Indenofluorenes

A concurrent report from the Yamashita group described the synthesis and characterization of 6,12-diarylindeno[l,2-f)]fluorenes 28k,r-t [72]. OFETs fabricated from thin films of the 28k exhibited hole transport. The 2,6-difluorophenyl 28r and 9-anthracenyl 28t derivatives had deeper LUMO energy levels and, as a result, showed ambipolar charge transport. The field-effect mobility was on the order of 10 cm s most likely due to the amorphous nature of the thin films. Further derivatization and device optimization was anticipated to improve the performance. 

Fully conjugated indeno[2,1-c]fluorene derivatives featuring an as-indacene 

In contrast to the preparation ofthe pentacene analog anthradithiophene [87,88], the preparation of both regioisomers (e.g., 34a syn vs 34b anti ) could be independently and easily accomplished. All compounds were characterized by singlecrystal X-ray diffraction and showed a /r-xylylene core but with more homogenous bond distances than 28q, indicating increased paratropicity of the indacene unit. Also notable is a short contact (3.35 A) between the five-membered rings of 35a and an adjacent sulfur atom. 

We have surveyed the emerging class of planar CPPAs. Recent examples of acenaphthylene-, pentalene-, and indacene-containing compounds demonstrate the breadth of synthetic work. The discovery of unusual reaction products followed by methods development is a central theme in the field. Resoundingly, Pd 

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As the next step in this way, Mullen and coworkers [608] have reported PPP-type polymers 512, containing planar pentaphenylene blocks. As expected, the emission maximum (Apl = 445 nm) of 512 was found between those of indenofluorene 510 (432-434 nm) and completely planar ladder-type PPP (450 nm) (see Section 2.5.2) [608]. Single-layer PLEDs ITO/PEDOT/512b/Ca/Al showed stable pure-blue emission with brightness in excess of 200cd/m2 (at 7 V) (Chart 2.121). 

P. Sonar, J. Zhang, A.C. Grimsdale, K. Mullen, M. Surin, R. Lazzaroni, P. Leclere, S. Tierney, M. Heeney, and I. McCulloch, 4-Hexylbithieno[3,2- /) 2, 3 -< ]pyridine an efficient electron-accepting unit in fluorene and indenofluorene copolymers for light-emitting devices, Macromolecules, 37 709-715, 2004. 

S. Setayesh, D. Marsitzky, and K. Mullen, Bridging the gap between polyfluorene and ladder-poly-p-phenylene synthesis and characterization of poly-2,8-indenofluorene, Macromolecules, 33 2016-2020, 2000. 

D. Marsitzky, J.C. Scott, J.-P. Chen, V.Y. Lee, R.D. Miller, S. Setayesh, and K. Mullen, Poly-2,8-(indenofluorene-co-anthracene) — a colorfast blue-light-emitting random copolymer, Adv. Mater., 13 1096-1099, 2001. 

A structural compromise between the fully bridged ladder system and the parent polyphenylene are stepladder polyphenylenes in which repeat units, such as fluorene, indenofluorene, or tetrahydropy-... 

Scheme 40 Indenofluorene-anthracene copolymer which produces a stable blue emission...

FIGURE 1.40 Molecular structure of R,o-bis(Ai-(2,6-diisopropylphenyl)-l,6-bis-(4-tert-butylphenoxy)-3,4-dicarbonicacidimide-9-perylene-poly-2,8-(6,6,-12,12-tetraethylhexyl) indenofluorene (PEC-PIFTEH). 

Bethell et al. (1989 a, 1989 b) studied the kinetics and products of the decomposition of three bis(diazo)indenofluorenes, e.g., ll,12-bis(diazo)-ll,12-dihydroinde-no[2.1-a]fluorene (9.63). They found electrochemically-induced chain processes in dimethylformamide solution leading to formation of polyazines. 

FIGURE 1.15 Chemical structure of polylfluorene) (PF) and poly(indenofluorene) (PIF). R is either a linear or a branched alkyl chain or bulkier groups such as butoxyphenyl (BP) or triphenylamine (TPA). For PIF, R is either... 

The conclusions drawn on the packing of PF chains can be extended to a parent polymer, poly (indenofluorene) (PIF see Figure 1.15). Indeed, thin deposits of n-octyl-substituted PIF (OPIF) show fibrillar patterns very similar to those observed for the other polymers in the series (Figure 1.23a). This suggests that the packing of the PIF chains is similar to that proposed for the poly(fluorene) chains. 

An intermediate structure between PPP and polyfluorene has been developed, the poly(2,8-indenofluorene). This blue emitting polymer is stable up to 380°C, and shows thermotropic LC behavior at high temperatures (250-300°C) making it a good candidate as the active material in polarized LEDs [278]. 

Indenofluorenes and Derivatives Syntheses and Emerging Materials Applications... 

Keywords Acene Indenofluorene Organic electronics Polyarene Polycyclic... 

This review focuses on the pentacyclic indenofluorenes (IFs), another reemerging class of CP-PAHs, where the B and D rings are each a five-membered ring. First synthesized in the late nineteenth century by Gabriel [16], IF derivatives... 

Fig. 1 Nomenclature and numbering for indenofluorene isomers. Italicized numbers denote numbering for methylene bridge orientation, non-italicized numbers denote atom...

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