Oligofluorenes

Y. Li, J. Ding, M. Day, Y. Tao, J. Lu, and M. D iorio, Novel stable blue-light-emitting oligofluorene networks immobilized by boronic acid anhydride linkages, Chem. Mater., 15 4936-4943, 2003. 

YH Geng, SW Culligan, A Trajkovska, JU Wallace, and SH Chen, Monodisperse oligofluorenes forming glassy-nematic films for polarized blue emission, Chem. Mater., 15 542-549, 2003. 

It was further possible to demonstrate the favorable charge-transfer interactions of the C60-oFL -exTTF systems in a series of quantum chemical calculations and hypothetically expand this series to the trimer-based system, i.e. that bearing three oligofluorene units as linker. In order to compare the molecular-wire behavior of the oFL wires, we have used very similar methods as for the corresponding C6o-oPPE -exTTF systems (see Sect. 9.1.1). 

Figure 9.49 represents the HOMO/LUMO orbital-energy distribution in 18a,b and the hypothetical trimer with three oligofluorene units as linker. Again, we clearly distinguish the HOMO and LUMO orbitals localized on the donor and acceptor, respectively, demonstrating the charge-transfer features in these triads. 

Cornelia van der Pol, Martin R. Bryce, Mateusz Wielopolski, Carmen Atienza-Castellanos, Dirk M. Guldi, Salvatore Filippone, Nazario Martin. Energy Transfer in Oligofluorene-Cgo and Cgo-Oligofluorene-Cgo Donor-Acceptor Conjugates. J. Org. Chem. 2007, 72, 6662. 

Recently, Anzenbacher et al. [55,56] first demonstrated molecular wire behavior occurring in solid state and in functional OLEDs in donor-bridge-acceptor triads consisting of Al(III) triquinolinolate (Alq3), oligofluorene... 

Fig. 3 Common reactions and cross-couplings in oligofluorene synthesis shown for example structures, where PdCl2(dppf) is [l,l -bis(diphenylphospino)ferrocene] dichloropaUadium(II), Pd(PPh3)4 is tetrakis(triphenylphosphino)palladium(0), and Ni(COD) is bis(l,5-cyclooctadiene)nickel(0)... 

Fig. 5 Example structures of fluorene co-oligomers and functionalized oligofluorenes ...

Fluorene oligomers, especially those functionalized at the C-9 position, are readily soluble in common organic solvents. The most striking example is in a study of a series of oligofluorenes static and dynamic solution properties, where they remain soluble at concentrations greater than 500 g L-1 in toluene, or > 50 wt. %, and even up to 800 g L-1 in the case of a terfluorene [ 120]. Routinely, fluorene oligomers are purified in solvent mixtures consisting mostly of nonpolar hexanes, and then solution-cast into thin films. 

Fig. 6 Structures of uniform chiral oligofluorenes and representative nematic and chiral oligofluorenes with mixed pendants...

Fig. 7 Additional example structures of liquid crystalline oligofluorenes...

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