Fluorene oligomers

EP Woo, WR Shiang, M Inbasekaran, and GR Roof, 2,7-Aryl-9-Substituted Fluorenes and 9-Substituted Fluorene Oligomers and Polymers, U.S. Patent 5,708,130, 1998. 

Aryl-9-substituted fluorenes and 9-substituted fluorene oligomers and polymers Fluorene copolymers and devices made therefrom... 

The synthesis of fluorene oligomers is intensive in terms of number of steps, but the unique properties and the new insight into structure-property relationships are well worth the effort. A number of approaches have been developed from the initial brute force fractionation of polydisperse systems to the more elegant deterministic synthesis of monodisperse systems. 

Yamamoto and Suzuki coupling, and other common reactions in fluorene oligomer synthesis are illustrated in Fig. 3. 

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. 

Liquid crystalline fluorene oligomers can emit polarized fight with proper alignment of their molecular axes and, hence, of their transition dipole moments. For example, linearly polarized emission results from uniaxial alignment of fluorene oligomers. One common way to characterize linearly polarized emission is to measure its emission dichroism, viz. the emission... 

Fig. 14 Representative fluorene oligomers used in lasing and amplified spontaneous emis...

Fluorene oligomers have seen only limited use in organic solar cells to date. If they incorporate any fluorene units at all, most efforts have focused on polyfluorene derivatives [19,20]. For example, Bryce et al. synthesized a series of oligofluorene-fullerene derivatives to study their fundamental photophysical and charge transfer properties [216] (compounds 62-67 in Fig. 17), but have not pursued such structures for organic solar cells yet. 

Kelly et al. remain the primary group involved in using fluorene oligomers for solar cell applications. Their initial effort utilized a fluorene oligomer, which incorporated a perylene diimide central unit (compound 68) [217],... 

Not departing too far from fluorenones, Iiu et al. have done an elegant study on the photodegradation of fluorene oligomers [220]. The structures they use vary from that of compound 51 to compound 72, shown in Fig. 19, by varying the amount of alkyl versus spiro-substitution. These compounds are carefully characterized and found to contain no detectable fluorenone as synthesized. Also shown are a number of defect sites they propose and subsequently detect after photoirradiating the samples. Figure 20 shows the matrix-assisted laser... 

Keywords Branched molecules Dendrimer Excitonic coupling Fluorene Oligomer Two-photon absorption... 

Zhang X-C, Zhang Y, Wang C-Y, Lai G-Q, Zhang L, Shen Y-J (2009) Fluorene oligomer with tetrathiafulvalenes as pendant groups synthesis, electrochemical and spectroscopic properties. Polym BuU 63 815-827... 

Fig. 7. 16 Top Chemical structures of crosslinkable fluorene oligomers. Bottom. Fluorescence microscope (left) [46] and SEM image (right) of a microstructured oligofluorene [62]...

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