The E and Z-isomers of the titled compound were synthesized by condensation of 2-carboxaldehyde-8alkyloxyquinoline and N-cyanomethylcarbazole, followed by hydrolysis. The alkoxy protection groups in 3b-c can be cleaved either in acid or in base to yield 3a. All compounds exhibit blue/green luminescence, which may be used as emitting materials in the fabrication of light-emitting diodes. Crystal diffraction analyses were performed for 3a-E, 3d-Z, and 4-Z, while the results indicated the presence of a common structural feature among these molecules. The rings of quinoline are co-planar with the double bond of acrylonitrile, forming a major conjugated chromophore. The carbazole group is twisted along the N(9²)-C(2) bond away from the major plane with a large dihedral angle. The major conjugated chromphore was found to be responsible for the spectral properties of these compounds. Protonation of the quinoline in these compounds redshifted their absorption bands substantially.Keywords: Carbazole; Hydroxyquinoline; OLED.pounds. These materials have the virtue of easy preparation, yet with a drawback of low stability due to the reactive nature of di-ene groups. Their chemical stability can be enhanced by replacing the styrene moiety with 8-hydroxyquinoline to form a new series of compounds which contain both HT and ET functional moieties. Their synthesis, structures and photoelectric properties are reported herein.
RESULTS AND DISCUSSION
PreparationThe main reaction for the preparation of 3b, both in E and Z forms, was a condensation between 2-carboxaldehyde-8-benzyloxyquinoline (2b) 4,5 and N-cyanomethylcarbazole. 6 The dehydration was carried out in a heterogeneous
Three derivatives of 2‐amino‐3‐naphthylacrylonitrile 2∼4 were synthesized as potential green luminance dyes. The green emission is derived from a charge transfer transition, which exhibits an apparent solvatochromic effect. The crystal structures of derivatives 2 and 3 were resolved by X‐ray diffraction analyses. The diphenylamino derivative 2 was found in monoclinic P21/n space group with a = 10.032(2), b = 17.034(5), c = 12.143(6), and β = 112.02(3)°. The carbazyl derivative 3 was found in triclinic P‐1 space group with a = 8.890(3), b = 9.296(6), c = 12.209(5), and α = 98.89(4)°, β = 93.46(3)°, γ = 116.47(4)°. The amino group in 2 forms a better resonance with acrylonitrile group than that in 3. The electronic nature of the amino group is responsible for the spectral difference among three compounds. The effect is verified by ab initio molecular modeling.
The printing dot pattern on diffuser plate is utilized for thin direct LED backlight and large LED pitch. Through the reflection of printing dot pattern, the light energy is redistributed and therefore the vertical and horizontal dark bands between LED arrays can be removed. Thinner LED backlight and larger LED pitch could thus be attained. Without using any external optical lens, this backlight structure does not suffer from extra optical interface loss. Furthermore, the luminance at normal direction of this LED backlight is kept the same as the conventional one.
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