and studied. Anomalous behavior and memory effects were observed from the current–voltage characteristics of the LEDs for both copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2629–2638     

Novel 5-(4-alkoxyphenyl)thieno[3,2-b]thiophene-2-carboxylate esters: Highly efficient synthesis and mesogenic evaluation of a new class of materials exhibiting the smectic C phase

A series of alkyl 5-(4-alkoxyphenyl)thieno[3,2-b]thiophene-2-carboxylates were prepared via a direct, efficient Pd(0)-catalysed Suzuki–Miyaura coupling approach. A series of long-chain alkyl thieno[3,2-b]thiophene-2-carboxylate esters, synthesised from newly reported alkyl mercaptoacetates, were elaborated into the target compounds via regioselective (C-5) halogenation followed by cross-coupling with 4-alkoxyphenyltrifluoroborate salts. As expected, these target alkyl 5-(4-alkoxyphenyl)thieno[3,2-b]thiophene-2-carboxylate ester mesogens exhibited the orthogonal smectic A phase; notably, they are the first materials built on the thieno[3,2-b]thiophene motif to also exhibit the smectic C mesophase.     

Highly Fluorescent Conjugated Copolymers Containing Dithieno[3,2‐b:2′,3′‐d]pyrrole

Three copolymers that incorporate dithieno[3,2‐b:2′,3′‐d]pyrrole with fluorene, carbazole, or pyridine have been prepared by Suzuki reaction and characterized by NMR spectroscopy and GPC. A new homopolymer of dithieno[3,2‐b:2′,3′‐d]pyrrole was also synthesized for the comparison of their structure–property relationships. Their thermal, optical, and electrochemical properties have been investigated. All the polymers exhibit good thermal stability with decomposition temperatures around 400 °C. The fluorescence quantum efficiencies of all these polymers in solution are in the range of 33.5–55.5%. The copolymers also show high film fluorescence quantum efficiencies of about 20% while the fluorescence of the homopolymer film is almost quenched.

     

Synthesis,photophysics, theoretical modeling,and electroluminescence of novel 2,7‐carbazole‐based conjugated polymers with sterically hindered structures

2,7‐dibromo‐N‐hexylcarbazole is successfully synthesized in three steps with an overall 37% yield. Novel 2,7‐carbazole‐based sterically hindered conjugated polymers are further synthesized. In the backbone structure of polymer P1 , alkylated bithiophene moiety is β‐substituted with dodecyl chains on both thiophene rings, adopting the tail‐to‐tail configuration. While for polymers P2 and P3 , partially planarized thieno[3,2‐b]thiophene moiety ( P2 ) and β‐pentyl substituted thieno[3,2‐b]thiophene ( P3 ) are incorporated. All polymers demonstrate efficient blue‐to‐green light emission, good thermal stability (T_d ≥ 379 °C), and high glass transition temperatures (T_g = 118 °C). The optical and electronic properties of the resulted polymers are tuned by the incorporated alkyl chains. For instance, the incorporation of β‐pentyl group in thieno[3,2‐b]thiophene moiety endows P3 with blue‐shifted photophysical spectra, reduced fluorescence quantum yield and larger band gap in comparison with P2 . The steric effect of incorporated alkyl chains is further illustrated by geometry optimization of three model oligomers (analogues to the repetition units of P1–P3 ) using density functional theory. Sterically hindered polymers P1 and P2 exhibit high charge transport ability and moderate electroluminescent properties in primarily tested single‐layer light‐emitting diodes (configuration: ITO/PEDOT:PSS/Polymer/Ca/Ag). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7725–7738, 2008     

Synthesis of 5‐Cyano‐2‐Carbethoxythieno[2,3‐b]thiophenyl‐3,4‐Diisothiocyanates and Its Utility IN Heterocyclic Synthesis under Phase Transfer Catalytic Technique

Regarding to the importance of thieno[2,3‐b]thiophens and isothiocyanaetes reactiveties in the physical, chemical and pharmaceutical fields, this study has been undertaken to prepare the target compound 5‐cyano‐2‐carbethoxythieno[2,3‐b]thiophenyl‐3,4‐diisothiocyanates via a safe method. The formed isothiocyanates derivative was reacted with aromatic amines, acid hydrazied and some active methylene groups, followed by cyclization reaction for the formed intermediates to give new series of heterocyclic compounds     

Synthesis and Reactions of 3‐Methylthiazolo[3,2‐a]Benzimidazole‐2‐Carboxylic Acid Hydrazide: Synthesis of Some New Pyrazole, 1,3‐Thiazoline, 1,2,4‐Triazole and 1,2,4‐Triazolo[3,4‐b]‐1,3,4‐Thiadiazine Derivatives Pendant to Thiazolo[3,2‐a]Benzimidazole Moiety

The reaction of 3‐methylthiazolo[3,2‐a]benzimidazole‐2‐carboxylic acid ethyl ester (1) with hydrazine hydrate gives the hydrazide 2 which reacts with CS₂/KOH to afford the potassium salt 3. Treatment of 3 with l‐aryl‐2‐bromoethanones 4a,b afforded the 1,3‐thiazoline derivatives 6a,b, respectively, while the reaction of 3 with hydrazine hydrate afforded 1,2,4‐triazole‐3‐thione derivative 9. The reaction of 9 with l‐aryl‐2‐bromoethanones 4a,b and with hydrazonyl chlorides 11a,b gave the 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazine derivatives 10a,b and 12a,b, respectively. Treatment of hydrazide 2 with phenyl isothiocyanate in refluxing benzene gave the thiosemicarbazide derivative 16. The latter reaction gave 1,3,4‐oxadiazole derivative 17 when benzene was replaced by DMF. Cyclization of the thiosemicarbazide derivative 16 with NaOH resulted in the formation of the 1,2,4‐triazole‐3‐thione derivative 18.     

Anthracene‐thieno[3,4‐c]pyrrole‐4,6‐dione based donor–acceptor conjugated copolymers for applications in optoelectronic devices

Three novel alternating copolymers of thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) and triisopropylsilylacetylene‐functionalized anthracene were prepared via Suzuki polymerization. Various solubilizing substituents were attached to the TPD moiety in order to ascertain the impact they have upon the optical, electrochemical, and thermal properties of the resulting polymers. All copolymers showed good solubility and thermal stability with decomposition temperatures in excess of 300°C. Optical properties revealed that PTATPD(O), PTATPD(DMO), and PTATPD(BP) displayed optical energy gaps in excess of 2.0 eV. It is speculated that steric repulsion between solubilizing groups on repeat units along polymer chains reduces their planarity and decreases their electronic conjugation. The amorphous nature of the polymers was confirmed with differential scanning calorimetry and powder X‐ray diffraction. The highest occupied molecular orbital levels of the three polymers are unaffected by the different solubilizing chains. However, they exert some influence over the lowest unoccupied molecular orbital (LUMO) levels with PTATPD(BP) and PTATPD(O) displaying the lowest LUMO levels (?3.4 eV). In contrast, PTATPD(DMO) displayed the highest LUMO level (?3.3 eV). © 2015 The Authors. Polymers for Advanced Technologies Published by John Wiley & Sons Ltd.