J O U R N A L O F C H E M I S T R Y Materials Functionalized polyolefinic nonlinear optic chromophores incorporating the 1,3-dithiol-2-ylidene moiety as the electrondonating part T. T. Nguyen,a M. Salle�,*a† J. Delaunay,a A. Riou,a P. Richomme,a J. M. Raimundo,a A. Gorgues,*a I. Ledoux,b C. Dhenaut,b J. Zyss,b J. Ordunac and J. Garý�nc aL aboratoire Inge�nierie Mole�culaire et Mate�riaux Organiques, UMR CNRS 6501, Universite� d’Angers, 2 Bd L avoisier, F-49045 Angers, France bCentre National d’Etudes des T e�le�communications, France T e�le�com, 196 Av Henri Ravera, F-92220 Bagneux, France cDepartamento de Quý�mica Orga�nica, ICMA, Universidad de Zaragoza, CSIC, E-50009 Zaragoza, Spain The synthesis of a series of push-pull systems [donor (D)–acceptor (A)], associating the 1,3-dithiol-2-ylidene moiety (D) to various (A) fragments through polyolefinic linkages of various lengths, is described.Design optimization of these NLO phores is via systematic determination of the molecular first hyperpolarizabilities b by the EFISH method. Selected compounds of this series, displaying the highest b values, are then chemically functionalized in order to promote their covalent grafting to polymeric backbones.The quest for new chromophores possessing large molecular second-order nonlinearity is of current interest because of their potential applications in electro-optic devices. In this context, the design and synthesis of new D–p–A systems, where the electron-donor (D) and electron-acceptor (A) groups are separated by a p-conjugated linker, are presently a major focus.Moreover, a growing eVort is devoted to the preparation of polymers covalently functionalized with such chromophores, in order to produce long-term stable nonlinear optical (NLO) systems.1 The 1,3-dithiol-2-ylidene moiety is well known for its electron- donating properties, and has been extensively used as such, notably in the synthesis of p-donating molecules of the tetrathiafulvalene family.2 This donating ability has also been explored in the design of NLO chromophores.3 Nevertheless, very few examples of push-pull chromophores possessing the 1,3-dithiol-2-ylidene moiety have been designed to further incorporate main-chain or side-chain polymers.In this paper, we report on the synthesis of new push-pull conjugated polyenic systems incorporating the 1,3-dithiol-2- ylidene fragment as the donor part and various acceptor moities.A careful structural optimization of this class of S S NO2 S NO2 CO2Et CO2Et CO2Et CHO CN CN CN R1 R2 R1 = R2 = Me R1–R2 = (CH=CH)2 R1–R2 = SCH2CH2S a b c A n 4a–c n = 2, A = 5a,b n = 2, A = n = 1, A = n = 2, A = n = 3, A = n = 1, A = n = 1, A = 6a,b 7a,b 8a,b 9a,b 10a,b chromophores has been carried out in order to reach high second-order hyperpolarizabilities as well as to introduce BuLi furnished chromophores 4 bearing the 4-nitrophenyl functionalities which could favour their subsequent incorpor- substituent as the acceptor part (only the E-configuration is ation into polymeric backbones.observed for the double-bond formed during the olefination step).On the other hand, compounds 5–8 were obtained via Wittig–Horner olefinations of 1 and 2 with a phosphonate Synthesis anion generated under basic conditions from the corresponding The access to chromophores 4–10 involves key precursors 2 phosphonate esters. and 3, whose syntheses were performed via adaptation of the All of these compounds were fully characterized using diVerpreviously described procedures.4 Taking advantage of the ent spectroscopic methods, a careful NMR study (1H NMR, great synthetic potential of the aldehyde functionality in 2 and 13C NMR, COSY, HMQC, HMBC) being often needed to 3, we prepared target compounds 4–10 either through Wittig fully assign the molecular structures of compounds 4–8.(–Horner) type olefinations or Knoevenagel condensations Whereas 4 and 5 were obtained as mixtures of Z and E (Scheme 1).isomers, the trans configuration of the double bond formed in Treatment of aldehydes 2 with the commercially available the synthesis of compounds 6–8 was fully ascertained by NMR 4-nitrobenzyl(triphenyl)phosphonium bromide in presence of studies, as well as the s-trans conformation adopted by 8a in [2H6]DMSO, assigned via an NOE experiment.Furthermore, methanol recrystallization of 8a produced † E-mail: marc.salle@univ-angers.fr J. Mater. Chem., 1998, 8(5), 1185–1192 1185O S S 123 R1 R2 4a–c m = 0 m = 1 m = 2 (57–71%) 5a,b (56–60%) 6a,b (53–60%) 7a,b (52–63%) 8a,b (28–33%) R1 = R2 = Me R1–R2 = (CH=CH)2 R1–R2 = SCH2CH2S a (78–85%) (69–81%) 9a,b 10a,b b c i ii vi iii iv v m Scheme 1 Reagents and conditions: i, 4-nitrobenzyl(triphenyl)phosphonium bromide, BuLi, THF, reflux; ii, dimethyl (5-nitro-2-thienyl)- methylphosphonate, BuLi, THF, reflux; iii, triethyl phosphonoacetate, BuLi, THF, 0 °C; iv, CH2(CN)2, Et3N, dioxane, 0 °C; v, NCCH2CHO, MeONa, THF, room temp.; vi, triethyl 4-phosphonocrotonate, BuLi, THF, 0 °C CN CN NC NC S S S CN CN NC NC CN CN S S S S CH2-P(O)(OMe)2 S S S NH 11 + 2a + (81%) 11 12 (84%) ii [2+4] i Scheme 2 Reagents and conditions: i, Bu t OK, THF, room temp.; ii, DMF, room temp.contribution from the charge-separated resonance form to the ground-state structure. In our quest to synthesize new push-pull systems, we also attempted to graft the 2-(tricyanovinyl )thiophene fragment as the acceptor (A) group.For this purpose, we first synthesized the unsubstituted 2-thienyl derivative 11 through a Wittig– Horner olefination of 2a with diethyl (2-thienyl)methylphosphonate (Scheme 2). Unfortunately this compound, when treated with tetracyanoethylene in DMF, did not give the required addition of the tricyanovinyl group to the terminal position of 2a, but to compound 12 thanks to a [4+2] cycloaddition of tetracyanoethylene to the central polyolefinic linkage, followed either by a [2+2] process or an intramolecular nucleophilic addition, with prototropy.This unexpected structure was confirmed via an X-ray structural determination using a single crystal of 12 (Fig. 2).8 Alternatively, new push-pull systems 9 and 10 were prepared using Knoevenagel type condensations between aldehydes 2 and either malononitrile or cyanoacetaldehyde.Fig. 1 ORTEP view of compound 8a crystals suitable for a X-ray structural determination5 (Fig. 1). The most noticeable features of this structure lie in the occurrence of a perfectly planar s-trans structure, with relatively low Dr values between single and double bond lengths (average rCNC=1.372 A ° ; average rCMC=1.454; Dr=0.08 A °), corresponding to an optimized bond alternation for enhancement of quadratic and cubic NLO properties.6 This Dr value has to be compared with the one encountered in the case of an unsubstituted polyene such as octa-1,3,5,7-tetraene, which displays a Dr value of 0.11 A ° (average rCNC=1.340 A ° ; average rCMC=1.445 A ° ).7 This comparison provides direct evidence for Fig. 2 ORTEP view of compound 12 a low bond-length alternation in 8a, associated to an important 1186 J. Mater. Chem., 1998, 8(5), 1185–1192selected among structures 4–10 as the best candidates to be NLO properties structurally modified due to easy chemical accessibility and The second-order hyperpolarizabilities b of chromophores 1–5, good hyperpolarizability values. 9 and 10 were determined using an the electric field induced Prior to the target NLO active monomers 14 and 23, we second harmonic (EFISH) generation experiment9 using a needed to synthesize mono- and bis-(2-hydroxyethylsulfanyl) laser source operating at 1.34 mm, the compounds being dis- derivatives 13 and 22. solved in chloroform (Table 1). The relevant parameter for In the case of 13, we took advantage of the specific ability electro-optic applications is mb, where m is the ground state of the ethane-1,2-diyldisulfanyl group to undergo a ring opendipole moment. Static mb(0) values are calculated from exper- ing under basic conditions11 (essive imental mb (1.34 mm) ones using a two-level dispersion model treatment of compound 4c with an excess of Bu4NF and for b.9 bromoethanol allowed the formation of the hydroxy intermedi- All of the NLO-phores studied present large mb and mb(0) ate 13 as a mixture of Z and E isomers, the hydroxyethyl and values.As expected for donor–acceptor substituted polyenes, vinyl groups being disposed in a random fashion with respect extension of the conjugation length from 1a to 3a results in a to the polyene part.Subsequent esterification of 13 with significant enhancement of the second-order nonlinearity methacryloyl chloride finally aVorded the required 14. [mb(0) values: 2a/1a=9.0, 3a/2a=1.3]. On the other hand, the two-fold introduction of the meth- Compounds 3a, 4a, 10a and 9a on the one hand, and 3b, acrylate moiety first involved the preparation of the 1,3- 4b, 10b and 9b on the other hand essentially display the same dithiolium salt 19a (scheme 4).This synthesis was achieved in qualitative increase of mb(0) values when increasing the acceptor character of the end group for both series, with confirmation of the superiority of the dicyanovinyl moiety over the aldehyde group, the mb(0) values being increased by a factor of 2.6 and 2.3 for the a and b series, respectively.Additionally, the introduction of the nitrothienyl substituent in compound 5b results in a strong increase of the nonlinearity when compared to 4b, which confirms the utility of this electron-attracting substituent in the designing of new D–p–A NLO-phores. Investigation of the donor part was limited to the study of the influence of the R groups at the 4,5-positions of the 1,3- dithiol-2-ylidene electron donating moiety.Of course, varying the R groups leads to smaller diVerences in mb(0) than in the preceding study on the acceptor part, where the whole A fragment was changed. The superiority of the methyl group as a donating substituent (3a, 4a, 9a, 10a) over the benzo-fused fragment (3b, 4b, 9b, 10b) was established in all cases, with as expected a very small increase in mb(0) [mb(0) values: 3a/3b= 1.02, 4a/4b=1.18, 9a/9b=1.18, 10a/10b=1.01].Moreover, the 4,5-(ethane-1,2-diyldisulfanyl) substituted derivative 4c displays a mb(0) value between those of 4a and 4b, as expected from previous studies of its electron-donating behavior.3b Synthesis of polymer precursors In order to obtain long-term stable nonlinear systems, these chromophores have been functionalized to allow further polymerization and to reach side-chain polymers bearing pendant active NLO moieties.This was achieved by introducing methyl methacrylate fragments10 on the donor extremity of the push- S S S S S S S S HO S S S S O C O -14 4c (77%) (84%) iii -13 ( E / Z ) ( E / Z ) i,ii NO2 NO2 NO2 pull system. Scheme 3 Reagents and conditions: i, Bu4 NF, THF, room temp.; ii, Addition of the methyl methacrylate fragment was carried BrCH2CH2OH (1.1 equiv.), THF, room temp.; iii, methacryloyl chloride, pyridine, THF, reflux out at the periphery of chromophores of type 4, which were Table 1 Experimental data: lmax, ground state dipole moment m, mb measured at 1.34 mm and static mb(0) values deduced from experimental mb ones using a two-level dispersion model for b compound lmax(CH2Cl2)/nma m/D mb/10-48 esu mb(0)/10-48 esu 1a 397 (4.26) 6.9 25 16 2a 432 (4.43) 8.2 273 144 3a 463 (4.24) 8.4 436 193 3b 431 (4.36) 6.1 369 189 4a 499 (4.50) 8.1 1130 464 4b 465 (4.40) 8.0 860 392 4c 479 (4.05) 8.6 981 403 5b 521 (4.27) 8.1 2540 850 9a 541 (4.37) 9.4 1870 508 9b 502 (4.81) 7.9 1200 431 10a 550 (4.56) 9.2 1590 401 10b 507 (4.44) 8.2 1147 397 aValues in parentheses are log e.J. Mater. Chem., 1998, 8(5), 1185–1192 1187several steps from thioxo derivative 15,12 whose hydroxy functionalities are first reacted with benzoyl chloride to produce 16a. This compound could be further S-methylated with methyl trifluoromethanesulfonate to aVord 17a; no reaction was observed when using methyl iodide or dimethyl sulfate as alkylating agents.Reduction of the latter with sodium borohydride and subsequent treatment with hexafluorophosphoric acid furnished the required dithiolium intermediate 19a. Formation of the corresponding phosphonate ester by addition of trimethyl phosphite was followed by Wittig–Horner olefination with fumaraldehyde mono(diethyl acetal ).Further hydrolysis led to aldehyde 20a, which was converted to the push-pull system 21 thanks to a Wittig olefination with 4-nitrobenzyl(triphenyl) phosphonium bromide. Deprotection of the alcohol functionalities and two-fold esterification of 22 with methacryloyl chloride aVorded the expected polymer precursor 23. Attempts to copolymerise monomers 14 or 23 with methyl methacrylate in the presence of AIBN all resulted in chemical evolution of the NLO active part, as evidenced by extinction of the absorption bands related to the individual chromophores in the electronic spectra.This observation strongly suggests a lack of stability of the conjugated backbone under these polymerisation conditions. Alternatively, we attempted to prepare polyesters, containing the same optimized optically active group, by polycondensation between diol 22 and terephthaloyl chloride.Using various experimental conditions, we have been unable to isolate the target polymer, finding only short oligomers beside the [2+2] cyclocondensation product (m/z 1142). The introduction of these chromophores into other classes of polymers, notably polyimides, is underway.Conclusion We have synthesized a wide range of D–p–A systems incorporating 4,5-disubstituted 1,3-dithiol-2-ylidene moieties as the D part. EFISH measurements have shown these NLO phores to possess high second order nonlinearities, and have allowed us to evaluate the eVect of (i) the length of the p-conjugating spacer and (ii) the nature of the electron-withdrawing and electron-releasing substituents on the mb(0) values.Chemical modifications on one model chromophore allowed us to intro- S S S O Bz SMe TfO– S S S O H SMe S S S O Bz H S S S O Bz O S S R2S R2S S S S O Bz S S S S NO2 S S S S Bz 21 16a R1 = CH2CH2OBz (87%) b R1 = CH3 (78%) PF6 – + + 17a (96%) b (94%) 18a (94%) b 19a (67%) b (66%) 20a (78%) b (65%) R2 = CH2CH2OBz (65%) 22 R2 = CH2CH2OH (79%) 23 R2 = CH2CH2OCOCMe=CH2 (58%) R1S R1S R1S R1S R1S 20a 24 R2 = CH2CH2OBz (51%) 25 R2 = CH2CH2OH (60%) 20b 15 R1 = CH2CH2OH , 15' R1 = Me R1S HO NO2 x xi MeS R2S i ii iii iv v–viii ix xii duce polymerizable fragment(s) at the periphery of the D–p–A Scheme 4 Reagents and conditions: i, BzCl, pyridine, THF, room temp.; system.Considering the very attractive mb(0) value obtained ii, TfOMe, CH2Cl2, room temp.; iii, NaBH4, Pr i OH, MeCN, 0 °C; iv, with compound 5b possessing a nitrothienyl group as the HPF6, Ac2 O, 0 °C; v, NaI, P(OMe)3, MeCN, room temp.; vi, BuLi, acceptor part, chemical modification of this chromophore to -80 °C; vii, fumaraldehyde mono(dimethyl acetal ), THF, -80 °C�room temp.; viii, Amberlyst-15, H2O–acetone; ix, 4-nitro- hydroxy derivative 25 has been performed according to a benzyl(triphenyl )phosphonium bromide, BuLi, THF, reflux; x, KOH, similar synthetic strategy as for compound 22 (Scheme 4).THF–MeOH–H2O (105551), reflux; xi, methacryloyl chloride, pyri- Attempts to covalently graft this chromophore onto poly(imdine, THF, reflux; xii, dimethyl (5-nitro-2-thienyl )methylphosphonate, ide-co-siloxanes) are in progress.BuLi, THF, reflux; xiii, KOH, THF–MeOH–H2O (105551), reflux Syntheses of 4a–c Experimental 4-Nitrobenzyl(triphenyl)phosphonium bromide (2.2 mmol) Melting points were obtained using a Rechert-Jung hot-stage was dissolved in dried THF (10 ml ), and BunLi (1.6 M in microscope apparatus and are uncorrected. IR spectra were hexane; 2.2 mmol) was added at room temperature.The mixrecorded on a Perkin-Elmer model 841 spectrophotometer, ture was stirred for 15 min and aldehyde 2 (2 mmol) was added samples being embedded in KBr discs or Fluorolube mulls. dropwise. The reaction mixture was refluxed for 2 h. After 1H and 13C NMR spectra were recorded on a JEOL cooli, the solvents were removed under reduced pressure GSX270WB spectrometer operating respectively at 270 and and the residue was dissolved in CH2Cl2, washed with water 67.5 MHz or on a Bruker Avance DRX500 operating at 500 and dried (MgSO4). The crude material obtained after evaporand 125.7 MHz, respectively; d values are given in ppm (relative ation of CH2Cl2 was chromatographed over silica gel (CH2Cl2 to TMS) and coupling constants (J) in Hz.Mass spectra were as eluent) to produce 4a–c as brown powders. recorded in EI or FAB mode on a VG Autospec. UV–VIS spectra were recorded on a Perkin-Elmer Lambda 2 spec- 5-(4,5-Dimethyl-1,3-dithiol-2-ylidene)-1-(4- trometer. Elemental analyses were performed by the Service nitrophenyl )penta-1,3-diene 4a. Yield 71%, mp 173–174 °C; 1H central d’analyses du CNRS (Vernaison, France).Column NMR (CDCl3) 8.14 (d, 2H, 3J=8.5 Hz), 7.66 (d, 2H, 3J= chromatography separations and purifications were carried 8.7 Hz), 7.29 (dd, 1H, 3J=10.5, 15.5 Hz), 6.63 (d, 1H, 3J= 15.5 Hz), 6.38–6.20 (m, 3H), 1.94 (s, 6H); 13C NMR (CDCl3) out on Merck silica gel 60 (0.040–0.0063 nm). 1188 J. Mater. Chem., 1998, 8(5), 1185–1192145.4, 144.1, 139.5, 133.9, 132.7, 126.8, 125.9, 125.6, 123.7, 121.6, Ethyl 4-(4,5-dimethyl-1,3-dithiol-2-ylidene)but-2-enoate 6a.Yield 60%; 1H NMR (CDCl3) 7.37 (dd, 1H, 3J=11.8, 14.8 Hz), 110.9, 13.1, 12.8 (Calc. for C16H15NO2S2: C, 58.53; H, 4.06. Found: C, 58.10; H, 4.17%); m/z (EI) (%) 317 (M+, 100), 195 6,10 (d, 1H, 3J=11.75 Hz), 5.54 (d, 1H, 3J=14.8 Hz), 4.22 (q, 2H), 1.96 (s, 3H), 1.93 (s, 3H), 1.30 (t, 3H); m/z (EI) (%) 242 (18), 131 (22), 59 (18); nmax(KBr)/cm-1 1504, 1336 (NO2).(M+, 87), 197 (100), 170 (74), 116 (53), 71 (48), 59 (20). 5-(1,3-Benzodithiol-2-ylidene)-1-(4-nitrophenyl )penta-1,3- diene 4b. Yield 57%, mp 246–248 °C; 1H NMR (CDCl3) 8.16 Ethyl 4-(1,3-Benzodithiol-2-ylidene)but-2-enoate 6b. Yield (d, 2H, 3J=8.7 Hz), 7.49 (d, 2H, 3J=8.7 Hz), 7.20 (m, 4H), 7.03 53%, mp 80–82 °C; 1H NMR (CDCl3) 7.34 (dd, 1H, 3J=11.5, (dd, 1H, 3J=11.0, 15.5 Hz), 6.54 (d, 1H, 3J=15.5 Hz), 6.42 (dd, 14.8 Hz,), 7.22 (m, 4 H), 6.24 (d, 1H, 3J=11.5 Hz), 5.65 (d, 1H, 1H, 3J=11.3, 13.8 Hz), 6.26 (dd, 1H, 3J=11.0, 13.8 Hz), 6.22 3J=14.8Hz), 4.22 (q, 2H), 1.30 (t, 3H); 13C NMR (CDCl3) (d, 1H, 3J=11.3 Hz); 13C NMR (CDCl3) 151.5, 135.7, 133.9, 167.0, 145.6, 139.3, 135.2, 134.7, 125.7, 125.6, 121.4, 121.2, 115.4, 132.5, 128.2, 126.2, 126.0, 125.8, 125.5, 124.2, 121.7, 121.5, 114.1 110.9, 59.7, 13.9; m/z (EI) (%) 264 (M+, 98), 236 (8), 219 (70), (Calc.for C18H13NO2S2: C, 63.71; H, 3.83; N, 4.13; O, 9.44; S, 192 (100), 147 (28), 69 (12); nmax(KBr)/cm-1 1696 (CO). 18.88. Found: C, 63.83; H, 4.03; N, 4.23; O, 9.91; S, 18.58%); m/z (EI) (%) 339 (M+, 100), 292 (29), 153 (26), 140 (30), 77 Ethyl 6-(4,5-Dimethyl-1,3-dithiol-2-ylidene)hexa-2,4-dieno- (7); nmax(KBr)/cm-1 1565, 1335 (NO2).ate 7a. Yield 52%, mp 120–123 °C; 1H NMR (CDCl3) 7.31 (dd, 1H, 3J=11.5, 15.0 Hz), 6.43 (dd, 1H, 3J=11.5, 14.6 Hz), 5-[4,5-(Ethane-1,2-diyldisulfanyl)-1,3-dithiol-2-ylidene]-1- 6,06 (d, 1H, 3J=11.5 Hz), 6.03 (dd, 1H, 3J=11.5, 14.6 Hz), (4-nitrophenyl )penta-1,3-diene 4c.Yield 60%, mp 220–221 °C; 5.76(d, 1H, 3J=15.0 Hz), 4.17 (q, 2H), 1.96, (s, 3H), 1.93 (s, 1H NMR (CDCl3) 8.17 (d, 2H, 3J=8.9 Hz), 7.47 (d, 2H, 3J= 3H), 1.28 (t, 3H); 13C NMR (CDCl3) 168.0, 145.6, 143.7, 137.5, 8.9 Hz), 6.98 (dd, 1H, 3J=10.1, 15.5 Hz), 6.53 (d, 1H, 3J= 124.3, 122.7, 122.9, 118.2, 111.1, 60.5, 14.8, 14.0, 13.7; m/z (EI) 15.5 Hz), 6.41 (dd, 1H, 3J=10.3, 13.8 Hz), 6.23 (dd, 1H, 3J= (%) 268 (M+, 41), 223 (8), 195 (100), 59 (8); nmax(KBr)/cm-1 10.1, 13.8 Hz), 6.22 (d, 1H, 3J=10.3Hz), 3.33 (s, 4H); 13C NMR 1697 (CO).(CDCl3) 146.2, 144.2, 135.1, 133.8, 132.2, 128.7, 128.4, 127.5, 126.3, 124.2, 114.3, 29.7, 29.6 (Calc. for C16H13NO2S4: C, 50.66; Ethyl 6-(1,3-Benzodithiol-2-ylidene)hexa-2,4-dienoate 7b. H, 3.43; N, 3.69. Found: C, 50.46; H, 3.53; N, 3.49%); m/z (EI) Yield 63%, mp 103 °C; 1H NMR (CDCl3) 7.34 (dd, 1H, 3J= (%) 379 (M+, 100), 184 (92), 152 (34), 88 (35); nmax(KBr)/cm-1 11.5, 15 Hz), 7.19 (m, 4 H), 6.53 (dd, 1H, 3J=11.3, 14.3 Hz), 1526, 1332 (NO2). 6.21 (d, 1H, 3J=11.3 Hz), 6.13 (dd, 1H, 3J=11.5, 14.3 Hz), 5.83 (d, 1H, 3J=15 Hz), 4.20 (q, 2H), 1.29 (t, 3H); 13C NMR Syntheses of 5a,b (CDCl3) 167.3, 144.6, 140.4, 136.3, 135.7, 135.5, 126.1, 125.9, 121.8, 121.6, 125.8, 119.2, 113.4, 60.2, 14.3 (Calc. for Using a similar procedure as for 4a–c, aldehyde 2 was reacted C15H14O2S2: C, 62.02; H, 4.82; O, 11.03; S, 22.06.Found: C, with dimethyl (5-nitro-2-thienyl)methylphosphonate as 61.70; H, 4.90; O, 10.88; S, 21.63%); m/z (EI) (%) 290 (M+, Wittig–Horner reagent. 36), 245 (9), 217 (100), 184 (23), 69 (8); nmax(KBr)/cm-1 1711 (CO). 5-(4,5-Dimethyl-1,3-dithiol-2-ylidene)-1-(5-nitro-2- thienyl)penta-1,3-diene 5a. Yield 56%, black powder, mp Ethyl 8-(4,5-Dimethyl-1,3-dithiol-2-ylidene)octa-2,4-dienoate 179–180 °C; 1H NMR (CDCl3) 7.78 (d, 1H, 3J=4.2 Hz), 6.85 8a. Yield 33%, mp 135 °C; Chemical shifts of diVerent 1H and (dd, 1H, 3J=10.8, 15.3 Hz), 6.81 (d, 1H, 3J=4.0 Hz), 6.47 (d, 13C nuclei were assigned from COSY [1H,1H] and HMQC 1H, 3J=15.0 Hz), 6.35 (dd, 1H, 3J=11.3, 14.6 Hz), 6.09 (d, 1H, spectra.The all-trans configuration of the conjugated spacer 3J=11.5 Hz), 6.05 (dd, 1H, 3J=11.0, 14.6 Hz), 1.98 (s, 3H), was confirmed from NOE measurements and X-ray diVraction: 1.95 (s, 3H); 13C NMR (CDCl3) 151.9, 143.0, 141.8, 135.2, 1H NMR (CDCl3) 7.18 (dd, 1H, 3J=11.5, 15.2 Hz), 6.47 (dd, 134.2, 130.0, 125.3, 123.5, 122.5, 120.7, 111.3, 13.6, 13.2; m/z 1H, 3J=10.9, 14.7 Hz), 6.13 (m, 2H), 5.93 (d, 1H, 3J=11.9Hz), (EI) (%) 323 (M+, 100), 147 (67), 131 (26), 59 (24); 5.91 (dd, 1H, 3J=11.0, 16.2 Hz), 5.18 (d, 1H, 3J=15.2 Hz), 4.10 nmax(KBr)/cm-1 1520, 1317 (NO2).(q, 2H), 1.96 (s, 3H), 1.93 (s, 3H), 1.20 (t, 3H); 13C NMR (CDCl3) 166.4, 144.9, 141.9, 139.3, 133.6, 127.9, 126.7, 122.3, 5-(1,3-Benzodithiol-2-ylidene)-1-(5-nitro-2-thienyl )penta-1,3- 122.1, 118.6, 111.7, 59.6, 14.2, 13.3, 12.9 (Calc.for C15H18O2S2: diene 5b. Yield 60%, violet powder, mp 203–205 °C; 1H NMR C, 61.22; H, 6.12; O, 10.88; S, 21.76. Found: C, 61.29; H, 6.12; (CDCl3) 7.8 (d, 1H, 3J=4.2 Hz), 7.21 (m, 4H), 6.88 (dd, 1H, O, 10.89; S, 21.57%); m/z (EI) (%) 294 (M+, 35), 265 (10), 221 3J=10.6, 15.5 Hz), 6.85 (d, 1H, 3J=4.5 Hz), 6.54(d, 1H, 3J= (100), 157 (15), 91 (19); nmax(KBr)/cm-1 1702 (CO). 15.5 Hz), 6.44 (dd, 1H, 3J=11.3, 14.3 Hz), 6.23 (d, 1H, 3J= 11.3 Hz), 6.14 (dd, 1H, 3J=14.3 Hz); 13C NMR (CDCl3) 151.9, Ethyl 8-(1,3-Benzodithiol-2-ylidene)octa-2,4-dienoate 8b. 138.4, 135.3, 135.1, 134.1, 133, 129.5, 126.7, 125.7, 125.5, 121.5, Yield 28%, mp 135 °C; 1H NMR (CDCl3) 7.35 (m, 4H), 7.28 121.4, 123.5, 113.5 (Calc.for C16H11NO2S3: C, 55.63; H, 3.21; (dd, 1H, 3J=11.5, 15.0 Hz), 6.85 (dd, 1H, 3J=10.8, 14.6 Hz), N, 4.05; O, 9.26; S, 27.84. Found: C, 55.49; H, 3.13; N, 4.05; O, 6.50–6.21 (m, 4H), 5.93 (d, 1H, 3J=15.0 Hz), 4.11 (q, 2H), 1.21 9.57; S, 27.52%); m/z (EI) (%) 345 (M+, 100), 147 (77), 69 (t, 3H); 13C NMR (CDCl3) 166.3, 144.7, 141.5, 136.6, 134.8, (60); nmax(KBr)/cm-1 1526, 1324 (NO2). 133, 129, 128.6, 126.6, 126.4, 122.3, 122.2, 119.4, 114.6, 59.7, 14.3 (Calc. for C17H16O2S2: C, 64.55; H, 5.06; O, 10.12. Found: Syntheses of 6a,b, 7a,b and 8a,b C, 64.39; H, 5.03; O, 10.21%); m/z (EI) (%) 316 (M+, 35), 287 A solution of aldehyde 1 (1 mmol) and triethyl phosphonoacet- (11), 243 (100); nmax(KBr)/cm-1 1698 (CO).ate (1 mmol) (for 6a,b), aldehyde 2 (1 mmol) and triethyl phosphonoacetate (1 mmol) (for 7a,b) or aldehyde 2 (1 mmol) Syntheses of 9a,b with triethyl 4-phosphonocrotonate (1 mmol) (for 8a,b) in dried THF (10 ml ) was treated with BunLi (1.6 M in hexane, A mixture of aldehyde 2 (1 mmol), malononitrile (1.1 mmol) and triethylamine (1 ml) in dioxane (20 ml ) was stirred for 1.1 equiv.) at 0 °C.The reaction mixture was stirred for 2 h, the solvents were removed under reduced pressure and the 10 min at 0 °C. The reaction mixture was then diluted with CH2Cl2 (100 ml), washed with water and dried (MgSO4). The residue was dissolved in CH2Cl2, washed with water and dried (MgSO4). Evaporation of the solvent and silica gel chromatog- solvent was removed and the reaction product was purified by silica gel chromatography (CH2Cl2 as eluent) to produce 9a,b raphy (CH2Cl2 as eluent) produced 6a,b, 7a,b and 8a,b as yellow powders.as blue powders. J. Mater. Chem., 1998, 8(5), 1185–1192 11896-(4,5-Dimethyl-1,3-dithiol-2-ylidene)-2-cyanohexa-2,4- Synthesis of 12 dienenitrile 9a. Yield 78%, mp 227–232 °C; 1H NMR (CDCl3) Tetracyanoethylene (1.5 mmol) was added portionwise to a 7.33 (d, 1H, 3J=12.2 Hz), 6.88 (dd, 1H, 3J=12.0, 13.4 Hz), 6.46 solution of compound 11 (1 mmol) in DMF (10 ml ).The (dd, 1H, 3J=11.8, 13.4 Hz), 6.28 (d, 1H, 3J=11.8 Hz), 2.09 (s, homogeneous mixture was stirred for one day at room tempera- 6H); 13C NMR (CDCl3) 160.3, 159.1, 146.5, 126.3, 126.2, ture, and then diluted with CH2Cl2 (100 ml), washed with 118.9, 116.0, 114.0, 111.0, 74.4, 14.1, 13.7; m/z (EI) (%) 246 water and dried (MgSO4).Solvent was removed under reduced (M+, 100), 249 (12), 71 (22), 59 (22), 54 (35); nmax(KBr)/cm-1 pressure and the yellow solid residue was chromatographed 2211 (CN). over silica gel (CH2Cl2 as eluent). Crystals suitable for X-ray analysis were obtained from chloroform. 6-(1,3-Benzodithiol-2-ylidene)-2-cyanohexa-2,4-dienenitrile 9b.Yield 85%, mp 242 °C; 1H NMR (CDCl3) 7.42 (d, 1H, 3J= 1,8,8-Tricyano-2-(2-thienyl )-6-(4,5-dimethyl-1,3-dithiol-2- 12.7 Hz), 7.31 (m, 4H), 6.97 (dd, 1H, 3J=12.0, 13.9 Hz), 6.49 ylidene)-7-iminobicyclo[3.2.1]oct-3-ene 12. Yield 84%, yellow (dd, 1H, 3J=12.0, 13.9 Hz), 6.42 (d, 1H, 3Jab=12.0 Hz); 13C powder, mp 245 °C; 1H NMR (CDCl3) 9.08 (s, 1H), 7.31 (d, NMR (CDCl3) 159.4, 155.1, 144.9, 140.8, 135.8, 127.4, 122.7, 1H, 3J=4.9 Hz), 7.03 (d, 1H, 3J=3.7 Hz), 6.99 (m, 1H), 6.47 121.4, 114.8, 112.8 (Calc.for C14H8N2S2: C, 62.68; H, 2.98; N, (dd, 1H, 3J=6.5, 9.6 Hz), 5.90 (dd, 1H, 3J=2.8, 9.6 Hz), 4.61 10.44; S, 23.88. Found: C, 62.33; H, 3.00; N, 10.33; S, 23.97%); (t, 1H), 3.92 (d, 1H, 3J=6.5 Hz), 2.14 (s, 3H), 2.11 (s, 3H); m/z m/z (EI) (%) 268 (M+, 100), 242 (8), 152 (25), 108 (14), 69 (EI) (%) 406 (M+, 100), 297 (23), 160 (26), 233 (85), 208 (40), (11); nmax(KBr)/cm-1 2220, 2204 (CN). 131 (47); nmax(KBr)/cm-1 3267 (NH), 2247 (CN). Synthesis of 13 Syntheses of 10a,b To a solution of 4c (0.5 mmol) in THF (10 ml ) was added in A solution of aldehyde 2 (1 mmol), cyanoacetaldehyde diethyl one portion an excess (5 mmol) of Bu4NF (1 M solution in acetal (1 mmol) and sodium methoxide (2 mmol) in dried THF THF) at room temperature.The red solution was stirred for (10 ml ) was stirred at room temperature for three days (in the 15 min, the colour turning to violet, and 2-bromoethanol case of 10a) or one day (in the case of 10b). Instantaneous (0.55 mmol) was added.The reaction mixture was stirred for hydrolysis was carried out by adding 50 ml of THF and 50 ml 6 h. The THF was then evaporated and the residue was of HCl (2 M). The solution was diluted with CH2Cl2 and dissolved in CH2Cl2, washed with water and dried (MgSO4). successively washed with water, saturated NaHCO3 and brine. The CH2Cl2 was evaporated and the residue was chromato- The organic phase was dried, evaporated and the residue was graphed over silica gel (CH2Cl2 as eluent) to give 13 as a chromatographed on silica gel (CH2Cl2 as eluent) to give 10a,b brown powder (probably as a mixture of Z and E isomers as violet powders. which are spectroscopically indistinguishable). 6-(4,5-Dimethyl-1,3-dithiol-2-ylidene)-2-cyanohexa-2,4- 5-[4-Ethenylsulfanyl-5-(2-hydroxyethylsulfanyl)-1,3-dithioldienal 10a.Yield 69%, mp 231 °C; 1H NMR (CDCl3) 9.39 (s, 2-ylidene]-1-(4-nitrophenyl)penta-1,3-diene 13. Yield 77%; 1H 1H), 7.57 (d, 1H), 7.02 (dd, 1H), 6.48 (dd, 1H), 6.36 (d, 1H), NMR (CDCl3) 8.17 (d, 2H), 7.48 (d, 2H), 6.98 (dd, 1H, 3J= 2.11 (s, 3H), 2.09 (s, 3H); m/z (EI) (%) 249 (M+, 70), 220 9.8, 15.4 Hz), 6.55 (d, 1H, 3J=15.4 Hz), 6.40 (dd, 1H, 3J=9.4, (100), 170 (12), 144 (12), 116 (21), 71 (24), 59 (28); 15.6 Hz), 6.25 (m, 3H), 5.48 (m, 2H), 3.79 (m, 2H), 3.00, (t, nmax(KBr)/cm-1 2211 (CN), 1659 (CO). 2H), 2.17 (t, 1H); 13C NMR (CDCl3) 146.3, 144, 135.6, 133.6, 131.5, 128.9, 128.8, 128.7, 126.3, 126.1, 117.7, 117.6, 114.9, 60.2, 39.0 (Calc for C18H17NO3S4: C, 51.04; H, 4.04; N, 3.30; O, 6-(1,3-Benzodithiol-2-ylidene)-2-cyanohexa-2,4-dienal 10b. 11.33; S, 30.27. Found: C, 50.91; H, 4.02; N, 3.32; O, 11.04; S, Yield 81%, mp 218 °C; 1H NMR (CDCl3) 9.44 (s, 1H), 7.63 30.32%); m/z (EI) (%) 423 (M+, 100), 184 (84), 152 (43), 103 (d, 1H, 3J=12 Hz), 7.52 (m, 4 H), 7.09 (dd, 1H, 3J=12.0, (43), 71 (44), 59 (12); nmax(KBr)/cm-1 3337 (OH), 1524, 13.6 Hz), 6.63 (dd, 1H, 3J=12.0, 13.6 Hz), 6.49 (d, 1H, 3J= 1334 (NO2). 12Hz); 13C NMR (CDCl3) 185.7, 157.1, 153.6, 144.8, 134.9, 126.4, 126.3, 121.8, 121.4, 114.0, 112.5, 109.1, 76.1 (Calc. for Synthesis of 14 C14H9NOS2: C, 61.97; H, 3.34; O, 5.89. Found: C, 61.92; H, 3.25; O, 5.22%); m/z (EI) (%) 271 (M+, 85), 242 (100), 108 To a solution of 13 (0.5 mmol) and pyridine (0.1 ml) in dried (34), 69 (30); nmax(KBr)/cm-1 2216 (CN), 1681 (CO). THF (10 ml ) was added dropwise a solution of freshly distillated methacryloyl chloride (1 mmol) in dried THF (5 ml).The reaction mixture was refluxed for 3 h, THF was removed Synthesis of 11 under reduced pressure and the residue was dissolved in Potassium tert-butoxide (1.5 mmol) was slowly added at room CH2Cl2, washed with water and dried (MgSO4). After removtemperature to a solution of aldehyde 2a (1 mmol) and diethyl ing the solvent, the residue was chromatographed over silica (2-thienyl)methylphosphonate (1.5 mmol) in THF (10 ml ).The gel (CH2Cl2 as eluent) to give 14 as a brown powder. mixture was stirred for 30 min and diluted with CH2Cl2 5-[4-Ethenylsulfanyl-5-(2-methacryloyloxyethylsulfanyl)- (50 ml ), washed with water and dried (MgSO4). The solvent 1,3-dithiol-2-ylidene]-1-(4-nitrophenyl)penta-1,3-diene 14.Yield was evaporated and the solid product was recrystallized from 84%; 1H NMR (CDCl3) 8.17 (d, 2H), 7.49 (d, 2H), 6.99 (dd, methanol. 1H, 3J=9.9, 15.5 Hz), 6.54 (d, 1H, 3J=15.5 Hz), 6.36 (dd, 1H, 3J=9.4, 16.4 Hz), 6.20 (m, 4H), 5.62 (1H), 5.45 (2H), 4.37 (t, 5-(4,5-Dimethyl-1,3-dithiol-2-ylidene)-1-(2-thienyl )penta- 2H), 3.09 (m, 2H), 1.96 (s, 3H); m/z (EI) (%) 491 (M+, 14), 1,3-diene 11.Yield 81%, yellow powder; 1H NMR (CDCl3) 184 (19), 113 (100), 69 (67); nmax(KBr)/cm-1 1720 (CO), 1530, (chemical shifts of diVerent protons were assigned via a COSY 1335 (NO2). 45 1H,1H experiment) 7.12 (d, 1H, 3J=4.9 Hz), 6.94 (d, 1H, 3J=3.7 Hz), 6.91 (dd, 1H), 6.62 (m, 2H), 6.10 (m, 3H), 1.94 (s, Synthesis of 16a 3H), 1.91 (s, 3H); 13C NMR (CDCl3) 143.5, 136.2, 130.0, 129.5, 127.6, 127.0, 125.0, 123.7, 123.1, 121.7, 121.6, 111.9, 13.6, 13.25; To a solution of 1511 (10 mmol) and pyridine (3.2 ml, 40 mmol) in THF (20 ml ) was added dropwise benzoyl chloride m/z (EI) (%) 278 (M+, 100), 191 (20), 160 (26), 147 (48), 131 (42), 115 (33).(40 mmol) in dry THF (10 mL) at room temperature. After 1190 J.Mater. Chem., 1998, 8(5), 1185–1192stirring for 3 h, the THF was evaporated. The residue was 4,5-Bis(2-benzoyloxyethylsulfanyl)-1,3-dithiolium hexa- fluorophosphate 19a. Yield 67%, pinkish powder, mp 148 °C; dissolved in CH2Cl2, washed with water and dried over MgSO4. After removing the solvent, 16 was purified by chrom- 1H NMR (CDCl3) 8.20 (dd, 4H), 7.43 (m, 6H), 6.38 (s, 1H), 4.49 (t, 4H), 3.16 (t, 4H).atography over silica gel ( light petroleum–CH2Cl2 152 as eluent) and obtained as a yellow powder. 4-(2-Benzoyloxyethylsulfanyl)-5-methylsulfanyl-1,3- dithiolium hexafluorophosphate 19b. Yield 66%, violet powder, 4,5-Bis(2-benzoyloxyethylsulfanyl)-2-thioxo-1,3-dithiole 16a. mp 110 °C; m/z (DAB) (%) 329 (100, M-PF6). Yield 87%, mp 82–85 °C; 1H NMR (CDCl3) 8.10 (dd, 4H), 7.52 (m, 6H), 4.50 (t, 4H), 3.20 (t, 4H); m/z (EI) (%) 494 (M+, Synthesis of 20a,b 25), 149 (100), 105 (61), 77 (33).To a solution of 19a or 19b (1 mmol) in dry acetonitrile Synthesis of 16b (10 mL) were added successively potassium iodide (1 mmol) and trimethyl phosphite (1 mmol) at room temperature. The Using a similar procedure as for 16a, a solution of thione 15¾ mixture was stirred for 15 min, the solvent was evaporated (10 mmol) and pyridine (20 mmol) was reacted with benzoyl and the residue was immediately dissolved in dry THF (10 ml ).chloride (20 mmol) in dry THF. The phosphonate anion was generated from BunLi (=1.1 equiv., 1.6 M in hexane) at -80 °C. A stoichiometric amount 4-(2-Benzoyloxyethylsulfanyl)-5-methylsulfanyl-2-thioxoof fumaraldehyde mono(dimethyl acetal) in dry THF was then 1,3-dithiole 16b.Yield 78%, mp <50 °C; 1H NMR (CDCl3) added dropwise and the reaction was allowed to warm to 8.10 (dd, 2H), 7.50 (m, 3H), 4.57 (t, 2H), 3.23 (t, 2H), 2.43 (s, room temperature. THF was removed in vacuo, the residue 3H); m/z (EI) (%) 360 (M+, 40), 149 (100), 105 (65), 77 (35). was dissolved in CH2Cl2 and washed with water. The obtained acetal was hydrolyzed with Amberlyst-15 (0.4 g) in wet acetone. Synthesis of 17a,b The course of the reaction was monitored by TLC.After removing the solvent, the residue was purified by chromatogra- Methyl trifluoromethanesulfonate (15.3 mmol) was added phy over silica gel (CH2Cl2 as eluent) and 20a or 20b was dropwise to a solution of 16a,b (8.5 mmol) in dry CH2Cl2 obtained as a yellow oil.(30 ml ). The solution was stirred at room temperature for 4 h. After addition of diethyl ether (200 ml), a yellow precipitate 4-[4,5-Bis(2-benzoyloxyethylsulfanyl)-1,3-dithiol-2- was formed, filtered and rinsed with diethyl ether. ylidene]but-2-enal 20a. Yield 78%; 1H NMR (CDCl3) 9.49 (d, 1H, 3J=8 Hz), 8.02 (dd, 4H), 7.54, 7.41 (m, 6H), 6.87 (dd, 1H, 2-Methylsulfanyl-4,5-bis(2-benzoyloxyethylsulfanyl)-1,3- 3J=11.5, 14.5 Hz), 6.21 (d, 1H, 3J=11.5 Hz), 5.91 (dd, 1H, dithiolium trifluoromethanesulfonate 17a.Yield 96%, mp 3J=8.0, 14.5 Hz), 4.52 (t, 2H), 4.51 (t, 2H), 3.19 (t, 4H); 13C 102–103 °C; 1H NMR (CDCl3) 8.06 (dd, 4H), 7.46 (m, 6H), NMR (CDCl3) 192.9, 161.1, 148.6, 145.7, 133.3, 129.7, 128.4, 4.63 (t, 4H), 3.53 (t, 4H), 3.10 (s, 3H). 128.2, 126.6, 111.7, 63.4, 34.7; m/z (EI) (%) 530 (M+, 11), 149 (100), 105 (66), 77 (33); nmax(KBr)/cm-1 1718 (CO), 1667 (CO). 2,5-Dimethylsulfanyl-4-(2-benzoyloxyethylsulfanyl )-1,3- dithiolium trifluoromethanesulfonate 17b. Yield 94%, mp 4-[4-(2-Benzoyloxyethylsulfanyl)-5-methylsulfanyl-1,3- 92–93 °C; 1H NMR (CDCl3) 8.10 (dd, 2H), 7.50 (m, 3H), 4.60 dithiol-2-ylidene]but-2-enal 20b.Yield 65%; 1H NMR (CDCl3) (t, 2H), 3.50 (t, 2H), 3.16 (s, 3H), 2.76 (s, 3H). 9.50, 9.47 (2d, 1H, Z+E isomers), 8.02 (dd, 2H), 7.45 (m, 3H), 6.95 (m, 1H, 3J=11.5, 14.5 Hz), 6.25 (m, 1H, 3J=11.5 Hz), 5.93 Synthesis of 18a,b (m, 1H, 3J=8.0, 14.5 Hz), 4.55 (t, 2H), 3.20 (t, 2H), 2.42, 2.40 (2s, 3H); m/z (EI) (%) 396 (M+, 25), 149 (100), 105 (54), 77 (30).Compound 17a or 17b (8 mmol), dissolved in a minimal amount of acetonitrile, was added dropwise to a suspension Synthesis of 21 of sodium borohydride (8.8 mmol) in isopropyl alcohol (4 ml) cooled at 0 °C, the temperature of the reaction mixture being Using a similar procedure as for 4a–c, aldehyde 20a was maintained below 5 °C. The mixture was then stirred at room reacted with 4-nitrobenzyl(triphenyl)phosphonium bromide as temperature for h, extracted with diethyl ether, washed with the Wittig reagent.water and dried (MgSO4). The solvents were evaporated and the resulting pinkish oil was used without further purification 5-[4,5-Bis(2-benzoyloxyethylsulfanyl)-1,3-dithiol-2-ylidene]- for the next step. 1-(4-nitrophenyl )penta-1,3-diene 21. Yield 65%, brown powder, mp 95–99 °C; 1H NMR (CDCl3) 8.16 (d, 2H, 3J=8.9 Hz), 8.05 2-Methylsulfanyl-4,5-bis(2-benzoyloxyethylsulfanyl)-1,3- (m, 4H), 7.49 (m, 8H), 6.98 (dd, 1H, 3J=10.1, 15.5 Hz), 6.54 dithiole 18a.Yield 94%; 1H NMR (CDCl3) 8.10 (dd, 4H) 7.55 (d, 1H, 3J=15.5 Hz), 6.17 (m, 3H), 4.51 (t, 4H), 3.18 (t, 4H); (m, 6H), 5.83 (s, 1H), 4.53 (t, 4H), 3.20 (t, 4H), 2.30 (s, 3H). 13C NMR (CDCl3) 166.2, 146.2, 144.1, 135.6, 133.7, 133.2, 131.7, 129.6, 128.8, 128.6, 128.4, 126.4, 124.2, 114.8, 63.5, 34.4 2,5-Dimethylsulfanyl-4-(2-benzoyloxyethylsulfanyl )-1,3- (Calc.for C32H27NO6S4: C, 59.15; H, 4.19; N, 2.15; O, 14.77; dithiole 18b. Quantitative yield; the crude product was immedi- S, 19.73. Found: C, 59.02; H, 4.39; N, 2.26; O, 15.20; S, 19.87%); ately used in the subsequent step (synthesis of 19b) without m/z (EI) (%) 649 (M+, 11), 149 (100), 105 (93), 77 (47); further characterization.nmax(KBr)/cm-1 1731, 1719 (CO), 1537, 1333 (NO2). Synthesis of 22 Synthesis of 19a,b Hexafluorophosphoric acid solution (1.97 g, 8 mmol, 60%) was A solution of 21 (1.2 mmol) and KOH (12 mmol) in a mixture of THF (10 ml ), MeOH (5 ml) and H2O (1 ml ) was refluxed added dropwise at 0 °C to a solution of 18a or 18b in acetic anhydride (10 ml ).The mixture was stirred for 10 min and for 1 h. The solution was diluted in CH2Cl2, washed with water and dried (MgSO4). The solvent was evaporated and ethyl acetate (20 ml ) was added. Stirring was maintained for 15 min before adding diethyl ether (100 ml). The resulting the residue was chromatographed over silica gel (ethyl acetate–CH2Cl2 151 as eluent).Compound 22 was obtained precipitate was filtered and washed twice with anhydrous diethyl ether . as a black powder. J. Mater. Chem., 1998, 8(5), 1185–1192 11912 For a review about tetrathiafulvalene chemistry: J. Garin, Adv. 5-[4,5-Bis(2-hydroxyethylsulfanyl)-1,3-dithiol-2-ylidene]-1- Heterocyclo Chem., 1995, 62, 249.(4-nitrophenyl )penta-1,3-diene 22. Yield 79%, mp 137–141 °C; 3 See for instance: (a) H. E. Katz, K. D. Singer, J. E. Sohn, C. W. 1H NMR (CDCl3) 8.17 (d, 2H), 7.49 (d, 2H) 6.98 (d, 1H, 3J= Dirk, L. A. King and H. M. Gordon, J. Am. Chem. Soc., 1987, 109, 8.0, 15.5 Hz), 6.55 (d, 1H, 3J=15.5 Hz), 6.25 (m, 3H), 3.78 (t, 6561; b) M. Blanchard-Desce, I. Ledoux, J. M. Lehn, J.Malthe�te 4H), 3.00 (t, 4H), 2.81 (s, 2H); 13C NMR (CDCl3) 146.3, 144.0, and J. Zyss, J. Chem. Soc., Chem. Commun., 1988, 737; (c) M. Barzoukas, M. Blanchard, D. Josse, J. M. Lehn and J. Zyss, Chem. 135.2, 133.6, 131.5, 129.1, 128.9, 127.7, 126.4, 124.2 115.2, 59.9, Phys., 1989, 133, 323; (d) M. Blanchard-Desce, J. M. Lehn, 39.2 (Calc. for C18H19NO4S4: C, 48.96; H, 4.33; N, 3.17; O, M.Barzoukas, I. Ledoux and J. Zyss, Chem. Phys., 1994, 181, 281; 14.49; S, 29.04. Found: C, 48.44; H, 4.22; N, 3.29; O, 14.95; S, (e) A. K. Y. Jen, V. P. Rao, K. J. Drost, K. Y. Wong and M. P. 29.36%); m/z (EI) (%) 441 (M+, 100), 184 (75), 121 (35); Cava, J. Chem. Soc., Chem. Commun., 1994, 2057; ( f ) D. Lorcy, nmax(Fluorolube)/cm-1 3319 (OH), 1566, 1333 (NO2). A. Robert, S.Triki, L. Ouahab and P. Robin, T etrahedron L ett., 1994, 33, 7341. 4 T. T. Nguyen, Y. Gouriou, M. Salle�, P. Fre` re, M. Jubault, A. Synthesis of 23 Gorgues, L. Toupet and A. Riou, Bull. Soc. Chim. Fr., 1996, 133, Using a similar procedure as for 14, diol 22 was reacted with 301. methacryloyl chloride. Diester 23 was obtained as black 5 Crystal data for compound 8a: C15H18O2S2, M=294.43, triclinic, P19, Z=2, a=8.395(3), b=9.830(4), c=10.909(4) A ° , a=114.09(2), crystals.b=99.99(3), c=96.42(3), V=792.5(6) A ° 3, l=0.71073 A ° . Data collection was carried out by the zig-zag v/2h scan technique 5-[4,5-Bis(2-methacryloyloxyethylsulfanyl)-1,3-dithiol-2- (2<h<25°) on an Enraf–Nonius CAD4 diVractometer. ylidene]-1-(4-nitrophenyl)penta-1,3-diene 23.Yield 58%, mp Conditions of measurements were tmax=40 s, range h, k, l [h (0, 76–79 °C; 1H NMR (CDCl3) 8.17 (d, 2H), 7.48 (d, 2H), 6.98 10); k (-12, 12); l (-13, 13)]. Intensity control reflections were (dd, 1H, 3J=9.9 Hz), 5.48 (m, 2H), 5.61 (s, 1H), 4.35 (q, 4H), measured every 2 h without appreciable decay (0.15%). A total of 3098 independent reflections were collected from which 1153 3.10 (q, 4H), 1.96 (s, 6H); 13C NMR (CDCl3) 170, 146.2, 144.1, corresponded to I>3s(I).Structure refinement: after Lorentz 135.8, 135.6, 133.7, 131.7, 128.8, 128.6, 127.6, 126.6, 126.2, 124.2, polarisation corrections, the structure was solved by direct 114.8, 63.2, 34.3, 18.3; m/z (EI) (%) 577 (M+, 7), 184 (8), 113 methods using the general tangent phasing procedure (GENTAN), (100), 69 (29); nmax(KBr)/cm-1 1711 (CO), 1528, 1330 (.which revealed all the non-hydrogen atoms. After anisotropic refinement of S, O and C atoms, the coordinates of the H atoms Synthesis of 24 were generated from the molecular geometry. The whole structure was refined by full-matrix least-squares techniques (refinement on Using a similar procedure as for 5a,b, aldehyde 20b (1 mmol) F, x, y, z, Uij for S, O and C atoms, x, y, z, and U fixed for H was reacted with dimethyl (5-nitro-2-thienyl )methylphosphon- atoms). 172 variables for 1153 observations, with the resulting R= 0.073, Rw=0.078. All the calculations were performed using the ate (1.1 mmol) as the Wittig–Horner reagent in the presence XTAL 3.2 package. of BunLi (=1.1 equiv., 1.6 M in hexane). 6 (a) D. N. Beratan, ACS Symp. Ser., 1991, 455, 89; (b) S. R. Marder, C. B. Gorman, L. T. Cheng and B. G. Tiemann, Proc. SPIE, 1993, 5-[4-(2-Benzoyloxyethylsulfanyl)-5-methylsulfanyl-1,3- 1775, 19. dithiol-2-ylidene]-1-(5-nitro-2-thienyl )penta-1,3-diene 24. Yield 7 S. R. Marder, C. B. Gorman, B. G. Tiemann and L. Cheng, J. Am. 51%, black powder; m/z (EI) (%) 521 (M+, 20), 489 (10), 149 Chem. Soc., 1993, 115, 3006. 8 Crystal data for compound 12: C20H14S3N4, M=406.55, mono- (100), 105 (76), 77 (47). clinic, P21/c, Z=4, a=10.856(2), b=12.447(3), c=14.995(13) A ° , b=99.69(3)°, V=1997(2) A ° 3, l=0.71073 A ° . Data collection was Synthesis of 25 carried out by the zig-zag v/2h scan technique (2<h<30°) on an Enraf–Nonius Mach III diVractometer. Conditions of measure- Using a similar procedure as for 22, ester 24 (1.2 mmol) was ments were tmax=40 s, range h, k, l [h (0, 15); k (0, 17); l (-21, 21)].hydrolyzed to alcohol 25. Intensity controls without appreciable decay (0.2%) gave 3801 reflections from which 2069 were independent with I>3s(I). 5-[4-(2-Hydroxyethylsulfanyl)-5-methylsulfanyl-1,3-dithiol- Structure refinement: after Lorentz and polarisation corrections, 2-ylidene]-1-(5-nitro-2-thienyl )penta-1,3-diene 25.Yield 60%, the structure was solved by direct methods (SIR) which revealed all the non-hydrogen atoms. After anisotropic refinement of all the dark violet powder; 1H NMR (CDCl3) 7.79 (d, 1H, 3J=4.2 Hz), non-hydrogen atoms, the coordinates of the H atoms were deter- 6.85 (d, 1H, 3J=4.2 Hz), 6.83 (dd, 1H, 3J=10.6, 15.1 Hz), 6.53 mined from the HYDRO program.The whole structure was (d 1H, 3J=15.1 Hz), 6.28 (m, 1H), 6.15 (m, 2H), 3.74 (m, 2H), refined by full-matrix least-squares techniques (use of F magnitude; 2.96, 2.94 (2t, 2H), 2.48, 2.45 (2s, 3H), 2.37 (t, 1H); 13C NMR Uij for C, S and N atoms, x, y, z and B fixed for H); 244 variables (CDCl3) 151.1, 137.5, 134.4, 132.6, 129.9, 127.4, 124.1, 122.2, for 2069 observations, weighting v=1/s(F0)2=[s2(I)+(0.04 114.5, 59.9, 39.0, 19.0, 18.9; m/z (EI) (%) 417 (M+, 100), 385 F02)2]-1/2 with the resulting R=0.048, Rw=0.062.All the calculations were performed using the MOLEN package. Full (38), 249 (40), 204 (45), 190 (60), 147 (67), 135 (62), 103 (68); Crystallographic details, excluding structure factors, have been nmax(KBr)/cm-1 3419 (OH), 1525, 1320 (NO2). deposited at the Cambridge Crystallographic Data Centre (CCDC). See Information for Authors, J.Mater. Chem., 1998, Issue The authors thank S. Brasselet for her kind help in EFISH 1. Any request to the CCDC for this material should quote the full data processing, as well as Professor J. P. Busnel for polymer literature citation and the reference number 1145/91. characterization. This work was partially supported by the 9 J. L. Oudar, J. Chem. Phys., 1977, 67, 446. 10 For methacrylate NLO active polymers, see for instance: (a) C. Xu, grant ‘Marche� d’e�tudes’ CNET No. 926B040. Financial support B. Wu, O. Todorova and L. R. Dalton, Macromolecules, 1993, 26, from DGICYT (PB94–0577) is gratefully aknowledged. 5303; (b) J. Y. Lee and H. J. Lee, Polym. Bull., 1997, 38, 265; (c) D. W. Kim, S. Hong, S. Y. Park and N. Kim, Bull. Korean Chem. Soc., 1997, 18, 198. References 11 (a) V. Y. Khodorkovsky, J. Y. Becker and J. Y. Bernstein, Synthesis, 1992, 1071; (b) J. S. Zambounis and C. W. Mayer, T etrahedron 1 (a) Nonlinear Optical Properties of Organic Molecules and Crystals, L ett., 1991, 32, 2737. ed. D. S. Chemla and J. Zyss, Academic Press, Orlando, 1987; (b) 12 (a) T. K. Hansen, T. Jorgensen, F. Jensen, P. H. Thygesen, Molecular Nonlinear Optics : Materials, Physics and Devices, ed. K. Christiansen, M. B. Hursthouse, M. E Harman, M. A. Malik, J. Zyss, Academic Press, Boston, 1994; (c) Nonlinear Optics of B. Girmay, A. E. Underhill, M. Begtrup, J. D. Kilburn, K. Belmore, Organic Molecules and Polymers, ed. H. S. Nalwa and S. Miyata, P. RoepstorV and J. Becher, J. Org. Chem., 1993, 58, 1359; (b) CRC Press, 1994; (d) Introduction to Nonlinear Optical EVects in A. J. Moore and M. R. Bryce, J. Chem. Soc., Chem. Commun., Molecules and Polymers, ed. N. Prasad and D. J. Williams, Wiley, 1991, 1639. New York, 1991; (e) L. R. Dalton, A. W. Harper, R. Ghosn, W. H. Steier, M. Ziari, H. Fetterman, Y. Shi, R. V. Mustacich, K. Y. Jen and K. J. Shea, Chem.Mater., 1995, 7, 1060. Paper 7/09055B; Received 17th December, 1997 1192 J. Mater. Chem., 1998, 8(5), 1185–