Novel optically transparent polyesters containing a high density of second-order non-linear optically active chromophores Nobukatsu Nemoto," Fusae Miyata," Yu Nagase,"* Jiro Abe,b Makoto Hasegawab and Yasuo Shiraib "Sagami Chemical Research Center, 4-4-1 Nishi-Ohnuma, Sagamihara, Kanagawa 229, Japan bDepartment of Photo-optical Engineering, Faculty of Engineering, Tokyo Institute of Polytechnics, 1583 Iiyama, Atsugi, Kanagawa 243-02, Japan The syntheses and second-order non-linear optical (NLO) properties of novel types of optically transparent polyesters containing a high density of second-order NLO-active chromophores are described. The chromophores used in this study contained either a perfluorooctyl- or an octyl-sulfonyl moiety as the electron-withdrawing group at the n-conjugating sites.The polyesters are prepared by condensation polymerization between isophthalic acid derivatives and 2-[N-( 2-hydroxyethyl)-4- (perfluorooctylsulfony1)anilino]ethanol by the use of triphenylphosphine and diethyl azodicarboxylate as the condensation reagents. The amorphous polyesters obtained, the optical transparency of which was down to 390 nm, exhibited good solubility in common organic solvents and provided optical-quality films by spin-coating. In addition, second-harmonic generation (SHG) measurements of spin-coated films of the polyesters were carried out by the Maker fringe method using a Q-switched Nd : YAG laser as the exciting beam after poling treatment. One of the polyesters, which was prepared from 5-{2-[N-methyl-4- ( perfluorooctylsulfonyl)anilino] ethoxy) isophthalic acid and 2-[N-( 2-hydroxyethyl)-4-( perfluorooctylsulfony1)anilino] ethanol, exhibited the desired optical-transparency and a second-order NLO coefficient, d33, of 3.0 pm V-l.In recent years, polymeric materials with second-order non- linear optical (NLO) properties have been required for NLO applications such as fast waveguide and electro-optic modu- lation. In many cases, polymeric materials incorporating aro- matic molecules that contain both electron-donating and electron-withdrawing groups at the n-conjugate sites have been the subject of intense studies.1-8 However, one difficulty with polymeric second-order NLO materials is that most of these chromophores tend to align in a centrosymmetric space group.Thus, second-order NLO susceptibility, x(~),vanishes in spite of high microscopic optical non-linearity, p. Therefore, high qpolymers such as aromatic polyimide~,~-'~ aromatic poly- amides,14-16 aromatic polyurethane^'^-^^ and aromatic poly- ester~"-~~have been used as polymeric matrices for the purpose of restraining the relaxation of the noncentrosymmetric chromophore-alignment induced by an electric field. However, organic molecules which contain both electron- donating and electron-withdrawing groups at n-conjugate sites have large /3 values since a high degree of delocalization gives a large value of p.35936 As a result, an intramolecular charge- transfer absorption is caused in visible region.In contrast, second-order NLO materials with short cutoff wavelengths are desirable for practical use because the absorption of the second harmonic wave generated by the near-infrared wave of diode lasers causes intolerable damage to materials. Therefore, there should be a trade-off between optical non-linearity and the cutoff wavelength. Indeed, some effort has been made to produce second-order NLO materials with blue shifted cutoff In general, aromatic-containing polyester matrices, which are easily prepared from the corresponding dicarboxylic- and dihydroxy-functionalized monomers, exhibit relatively high q and optical transparency. In fact, the preparation of second-same functionality, i.e. second-order NLO active chromophore moieties, a high chromophore concentration in the polymer matrices should result.We have proposed that a high chromo- phore concentration in polymer matrices should result in a high second-order NLO s~sceptibility.~~ From these perspectives, we report here the syntheses of novel types of polyesters obtained by the condensation poly- merization of two comonomers, both of which contain second- order NLO active chromophore moieties as shown in Scheme 1. The chromophore used in this study contained a perfluorooctyl- or octyl-sulfonyl moiety as the electron-with- drawing group to achieve optical transparency down to 400nm. In addition, the thermal, linear optical and second- order NLO properties of the polyesters obtained are also reported. Experimenta1 Materials N,N-Dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were distilled over CaH, under reduced pressure, and tetrahydrofuran (THF) was distilled twice (over CaH, and sodium) to remove traces of water.Diethanolamine, N-methyl- ethanolamine, 4-hydroxypiperidine, 4-(2-hydroxyethyl)piper-idine, diethyl azodicarboxylate (Tokyo Kasei Kogyo Co.), 4-fluorothiophenol (4-fluorobenzenethiol) (Aldrich Chemical Company), acetic acid, 30% aqueous hydrogen peroxide ( Wako Pure Chemical Industry) and perfluorooctyl iodide were commercially available and used as received. 1-Bromooctane was purchased from Tokyo Kasei Kogyo Co. and purified by distillation under reduced pressure. Triphenylphosphine was purchased from Tokyo Kasei Kogyo Co., and purified by recrystallization from ethanol prior to order NLO active main-~hain-~~"~ use.Dimethyl 5-hydroxyisophthalate was prepared by methyl and side-~hain-type~~q~~ polyesters have been reported as mentioned above. Our pri- esterification of 5-hydroxyisophthalic acid with methanol mary interest was to investigate the NLO properties of poly- catalysed by sulfuric acid as reported elsewhere.45 esters which can be easily processed owing to the alternate alignment of the same or different functionalities. This can be Instrumentation easily realized by using comonomers with the same or different UV-VIS absorption spectra were recorded on a Hitachi Model functionalities. For example, if each comonomer contains the U-3200 spectrophotometer.'H NMR and 19F NMR were J. Muter. Chem., 1996, 6(5),711-717 711 (F-phenyl-S-CF,+), 169 [CF,(CF,),+], 127 (F-phen-OQ" H4 yl-S+), 119 (CF3CFz+),95 (F-phenyl'), 69 (CF,+) Od HdbH jl r 1 L Pl-P4 Scheme 1 Reagents and conditions 1, PPh,, diethyl azodicarboxylate (DEAD), dimethyl sulfoxide (DMSO), 100"C, 12 h recorded on a Hitachi R-90H FT NMR (90 MHz) spectrometer and a Bruker AC200P FT NMR (200MHz) spectrometer, respectively J values are given in Hz DSC measurements were carried out on a Shimadzu Model DSC-50 under a helium flow rate of 20 ml min-l and a heating rate of 10"C min-' Gel permeation chromatography (GPC) was performed on a Tosoh HLC-802A instrument equipped with TSK gels G5000H6, G4000H6, G3000H6, and G2000H6 using poly- styrene standards with THF as eluent X-Ray diffraction patterns were recorded on a MAC Science MXP3 X-ray diffractometer, equipped with a thermal controller Model 53 10 4-Fluorophenyl perfluorooctyl sulfide (1) Sulfide 1 was prepared using a modification of the method of Feinng et al 46 47 Under an argon atmosphere, 4-fluorothio- phenol (10 40 g, 81 1mmol) in dry DMF (10 ml) was added dropwise to sodium hydride (60% in mineral oil, 3 75 g, 93 8 mmol) suspended in dry DMF (40 ml) in an ice bath The reaction mixture was stirred at ambient temperature for 1 h, and then perfluorooctyl iodide (35 42 g, 64 9 mmol) was added dropwise After the reaction mixture had been stirred at ambient temperature for 16 h, the DMF was evaporated under reduced pressure Water and diethyl ether were added to the residue, and the organic layer was washed with water The organic layer was dried over anhydrous sodium sulfate and the solvent was evaporated The crude product was purified by silica gel column chromatography with hexane as eluent to give the title compound 1 as a colourless liquid (30 6 g, 86%), GH(CDCl,, 90 MHz) 7 0-7 2 (m, 2 H, Ar-H), 7 5-7 7 (m, 2 H, Ar-H), G,(CDCl,, CFC1,) -126 6 (m, 2 F), -123 2 (m, 2 F), -122 3 (m, 4F), -121 7 (m, 2 F), -119 6 (m, 2 F), -108 7 (m, 1 F, F-Ph), -87 7 (m, 2 F, -CFz-S-), -81 3 (t, J 9 9, 3 F, -CF,), vmax/cm-' 2920, 2850, 2905, 2825, 1590, 1490, 1400, 1365, 1320, 1240 (perfluoroalkyl), 1210 (perfluoroalkyl), 1145, 1115, 1100, 1020, 945, 935, 835, 780, 760, 720, 700, 670, 655, 560, 520, m/z 546 (M'), 527 (M+-F), 177 712 J Mater Chem, 1996, 6(5),711-717 4-Fluorophenyl octyl sulfide (2) Sulfide 2 was prepared by a similar method as for the prep- aration of 1 using 1-bromooctane as a raw material Purification by silica gel column chromatography with hexane as eluent gave the title compound 2 as a colourless liquid (85%), d,(CDCl,, 90MHz) 07-1 9 [m, 15H, CH3(CHz),CHz-], 2 85 (t, J 6 9, 2 H, -CHZ-S-), 6 8-7 2 (m, 2 H, Ar-H), 7 2-7 5 (m, 2 H, Ar-H), v,,,/cm-' 2960,2930, 2950,1590,1490,1460,1380,1260,1230, 1160, 1090,1010,820, 720,630,500, m/z 240 (M'), 141 (F-phenyl-S-CH,'), 127 (F-phenyl-S'), 71 (C5Hllf), 57 (C4H,+), 43 (C,H,+), 29 (C2H5+) 4-Fluorophenyl perfluorooctyl sulfone (3) A mixture of 1 (16 39 g, 30 0 mmol), acetic acid (60 ml) and hydrogen peroxide (30% aqueous, 17 01 g, 150mmol) was refluxed for 12h The reaction mixture was poured into saturated aqueous sodium hydrogen carbonate (300 ml) The crude product was extracted with chloroform (50 ml x 6), and the combined chloroform extracts were dned over anhydrous sodium sulfate The chloroform was evaporated and the residue was purified by silica gel column chromatography with hexane as eluent Finally, recrystallization of the product from hexane provided the title compound 3 (15 1 g, 87%), d~(cDC13, 90MHz) 72-76 (m, 2H, Ar-H), 80-84 (m, 2H, Ar-H), dF(CDC1,, CFC1,) -126 6 (m, 2 F), -123 2 (m, 2 F), -122 2 (m, 6F), -1202 (m, 2F), -1117 (m, 2F), -979 (m, lF, F-Ph), -81 2 (t, J 9 8, 3 F, -CF,), vmax/cm-' 3110, 3070, 2905,1590,1495,1410,1370, 1330,1305,1250 (perfluoroalkyl), 1205 (perfluoroalkyl),1150 (-SOz-), 1080, 1055, 1015, 850, 820, 745, 710, 690, 655, 605, 580, 550, 540, 515, 495, m/z 559 (M+ -F), 169 [CF,(CF,),+], 159 (F-phenyl-SO,'), 119 (CF3CFz+),95 (F-phenyl+), 69 (CF,') 4-Fluorophenyl octyl sulfone (4) Sulfone 4 was prepared by a similar method as for the preparation of 3 using 2 as the raw material Purification by silica gel column chromatography with hexane as eluent gave the title compound 4 as colourless crystals (82%), dH(CDC1,, 90 MHz) 07-1 9 [m, 15 H, CH3(CHz)6CH2-], 3 0-3 3 (m, 2 H, -CH,-SO2-), 7 1-7 5 (m, 2 H, Ar-H), 7 8-8 2 (m, 2 H, Ar-H), v,a,/cm-l 2960, 2920, 2950, 1600, 1500, 1470, 1410, 1320, 1280, 1240, 1150 (-SOz-), 1090, 1010, 840, 820, 770, 730, 680, 570, 530, 450, m/z 272 (M'), 187 (F-phenyl-SOz-C2H4+), 173 (F-phenyl-SO, -CHzf), 159 (F-phenyl-SO,'), 95 (F-phenyl'), 71 (C5Hll+),57 (C4H9+ ), 43 (C3H7+ 1, 29 (CZH5+ 2-[N-Methyl-4-( perfluorooctylsulfonyl )anilino] ethanol (5) Under an argon atmosphere, dry DMSO (3 ml) was added to a mixture of N-methylethanolamine (0520 g, 6 92 mmol) and anhydrous potassium carbonate (1 06 g, 7 70 mmol) To this mixture, 3 (4 00 g, 6 92 mmol) was added The reaction mixture was stirred at 100°C for 12 h and then poured into water (300 ml) The resulting precipitate was collected by filtration and recrystallized from methanol to give the title compound 5 (3 92 g, 90%), GH(CDC1,, 90 MHz) 1 65 (t, J 5 1, 1 H, -OH), 3 16 (s, 3H, -N-CH3), 364 (t, J 51, 2H, -N-CHz-), 3 87 (t, J 5 1, 2H, -0-CH2-), 681 (d, J 92, 2 H, Ar-H), 7 77 (d, J 9 2, 2 H, Ar-H), vmax/cm-' 3580 (-OH), 1240 and 1210 (perfluoroalkyl), 1160 (-SOz-), m/z 633 (M'), 214 CM+ -(C*F17)I7 169 CCF,(CFz)z+l, 150 CM+ -(S02C8F,,)I, 119 [CF3CFz+ or Ph-N(CH3)CHzf], 69 (CF,') (Found C, 32 2, H, 165, N, 2 0 Calc for CI7Hl2NO3Fl7S C, 3224, H, 191, N, 2 21%) 1-[ 4-( Pe~uorooctylsulfony1 )phenyl] piperidin-4-01 (6) and 2-{1-[ 4-( perfluorooctylsulfonyl)phenyl] piperidin-4-yl )ethanol (7) Piperidines 6 and 7 were prepared by a similar method as for the preparation of 5 using 4-hydroxypiperidine and 4-( 2- hydroxyethy1)piperidine instead of N-methylethanolamine as the raw materials, respectively.Compound 6 (90%); 6,(CDCl,; 90 MHz) 1.5-2.2 (m, 5 H, 4 x piperidinyl-H and -OH), 3.2-4.2 (m, 5 H, piperidinyl-H), 6.93 (d, J 9.2, 2 H, Ar-H), 7.76 (d, J 9.2, 2 H, Ar-H); vmax/cm-l 3250 (-OH), 1240 and 1210 (perfluoroalkyl), 1160 (-SO2-); WZ/Z659 (M'), 240 [M' -(c8F17)], 176 [M+ -(SO2c,F17)], 169 [CF,(CF,),+], 119 (CF3CF2+), 69 (CF,+). (Found: C, 34.5; H, 2.0; N, 2.0. Calc. for Cl9Hl4NO3Fl7S: C, 34.61; H, 2.14; N, 2.12%). Compound 7 (87%); dH(CDC1,; 90MHz) 1.2-1.7 (m, 4H, 3 x piperidinyl-H and -OH), 1.7-2.1 (m, 4 H, piperidinyl-H), 3.00 (t, J 12.5, 2 H, -CCH2-piperidine), 3.6-4.2 (m, 4H, 2 x piperidinyl-H and -CCH2-OH), 6.90 (d, J 9.2, 2 H, Ar- H), 7.76 (d, J 9.2, 2 H, Ar-H); vmax/cm-l 3360 (-OH), 1250 and 1210 (perfluoroalkyl), 1150 (-SO2-); m/z 687 (M+), 268 CM+ -(c8F17)1, 204 cM+ -(S02C8F17)1, 169 CCF,(CF2)2+I, 119 (CF3CF2+), 69 (CF,'). (Found: C, 36.6; H, 2.55; N, 2.0.Calc. for C21H18NO3F17S: C, 36.69; H, 2.64; N, 2.04%). 2-[N-Methyl-4-(octylsulfonyl)aniline]ethanol (8) Aniline 8 (90%) was prepared by a similar method as for the preparation of 5, using 4 instead of 3 as the raw material; ~H(CDCI,;90 MHZ) 0.7-1.9 [m, 16 H, CH,(CH2)&H2- and -OH], 2.9-3.2 (m, 2 H, -CH2-SO2-, overlapped by a singlet signal at 6 3.09), 3.09 (s, 3 H, -N-CH,), 3.58 (t, J 5.1, 2 H, -N-CH2-), 3.82 (t, J 5.1, 2 H, -CCH2-OH), 6.76 (d, J 9.0, 2 H, Ar-H), 7.66 (d, J 9.0, 2 H, Ar-H); vmax/cm-l 3250 (-OH), 1160 (-SO2-); rn/z 327 (M+), 214 [Mf-(C8H17)1, l50 [M+ -(SO2C8H17)], 71 (C5H11'), 57 (C4H9'), 43 (C3H7+), 29 (C2H5').(Found: C, 62.1; H, 9.1; N, 4.25; S, 9.8. Calc. for C17H29N03S: C, 62.35; H, 8.93; N, 4.28; s, 9.79%). Dimethyl 5-substituted isophthalate derivatives (9-12) Typical procedures, applying the Mitsunobu reaction,48 are as follows. Under an argon atmosphere; 5 (1.267 g, 2.0 mmol), dimethyl 5-hydroxyisophthalate (0.631 g, 3.0 mmol), and tri- phenylphosphine (0.63 1 g, 2.4 mmol) were dissolved in dry THF (10 ml) in an ice bath. To this solution diethyl azodicar- boxylate (0.51 g, 3.0 mmol) was added dropwise, and the mixture was stirred at ambient temperature for 1 h. The solvent was evaporated and the residue was purified by silica gel column chromatography with chloroform as eluent.Finally, recr ys t alliza tion from ace t one-me thanol provided dime t h yl 5-{ 2-[N-methyl-4-( perfhorooctylsulfony1)anilino] ethoxy} iso- phthalate (9) (1.53 g, 93%), mp, 135 "C (determined from the DSC thermogram); G,(CDCl,; 90MHz) 3.22 (s, 3 H, -N-CH,), 3.8-4.1 (m, 2 H, -N-CH2-, overlapped by a singlet signal at 6 3.93), 3.93 (s, 6 H, -COOCH,), 4.28 (t, 2H, J 5.1, -0-CH2-), 6.83 (d, J 9.2, 2H, anilino-H), 7.71 (d, J 1.1, 2 H, isophthalate Ar-H), 7.82 (d, J 9.2, 2 H, anilino- H), 8.29 (s, 1 H, isophthalate Ar-H); vmaX/cm-' 1720 (-C=O), 1250 and 1230 (perfluoroalkyl), 1120 (-SO2-); m/z 825 +(M ), 61 6 [+CH2CH2N(CH3)-phenyl- S02C8F17], 406 [M' -(C*F17)], 342 [M+ -(SO2C,F17)], 179, 169 [CF,(CF,),+], 119 (CF3CF2+), 69 (CF,').(Found: C, 39.3; H, 2.3; N, 1.5. Calc. for C27H20N07F17S: C, 39.28; H, 2.44; N, 1.70%); Amax(CHC13)/nm (~/1 mol-I cm-l), 309 (42 660; Ll,off/nm, 348. Isophthalates 10-12 were prepared by the similar method as for the preparation of 9 using 6-8 as the raw materials instead of 5, respectively. Compound 10 (72%), mp 128 "C (determined from the DSC thermogram); d,(CDC13; 90 MHz) 1.9-2.3 (m, 4 H, piperidinyl- H), 3.5-3.9 (m, 4 H, piperidinyl-H), 3.95 (s, 6 H, -COOCH,), 4.7-5.0 (m, 1 H, piperidinyl-H), 6.96 (d, J 9.2, 2 H, anilino-H), 7.71 (d, J 1.1, 2 H, isophthalate Ar-H), 7.82 (d, J 9.2, 2 H, anilino-H), 8.30 (s, 1 H, isophthalate Ar-H); vmax/crn-l 1730 (-C=O), 1250 and 1210 (perfluoroalkyl), 1160 (-SO2-); rn/z 851 (M'), 642 {M' -[OPh(COOCH,),]), 432 [M+ -(CsF17)], 368 [M' -(S02CgF17)], 179, 169 [CF,(CF,),+], 119 (CF3CF2+), 69 (CF,+).(Found: C, 41.0; H, 2.5; N, 1.4. Calc. for C2,H22N07F17S: C, 40.91; H, 2.60; N, 1.64%). RmaX(CHC1,)/nm (~/1 mol-l cm-l), 312 (43 060); &,toff/nm, 350. Compound 11 (64%), mp 117 "C (determined from the DSC thermogram); d,(CDCl,; 90 MHz) 1.2-1.7 (m, 3 H, piperidinyl- H), 1.7-2.2 (m, 4H, piperidinyl-H), 3.12 (t, J 11.6, 2H, -CCH,-piperidine), 3.94 (s, 6 H, -COOCH3), 4.0-4.3 (m, 4 H, 2 x piperidinyl-H and -CH2 -0-), 6.91 (d, J 9.2, 2 H, anilino-H), 7.71 (d, J 1.1, 2 H, isophthalate Ar-H), 7.82 (d, J 9.2,2 H, anilino-H), 8.29 (s, 1 H, isophthalate Ar-H); vmax/cm-l 1730 (-C=O), 1240 and 1210 (perfluoroalkyl), 1160 (-SO2-); WZ/Z 879 (M'), 670 {[M+ -[OPh(COOCH,)2]}, 460 [Mf-(C8F,7)], 396 [M+-(SO2C8F17)], 179, 169 [CF,(CF,),+], 119 (CF3CF2'), 69 (CF,+).(Found: C, 42.3; H, 2.7; N, 1.3. Calc. for C31H26N07F17S: C, 42.33; H, 2.98; N, 1.59%); ~max(CHCl,)/nm (~/1 mol-l cm-l), 316 (48 780); Lltoff/nm, 351. Compound 12 (6l%), mp 92 "C (determined from the DSC thermogram); GH(CDC1,; 90 MHz) 0.7-1.9 [m, 15 H, CH3(CH2)6CH2-], 2.9-3.2 (m, 2 H, -CH2-SO2-, over-lapped by a singlet signal at 6 3.16), 3.16 (s, 3 H, -N-CH,), 3.8-4.0 (m, 2 H, -N-CH2-, overlapped by a singlet signal at 6 3.93), 3.93 (s, 6 H, -COOCH,), 4.25 (t, J 4.8, 2 H, -CH,-0-), 6.77 (d, J 9.0, 2H, anilino-H), 7.6-7.9 (m, 4H, anilino-H and isophthalate Ar-H), 8.28 (s, 1 H, isophthalate Ar-H); vmax/cm-l 1730 (-C=O), 1130 (-SO2-); m/z 519 (M+), 406 [M+ -(C8H17)], 342 [M+ -(S02C&17)], 3 10 [+CH2CH2N(CH,)-phenyl-S02C8H17], 133 [+CH2CH2N (CH, )-phenyl] , 1 1 9 [+ CH2N(CH, )-phen yl ], 105 [+N(CH,)-phenyl], 71 (C5Hll+], 57 (C,H,+), 43 (C3H7+), 29 (C2H5').(Found: C, 62.4; H, 7.3; N, 2.55; S, 6.3. Calc. for C2,H3,N07S: C, 62.41; H, 7.18; N, 2.70; S, 6.17%); Amax( CHCl,)/nm (~/lmol -cm -'), 282 (3 1 640); ~,,,off/nm, 337. 5-Substituted isophthalic acid derivatives (13-16) A typical procedure is as follows. Isophthalate 9 (LOOg, 1.21mmol) and sodium hydroxide (0.242 g, 6.0 mmol) were dissolved in methanol (3 m1)-THF (3 m1)-water (3 ml). The mixture was refluxed for 3 h and then allowed to cool, Hydrochloric acid was added to the reaction mixture until the supernatant solution was slightly acidic.The precipitate was collected by filtration. Recrystallization from acetone- water gave 5-{ 2-[N-methyl-4-(perfluorooctylsulfony1)anilino] ethoxy}isophthalic acid (13) (0.819 g, 85%); 6,(CDCl, + [2H6]DMSO; 90 MHz) 3.23 (s, 3 H, -N-CH,), 3.8-4.1 (m, 2H, -N-CH2-), 4.2-4.5 (m, 2H, -0-CH2-), 6.87 (d, J 9.2, 2 H, anilino-H), 7.5-8.0 (m, 4 H, anilino-H and isophthal- ate Ar-H), 8.29 (s, 1 H, isophthalate Ar-H); vmax/cm-l 3445 (carboxylic -OH), 1705 (-C=O), 1245 and 1215 (perfluoro- alkyl), 1155 (-SO2-); m/z 797 (M'), 616 (M'- [OPh (c00H)21>, 378 rM+ -(GFI~)I, 314 [M' -(S02CfjF17)1, 169 [CF3CF2)2+], 119 [CF3CF2' or PhN(CH3)CH2+], 69 (CF,'). (Found: C, 37.4; H, 1.8; N, 1.7.Calc. for C~~H~~NO~FI~S:C, 37.66; H, 2.02; N, 1.77%). Compounds 14-16 were prepared by a similar method as for the preparation of 13 using 10-12 as the raw materials instead of 9, respectively. Compound 14 (86%); dH(CDC1, + [2H6]DMS0, 90 MHz) 1.9-2.3 (m, 4 H, piperidinyl-H), 3.5-3.9 (m, 4 H, piperidinyl- J. Mater. Chern., 1996, 6(5), 711-717 713 H), 4.7-5.0 (m, 1 H, piperidinyl-H), 7.05 (d, J 9.2, 2 H, anilino-H), 7.6-7.9 (d, 4 H, anilino-H isophthalate Ar-H), 8.24 (s, 1 H, isophthalate Ar-H); v,,/cm- 3440 (carboxylic -OH), 1700 (-C =0),1240 and 1220 (perfluoroalkyl), 1160 (-SO, -); W/Z 823 (M'), 642 {M+-[OPh(COOH),]), 404 [M' -(c8F17)], 340 [M' -(S02c&,7)], 182, 169 [CF,(CF,),+], 119 (CF3CF2'), 69 (CF,').(Found: C, 39.6; H, 1.9; N, 1.6. Calc. for C,7H18N07F,7S: C, 39.38; H, 2.20; N, 1.70%). Compound 15 (68%); &(CDCl, +C2H6]DMSO; 90 MHz) 1.2-1.7 (m, 3 H, piperidinyl-H), 1.7-2.2 (m, 4 H, piperidinyl- H), 2.8-3.4 (m, 2 H, -CCH,-piperidine), 3.9-4.4 (m, 4 H, -0-CH2-and 2 x piperidinyl-H), 7.00 (d, J 9.2, 2 H, anilino-H), 7.6-7.9 (m, 4 H, anilino-H and isophthalate-H), 8.20 (s, 1H, isophthalate-H); v,x/cm-l 3430 (carboxylic -OH), 1700 (-C=O), 1240 and 1220 (perfluoroalkyl), 1160 (-SO,-) m/z 851 (M+), 670 (M+-[OPh(COOH),]}, 432 [M+ -(CsF17], 368 [M+ -(SO,C,F17)], 182, 169 [CF3(CF2),+], 119 (CF3CF2'), 69 (CF,'). (Found: C, 40.9; H, 2.4; N, 1.5. Calc. for C2,H,,N07F17S: C, 40.90; H, 2.60; N, 1.64%). Compound 16(69%); 6,(CDCl,; 90 MHz) 0.7-1.9 [m, 15 H, Cfi,(CH,)6CH2-), 2.9-3.3 (m, 2 H, -CH2-S02-, over-lapped by a singlet signal at 6 3.16), 3.16 (s, 3 H, -N-CH,), 3.7-4.2 (m, 2 H, -N-CHI-), 4.2-4.5 (m, 2 H, -0-CH,-), 6.78 (d, J 9.0, 2 H, anilino-H), 7.6-7.9 (m, 4 H, anilino-H and isophthalate Ar-H), 8.32 (s, 1 H, isophthalate Ar-H); v,,x/cm-l 3430 (carboxylic -OH), 1700 (-C=O), 1120 (-SO2-); m/z 491 (M'), 378 [M' -(c'H17)], 330 [M' -(SozCsH17)], 133 [+CH2CH2N(CH3)- Ph], 119 [+CH2N(CH3)- Ph], 105 ['N(CH,)-Ph], 71 (C5Hll'), 57 (C4H9'), 43 (C3H7'), 29 (C2H5') (Found: C, 61.0; H, 6.9; N, 2.85; S, 6.6.Calc. for C25H33N07S: C, 61.08; H, 6.77; N, 2.85; S, 6.52%). 2-[N-(2-H ydroxyethyl )-44 perfluorooctylsulfon yl )anilino] ethanol (17) Compound 17 (76%) was prepared by a similar method as for the preparation of 5 using diethanolamine as the raw material, mp, 113°C (determined from the DSC thermogram); 6,(CDC13; 90 MHz) 2.6-2.8 (brs, 2 H, -OH), 3.6-4.2 (m, 8 H, -N-CH2-), 6.80 (d, J 9.2, 2 H, Ar-H), 7.78 (d, J 9.2, 2 H, Ar-H); v,,,/cm-' 3335 (-OH), 1230 and 1215 (perfluoro- alkyl), 1160 (-SO2-); m/z 663 (M'), 632 [M+-(CH,OH)], 244 [M+ -(cgF17)], 180 [M' -(S02CsF17)], 169 [CF,(CF,),'], 149 [Ph-N(CH2')CH2CH20H], 119 (CF3CF2'), 69 (CF,'). (Found: C, 32.4; H, 1.8; N, 1.9.Calc. for C18H14N04F17S: C, 32.59; H, 2.13; N, 2.11%); Amax(CHC13)/nm(~/1mol-l cm-l), 311 (38 090); ;lcUtoff/nm, 362. General procedure for polymerization All polyesters were prepared by the same procedures. The preparation of Pl is given as a representative example. Under an argon atmosphere, 13 (0.399 g, 0.50 mmol), 17 (0.332 g, 0.50mmol) and triphenylphosphine (0.3 15 g, 1.20 mmol) were dissolved in dry DMSO (0.5 ml) and maintained at 50°C.To this solution diethyl azodicarboxylate (0.204 g, 1.20 mmol) was added. The reaction mixture was stirred at 100 "C for 12 h and then poured into methanol (100 cm3). The precipitate produced was collected by filtration and reprecipitated in a THF-methanol system. Finally, the product was dried in U~CUOto give polymer P1 (0.225 g, 32%); 6,(CDC13; 90 MHz) 3.17 (s, 3 H), 3.7-4.1 (m, 6 H), 4.1-4.3 (m, 6 H), 6.6-7.1 (m, 4 H), 7.4-8.1 (m, 7 H); vm,x/cm-l 2960, 1730 (-C=O), 1590, 1560, 1510,1450, 1390, 1360, 1330, 1310, 1250 (perfluoroalkyl), 1220 (perfluoroalkyl), 1160 (-SO2 -), 1080, 1060, 1000, 910, 860, 820, 760, 710, 650, 580, 560, 530.'H NMR and IR spectral data and yields for the polyesters obtained are as follows. 714 J. Muter. Chem., 1996, 6(5),711-717 P2 (53%); GH(CDC1,; 90MHz) 1.1-1.5 (m, 4 H), 1.8-2.3 (m, 4 H), 3.3-4.3 (m, 5 H), 4.5-4.8 (m, 4 H), 6.5-7.2 (m, 4 H), 7.5-8.2 (m, 7 H); vrnax/cm-' 2930, 2850, 1730 (-C=O), 1590, 1510, 1450, 1390, 1360, 1330, 1310, 1250 (perfluoroalkyl), 1220 (perfluoroalkyl), 1160 (-SO2 -), 1090, 1030, 1000, 860, 820, 760, 710, 650, 580, 550, 530. P3 (56%); h~(cDC1,; 90 MHz) 1.1-1.5 (m, 3 H), 1.8-2.3 (m, 4 H), 2.8-3.3 (m, 2 H), 3.3-4.3 (m, 8 H), 4.5-4.8 (m, 4 H), 6.9-7.2 (m, 4 H), 7.6-8.2 (m, 7 H); vm,x/cm-l 2930, 2850, 1730 (-C=O), 1590, 1510, 1460, 1390, 1360, 1330, 1310, 1250 (perfluoroalkyl), 1220 (perfluoroalkyl), 1160 (-SO2-), 1090, 1030, 860, 820, 760, 710, 650, 580, 550, 530.P4(67%) 6,(CDC13; 90 MHz) 0.8-1.9 (m, 17 H), 2.9-3.1 (m, 2 H), 3.09 (s, 3 H), 2.8-3.3 (m, 2 H), 3.7-4.8 (m, 10 H), 6.8-7.2 (m, 4 H), 7.5-8.1 (m, 7 H); vmaX/cm-' 3090, 2930, 2860, 1730 (-C=O), 1590, 1510, 1460, 1380, 1360, 1330, 1310, 1240 (perfluoroalkyl), 1150 (-SO2 -), 1090, 1060, 1000, 910, 820, 780, 760, 720, 710, 650, 590, 560, 530. SHG measurements First, the polymer was deposited on an ordinary cover glass by spin-coating at a rate of 2000 rpm from a 5 wt% THF solution. The poling procedure for a spin-coated film was achieved by poling normal to the surface by corona discharge.The distance of the tungsten needle from the surface was 25mm. The needle side was set to 10 kV negative to an aluminium heating plate. A spin-coated film of the polyester on a cover glass substrate was heated on an aluminium plate connected to a heater. After 20min of poling around q,the spin-coated film was cooled down to ambient temperature with continuous poling. The SHG activities of the polyesters were measured in transmission by means of the Maker fringe method.49 The experimental apparatus used for the Maker fringe measurement was shown in a previous report." The exciting light source was a Q-switched Nd:YAG laser (Spectron SL404G, A= 1064 nm, 10 Hz repetition rate, 6 ns pulse duration) with its pulse energy less than 1 mJ.The sample was placed on a rotating stage and rotated around a horizontal axis from an incident angle of -80" to +80". SHG signals detected by a photomultiplier were integrated with a boxcar integrator (Stanford Research SR-250). The p-polarized laser beam was chosen using a ;1/4 wave plate and a linear polarizer. Determination of non-linear optical coefficients The second-order NLO coefficients, d33, of the polyesters obtained were determined from the relationship between the SH light intensity and the incident angle of the exciting beam obtained by the Maker fringe method." The d33values of the resulting polyesters were determined by applying the mean square method to eqn. (1) proposed by Jerphagnon et where I,, is the intensity of the SH wave in the uniaxial poled materials generated by the p-polarized exciting wave, the intensity of which is represented by I,, c is the light velocity, w the spot radius of the Gaussian beam, 8 the incident angle of an exciting wave, t, and q,Fresnel-like transmission factors, n, and n2, the refractive indices, R(8) the multiple reflection correction, p(8) a projection factor', B(8) the beam size correction, and Y(8)the angular dependence of the SH power.1 mm Thick y-cut quartz (dll=0.5 pm V-l) was used as a reference sample. Results and Discussion Synthesis of polyesters containing a high density of NLO-active chromophores The synthetic routes to the 5-substituted isophthalic acid derivatives 13-16 and 2-[N-( 2-hydroxyethyl)-4-( perfluorooct- ylsulfonyl)anilino] ethanol (17),which are precursors for the preparation of the polyesters, are shown in Scheme 2.4-Fluorophenyl sulfide derivatives 1 and 2 were prepared by a modification of the method of Feiring et The oxidation of 1 and 2 was carried out using hydrogen peroxide as the oxidative reagent instead of chromium oxide as applied by Feiring et al. in acetic acid. These oxidations proceeded with good yields of over 80%. 5-Substituted isophthalic acid derivatives were prepared by the Mitsunobu reaction between dimethyl 5-hydroxyisophthalate and hydroxy-functionalized chromophores, followed by the hydrolysis of the corresponding dimethyl isophthalate derivatives. All these reactions provided 5-substituted isophthalic acid derivatives in favourable yields.Scheme 1 shows the preparation of polyesters containing a high density of NLO-active chromophores. All of the polyesters were prepared by solution polycondensation of the above isophthalic acid derivatives 13-16 and 2-[N-(2-hydroxyethy1)-4-(perfluorooctylsulfony1)anilino] ethanol (17) in DMSO at 100"C using triphenylphosphine and diethyl azodicarboxylate as the condensation reagents. Pouring the reaction solution into methanol provided 30-70% of the polyesters as colourless powders. Polyesters Pl-P4 are soluble in common polar organic solvents, such as THF, DMF, DMSO and l-methyl- Mil, ixI 14,15 pyrrolidin-2-one (NMP) at room temperature, and slightly soluble in acetone or ethyl acetate but insoluble in methanol or ethanol.The aliphatic components in the backbone are expected to improve the solubility of these polyesters. Optical- quality thin films can be easily obtained by spin-coating from THF solutions of polyesters Pl-P3.However, polyester P4 containing octylsulfonyl moieties in the side chain formed a turbid thin film by spin-coating from the THF solution. This finding may be attributed to the aggregation of the side-chain octyl groups. Table 1 summarizes the results of the elemental analyses and the general characteristics of the resulting polyesters. The results of the elemental analyses agree with the structure of polyesters shown in Scheme 1. The weight-average molecular weights of polyesters estimated from GPC indicate the degree of polymerization was cu.10. DSC thermograms for Pl-P4 are shown in Fig. 1. In each DSC thermogram, a glass trans- ition was observed, however, no other endothermic or exother- mic peaks appeared between 20 and 200°C. The qs of polyesters, which were determined from a second heating scan in the DSC measurements, were in the range of 80 to 99°C as shown in Table 1. These relatively low qs are detrimental to the stabilization of noncentrosymmetric chromophore-align- ment, and are attributed to the incorporated perfluoroalkyl or alkyl group which would increase the free volume around the polymer linkage. There was no significant difference in q between P1 and P4,which indicates that the incorporation of the octyl moiety as a side-chain terminal group instead of a perfluorooctyl one exerts no significant effect on q.P3 exhib-9,12 tvfirt ix 0 13,16 Scheme 2 Reagents: i, NaH-DMF; ii, F(CF2)gI-or H(CH,),Br-DMF; iii, H,O,-CH,COOH; iv, diethanolamine-K,CO,-DMSO; v, N-methylethanolamine-K~C03-DMSO; vi, 4-hydroxypiperidine- or 4-(2-hydroxyethy1)piperidine-K,CO3-DMSO;vii, dimethyl 5-hydroxyiso- phthalate-PPh,-diethyl azodicarboxylate-THF; viii, NaOH-H,O-CH,OH-THF ix, aq.HC1 Table 1 Results of the elemental analyses and characterization of polyesters Pl-P4 results of elemental analyses (YO) polymer C H N MW" hf-fwIM,b ly3Cc PI Calc.36.25 1.84 1.97 9 850 1.26 83 Found 36.3 1.7 1.2 P2 Calc. 37.26 1.95 1.93 11 100 1.28 99 Found 37.5 1.8 2.5 P3 Calc.38.27 2.19 1.90 9 600 1.25 86 Found 38.3 2.0 2.55 P4 Calc. 46.16 3.87 2.50 9 390 1.65 80 Found 46.3 3.9 2.7 "Values estimated from GPC using polystyrene standards. bPolydispersity index. 'Values determined from DSC on a second heating scan. J. Muter. Chem., 1996, 6(5),711-717 715 0 50 100 150 20 TI"C Fig. 1 DSC traces on a second heating scan at a rate of 10 "Cmin and a helium flow rate of 20 ml min ',(a) P1, (b)P2, (c) P3, (d) P4 ited the highest in the present system, because P3 contains the bulky piperidinyl moiety near-around the polymer back- bone Fig 2 shows a typical X-ray diffraction pattern of the polyesters carried out by the powder method at various temperatures There were no diffraction peaks except for a broad halo around 18" in the diffraction pattern of P1 Similar diffraction patterns were obtained for polyesters P2-P4 The lack of optical anisotropy of the present polyesters was con- firmed by polarized microscopic observations at various tem- peratures Thus, the polyesters obtained are concluded to be amorphous UV-VIS spectroscopy and SHG measurement Fig 3 shows the UV-VIS absorption spectrum of P1 as a spin- coated film (thickness <1 pm) on a quartz glass substrate The UV-VIS spectral data are summarized in Table 2 We defined the cutoff wavelength as the wavelength where the value of the c v)C CIG 1 1 rJ 0 10 20 30 2fNdegrees Fig.2 X-Ray diffraction patterns of P1 obtained by the powder method at various temperatures Table 2 Optical properties of polyesters Pl-P4 polymer &,,,/nm A,,,,ff/nm poling temp /"C d,,/pm V P1 307 390 80 30 P2 308 397 90 18 P3 308 391 80 31 P4 321 430 100 34 716 J Muter Chem, 1996,6(5), 711-717 300 400 500 600 3L Inm Fig.3 Typical example of a UV-VIS absorption spectrum of a spin- coated film of P1 first deviation for absorbance becomes 0 When the film- thickness was <1 pm, the present polyesters Pl-P3 exhibited a cutoff wavelength <400 nm, which is desirable for practical use However, Amax and Acutoff of a thin film of P4 were longer than those of Pl-P3 This result is due to the scattering of the incident light, since a turbid thin film is obtained by spin- coating and since A,,, and icutoffof 12, ze the precursor of P4, are shorter than those of 9-11, z e the precursors of Pl-P3, respectively (see Experimental section) Fig 4 shows the relationship between SH light intensity and the incident angle of the exciting beam for a spin-coated film of P4 after corona poling treatment It was confirmed that similar Maker-fringe patterns were obtained for spin-coated films of Pl-P3 after corona poling treatment The calculated second-order NLO coefficients, d33,are sum- marized in Table 2 The present polyesters exhibited d33values of 18-3 4 pm V-' P4 provides a turbid film by spin-coating from a THF solution, however, it exhibited almost the same d,, value as those of P1 and P3 Clays et have reported that the second-order NLO susceptibility, x(2)zzz, of a Langmuir-Blodgett (LB) film composed of an acrylate polymer containing a similar chromophore, N,N-dialkyl-4-(perfluoro-decy1)anilino moiety (p=9 x esu), is estimated to be 3 pm V-' for an exciting wavelength of 1907 nm using the free gas approximation On using a relationship5' of x(2)zzz=2d33, I 0.4 # Y 8? 0\ c 0.2 v,SF I 0.0 f I I I I L -80 -60 -40 -20 0 20 40 60 80 incident anglejdegrees Fig. 4 Relationship between SH light intensity and the incident angle of the exciting beam for a spin-coated film of P4 after heating with corona poling the x(2)zzzvalues of the present polyesters can be estimated to be 3 6-6 8 pm V-l for an exciting wavelength of 1064 nm The use of different exciting wavelengths has been shown to result in different x(2)zz values Therefore, the f2)-values in these cases cannot be directly compared, however, the x(2)zzzvalues in the present system appear to be of a similar magnitude to that of a highly-ordered LB film composed of an acrylate polymer as estimated by Clays et ul Detailed studies on the alignment of chromophores and the stability of chromophore orientation will be the subject of future studies 17 18 19 20 21 22 M Chen, L R Dalton, L P Yu, Y Q Shi and W H Steier, Macromolecules, 1992,25,4032 C Z Xu, B Wu, L R Dalton, P M Ranon, Y Q Shi and W H Steier, Macromolecules, 1992, 25,6714 P Kitipichai, R La Peruta, G M Korenowski and G E Wnek, J Polym Sci ,Polym Chem Ed, 1993,31,1365 P M Ranon, Y Q Shi, W H Steier, C Z Xu, B Wu and L R Dalton, Appl Phys Lett, 1993,62,2605 J E Beecher, J M J Frechet, C S Willand, D R Robello and D J Williams, J Am Chem Soc, 1993,115,12216 M Conroy, Z Ah-Adib, P Hodge, D West and T King, J Muter Chem ,1994,4,1 In conclusion, we have achieved the synthesis of novel types of optically transparent polyesters containing a high density of second-order NLO active chromophores, which were obtained by condensation polymerization between isophthalic acid derivatives and 2-[N-(2-hydroxyethyl)-4-( perfluorooctyl- sulfonyl)anilino] ethanol The amorphous polyesters obtained exhibited good solubility in common organic solvents and a cutoff wavelength shorter than 400 nm Spin-coating from a THF solution of the polyesters provided optical-quality films The SHG measurements of the poled films of the polyesters using a 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