Triphenylene derivative

Acetylene dicarboxylate and maleic anhydride failed to react with simple methylene cyclopropenes, but reacted readily with calicene derivatives, as shown by Prinz-bach293. Thus ADD combined with benzocalicene 497 to give the dimethyl tri-phenylene dicarboxylate 499, whose formation can be rationalized via (2 + 2) cycloaddition across the semicyclic double bond as well as (4 + 2) cycloaddition involving the three-membered ring (498/501). The asymmetric substitution of 499 excludes cycloaddition of ADD to the C /C2 triafulvene bond (500), which would demand a symmetrical substituent distribution in the final triphenylene derivative. 

Praefcke et al.47 and Boden et al.48 have both synthesized triphenylene derivatives with halogens attached to the core (46). It was assumed that the resulting chirality would express itself more strongly than chirality present in the side chains. These halogenated compounds could be readily modified to give the hepta-alkylated triphenylenes however, in spite of calculations which revealed that the triphenylene core indeed becomes helical, no expression of the helicity at the mesoscopic level could be achieved. 

A second example from the same group is the synthesis of an elaborate diethynyltriphenylene derivative (Scheme 7 Table 8,entries 12,13) [58].Zn/Pd-promoted homocoupling of a 4-iodo-l,2-dialkoxybenzene furnishes the desired tetraalkoxybiphenyl, an electron-rich aromatic system. Iron trichloride-catalyzed Friedel-Crafts arylation of the biphenyl derivative with dimethoxy-benzene furnishes an unsymmetrical triphenylene derivative. Deprotection, oxidation, and subsequent Diels-Alder reaction with cyclohexadiene is followed by catalytic hydrogenation and reoxidation. TMS-CC-Li attack on the quinone delivers the alkyne modules, treatment with SnCl2 aromatizes the six-mem-bered ring, while KOH in MeOH removes the TMS groups cleanly to give the elaborate monomer. 

Govindaswamy P, Furrer J, Suss-Fink G, Therrien B (2008) Encapsulation of triphenylene derivatives in the hexanuclear arene ruthenium metallo-prismatic cage [Ru6(p-Pr C6H4Me)6 (tpt)2(dhbq)3]6+ (dhbq = 2,5-dihydroxy-l,4-benzoquinonato). Z Anorg Allg Chem 634 1349-1352... 

The coelectrolysis of veratrole with anisole derivatives afforded in TFA-CH2CI2 good yields of aryl-substituted triphenylene derivatives (Table 4, number 9). Product formation probably occurs by initial coupling of the veratrole cation radical with anisole to an unsymmetrical dimer. This is followed by coupling of the dimer and intramolecular cyclization to the product. 

In general, for side chain liquid-crystalline polymers, macroscopic molecular alignment is not easy and therefore clear evidence of electronic charge carrier transport was confirmed first in liquid crystals with low molecular weight. In the 1990s, fast electronic conduction was verified in discotic columnar phases of triphenylene derivatives [79,80] and hexabenzocoronene derivatives [81,82] as well as smectic phases of 2-phenylbenzothiazole [83, 84] and 2-phenylnaphthalene derivatives [85], as shown in Fig. 14. Carrier... 

Polymerization of mesogenic monomers is very effective for obtaining more stable ordered thin films. Triphenylene monomer containing acrylate moiety 18 was photopolymerized by UV light irradiation (Fig. 17). UV light was shone onto the mixture of the triphenylene derivative and a photoinitiator under inert atmosphere. Carrier transport characteristics of the ob-... 

Because of the conformation change and defect formation during the photopolymerization process, long coherence length of the columns in the columnar phase was difficult to maintain. Therefore, the excellent carrier transport characteristics in the columnar phases of monomeric triphenylene derivatives could not be retained in the polymerized films. 

Enhanced photoconductive properties were reported for physical gels of a liquid-crystalline triphenylene derivative [112],... 

Bacher et al. [15] reported on a series of triphenylene derivatives with one, two or three reactive acrylate units for crosslinking (Fig. 9.8(a)). No influence of the number of acrylate units on the degree of crosslinking was reported. Bi-layer OLEDs with the triphenylene as hole-transport agent and vapor-deposited A1Q3... 

Ordered thin layers can also been obtained from dilute solutions of discotic compounds onto gold or silicon surfaces. For example, triphenylene derivatives with a single long (o-alkylthiol chain have been shown to self-assemble into monolayers, in which the two types of orientation, face-on and... 

One of the first studies involved non-mesomorphic triphenylene derivatives mixed with 2,4,7-trinitrofluorenone (TNF) [116] shown in Fig. 27. 

A mixed ether ester triphenylene derivative 11 has been observed to spontaneously align homeotropically on a single substrate in the presence of an air-interface (Fig. 7.3) [99]. This observation is very significant since DLCs generally tend to align in planar manner on single substrates in the presence of air-interface. 

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