Spirofluorene

Fusion of the two arylamino groups of a triarylmethane phthalide color former results in the formation of spirofluorene phthalides. Due to the increased planarity of this system, a bathochromic shift results leading also to color formers showing infrared absorption when developed. This was first exemplified in 1983102 by preparation of phthalide 26 as shown in Scheme... 

SCHEME 3.64 Chemical structures of spirofluorene substituted anthracenes. 

Qiu s group investigated the spirofluorene linked dihydroanthracene compound di-Spiro-9, 9 -di-fluorene-9",9" -(9,10-dihydro-anthracene) (DSFA), originally developed in the 1930s, as a blue emitter in ITO/m-MTDATA/NPD/DSFA/Mg Ag [258]. The device exhibited a... 

The preparation of additional spirofluorene monomers are described by Parham et al. (1). 

Hetero spirofluorenes, (III), were prepared by the author et al. (4) in an earlier investigation and used in polymer organic light-emitting diodes having extended lifetimes. 

Photolyses carried out in acetic acid give allylic acetates, apparently via a diazoacetate (Scheme 60)51,57. Carbenes derived from spirofluorene derivatives have been trapped with pyridines and pyridazines to give useful photo-chromic spirodihydroindolizines.163... 

The radical cation of spirofluorene, 19, is mentioned only in passing. The orientation of the fragments allows only the second highest MO of the biphenyl moiety to interact with a cyclopropane FMO (the A HOMO). Thus, the type B structure should be stabilized to a lesser extent. The extent of homoconjugation also is expected to be weak because of a more serious mismatch in orbital energies [110, 127]. 

This review focuses on the synthesis, characterization, and performance of monodisperse fluorene-based conjugated oligomers with potential applications to organic electronics and photonics. Included herein are oligomers and co-oligomers that contain at least two fluorene units in their backbone structures, while excluding those with a lone spirofluorene unit without other fluorene units in the backbone, as these have been covered elsewhere [42,43]. 

Because of its spin-forbidden nature, the decay rate of the first excited triplet state is extremely low, and very difficult to quantify accurately. What can be measured is the phosphorescence lifetime. Typical long time decays for a poly(bi-spirofluorene) (PSBF) are shown in Fig. 6. 

Disubstituted hydantoins and 2-thiohydantoins, especially their 5,5-diaryl derivatives, have been prepared by means of a condensation that involves a rearrangement similar to that in which benzilic acid is formed from benzil.1,3 Examples include the synthesis of fluorinated hydantoins,35 spirofluorene-,36 and spiroacenaphthylenehydantoins,37 2-thiohydantoins,30 38 39 and 5,5-diphenylhydantoin-2,4,5-13C3.40... 

The first oxetane-functionalized emitter were pyrene derivatives (Fig. 9.19(b), [46]), however, with very limited performance in OLEDs. Later, a poly(pheny-lene-fluorene)-copolymer was reported, however, without any electroluminescence data (Fig. 9.19(c), [47]). The breakthrough came with a recent report on a crosslinkable class of state-of-the-art spirofluorenes (Fig. 9.19(a), [48, 49]). By incorporating a green- and red-emitting comonomer, it was possible to generate the three primary colors (RGB) necessary for color-display applications. More recent concepts use sterically hindered 9,9 -diarylfluorene blocks to link conjugated oligomers (Fig. 9.19(d), [50]). 

In contrast with the behaviour of the radical POBF-, the carbanion POBF does not cyclize to the spirofluorene (p. 386). This is attributed to a high charge delocalization in the fluorenyl system due to the negative inductive effect of the chlorines, diminishing that on the 9-carbon. 

Phthalide derivatives are of major importance in the dye industry, particularly in the area of recording material color formers. Pressure-sensitive carbonless copy paper and thermal recording paper are typical applications. Five principal structural classes have been developed extensively the xanthene dyes (fluorans (208)), 3,3-diarylphthalides (209), spirofluorenes (210), 3,3-bis(di-arylethylene)phthalides (211), and 3-substituted phthalides <84Mi 208-03>. Some of these structures are common to many familiar acid/base indicators, dyes, biological stains, or laser dyes such as fluorescein (212) and phenolphthalein (213) ,... 

If spirofluorene is equally substituted only in the 2 and 2 positions, the symmetry is C2, and the compounds are also chiral. This is the case for a series of materials discussed in previous sections, but usually racemic mixtures are obtained and characterized. In a few cases, however, the enantiomers were separated, and the chiroptical properties of the individual enantiomers... 

A similar orientation of sulfonation was found in the reaction of 9-alkylfluorenes and 9,9 -spirofluorene these positions are para with respect to the bridge bond, so the substitution orientation is analogous to that of biphenyl itself... 

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