| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 가을 (10/13 ~ 10/14, 제주 ICC) |
| 권호 | 30권 2호 |
| 발표분야 | 분자전자 부문위원회 |
| 제목 | Organic Chromophores for Electro-Optical Applications: Effect of Donors, Conjugation Bridges, and Shape on Their Properties |
| 초록 | In recent years, organic nonlinear optical (NLO) materials have continuously drawn interest because they have several advantages for photonic applications such as electro-optical modulators and optical switching devices. Macroscopic electro-optic activity is strongly dependent upon the chromophore’s first hyperpolarizability (β) and upon the efficiency of alignment, which is closely related with its dipole moment (μ). For a practical application, thermal stability of the chromophores is another critical criterion for long-term device efficiency. The interaction between neighboring chromophores should be also considered especially at high chromophore loading density, because the interaction becomes strong enough to resist the external electric poling field. In this work, we designed and synthesized new kinds of push-pull type chromophores with different donors and conjugation bridges, which exhibited relatively high electro-optic coefficient as well as thermal and photochemical stability. The chromophores with julolydyl group as a donor showed higher thermal stability, longer absorption maximum, and superior electro-optic characteristics than those with 4-aminobenzene. Instead of polyene, phenylene and/or thiophene aromatic rings were incorporated as a conjugation bridge for higher thermal and photochemical stability. Bulky alkyl chains were substituted to the phenylene bridge to minimize the electrostatic interaction of the chromophores. The chromophores were also chemically bonded to the end of dendrimeric structure. Synthesis: A Williamson etherification of methylhydroquinone with 2-ethylhexylbromide gave 1,4-bis(2-ethyl-hexyloxyl)-2-methylbenzene, 1, in 66% yield. Compound 2 was prepared in 51% yield by radical bromination of 1 with 1.2 equiv of N-bromosuccinimide (NBS) and 2,2`-azobis(2-methylpropionitrile) (AIBN) in dry refluxing carbon tetrachloride followed by ionic bromination of the intermediate with 1.3 equiv of NBS in dry refluxing tetrahydrofuran (THF). Phosponate 3 was obtained from 2 by a Michaelis-Arbuzov reaction. The Wittig-Horner coupling reaction of 3 with 4-(diethylamino)benzaldehyde gave compound 4 in 84% yield. The terminal bromide of compound 4 was transformed into aldehyde (compound 5) by treatment with n-butyllithium and N,N-dimethylformamide(DMF) according to the Bouveault method. Compound 5 was isolated in 68% yield. (5-Bromo-thiophen-2-yl-methyl)-phosphonic acid diethyl ester was obtained from 2-methylthiophene by bromination and subsequent Michaelis-Arbuzov reaction. The Wittig-Horner coupling of 5 with (5-bromo-thiophen-2-ylmethyl)-phosphonic acid diethyl ester gave compound 6 in 86% yield. The terminal bromide of compound 6 was transformed to aldehyde by treatment with n-butyllithium and DMF. The resulting compound 7 was reacted with 2-dicyanomethylene-3-cyano-4,5-dimethyl-5-methyl-2,5-dihydrofuran to give a NLO chromophore, 2-{3-Cyano-4-[2-(5-{2-[4-[2-(4-diethylamino-phenyl)-vinyl]-2,5-bis-(2-ethyl-hexyloxy)-phenyl]-vinyl}-thiophen-2-yl)-vinyl]-5,5-dimethyl-5H-furan-2-ylidene}-malononitrile (PT-TCF) as a dark purple solid. |
| 저자 | 김동욱, 최진주, 주현경, 윤성철, 임종선, 김경만, 이창진 |
| 소속 | 한국화학(연) |
| 키워드 | Electro optics; Nonlinear optical chromophores; optical modulators |
