Fluorene-dibenzothiophene

Dibenzothiophene acts as a 7r-electron donor and readily forms complexes with known electron acceptors. In such cases the electronic spectrum of a solution of the two compounds shows a new absorption band, usually in the visible region. The order of donor strengths of several o,o -bridged biphenyls has been estimated from their respective charge-transfer spectra and found to be carbazole > fluorene > dibenzothiophene >dibenzofuran. Dibenzothiophene forms complexes with tetracy-anoethylene, various polynitro derivatives of fluorenone, > naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, and tetra-methylmic acid. ... 

Several random fluorene-dibenzothiophene copolymers 584a-e (03JPS (A)(41)1521 03MI1351) have been reported. 

Dias FB, Pollock S, Hedley G, Palsson LO, Monkman A, Perepichka II, Perepichka IF, Tavasli M, Bryce MR (2006) Intramolecular charge transfer assisted by conformational changes in the excited state of fluorene-dibenzothiophene-S,S-dioxide cooligomers. J Phys Chem B 110(39) 19329—19339... 

Adapted with permission from Table 1 of F. 6. Dias, S. Pollock, C. Hedley, L. O. Palsson, Andy Monkman, I. I. Perepichka, I. F. Perepichka, M. Tavasli and M. R. Bryce, Intramolecular charge transfer assisted by cx>nformational changes in the excited state of fluorene-dibenzothiophene-5, -dioxide co-oligomers, /. Phys. Chem. B, 110, 19329-19339 (2006). Copyright 2006 American Chemical Society. 

Several random fluorene-dibenzothiophene copolymers 67a-e [106,107] have been reported. The meta linkage in the dibenzothiophene in copolymers 67a-e hinders the conjugation, resulting in a hypsochromic shift of the emission bands to the deep-blue color region (kmax 420 and 440 nm) [106]. Furthermore, hindered conjugation and hindered n-aggregation suppress the parasitic green emission at 520 nm in the solid state of the polymer, often observed in polyfluorenes. 

Systematic structural modiflcations were undertaken in the series of fluorene-dibenzothiophene-5,5 -dioxide co-oligomers 127-130. The oligomers displayed efficient PL both in solution (65-67%) and in films (44-63%) and 0.35-0.65 eV lower-lying LUMO compared with the parent oligofluorenes... 

S. M. King, I. I. Perepichka, I. F. Perepichka, F. B. Dias, M. R. Bryce, A. P. Monkman, Exploiting a dual fluorescence process in fluorene-dibenzothiophene-5,5-dioxide co-polymers to give efficient single polymer LEDs with broadened emission, Adv. Funct. Mater., 19, 586-591 (2009). 

As might be anticipated from the behaviour of the parent heterocycles, C-2 of indole, benzo[i]furan and benzo[i]thiophene (Table 13) is shifted to lower field than C-3. However, the shifts for C-2 (O, 144.8 Se, 128.8 S, 126.1 NH, 124.7 Te, 120.8) and C-7a (O, 155.0 Se, 141.3 S, 139.6 NH, 135.7 Te, 133.0) in the benzo[i] heterocycles vary irregularly (80OMR(l3)3l9), and the sequence is different to that observed for C-2 in the parent heterocycles, namely 0>Se>Te>S>NH. Also noteworthy is the upheld position of C-7, especially in indole and benzofuran, relative to the other benzenoid carbons at positions 4, 5 and 6. A similar situation pertains in the dibenzo heterocycles (Table 14), where not only are C-1 and C-8 shifted upheld in carbazole and dibenzofuran relative to the corresponding carbons in dibenzothiophene and fluorene, but similar, though smaller, shifts can be discerned for C-3 and C-6 in the former compounds. These carbon atoms are of course ortho and para to the heteroatom and the shifts reflect its mesomeric properties. Little variation in the carbon-hydrogen coupling constants is observed for these dibenzo compounds with V(qh) = 158-165 and V(c,h) = 6-8 Hz. 

Figure 1.4 Two-dimensional plot of HPLC (log /J and GC (log Iq) retention indexes (1) naphthalene (2) 2-methylnaphthalene (3) 2,3-dimethylnaphthalene (4) 2,3,6-trimethyl-naphthalene (5) biphenyl (6) fluorene (7) dibenzothiophen (8) phenanthrene (9) 2-methylphenanthrene (10) 3,6-dimethylphenanthrene (11) benzo[a]fluorene (12) chrysene (data replotted from reference (31)).

Resnick SM, DT Gibson (1996) Regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene by naphthalene dioxygenase from Pseudomonas sp. strain NCIB-4. Appl Environ Microbiol 62 4073-4080. 

Carbazole, A-methylcarbazole, IV-ethylcarbazole, dibenzofuran, dibenzothiophene, fluorene, dibenzo-p-dioxin, phenoxathiin, phenoxazine, phenothiazine, xanthene, biphenyl, naphthalene, phenanthrene, anthracene, and fluoranthene could be transformed by E. coli, [314] which was transformed using a plasmid bearing the carAa, Ac, and Ad genes, and expressing only the carA-encoded proteins. Further work is needed to develop a final biocatalyst and to prove the advantages that this degradative pathway would incorporate in a refining bioprocess. 

The currently accepted name for (1) in Chemical Abstracts is dibenzothiophene, although biphenylene, diphenylene, or biphenylylene sulfide are still used, especially in the Russian literature. Occasionally 9-thia-fluorene is used and recently, in one instance, dibenzo[6,d]thiophene. An alternative numbering system for (1) is met with on occasions in which C-4 is taken as C-1, as in carbazole. In the absenee of moleeular diagrams this system must be detected by reference to the chemistry described. For example, in a few dyestuff patents 2,7-diaminodibenzothiophene 5,5-dioxide is referred to and this is obviously the 3,7-diamino compound, also known as benzidine sulfone. 

In the absence of any accurate isomer distribution studies the question of theoretical positional reactivities in dibenzothiophene becomes somewhat meaningless. However, when viewed within the context of the behavior of the related heterocycles dibenzofuran, carbazole, and fluorene, specific studies on dibenzothiophene are more valid. Such studies have been made by Eaborn and co-workers. The rates of cleavage of the four isomeric trimethylsilyldibenzothiophenes (Section VI, H, 2) were studied at 50° using a mixture of methanol and aqueous perchloric acid and compared with the rates of protodesilylation of 2- and 4-trimethylsilyldiphenyl sulfide. The reactivities shown in Fig. 3... 

In biphenyls bridged at the 2 and 1 positions, the inversion center of the ideal planar biphenyl is removed and transitions can be allowed in both IPA and 2PA cases. As a consequence, the IPA and 2PA peaks are observed at approximately the same energy for fluorene (the lowest 2PA peak is located at 586 nm) [52]. Similar observations hold true for carbazole, dibenzofuran, and dibenzothiophene. However, the fine details of the spectra are hard to interpret. In a number of cases, 2PA peaks actually appear at the edge of the timing... 

Figure 1. Gas chromatogram of PAH in a work atmosphere a, particulate PAH b, gaseous PAH. The peak identities are 1, naphthalene 2, 2-methylnaphthalene 3, 1 -methylnaphthalene 4, biphenyl 5, acenaphthene 6, dibenzofuran 7, fluorene 8, 2-methylfluorene 9, 1-methylfluorene 10, dibenzothiophene 11, phenanthrene 12, anthracene 13, methylphenanthrene/methylanthracene 14, methylphenan-threne/methylanthracene 15, 2-methylanthracene 16, 4,5-methylenephenanthrene 17, methylphenanthrene/methylanthracene 18,1-methylphenanthrene 19, fluoranthene 20, benzo(def)dibenzothiophene 21, pyrene 22, ethylmethylenephena-threne 23, benzo(a)fluorene 24, benzofb)fluorene 25, 4-methylpyrene 26, meth-ylpyrene 27, 1-methylpyrene 28, benzothionaphthene 29, benzo(c)phenanthrene 30, benzophenanthridine 31, benzo(2i)anthracene 32, chrysene/triphenylene 33, benzo(b)fluoranthene 34, benzof])fluoranthene 35, benzo(k)fluoranthene 36, ben-zo(c)pyrene 37, benzofa)pyrene 38, perylene 39, indenof 1,2,3-cd)pyrene 40, dibenz(a, /a,h)anthracenes 41, benzofghi)perylene 42, anthanthrene 43, coro-...

In the dibenzo heterocycles (Table 11), C-l and C-8 are shifted upfield in carbazole and dibenzofuran relative to the corresponding carbons in dibenzothiophene and fluorene, and similar, though smaller, shifts can be discerned for C-3 and C-6 in the former compounds. 

Hutchison reported the first ESR spectrum of a metastable phosphorescent state by study of naphthalene oriented in durene crystals.4 Since then, similar spectra have been recorded for several other polynuclear aromatics both oriented in host crystals and randomly suspended in glassy matrices. D values for all these ir,n excited states are quite low, indicating little interaction between the unpaired electrons. Interestingly, D for the quinolines equals 0.10cm"1 just as in naphthalene,197 indicating that the presence of a heteroatom does not necessarily change the ir,w nature of the lowest triplet state very much. A similar conclusion has been reached from a comparison of the ESR spectra of fluorene, carbazole, dibenzofuran, and dibenzothiophene.198... 

Giraud, J. and Marzin, C., Comparative 13C NMR study of deuterated and undeuterated dibenzothiophenes, dibenzofurans, carbazoles, fluorenes, and fluorenones, Org. Magn. Reson., 12, 647, 1979. 

The central ring systems found to yield antiviral compounds have included fluorene (fluorenone), dibenzofuran, dibenzothiophene, fluoranthene, anthraquinone, acenaphthene, xanthene, thioxanthene, phenothiazine, carbazole, phenanthrene and others. The side chains were represented by basic ethers, basic ketones, basic esters plus carboxamides, sulphonamides, alkanols, methylene and others attached to the various ring systems. The amine function was usually substituted to the tertiary amine with various alkyl substituents although a few ring types (e.g., pyrrole or piperidino) were synthesized. 

The effect of tilorone and congeners (Fig. 6) on the DNA-dependent RNA polymerase reaction is shown in Fig. 7). The template activity of native DNA is strongly inhibited by DEAP-fluoranthene, showing an 80% inhibition at a concentration 8 x 10 6 M. Other derivatives, at this concentration do not show any significant inhibition of the template activity of DNA. However, at higher concentrations one observes a dose-dependent inhibition of DNA-template activity by DEAE-fluorenone, DMAA-dibenzothiophene, DEAA-fluorene and DMAA-dibenzofuran. The monosubstituted derivative, MEAA-fluorene does not show any activity, even at higher concentrations. 

Fig.8. Effect of tilorone and congeners on the thermal transition temperature (Tm) of calf thymus DNA. Solvent is 0.01 M Tris-HCl pH 7.0 and the concentrations of DNA-P and congeners are 5 x 10-6M, respectively. Curve 1 = DNA 2 = DNA + MEAA-fluorene 3 = DNA + DEAA-fluorene 4 = DNA + DMAA-dibenzothiophene 5 = DNA + DMAA-dibenzofuran and 6 = DNA + DEAE-fluorenone...

The inhibition of the endogenous activity of FLV-DNA polymerase by tilorone and congeners is shown in Fig. 9. A maximum inhibition was obtained with DEAP-fluoranthene. The inhibitory responses of tilorone (DEAE-fluorenone), DMAA-dibenzothiophene and DEAA-fluorene were of the same magnitude whereas, DMAA-dibenzofuran showed a weak response. It is interesting to note that the mono-substituted congener MEAA-fluorene did not inhibit the endogenous reaction at any concentration. 

Fig. 1 Gas chromatography-flame ionization detection chromatogram of a complex mixture of PAHs extracted by SFE from a contaminated soil. (1) naphthalene (2) 2-methylnaphthalene (3) 1-methylnaphthalene (4) acenaphthene (5) fluorene (6) dibenzothiophene (7) phenanthrene (8) anthracene (9) fluoranthene (10) pyrene (11) benzo(a)anthracene (12) chrysene (13) benzo(e)pyrene (14) benzo(a)pyrene (15) indeno(l,2,3-cd)pyrene (16) dibenzo(a,h)anthracene (17) benzo(g,h,i)perylene. (From Ref. [12].)...

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