Diphenylamino groups

The cyclohexane 61 is formed as a ratio of 2 1 of a mixture of two geometric isomers which differ in the arrangement of the diphenylamino group. In one isomer this group is in an axial position and in the other in an equatorial position. Both trimethylgermyl groups in 61 are equatorial, i.e. they retain the configuration of precursor cw-136. 

Acetylene bonds carrying a diphenylamino group are only moderately reactive, which permits the synthesis of the first ynamine carboxylic acid 80 using carbon dioxide as reagent (131) 37). 

Realizing that the diphenylamino group is -N write the entire structure as ... 

Much higher EL efficiencies have recently been achieved using oligomers composed of fluorene, thienyl-5,5-dioxide or dibenzothiophene-5,5-dioxide and end-capping diphenylamino groups [25, 32]. Figure 4.11 shows the stmcture and some electroluminescence characteristics of two of these compounds... 

Fluoran compounds having two diarylamino groups at 3 - and 6 -positions generally develop blue tone colors. For example, 3, 6 -bis-(diphenylamino)fluoran (34 R1, R2 = H)29 develops reddish blue color, and 3 -diphenyl amino-6 -di-/ -tolylaminofluoran (34 R1 = H, R2 = CH3)29 and 3, 6 -bis(di-/i-tolylamino)fluoran (34 R1, R2 = CF13)29 blue color. 

If at least one of the aryl groups at 3 -position is replaced with an alkyl group, then the developed color is more reddish as a result of a hypso-chromic shift. Thus, 3 -diethylamino-6 -diphenylaminofluoran (35 R = C2H5)29 and 3 -diphenylamino-6 -(/V-ethyl-/i-toluidino)fluoran (35 R = 4-CH3C6H4)29 develop reddish violet and bluish violet colors, respectively. 

The benzyl 1,2,4-thiadiazolium salt 59 can be isomerized to the 5-imino-l,2,4-thiadiazolidine 60 when treated with a strong base like potassium /-butoxide (Equation 17) <1997ZOR1728>. If the 2-substituent is replaced with a tosylmethyl group and the 5-position substituent is a diphenylamino in place of an aniline such as compound 61, then a rearrangement occurs to give an imidazole 62 (Equation 18) <1997ZOR1728>. 

The diphenylamino-substituted PPV107, with solubilizing alkoxy groups, was synthesized by Shi and Zheng [150] via Wittig-Horner reaction (Chart 2.23). Its PL (555 nm) is very similar to that of diamino-PPV 64 and dialkoxy-PPV 14 homopolymers. The PLQY is rather high in solution (80%), but it drops to only 8% in films. Consequently, only a moderate EL efficiency of 0.6cd/A was obtained with this material (device ITO/PEDOT/107/Mg/Al) [150]. Almost simultaneously, Kido and coworkers [151] reported a similar diphenylamino-substituted PPV copolymer 108, which affords very efficient PLEDs. The device ITO/PEDOT/108/Ca/Al... 

Stilbeneamines. The functionalization of stilbenes with arylamino groups leads to materials that emit in the green-to-yellow spectral region. For example, 9,10-bis(4-(7V,/V-diphenylamino)styryl-anthracene (BSA, 21) absorbs at429nm and emits at 585 nm [141]. Compound 21 and other derivatives of bistyrylanthra-cene have been successfully applied in yellow emitting OLEDs [64]. Tetra(tri-phenylamino)ethylene (TTPAE, 20) emits at 539 nm [109]. The latter compound exhibits a large quantum yield of 25% in the amorphous film, but does not show fluorescence in solution. 

Weaker O—H- n hydrogen bonds were also observed in M dipheny-laminosquarate complexes (M = Mn, Co, Cu, Zn) and involve the interaction of aqua hydrogen atoms and the phenyl groups of neighboring diphenylamino substituents (134) (Fig. 31). 

It should be pointed out that thermostability of donor and acceptor groups has rarely been addressed. For example, it is known from classical textile dyeing that benzylic C-H bonds and C-H bonds in the a-position with respect to a heteroatom are to be avoided (because they are weak and susceptible to radical attack). Therefore, it is understandable that molecules with diphenylamino donors are regularly more stable than their congeners with dia//cy/amino groups (Moylan et al., 1993 Jen et al., 1997). Likewise, nitro groups are photoreducible in some media and often impart thermal instability to the molecule. They may be replaced by sulphones that lead to hypsochromic shifts and decreased second-order polarizabilities (Beecher et al., 1993). 

Fukudome, M., Kamiyama, K., Kawai, T., and Irie, M, Photochromism of a dithienylethene having diphenylamino side groups in the bulk amorphous phase25 refractive index change of an amorphous bisbenzothienylethene. Chem. Lett. 70, 2001. 

Low TPA was observed for 73, which has a thiophene-vinylene-thiophene core at the center and phenylene-vinylene hinge between the core and the end capped diphenylamino donor group. Thiophene is an electron-rich heterocycle and it is therefore an electron-donating group. Thus, a bigger amplitude for TPA was expected for this chromophore. Experiments, however, demonstrated a lower TPA ampliude. Therefore, incorporation of such electron-rich moieties... 

Dichloro(diphenylamino)borane forms monoclinic crystals (space group P2i). The CI2BNC2 skeleton is very nearly planar, with the Ph groups tilted out of this plane. The B—N distance is 1.38 A, suggestive of B—N bonding. " ... 

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