Structural Design and Applications of Stereoregular Fused Thiophenes and Their Oligomers and Polymers

Abstract

Stereoregular fused thiophenes (SFTs: especially thieno[3,2-b]thiophene (TT) and dithieo[3,2-b:2′,3′-d]thiophene (DTT)), as stable conjugated structures deriving from thiophene ring enlargement, possess outstanding properties and special configuration, such as the superior carrier transfer efficiency and a high degree backbone of planarity. In comparison to stand-alone SFTs structures, oligomers and polymers containing different heteroaromatic units have been much widely researched and used in many fields. In decade, several important reviews have summarized the broad field of fused thiophenes including SFTs, and their synthesis and optoelectronic applications. Here, we critically present the structure–performance relationships and application of oligomers and polymers containing SFTs (exhibiting thiophene ring number from 2 to 7) units. First, the basic structures and properties of SFTs are briefly stated. Then, oligomers classified by extra conjugated heterocyclic attachments are carefully discussed, focusing on the structure–performance relationships for their optoelectronic applications including organic photovoltaic cells and organic field-effect transistors. Moreover, such relationships in polymers have been applied in much wider fields such as organic light-emitting diodes, electrochromic devices, thermoelectric devices, and supercapacitors are discussed. Finally, a summary and prospect are given. Through this review, instruction for molecular design and novel ideas for the future development of SFTs-contained are provided.     

基于螯合导向C—H/C—H氧化交叉偶联/环化反应策略构筑稠杂芳烃化合物

稠杂芳烃的合成是有机化学的重要研究内容之一,对有机光电功能材料和器件研究具有重要意义。C—H键是有机化合物中最广泛存在的化学键。利用C—H键的断裂与重组成键直接构筑稠杂芳烃具有简洁、高效的优势,能够解决传统合成方法在底物制备和产物结构类型方面的局限。本文对近六年来,本课题组在基于导向过渡金属催化(杂)芳环与(杂)芳环之间的C—H/C—H氧化交叉偶联/分子内环化反应策略构筑稠(杂)芳环方面所做的系列工作进行了评述,重点讨论了有关反应的特点、优势和催化机理,并对该策略在新型有机光电材料开发中的应用进行了阐述。最后,对该策略目前存在的问题进行了总结,并展望了其发展前景。     

Reaction of Vinyl Aziridines with Arynes: Synthesis of Benzazepines and Branched Allyl Fluorides

We report the cycloaddition between vinyl aziridines and arynes. Depending on the reaction conditions and the choice of the aryne precursor, the aziridinium intermediate can be trapped through two distinct mechanistic pathways. The first one proceeds through a formal [5+2] cycloaddition to furnish valuable multi-substituted benzazepines. In the second pathway, the aziridinium is intercepted by a fluoride ion to afford allylic fluorides in good yields. Both reactions proceed stereospecifically and furnish enantiopure benzazepines and allylic fluorides.     

Effects of cross-linkers with different molecular weights in cross-linked Matrimid 5218 and test temperature on gas transport properties

The poly(ethylene oxide) (PEO) was introduced by the cross-linking method in the commercial Matrimid 5218. The two kinds of membranes were prepared from the Matrimid 5218 and the cross-linkers poly(propylene glycol) block poly(ethylene glycol) block poly(propylene glycol) diamine (PPG/PEG/PPGDA) with different molecular weights. The cross-linking reaction process was monitored by FTIR. The cross-linked Matrimid 5218 membranes display excellent CO₂ permeability and CO₂/light gas selectivity. The effects of cross-linkers with different molecular weights on gel content, thermal properties and H₂, CO₂, N₂ and CH₄ gas transport properties were reported. The effect of temperature on gas transport properties was also reported, and the permeabilities of these materials as a function of temperature were compared with other gas membrane materials.     

Investigation of the Benzene–Naphthalene and Naphthalene–Naphthalene Potential Energy Surfaces: DFT/CCSD(T) Correction Scheme

The potential energy surfaces of the naphthalene dimer and benzene–naphthalene complexes are investigated using the recently developed DFT/CCSD(T) correction scheme [J. Chem. Phys. 2008 , 128, 114 102]. One and three minima are located on the PES of the benzene–naphthalene and the naphthalene dimer complexes, respectively, all of which are of the parallel‐displaced type. The stabilities of benzene–naphthalene and the naphthalene dimer are ?4.2 and ?6.2 kcal mol^?1, respectively. Unlike the benzene dimer, where the T‐shaped complex is the global minimum, the lowest‐energy T‐shaped structure is about 0.2 and 1.6 kcal mol^?1 above the global minimum on the benzene–naphthalene and the naphthalene dimer potential energy surfaces, respectively.     

2-Deoxy-2-C-(2,3-dideoxy-α-d-erythro-hexopyranosyl)-β-d-glucopyranoses: Reinvestigation of Synthesis,Use in Glycosylation,and Conformational Analyses by NMR

Abstract

Conformational investigations using 1D TOCSY and ROESY ¹H NMR experiments on 1,3,4,6-tetra-O-acetyl-2-C-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hexopyranosyl)-2-deoxy-β-D-glucopyranose (8) and related disaccharides showed that for steric reasons the C-linked hexopyranosyl ring occurs in the usually unfavoured ¹C₄ conformation and reconfirmed the structure of 1,3,4,6-tetra-O-acetyl-2-C-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranosyl)-2-deoxy-β-D-glucopyranose (5). Glycosylation of 2,3,6-tri-O-benzyl-α-D-glucopyranosyl 2,3-di-O-benzyl-4,6-(R)-O-benzylidene-α-D-glucopyranoside (13) with acetate 8 using trimethylsilyl triflate as a catalyst afforded the α-D-linked tetrasaccharide 14. A remarkable side product in this reaction was the unsaturated tetrasaccharide 2,3,6-tri-O-benzyl-4-O-[4,6-di-O-acetyl-2,3-dideoxy-2-C-(4,6-di-O-acetyl-2,3-dideoxy-β-D-erythro-hexopyranosyl)-α-D-erythro-hex-2-enopyranosyl]-α-D-glucopyranosyl 2,3-di-O-benzyl-4,6-(R)-O-benzylidene-α-D-glucopyranoside (16) where in the C-linked hexopyranosyl ring an isomerization to the β-anomer had taken place to allow for the favoured ⁴C₁ conformation. The tetrasaccharide 14 was deacetylated and hydrogenolyzed to form the fully deprotected tetrasaccharide 18. The ¹ C ₄ conformation of the C-glycosidic pyranose of this tetrasaccharide was maintained as shown by an in depth NMR analysis of its peracetate 19.     

Thiepin‐Fused Heteroacenes: Simple Synthesis,Unusual Structure,and Semiconductors with Less Anisotropic Behavior

The simple one‐pot syntheses of sulfur‐rich thiepin‐fused heteroacences with an alkylidene–fluorene framework, THA1 and THA6 (thiepin‐fused heteroacene 1 or 6, in which the thiepin is conjugated at both ortho positions with S? CH₃ or S? C₆H₁₃, respectively), is reported. Based on electrochemical studies and theoretical calculations, their LUMO energies are relatively low (?3.26 eV), and their HOMO and HOMO?1 orbitals are nearly degenerate. The thiepin ring contributes mainly to HOMO?1 and LUMO orbitals, however, HOMO orbitals dominantly reside on thienoacence rings. Within the crystal of THA1, the molecules adopt a herringbone arrangement and multiple intermolecular interactions lead to the formation of a 2D network. Interestingly, THA6 shows totally different intermolecular arrangements. Organic field‐effect transistor (OFET) devices show both compounds exhibiting p‐type semiconducting behavior. Thin films or microcrystals of THA1 possess relatively high hole mobility. Moreover, the mobilities of the microcrystal of THA1 along three directions are in the same order, thus the hole‐carrier transporting within the hexagonal‐plane of microcrystal of THA1 exhibits less anisotropic behavior. In comparison, both thin films and microrods of THA6 show low hole mobilities. This agrees well with the intermolecular arrangements and interactions within crystal of THA6. Further theoretical calculations reveal that significant intermolecular electronic coupling among HOMO?1 orbitals and sulfur atoms play an important role in intermolecular electronic coupling for THA1.     

Bidentate Disilicate Framework for Bis-Grafted Surface Species

Recent advances in surface organometallic chemistry have enabled the detailed characterization of the surface species in single-site heterogeneous catalysts. However, the selective formation of bis-grafted surface species remains challenging because of the heterogeneity of the supporting surface. Herein, we introduce a metal complex bearing bidentate disilicate ligands, −OSi(O^tBu)₂OSi(O^tBu)₂O−, as a molecular precursor, which has a silicate framework adjacent to the metal (Pt) center. The grafting of the precursors on silica supports (MCM-41 and CARiACT Q10) proceeded through a substitution reaction on the silicon atoms of the disilicate ligand, which was verified by the detection of isobutene and ^tBuOH as the elimination products, to selectively yield bis-grafted surface species. The chemical structure of the surface species was characterized by solid-state NMR, and the chemical shift values of the ancillary ligands and ¹⁹⁵Pt nuclei suggested that the bidentate coordination sphere was maintained following grafting.     

Design,Synthesis and Antiparasitic Evaluation of Click Phospholipids

A library of seventeen novel ether phospholipid analogues, containing 5-membered heterocyclic rings (1,2,3-triazolyl, isoxazolyl, 1,3,4-oxadiazolyl and 1,2,4-oxadiazolyl) in the lipid portion were designed and synthesized aiming to identify optimised miltefosine analogues. The compounds were evaluated for their in vitro antiparasitic activity against Leishmania infantum and Leishmania donovani intracellular amastigotes, against Trypanosoma brucei brucei and against different developmental stages of Trypanosoma cruzi. The nature of the substituents of the heterocyclic ring (tail) and the oligomethylene spacer between the head group and the heterocyclic ring was found to affect the activity and toxicity of these compounds leading to a significantly improved understanding of their structure–activity relationships. The early ADMET profile of the new derivatives did not reveal major liabilities for the potent compounds. The 1,2,3-triazole derivative 27 substituted by a decyl tail, an undecyl spacer and a choline head group exhibited broad spectrum antiparasitic activity. It possessed low micromolar activity against the intracellular amastigotes of two L. infantum strains and T. cruzi Y strain epimastigotes, intracellular amastigotes and trypomastigotes, while its cytotoxicity concentration (CC₅₀) against THP-1 macrophages ranged between 50 and 100 μM. Altogether, our work paves the way for the development of improved ether phospholipid derivatives to control neglected tropical diseases.