Korean Chemical Engineering Research

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(1)Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005, pp. 176-180. ! +. Schiff Base !Ç- Z ¿×C´W£ ¬<|. <G §F ¿h <GÐ +Gë {£ ¤* ¿K* ×TG* ¿?/* †. D¬H/ ÉõêHz £ 4Q ö

(2) §- 29-1 *K¬H/ ÉõêHz 306-791 ¬MQ ¬ C 1_ 133 (2004¸ 8ö 10³ [¤, 2004¸ 10ö 7³ >) 336-795. Liquid Crystalline Properties of Schiff Base Mono- and Dimesogenic Compounds Joo-Hoon Park†, Ok-Byung Choi, Jin-Seok Lee, Keun-Myoung Kang, Joo-Cheol Shin, Ki-Hwan Kim, Hak-Jin Kim*, Chang-Joon Lee*, Bong-Keun So* and Soo-Min Lee* School of Natural Science, Hoseo University, San 29-1, Sechul-ri, Baebang-myun, Asan, Chungnam 336-795, Korea *School of Natural Science, Hannam University, 133, Ojeong-dong, Daedeok-gu, Daejeon 306-791, Korea (Received 10 August 2004; accepted 7 October 2004). ß È. öÇ Schiff base èfo .Q ·-èW KõÉ³ «P´D K ªù ? 1 U_OYZQ ªù dY í U_ s oÝI. «Ë ùJ Hê U_ o Qó ? ù~DQ Íù¶« zôê s Â Ñ G ñ Æ G. OYZQ dYí U_ Ho OJ ·-èW KõÉQ S <VQD L«Ñ ¿j ÊG . OYZ Iê ªù III dYío õ2Yê Ùö UZd M«5Ñ _¤-L¤ Áêõ Ýñ ?Ék÷ ªù IIQ IV dYío Ùö UZd M«5ÑO _¤-L¤ Áêõ ÷É. s Â s Gñ «Ë HCÆõ îû Gs ) Kê )é U_ s G. Abstract − The liquid crystalline properties of a series of main chain liquid crystalline polymers and four series compounds consisting of aromatic type Schiff base mesogenic units and polymethylene flexible spacers were studied. The thermal and liquid crystalline properties were investigated by differential scanning calorimetry and on the hot stage of a polarizing microscope. The nature of the liquid crystalline phase of the polymers and compounds depended greatly on the length of the central polymethylene spacer and on the terminal alkoxy groups. Polymers I and Series III exhibited an even-odd effect in melting and isotropization temperatures but Series II and Series IV exhibited an even-odd effect in isotropization temperatures. They formed nematic and smectic mesophases in melts as judged by their optical textures observed through a polarizing microscope. Key words: Liquid Crystalline Compounds, Non-Conventional Liquid Crystals, Dimesogenic Liquid Crystals, Schiff Base Mesogen. 1.. C «. Î-2 O õgÑ 4Ö gÆõ ä2 ? I U_ OY Z ê K K èfo .Q KõÉõ ä2 dYís è,G 2)[16, 20], « dYío U_ OYZ âo HdYí³ } [15-19]. I. Ù K èfo .Q Ù KõÉõ Í@2 non-conventional U_ dYíËo U_dHÑ Ã îê kts @nÊ À[1-5]. «Ë OÑ siamese µ<« èj«¶ -2 «èfo dYí o U_dH *³Ò O®K ~tõ fàGÊ À[6-14]. ñDÑ , & ³K èfo .2 OJ KõÉõ 0Gñ õæ´ À2), «6K dYíËo ço èfo .Q KõÉ³ «P ´D ? I U_ OYZÑ ¬K âo HdYí³ Êsæ´ -COO-, -CH=N-, -N=N-, -CONH-(CH2)n-, -O-(CH2)n-O-. † To. whom correspondence should be addressed. E-mail: [email protected] 176.

(3) ³- Ú «èfo d;í 7_ . Ws < ¤ ÀÉÊ, «6K o Jin Ù[15, 16, 18], Griffinê Britt[17]Ñ Gñ è,æ´. 6÷ «6K «èfo dYí U_}o ¬G2 ³ èfo dYí }ê2 ÜÜ ñ s Ýñ?Î K. ¶, á õgÑ2 Schiff base èfo .Q ·-èW Kõ Éõ ä2 ³ èfo dYíê «èfo dYí ~Ég ÆQ U_ Ñ îîªõ é¾D .Gñ 4ÖQ ço Í@ ªù dYís oÝI.. 177. 1375(-CH3), 1280-1035(C-O stretch). 1H-NMR (DMSO-d6, δ ppm): 0.85-0.95(t, 6H, -CH3), 1.25-1.90(m, 32H, -CH2-), 3.95-4.05(m, 8H,. ³ èj. -OCH2-), 6.80-7.85(m, 16H, Ar-H), 8.40(s, 2H, =CH-). ρ-decyloxybenzylidene ρseries II hexyloxyaniline . ρ-hexyloxy aniline(0.003 mol) (30 mL) , ρ-decyloxybenzaldehyde(0.003 mol). s ä2 dYí ¬,J dYí¯ Y ro {ê ç s Ñ!9 Ñ õ«Ê sÑ !9(30 mL)Ñ õñ 4Ñ 8 hÍÿÊ 5b@ U6 S . DMSO : EtOH=1 : 1(v/v)³ é_Gk, ¤ÄÕo 80.0% Ê, õ2Yo 92.5 C. «Ë ~ HJ ê2 {ê ç. IR(KBr, cm ): 3013ê 2930(aromaticê aliphatic C-H stretch), 1615 o. −1. (=C-N- stretch), 1370(-CH3), 1260-1020(C-O stretch). 1H-NMR (DMSO-d6, δ ppm): 0.86-0.98(t, 6H, -CH3), 1.20-1.93(m, 24H, -CH2-), 3.95-4.05(m, 4H, -OCH2-), 6.93-7.90(m, 8H, Ar-H), 8.42(s, 1H, =CH-). du pont DSC 910S. dYí ùJMo H DÍGÑ s. ÄGñ Íù Ú -Î 10 C/min³ oÝI. 5 Ý_ê M«Ñ ¬K ùòHJ às »D .Gñ ¯³s DCíH³ «ÄG Ê, dYí HgÆ2 Íù¶(Mettler Hot Stage FP-82HT)« zôê s Â (Leitz, Ortholux)s ÄGñ Æ G. o. 3. 2.. / . dYí Y o & ª³ «P´. OÑ dYí s »D .Gñ, H DÍGÑ ê 1,10-dibromodecane Series I. decamethylene-1,10-bis-ρ-oxybenzaldehyde(1) 4-hydroxybenzaldehyde (0.21 mol). s DMF (50 mL)Ñ Ê 4Ñ 8 hÍZ äís 5b@ ¾Ê, 2 L Í¤Ñ z´ z Ms »ÉÊ, Í¤³ 4 C á 5Ñ QÆK á Ñ!9³ é _Gñ + ÊZ _s »Ék, ¤ÄÕo 83.0%Ê, õ2Y o 80 Ck, éËàê[21] Ñ ³jG. MÜ@ í¯ decamethylene-1,10-bis-(ρ-oxybenzylidene ρ-alkoxyaniline)(series I)s »D .Gñ OÑdYí(1)Ñ ρ-jhê 4v1s äZ. «Ë Y öro çID )éÑ ¬,Jk³ n=6¯ dYí Y rO s ñDÑ D¬G. H DÍGÑ, OÑdYí(1)(0.002 mol) s Ñ!9(30 mL)Ñ õ«Ê, ρ-hexyloxyaniline(0.006 mol)s Ñ! (0.07 mol), Na2CO3(0.21 mol) .. o. ûG Z +{. KõÉQ èfo .õ dÕ4 ä2 ? I U_ OYZ I HÑ Y¢K H dYís oÝD .Gñ )èW Kõ Éõ OJÑ äk Schiff baseèjDõ õD³ Gñ ³Ñ ¡dê <Dõ ä2 «èj series I dYís Y GÊ, K \Ñ )èW KõÉõ äk èjDõ õD³ Gñ < Dõ ¡d Kõ Éõ ä2 ³ èj dYí¯ series II õ Y G. K, ³Ñ Ñ jhDÍ À2 èjs ä k OJ KõÉ³ ÑWÑz )èWb@ ¡d series III dYís oÝIÊ KõÉ³ ÑDõ ä2 èj .Ñ KõÉõ èWÑz ô÷èWb@ ¡d series IV dYíË ùJ Hê U_ s oÝI. )èW KõÉõ Ok³ \Ñ & í Schiff base èfo .õ äk, ³ <Dõ ¡d series I dYí M«Ñ ¬K ùJ Hê ùòHJ êõ Table 1Ñ ÷É. Table 1Ñ Ý2 àQ ç«, n=1¯ dYío ÍùÑ2 199 CÑ Ñà³ Ê Z_(Cr)Ñ Ùö UZ(I)³ ù M«Í æÉÊ, -ÎÑ 2 189 CÑ Ùö UZ(I)→U_(N)k³ èù M«Í ³´

(4) k, 167 CÑ U_(N)→ÊZ_(Cr)k³ èù M«Í ³´ ÷2 ö U_s G. n=5¯ dYío Íù 174 CÑ o. o. o. o. Table 1. Transition temperatures and liquid crystal phases of Series I a),b). 9(30 mL)Ñ õñ, & äís 4Ñ 8 hÍZ. 5b @ Â á U6 S-Ê, DMSO : EtOH=1 : 1(v/v)³ é_G k, Dà1Ñ SÊ ¤ÄÕo 72.0%k, õ2Yo 117 C. dYí gÆe¯o IR(Perkin Elmer 1000 FT-ID Spectrometer) Ú NMR(Varian Mercury 300(300 MHz)) APTFÑ Gñ }Gk, «Ë ~ HJ ê2 {ê ç. IR(KBr, cm ): 3020ê 2915(aromaticê aliphatic C-H stretch), 1620(=C-N-stretch),. n 1 2 4 5 6. o. −1. Cr. Transition temperatures (oC) N 199(167) -(189) 233(210) 285(265) 119(106) 175(165) 174(165) 117(104) 160(156). I. a). Cr: crystal state, N: nematic phase, and I: isotropic state. Values in the parentheses are those obtained from the cooling DSC themograms.. b). Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005.

(5) á?åöM ³ö«,öãöU?{ö6,hö60,ö« Cöóö«¤Æ. 178. Table 2. Transition temperatures and liquid crystal phases of Series II a),b) n. Cr. S3. 1 2 3 4 5 6. Transition temperatures (oC) S1 -. S2. 177 102 104 104 94.5 92.5. 91.0 89.8. N. I. (91.0) 100 109 107 110. (88.5) (92.5) 106 109. (96.9) 116 113 110 112. c) c) c). a). Cr: crystal state, S1,2,3: unidentified smectic phase, N: nematic phase, and I: isotropic state. Values in the parentheses are those obtained from the cooling DSC themograms. c) Obtained from ref. 4. b). ÊZ_(Cr)→Ùö UZ(I)³ ùM«, -Î 165 CÑ Ùö UZ(I)→ÊZ_(Cr)k³ èùM«O ³´÷D )éÑ U_ s G@ \G. n=2¯ dYío Íù 233 CÑ ÊZ_(Cr)→U_(N)k³ ù M«Í ³´÷Ê, 285 CÑ U _(N)→Ùö UZ(I)³ ù M«Í ³´

(6) k, -Î 265 C Ñ Ùö UZ(I)→U_(N)k³ èù M«Í ³´

(7) Ê, 210 C Ñ U_(N)→ÊZ_(Cr)k³ èù M«Í ³´

(8) k, «6 K o n=4 Ú 6Ñ îûæÉ. « dYíËo Íùê Î H& U_ s G2 µö U_»s e¯O ¤ ÀÉ. K, s Â îûÑ Gñ 2-,4-brushõ Ñ Ýñ?2 K UK schlieren texturesõ o å ¤ ÀÉ[22]. Ks, ) èW KõÉõ Ê_k³ GÊ K í Schiff base èfo .õ äk < KõÉõ ¡d series II dYí M«5 Q U_ s Table 2Ñ ÷É. Table 2Ñ Ý2 àQ ç«, n=1¯ dYío ÍùÑ2 117 CÑ ÊZ_(Cr)→Ùö UZ (I)³ ù M«Í ³´

(9) Ê, -ÎÑ2 96.9 CÑ Ùö UZ (I)→U_(N)k³ èù M«Í, 93.0 CÑ U_(N)→ÊZ_ (Cr)k³ èù M«Í ³´÷2 ö K U_«É. n=2 ¯ dYío Íù 102 CÑ ÊZ_(Cr)→U_(N)k³ ù M«, 116 CÑ KU_(N)→Ùö UZ(I)³ M«õ Ýñ? ÉÊ, -ÎÑ2 114 CÑ KU_ (N)s, 91.0 CÑ Aé U_ (S )s Ýñ ?É. n=3¯ dYío Íù Aé O(S) s Ýñ ?ÉÊ, -ÎÑ 88.5 CÑ G÷ Aé (S)s ÷ É. n=4¯ dYío Íù 109 CÑ Aé (S)ê 113 Ñ K (N)s Ýñ ?ÉÊ, -ÎÑ2 92.5 CÑ ñ Aé (S)s Ýñ ?É. n=5Q n=6¯ dYí ùJ }o W UGÊ, n=6 dYí ùJ ò õ ¬,Jk³ D¬Gñ Ý

(10) , Í ù 92.5 CÑ Cr→S ù M«õ, 109 CÑ S →S ù M «õ, 110 CÑ S →N ù M«õ, 112 CÑ K(N)→Ùö (I) UZ ù M«õ ÷ÉÊ, -ÎÑ2 89.8 CÑ S →S èù M«¯ G÷ Aé s Ýñ ?É. Table 3Ñ series III d Yí M«Ñ ¬K M«5 às ÷É. «Ëo H& Í ùê -ÎÑ U_ s G2 µö U_«Ék, K U _ s îûO ¤ ÀÉ[20, 22]. «Ë dYío õ{ Ú Ùö U Zd M«5Ñ OÑ KõÉ, n ¡dÑ ¶, _¤-L¤ Á êõ ÷ÉÊ, K Ñ Ùö UZ k³ M«Ñ ¬K Õ%) ¡dÑ _¤-L¤ Áêõ Ýñ?É[20]. series IIIQ K K gÆõ äk, ³ èjs ä2 series IV dYí M «5Q U_ s Table 4Ñ ÷É. n=1-3b@2 -ÎÑO o. o. o. o o. o. Table 3. Transition temperatures and liquid crystal phases of Series III a),b) Transition temperatures (oC) N 2 233 285 3 175 186 4 216 263 5 183 200 6 205 235 7 169 196 8 196 216 9 161 187 10 190 202 a) Cr: crystal state, N: nematic phase, and I: isotropic state. b) Obtained from ref. 20 n. Cr. Table 4. Transition temperatures and liquid crystal phases of Series IV a),b),c) Transition temperatures (oC) S2 S1 N. o. n. o. 1 2 3 4 5 6 7 8 9. o. o. o. o. 1. o. o. o. o. o. 2. o. 2. 1. o. 1. o. 2. ¤@¤ C43× C1 2005 2. 3. I. Cr 129 149 125 106 103 97.5 101 99.0 102. (79.0). (84.0). I (122) (143) (124) 130 119 123 118 119 115. a). Cr: crystal state, S1,2: unidentified smectic phase, N: nematic phase, and I: isotropic state. b) Values in the parentheses are those obtained from the cooling DSC themograms. c) Obtained from ref. 4.. K U_ s G2 ö U_«ÉÊ, n=4-8b@2 Íùê -ÎÑ H& K U_ s G2 ö U_«É. n=9 ¯ dYío ÍùÑ2 115 CÑ K U_ (N)Os G k÷, -ÎÑ2 79.0 CQ 84.0 CÑ Aé (S)s G . ªù dYíËs oÝIs ), «èfo .õ ä2 series I Ú III dYíËo H& K Os Ýñ?ÉÊ, ³ è fo .õ ä2 series II Ú IV dYío Aéê K s ÷É. KõÉQ èfo .õ dÕ4 ä2 ? I U_ OYZ I ùòHJ às Table 5Ñ ÷É. OYZ Iê series I, II, III Ú IV dYí õ2Ys Fig. 1Ñ, Ùö UZd M« 5 o. o. o.

(11) ³- Ú «èfo d;í 7_ . 179. Table 5. Transition temperatures and liquid crystal phases of Polymers I a),b) n. Cr. 2 3 4 5 6 7 8 9 10. Transition temperatures (oC) N 179 216 114 196 173 203 138 180 167 202 131 176 162 186 126 171 166 181. I. a). Cr: crystal state, N: nematic phase, and I: isotropic state. Obtained from ref. 16.. b). ð. 3. .. Fig. 2. Dependence of isotropization temperatures of polymers I( ), series I( ), series II( ), series III( ) and series IV( ) on the length, n, of polymethylene spacer.. -. Ýñ?ÉÊ, series IIIo K U_ Os ÷Ék÷, series IV 2 Kê Aé s Ýñ?É. ¶, KõÉQ èfo .õ G¬³ ä2 ? I U_ OYZ Iê WUK ~ÉgÆõ ä 2 series I, II, III Ú IVõ oÝIs ), Íß WUK õ2Yê Ù ö UZd M«5 ùJ }s Ýñ?Ê, ço K U_ s G2 series III dYí« OYZ ùJ ò õ Íß Ñ ¬ ¡ O ¤ À2 Íß âo H dYí»s e¯O ¤ ÀÉ. ð. 3. .. Fig. 1. Dependence of melting temperatures of polymers I( ), series I( ), series II( ), series III( ) and series IV( ) on the length, n, of polymethylene spacer.. -. õ Fig. 2Ñ ÷É. «Ë ùJ }o 4? Ë. Fig. 1Ñ Ý

(12) , series I, II Ú IV õ2Yo KõÉ, n ¡dÑ ¶ ¢¾ äkK as å ¤ À. 6÷ OYZ Iê series III o õ2YÑ KõÉ ¤Ñ ñ ‘_¤-L¤’ Áê¯ äkJ¯ zig-zag Ý s Ýñ ?É. ¶, series IIIo õ2YÑ OYZ Iê WUK ùJ }s Ýñ?É. Ks, Fig. 2 Ùö UZd M« 5Ñ2 series II, III, IVÍ OYZ I Ùö UZ d M«5Q WUK ‘_¤-L¤’Áê¯ zig-zag Ý s ÷ É. 6÷ 5 p.Q 5 ¡dÑ series III« OYZ Iê ¢¾ WUK ùJ }s Ýñ?Ê À. ¶, series III« õ 2Yê Ùö UZd M«5Ñ OYZ Iê WUK ùJ Hs ÷Ê À2 as o å ¤ À. K, «Ë U_ s o Ý

(13) , OYZ Io H& K U_Os ÷ÉÊ, series I H& K U_ Os G. series II2 K ê Aé s. [ ÷ á øéo 2003¸ D¬HG H¬ õg Æ WÑ Gñ õ gæÉk, «Ñ _o Ý õ Ã?n.. +S 1. Collings, P. J., Liquid Crystals, Princeton university Press, Princeton and Oxford(2002). 2. Demus, D., Goodby, J., Gray, G. W., Spiess, H.-W. and Vill, V., Handbook of Liquid Crystals, Wiley-VCH, Weinheim, Vol. 1. (1998). 3. Collings, P. J. and Hird, M., Introduction to Liquid Crystals, Taylor & Francis, London(1997). 4. Demus, D., Demus, H. and Zaschke, H., Flussige Kristalle in Tabellen, VEB Deutscher Verlag fur Grundstoffindustire, Leipzig (1974). 5. Demus, D. and Zaschke, H., Flussige Kristalle in Tabellen II, VEB Deutscher Verlag fur Grundstoffindustire, Leipzig(1984). Korean Chem. Eng. Res., Vol. 43, No. 1, February, 2005.

(14) 180. á?åöM ³ö«,öãöU?{ö6,hö60,ö« Cöóö«¤Æ. 6. Demus, D., Goodby, J., Gray, G. W., Spiess, H.-W. and Vill, V., Handbook of Liquid Crystals, Wiley-VCH, Weinheim, Vol. 2B(1998). 7. Henderson, P. A., Niemeyer, O. and Imrie, C. T., “MethyleneLinked Liquid Crystal Dimers,” Liquid Crystals, 28(3), 463-472 (2001). 8. Park, J.-H., Lee, H. M., Choi, O. B., Lee, C. J., So, B.-K. and Lee, S.-M., “The Effect of Flexible Spacers on the H-Shaped Dimesogenic Liquid Crystalline Compounds,” J. Korean Chem. Soc., 45(6), 562-569(2001). 9. Park, J.-H., Kim, E.-Y., Choi, O.-B., Kim, K.-S., So, B.-K. and Lee, S.-M., “Synthesis and Thermotropic Properties of New Liquid Crystalline Compounds;1,10-Bis[2,5-bis(4-alkyloxyphenoxycarbonyl)phenoxy]decane,” J. Korean Chem. Soc., 45(1), 67-75 (2001). 10. Kim, J.-H., Lee, S.-M. and Jin, J.-I., “α,ω-Bis[4-(4'-(S)-(+)-2methylbutylbiphenyl-4-carboxy)phenoxy]alkans-Synthesis and Liquid Crystalline Properties of New Dimesogenic Compounds,” J. Korean Chem. Soc., 42(6), 679-695(1998). 11. Andersch, J. and Tschierske, C., “Synthesis and Liquid Crystalline Properties of Novel Laterally Connected Twins,” Liquid Crystals, 21(1), 51-63(1996). 12. Weissflog, W., Demus, D., Diele, S., Nitschke, P. and Wedler, W., “From Laterally Branched Mesogens to Novel Twin Molecules,” Liquid Crystals, 5(1), 111-122(1989). 13. Imric, C. T., Structure and Bonding, 95, 149(1999). 14. Huh, S.-M., Jin, J.-I., Achard, M.-F. and Hardouin, F., “H-Shaped Dimeric LC Compound: Synthesis and Thermotropic Properties. ¤@¤ C43× C1 2005 2. of α,ω-bis[2,5-bis(4-ethoxyphenoxycarbonyl)phenoxy]alkanes,” Liquid Crystals, 25(3), 285-293(1998). 15. Jin, J.-I., Choi, E.-J., Ryu, S.-C. and Lenz, R. W., “Thermotropic Main Chain Polyesters with Polymethylene Spacers and Their Low Molecular Weight Model Compounds-Odd-Even Effect of Polymethylene Spacers,” Polymer Journal, 18(1), 63-70(1986). 16. Jin, J.-I and Park, J.-H., “Main Chain Thermotropic Copolyesters Containing Imino Group Linked Mesogenic Units and Polymethylene Spacers,” Eur. Polym. J., 23(12), 973-977(1987). 17. Griffin, A. C. and Britt, T. R., “Effect of Molecular Structure on Mesomorphism. 12. Flexible-Center Siamese-Twin Liquid Crystalline Diesters-A “Prepolymer” Model,” J. Am. Chem. Soc., 103, 4957-4959(1981). 18. Jin, J.-I., Oh, H.-T. and Park, J.-H., “Thermotropic Compounds having Two Terminal Mesogenic Units and Central Spacers. Part 7. Homologous α,ω-Bis-[ρ-(4-alkoxyphenoxycarbonyl)phenoxy]alkans,” J. Chem. Soc. Perkin Trans. II, 343-347(1986). 19. Jin, J.-I., “Liquid Crystalline Behavior of Novel Dimesogenic Compounds,” Mol. Cryst. Liq. Cryst., 267, 249-265(1995). 20. Jin, J.-I. and Park, J.-H., “Thermotropic Compounds with Two Terminal Mesogenic Units and A Central Spacer. 5. Homologous Series of Polymethylene-α,ω-Bis(ρ-oxybenzylidene Aniline),” Mol. Cryst. Liq. Cryst., 110, 293-308(1984). 21. Donahoe, H. B., Benjamin, L. E., Fenney, L. V. and Greiff, D., “Synthesis of Potential Rickettsiostatic Agents. I. 4, 4'-Dicarboxyα,ω-diphenoxyalkanes,” J. Org. Chem., 26, 474-475(1961). 22. Demus, D., Textures of Liquid Crystal, Verlag Chemie, New York (1978)..

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