Fluorene-dibenzothiophene-5,5-dioxide

F. B. Dias, S. PoUock, G. Hedley, L. O. Palsson, Andy Monkman, I. I. Perepichka, I. F. Perepichka, M. Tavasli and M. R. Bryce, Intramolecular charge transfer assisted by conformational changes in the excited state of fluorene-dibenzothiophene-5,5-dioxide co-oligomers, J. Phys. Chem. B, 110, 19329-19339 (2006). 

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... 

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. 

Perepichka, I.I., I.F. Perepichka, M.R. Bryce, and L.-O. Palsson. 2005. Dibenzothiophene-S,S-dioxide-fluorene co-oKgomers. Stable, highly-efficient blue emitters with improved electron affinity. Chem Commun 3397-3399. 

Much higher EL efficiencies have recently been achieved using oligomers composed of fluorene, thienyl-5,5-dioxide or dibenzothiophene-5,5-dioxide and end-capping diphenylamino groups [25, 32]. Figure 4.11 shows the stmcture and some electroluminescence characteristics of two of these compounds... 

In contrast to thiophene-5,5 -dioxide, the non-aromatic character of which limits the stability of the derived materials, the aromatic dibenzothiophene-5,5 -dioxide is very stable and topologically equivalent to a fluorene moiety. Its LUMO energy level is 1 eV Iowct than that in fluorene [168], and several highly fluorescent molecular and oligomeric materials based on dibenzothiophene-5, 5 -dioxide have been synthesized and studied (125 and 126). Diphenylamino end-capped dibenzothiophene-5,5-dioxide derivatives 125a-c were used as emitters [73a, 169, 170], the dibenzothiophene-5,5-dioxide-quinoxaline derivative 126 was used as an electron-transporting material [171], and multilayer OLEDs based on these compounds demonstrated excellent performance (Table 19.5). 

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