Light Absorption Properties of Anthraquinone Dyes and Guest-Host Liquid Crystal Displays
- PDF / 493,030 Bytes
- 8 Pages / 417.6 x 639 pts Page_size
- 83 Downloads / 145 Views
EXPERIMENT 1,5-dihydroxyl-9,10-anthracedione is available from Aldrich Chemical Company. Liquid crystal mixtures E-48, ZLI 5100-100, ZLI 2806 and ZLI 2861 were purchased from EM industries. Glass sample cells, whose inner surfaces were coated with rubbed polyimide alignment layers and separated by 10-pm spacers, were obtained from industry. A typical sample cell was prepared by introducing a 1% Wt solution of the dye 1, 5-bis(4-butylphenylamino)-2-(4-heptoxylphenyl)- 4, 8-dihydroxyl -9, 10-anthracedione dissolved in a liquid crystal mixture. UV-vis absorbance was determined using a HP 8453 spectrometer fitted with a linear polarizer. The absorbance of this solution in polarized light was recorded at its maximum wavelength of absorption with the direction of the polarizer parallel (A//) and perpendicular (A±) to the alignment direction. The two orientations were obtained by rotation of the cell, while the polarizer was fixed. The order parameter SD for the dichroic dye in a liquid crystal host is given by SD = (A//- AJ/(A, + 2A±) where A/, and A± are the absorbance of light polarized parallel and perpendicular to the rubbing direction of the alignment layer, respectively.
249 Mat. Res. Soc. Symp. Proc. Vol. 559 ©19 99 Materials Research Society
The 'H and 13C NMR spectra were recorded with Varian 200 spectrometer in CDCI 3 or DMSO-d 6 with tetramethylsilane as an internal standard. IR spectra in KBr pellet were obtained with a Shimadzu FTIR-8201PC infrared spectrophotometer. Mass spectra were obtained on a Finnigan MAT 95 mass spectrometer. The synthetic procedure for the dichroic dye 1, 5-bis(4-butylphenylamino)-2-(4-heptoxylphenyl)- 4, 8-dihydroxyl -9, 10-anthracedione (4) is outlined in Scheme 1. The preparative methods and physical data for intermediate compounds and the final product are given below. Synthesis of 2-(4-heptoxyaryl)-], 5-dihydroxyl-4, 8-dinitro-9, 10-anthracedione (3): 1, 5dihydroxyl-4, 8-dinitro-9, 10-anthracedione (12.5 g) was dissolved at room temperature in a mixture of conc. sulphuric acid (200 mL) and boric acid (24 g). The solution was cooled to --15 'C, and heptoxylbenzene (7.5 g) added in a dropwise fashion during 1hour. After stirred at -15 'C for 2 hours, the solution was poured upon crushed ice and the aqueous suspension was boiled for 4 hours to destroy boric ester. The crude was collected by filtration and purified by chromatography on sillica gel using hexane/toulene/ethyl acetate (3:2: l/v) as an eluent to afford the 3.1 g of product. 'H NMR (CDC13 ) 8 7.83 (H, 1Hs, J = 8.8 Hz, anthracedione-H), 7.398 (1H, s, anthracedione-H), 7.375 (1I-, d, J = 8.8 Hz, anthracedione-H), 6.993 (2H, d, J = 8.2 Hz, Ar-H), 6.993 (2H, d, J = 8.2 Hz, Ar-H), 4.051 (2H, triplet, J = 6.4 Hz, -OCH 2-), 2.048-1.012 (10H, multiplet, -C5 H•O-), 0.908 (3H, triplet, -CH 3 ). "C NMR (CDC13, 200 MHz): 8 184.7, 184.5, 18-3.8, 181.2, 180.2, 150.7, 142.8, 142.7, 137.3, 131.0, 128.2, 125.3, 118.8, 116.0. 113.6, 10.5.3, 69.4, 33.1, 30.4, 27.3, 23.9, 15.8. IR (KBr pellet, cm'): 3473.5(br, Ar-OH), 2960-22920, 2841 (C
Data Loading...
