Thiophene chemical structure

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

Oxidation of these model sulfur compounds was studied without solvent to investigate the chemical structure of the products using S K-edge XANES. A solvent free tri-phase (organic/ H202aq./catalyst) was used under the described conditions. Figure 1 shows the XANES spectra from the organic and aqueous phases as well as reference materials. The thiophene oxidized to thiophene-sesquioxide [3a,4,7,7a-tetrahydro-4,7-epithiobenzo[b]-thiophene 1,1.8-trioxide ] first.. The sesquioxide solid precipitated from the solvent free reaction mixture and was identified by NMR, IR and C,H,S elemental analytical. The sesquioxide oxidized to sulfate. 2-MT and 2,5 DMT also oxidized to... 

Figure 9.19 Chemical structure of poly 3-[2-((S)-2-methylbutoxy)ethyl]thiophene. Number of repeating units is 50.

An increase in the PL QE of the fluorene-thiophene copolymers can be achieved by introduction of -oxidized thiophene units (although no efficient EL from such materials was reported). This aspect and the chemical structures of thiophene-iS,5 -dioxide-fluorene copolymers are discussed in more detail in Section 2.4. 

The data shown in Table 2 illustrate the general paucity of comparative toxicity data within an isosteric series of chemicals. In this Table a variety of toxic end-points observed for benzene and naphthalene have been compared with those of their simple heterocyclic analogues, and it is clear that it is almost impossible to derive chemical structure-biological activity relationships from the published literature for even such a simple series of compounds. Even basic estimates of mammalian toxicity such as LD50 values cannot be accurately compared due either to the absence of relevant data or the noncomparability of those available. Thus in a field where there are little comparative data on the relative toxicity to mammals of pyrrole, thiophene and furan for example, it is difficult to relate chemical structure to biological activity in historical heterocyclic poisons such as strychnine (3) and hemlock [active agent coniine (4)]. 

Fig. 5.8. Chemical structure of poly(3-hexyl thiophene) P3HT [129].

Very thin films (monolayer or multilayer) can be studied by IR spectroscopy, provided that the IR beam crosses a reasonably large fraction of the monolayer this can be done by (i) grazing-angle techniques (whereby the IR beam angles of incidence and reflection are of the order of 1° to 3°) or (ii) multiple internal reflections of the IRbeam inside the monolayer (infrared reflectance and absorbance spectroscopy (IRRAS). Fig. 11.19 shows the chemical structure of an analyte (Fullerene-fcz s-[ethylthio-tetrakis(3,4-dibutyT2-thiophene-5-ethenyl)-5-bromo-3,4-dibutyl-2-thiophene] malonate),... 

Chemical structure of Fullerene-b/s-[ethylthio-tetrakis(3,4-dibutyl-2-thiophene-5-ethenyl)-5-bromo-3,4-dibutyl-2-thiophene] malonate [8]. 

Figure 4.8-1 Electronic structure and chemical structure of hole and electron polarons (a), hole and electron bipolarons (b), and hole and electron solitons (c). Examples of chemical structures refer to poly(thiophene) and poly(acetylene), respectively.

Chart 2.2 Chemical structures of N-M-propyl-(3-thiophen-2-yl-ethyl)-thiophen-3-ylethy 1-amine (29), N- -propyl-(2-thiophen-2-yl-ethyl)-thiophen-3-ylethyl-amine (30). 

Chart 3.1 Chemical structures of 6-(N,N-di- -propyl)amino-4,5,6,7-tctrahydrobcnzo /)]thiophene (34), 2-fomiyl-6-(N,N-di- -propyl)amino-4,5,6,7-tctrahydrobcnzo /> thiophene (65), 2-hydroxymethyl-6-(N,N-di- -propyl)amino-4,5,6,7-tctrahydrobcnzo /> thiophenc (66),... 

Scheme 5 Chemical structures of polyfluorenes with on-chain Ir complexes containing pyridine or thiophene on the main-chain...

Figure 22.4 Chemical structure of a- T, with n as the number of thiophene units in the oligomer.

FIGURE 5.3.4 Chemical structures of phenylene-thiophene co-oligomers. 

FIGU RE 5.3.7 Chemical structure of the first n-channel, solution-deposited, thiophene oligomer. 

The first soluble doped polymer was the polyfp-phenylene. sulphide) with AsFs- in AsFs [44]. Even if a quite unusual solvent was needed, it was the first to show the possibility of having a solution of doped polymers. Later, the discovery that Poly-n-alkylthio-phene was soluble in a common organic solvent [45], provided a new route. Besides, the films show thermochromism properties that varj as a flinction of the chemical structure of the side groups [8]. The stability and the great variety of substituents that can be added at the thiophene ring ensure that many structural studies are still being carried out [46]. 

It is also possible to choose substituents that reduce the sterical hindrance. This approach has been used by Leclercs group in studies of polymers of 3-alkoxy-thiophenes [41]. The oxygen of the alkoxy group offers less steric hindrance than the methyl or methylene of the alkyl group therefore there is smaller steric hindrance in the poly(3-octyloxythiophenes), and much less thermochromism. Therefore, the chemical structure and size of the substituent side chain is of major importance in determining the character of the thermo-chromic effect. 

Figure 1.1 Chemical structures for monomers of the conjugated polymers discussed in this chapter (a) vinylene (the repeat unit of polyacetylene) (b) ethynylene (polydiacetylene is alternating vinylene-ethynylene) (c) phenylene (d) thiophene (e) leucoemeraldine form of polyaniline (f) pernigraniline form ofpolyaniline (the number of protons can vary between the...

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