2078
Langmuir 2000, 16, 2078-2082
Fibrous Assemblies Made of Amphiphilic Metallophthalocyanines Mutsumi Kimura,*,† Tsuyoshi Muto,† Hideaki Takimoto,† Kazumi Wada,† Kazuchika Ohta,† Kenji Hanabusa,† Hirofusa Shirai,† and Nagao Kobayashi‡ Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan Received June 22, 1999. In Final Form: September 17, 1999 A family of copper and zinc phthalocyanine-based amphiphililes possessing racemic and optically active diol units, (rac)-ZnPc(OH)16, (rac)-CuPc(OH)16, and (S)-CuPc(OH)16, have been synthesized. The selfassembling properties of these amphiphiles in aqueous solution have been studied by UV-vis, Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopies, X-ray diffraction (XRD) patterns, and transmission electron microscopy (TEM). Only the copper complexes produced fibrous assemblies from aqueous solutions through two noncovalent bondings: π-π interaction among phthalocyanine rings and hydrogen bonds among diol units. The formation of fibrous assemblies strongly depends on the central metal of the phthalocyanine complex. The optically active (S)-CuPc(OH)16 is stacked and arranged in a left-handed helix. The chirality of diol units in (S)-CuPc(OH)16 also affects the intercolumnar lattice of phthalocyanine stacks.
Introduction In recent years, much attention has been drawn to the construction of supramolecular assemblies having welldefined nanoscale dimensions.1,2 The design of building components results in the spontaneous generation of the controlled molecular assemblies through intermolecular noncovalent interactions. Porphyrins, phthalocyanines, and their metal complexes are attractive building blocks for the formation of supramolcular assemblies since their ordered assemblies display an extensive range of properties.3-10 The cofacially stacked arrays of their π-conjugated systems may enable the efficient transport of electrons and energy. In this context, the structural modifications of these macrocycles for the ordered stacks have been investigated. Fuhrhop and co-workers succeeded in constructing of micellar fibers through the spontaneous organization of the amphiphilic unsymmetrical porphyrins with chiral carbohydrate groups in aqueous media.11-14 † ‡
Shinshu University. Tohoku University.
(1) Vo¨gtle, F. Supramolecular Chemistry; Wiley: Chichester, 1991. (2) Lehn, J.-M. Supramolecular Chemistry: Concepts and Perspectives; VCH: Weinheim, 1995. (3) Schenning, A. P. H. J.; Benneker, F. B. G.; Geurts, H. P. M.; Liu, X. Y.; Nolte, R. J. M. J. Am. Chem. Soc. 1996, 118, 8549-8552. (4) van Nostrum, C. F.; Picken, S. J.; Schouten, A.-J.; Nolte, R. J. M. J. Am. Chem. Soc. 1995, 117, 9957-9965. (5) van Nostrum, C. F.; Nolte, R. J. M. Chem. Commun. 1996, 23852392. (6) Feiters, M. C.; Fyfe, M. C. T.; Martı´nez, M.-V.; Menzer, S.; Nolte, R. J. M.; Stoddart, J. F.; van Kan, P. J. M.; Williams, D. J. J. Am. Chem. Soc. 1997, 119, 8119-8120. (7) Blower, M. A.; Bryce, M. R.; Devonport, W. Adv. Mater. 1996, 8, 63-65. (8) Drain, C. M.; Nifiatis, F.; Vesenko, A.; Batteas, J. D. Angew. Chem., Int. Ed. Engl. 1998, 37, 2344-2346. (9) Arimori, S.; Takeuchi, M.; Shinkai, S.; Supramolec. Sci. 1998, 5, 1-8. (10) Takeuchi, M.; Imada, T.; Shinkai, S. Angew. Chem., Int. Ed. Engl. 1998, 37, 7, 2096-2099. (11) Fuhrhop, J.-H. Comprehensive Supramolecular Chemistry; Atwood, J. L., Davise, J. E. D., Macnicol, D. D., Vo¨gtle, F., Lehn, J.-M., Sauvage, J.-P., Hosseini, M. W., Eds.; Pergamon: Oxford, U.K., 1996, pp 408-448; Vol. 9. (12) Fuhrhop, J.-H.; Demoulin, C.; Boettcher, C.; Ko¨ning, J.; Siggel, U. J. Am. Chem. Soc. 1992, 114, 4159-4165.
The rigid and hydrophobic porphyrin moiety acted as a skeleton for the fiber formation. In this paper, we describe the synthesis and self-organizing properties of novel amphiphilic metallophthalocyanines decorated with eight peripheral diol units. The alkane-1,2-diols can form lyotropic liquid crystalline phases, which consist of lamellar layers stabilized by hydrogen bonding among hydroxyl groups.15-19 The hydrogen bonds have been utilized as an organizing force for building blocks to construct supramolecular structures.20 We considered that the introduction of diol units into the phthalocyanine core provides new opportunities for the construction of highly ordered supramolecular organizations. Experimental Section Materials and Apparatus. All chemicals were purchased from commercial suppliers and used without purification. The optically active (S)-2,2-dimethyl-1,3-dioxolane-4-ylmethanol was purchased from Tokyo Kasei Organic Chemicals. 4,5-Dibromocatechol and optically active (S)-2,2-dimethyl-1,3-dioxolan4-ylmethyl p-toluenesulfonate were prepared according to literature methods.4 Column chromatography was performed with Wakogel C-200 (silica gel). NMR spectra were recorded on JEM LA400 FT-NMR spectrometer operating at 399.65 MHz for 1H in CDCl3 solution. Chemical shifts were relative to internal TMS. Elemental analyses were performed with a Perkin-Elmer series II CHNS/O analyzer 2400. MALDI-TOF mass spectra were obtained on a PerSeptive Biosystems Voyager DE-Pro spectrometer with 2-(4-hydroxyphenylazo) benzoic acid as matrix. (13) Fuhrhop, J.-H.; Bindig, U.; Siggel, U. J. Am. Chem. Soc. 1993, 115, 11036-11037. (14) Bindig, U.; Schulz, A.; Fuhrhop, J.-H. New J. Chem. 1995, 19, 427-435. (15) Jefferey, G. A. Mol. Cryst. Liq. Cryst. 1984, 110, 221-237. (16) Baeyens-Volant, D.; Fornasier, R.; Szalaı´, David, C. Mol. Cryst. Liq. Cryst. 1986, 135, 93-110. (17) Tschierske, C.; Zaschke, H. J. Chem. Soc., Chem. Commun. 1990, 1013-1014. (18) Qian, P.; Nanjo, H.; Yokoyama, T.; Suzuki, T. M. Chem. Lett. 1998, 1133-1134. (19) Ko¨lbel, M.; Beyersdorff, T.; Sletvold, I.; Tschierske, C.; Kain, J.; Diele, S. Angew. Chem., Int. Ed. Engl. 1999, 38, 1077-1080. (20) Shimizu, T.; Kogiso, K.; Masuda, M. J. Am. Chem. Soc. 1997, 117, 6209-6210 and references therein.
10.1021/la990801j CCC: $19.00 © 2000 American Chemical Society Published on Web 02/05/2000
Amphiphilic Metallophthalocyanine Fibrous Assemblies
Langmuir, Vol. 16, No. 5, 2000 2079
Scheme 1. (i) K2CO3, Acetonitrile, Reflux, 48 hr; (ii) CuCN, Dry DMF, 140 °C, 24 hr; (iii) CuCl2, (Dimethylamino)ethanol, NH3, 72 hr; (iv) HCl, 1,4-dioxane
Figure 1. Absorption spectra of (rac)-CuPc(OH)16 in DMSO and DMSO-water of ratios 1:9, 4:6, 7:3, 8:2, and 9:1. The inset shows the absorbance changes of Q-bands of (rac)-CuPc(OH)16 (b), (rac)-ZnPc(OH)16 (2), and (S)-CuPc(OH)16 (9). [Complex] ) 10.0 µM.
Differential scanning calorimetry and thermogravimetric analysis/ differential thermal analyses were carried out with a SEIKO DSC 220 and TG/DTA 220, respectively. FTIR spectra were carried out with a JASCO FS-420 spectrometer. UV-Vis spectra were measured on a JASCO V-570 spectrophotometer. CD spectra were recorded on a JASCO J-600 spectropolarimeter at 298 K. XRD patterns were measured with Cu KR radiation using a Rigaku Geigerflex. Electron Microscopy. Droplets of the aqueous solution (DMSO-water ) 1:15) containing (rac)-ZnPc(OH)16, (rac)-CuPc(OH)16, and (S)-CuPc(OH)16 (1.0 mM) were placed onto carboncoated copper grids (400 mesh). The solvent was evaporated in vacuo for 1 h. The grids were observed in a JEOL JEM-2010 electron microscope at an acceleration voltage of 200 kV.
Results and Discussion The amphiphilic metallophthalocyanines were prepared from 4,5-dibromocatechol and 2,2-dimethyl-1,3-dioxolan4-ylmethyl p-toluenesulfonate (Scheme 1). Refluxing 3 in (dimethylamino)ethanol with metal salts under an ammonia atmosphere provided the protected zinc and copper complexes. These complexes were mixtures of stereoisomers. We prepared the optically active complex (S)-CuPc(OH)16 from the optically pure starting material to
investigate the influence of optical purity on the selfassembly processes. Only protected complexes could be purified by chromatography on silica gel, and the complexes were fully characterized by elemental analysis, spectroscopy (1H NMR, UV-Vis, IR), and MALDI-TOFmass spectra. Deprotection with HCl gave the amphiphilic metallophthalocyanines (rac)-ZnPc(OH)16, (rac)-CuPc(OH)16, and (S)-CuPc(OH)16 containing eight diol units. These compounds were characterized by mass spectra and IR spectra. Figure 1 shows the absorption spectra of (rac)-CuPc(OH)16 in dimethyl sulfoxide (DMSO) and mixtures of water and DMSO. The UV-vis spectrum of (rac)-CuPc(OH)16 in DMSO shows a strong sharp Q-band at 676 nm, typical of nonaggregated phthalocyanine.21 When water was admixed, the spectrum changed, as shown by the arrows, and finally the spectra shown by dotted lines were recorded. The Soret and Q-bands in the absorption spectra were broadened, and the maximum was blue shifted by increasing the water content. This spectral change can be ascribed to the formation of aggregated phthalocyanine species having a cofacial arrangement.22-26 The hydrophobic phthalocyanine moieties come closer with an increase in solvent polarity, and form a cofacial stack in aqueous solution. The inset of Figure 1 displays the absorbance change of the Q-band for (rac)-CuPc(OH)16, (rac)-ZnPc(OH)16, and (S)-CuPc(OH)16 in various water contents. The absorbance at the Q-band of (rac)-CuPc(OH)16 decreased steeply with increasing water content and reached a constant value in mixed solvents containing above 40 vol % water. In contrast, the absorbance of (rac)ZnPc(OH)16 gradually decreased. This difference in the aggregation behavior reflected the attracting force be(21) Stillman, M. J.; Nyokong, T. Phthalocyanines Properties and Applications; Leznoff, C. C., Lever, A. B. P., Eds., VCH: New York, 1989, Vol. 1, pp 135-247. (22) Kobayashi, N.; Lam, H.; Nevin, W. A.; Janda, P.; Leznoff, C. C.; Koyama, T.; Monden, A.; Shirai, H. J. Am. Chem. Soc. 1994, 116, 879890. (23) Kobayashi, N.; Ojima, F.; Osa, T.; Vigh, S.; Leznoff, C. C. Bull. Chem. Soc. Jpn. 1989, 62, 3469-3474. (24) Kobayashi, N.; Nishimura, Y. J. Chem. Soc., Chem. Commun. 1986, 1462-1463. (25) Sielcken, O. E.; van Tilborg, M. M.; Roks, M. F. M.; Hendriks, R.; Drenth, W.; Nolte, R. J. M. J. Am. Chem. Soc. 1987, 109, 42614265. (26) Koray, A. R.; Ahsen, V.; Bekaˆroglu, O ¨ . J. Chem. Soc., Chem. Commun. 1986, 932-933.
2080
Langmuir, Vol. 16, No. 5, 2000
Kimura et al.
Figure 2. Dependence of viscosity on concentration in DMSOwater ) 1:15 at 25 °C: (b); (rac)-CuPc(OH)16, (9); (rac)-ZnPc(OH)16.
tween metallophthalocyanines having different central metals. The attracting force between copper phthalocyanines was stronger than that of zinc complexes. It is noteworthy that a marked rise in viscosity was observed by adding (rac)-CuPc(OH)16 to an aqueous solution at very low concentrations. The specific viscosity (ηsp) in aqueous solutions was determined for various concentrations of (rac)-CuPc(OH)16 and (rac)-ZnPc(OH)16 using an Ubbelohde viscosimeter at 25 °C (see Figure 2). The viscosity of the aqueous solution was strongly dependent on the concentration of (rac)-CuPc(OH)16; on the contrary, the rise in viscosity was not observed in (rac)-ZnPc(OH)16. Hence, the remarkable rise of viscosity in the aqueous solution suggests the formation of macromolecule-like aggregates.27 Physical gelations by these complexes were not observed under this experimental condition.28-30 Viscosity differences also indicate the difference of aggregation behavior between copper and zinc complexes. Despite the similar behavior of the absorbance changes shown in Figure 1, the optically active (S)-CuPc(OH)16 had somewhat higher solubility in the aqueous solution, and lower viscosity than the racemic mixture (rac)-CuPc(OH)16. A slow evaporation of the viscous solution of (rac)-CuPc(OH)16 gave a green film on a glass plate. The (rac)-CuPc(OH)16 film contains a small amount of water according to DSC and DTA measurements. The X-ray diffraction patterns of this green film were characterized by four sharp reflections of 1.94, 1.15, 0.98, and 0.75 nm (Figure 3). This diffraction pattern could be due to the reflections from a two-dimensional hexagonal lattice with a lattice constant a ) 2.27 nm (Table 1). In addition, there was a peak at 0.38 nm due to the stacking distance between the phthalocyanine moiety within the column. Phthalocyanine macrocycles substituted with flexible hydrocarbon chains form a discotic liquid crystalline in which the columns are ordered in a two-dimensional hexagonal lattice.31-34 In such mesophases, the π-π interaction among phthalocyanine moieties as well as van der Waals interactions (27) Sibesma, R. P.; Beijer, F. H.; Brunsveld, L.; Folmer, B. J. B.; Hirschberg, J. H. K.; Lange, R. F. M.; Lowe, J. K. L.; Meijer, E. W. Science 1997, 278, 1601-1604. (28) Hanabusa, K.; Yamada, M.; Kimura, M.; Shirai, H. Angew. Chem., Int. Ed. Engl. 1996, 17, 1949-1950. (29) Hanabusa, K.; Koto, C.; Kimura, M.; Shirai, H.; Kakehi, A. Chem. Lett. 1997, 429-430, and references therein. (30) de Loos, M.; van Esch, J.; Stokroos, I.; Kellogg, R. M.; Feringa, B. L. J. Am. Chem. Soc. 1997, 119, 12675-12676. (31) Cook, M. J.; Daniel, M. F.; Harrison, K. J.; Mckeown, N. B.; Thomson, A. J. J. Chem. Soc., Chem. Commun. 1987, 1086-1088. (32) Blanzat, B.; Barthou, C.; Tercier, N.; Andre´, J.-J.; Simon, J. J. Am. Chem. Soc. 1987, 109, 6193-6194. (33) Markovitsi, D.; Tran-Thi, T.-H.; Briois, V. J. Am. Chem. Soc. 1988, 110, 2001-2002. (34) Ohta, K.; Watanabe, T.; Fujimoto, T.; Yamamoto, I.; J. Chem. Soc., Chem. Commun. 1989, 1611-1612.
Figure 3. Diffraction pattern of X-ray reflected from a glass surface coated with (rac)-CuPc(OH)16.
Figure 4. Circular dichroism spectra of (S)-CuPc(OH)16 in DMSO (a) and DMSO-water ) 1:15 (b). Table 1. X-ray Diffraction Data of (rac)-CuPc(OH)16 at Room Temperature spacing (nm) dobsd
dcalcd
Miller indices
1.94 1.15 0.98 0.75
1.96 1.14 0.98 0.74
(100) (110) a ) 2.27 nm (200) h ) 0.38 nm (210)
between the hydrocarbon chains are responsible for the formation of the discotic mesophase. According to the results of visible spectra, the cofacial stack of (rac)-CuPc(OH)16 formed through the hydrophobic interaction in the aqueous solution. The alkane-1,2-diols exhibited liquid crystalline behavior as a result of the formation of polymeric hydrogen networks among diol segments.15-19,35 The FTIR spectrum of the DMSO solution of (rac)-CuPc(OH)16 is characterized by broad bands at 3530 and 3420 cm-1, which are assigned to nonhydrogen and hydrogen bonding stretching vibrations.35 In contrast, the film of (rac)-CuPc(OH)16 on a CaF2 plate only affords one broad band at 3350 cm-1, which is indicative of a polymeric hydrogen bonding stretching vibration. The subsequent aggregation of columns may be induced by the hydrogen bonding among diol segments in (rac)-CuPc(OH)16. By combining the spectroscopic data and X-ray diffraction patterns, we propose that (rac)-CuPc(OH)16 assembles spontaneously to the hexagonal lattice by two noncovalent interactions. (35) Joachimi, D.; Tschierske, C.; Mu¨ller, H.; Heinz, J.; Wendorff, H.; Schneider, L.; Kleppinger, R. Angew. Chem., Int. Ed. Engl. 1993, 32, 1165-1167.
Amphiphilic Metallophthalocyanine Fibrous Assemblies
Langmuir, Vol. 16, No. 5, 2000 2081
Figure 5. Diffraction pattern of X-ray reflected from a glass surface coated with (S)-CuPc(OH)16 and assigned Miller indices (hkl). h1 ) stacking distance between phthalocyanine rings. h2 ) distance between the peripheral side chains.
A chiral structure is expected from the formation of intermolecular hydrogen bonding through hydroxyl groups of optically active (S)-CuPc(OH)16. The CD spectrum provides the structural information on the chiral aggregate. A solution of (S)-CuPc(OH)16 in DMSO was CDinactive. The aqueous solution displayed CD activity as shown in Figure 4. The CD activity in the aqueous solution was caused by the formation of a chiral aggregation. The chiral aggregation of optically active porphyrins, phthalocyanines, and related macrocycles has been investigated.36-41 The optically active (S)-CuPc(OH)16 shows an asymmetric negative band at 631 nm and a positive one at 582 nm. These bands roughly correspond to the split of the Q-band of the UV-vis spectrum, suggesting that the phthalocyanine rings are arranged in a lefthanded helix.42 This result suggests that the formation of the hydrogen bond network through chiral diol units results in the helical arrangement of phthalocyanine rings. The X-ray diffraction pattern of (S)-CuPc(OH)16 film is remarkably different from that of the racemic mixture (Figure 5). This diffraction pattern might be due to the reflections from a discotic lamellar structure.43 The chirality of amphiphilic copper phthalocyanine affected the lattice of the assembly of phthalocyanine stacks. The chiral effect on the aggregation of amphiphilic compounds has been reported as a chiral bilayer effect for Nalkylgluconamides and amphiphilic porphyrins by Fuhrhop et al.11-14,44,45 The chirality of amphiphilic compounds played an important role in the stabilization of micellar fibers. Our results indicate that (i) the chiral (36) Engelkamp, H.; van Nostrum, C. F.; Picken, S. J.; Nolte, R. J. M. Chem. Commun. 1998, 979-980. (37) van Nostrum, C. F.; Bosman, A. W.; Gelinck, G. H.; Schouten, P. G.; Warman, J. M.; Kentgens, A. P. M.; Devillers, M. A. C.; Meijerink, A.; Picken, S. J.; Sohling, U.; Schouten, A.-J.; Nolte, R. J. M. Chem. Eur. J. 1995, 1, 171-182. (38) Kobayashi, N.; Nevin, W. A. Chem. Lett. 1998, 851-852. (39) Kobayashi, N. Chem. Commun. 1998, 487-488. (40) Kobayashi, N.; Kobayashi, Y.; Osa, T. J. Am. Chem. Soc. 1993, 115, 10994-10995. (41) Engelkamp, H.; Middelbeek, S.; Nolte, R. J. M. Science 1999, 284, 785. (42) Harada, N.; Nakanishi, K. Circular Dichroic Spectroscopys Exciton Coupling in Organic Stereochemistry; Oxford University Press: Oxford, U.K., 1983. (43) Ohta, K.; Higashi, R.; Ikejima, M.; Yamamoto, I.; Kobayashi, N. J. Mater. Chem. 1998, 8(9), 1979-1991. (44) Fuhrhop, J.-H.; Svenson, S.; Boettcher, C.; Ro¨ssler, E.; Vieth, H.-M. J. Am. Chem. Soc. 1990, 112, 4307-4312. (45) Fuhrhop, J.-H.; Schnieder, P.; Rosenberg, J.; Boekema, E. J. Am. Chem. Soc. 1987, 109, 3387-3390.
amphiphilic phthalocyanine can form a helical arrangement in the phthalocyanine stack, and (ii) the intercolumnar lattice of the phthalocyanine stacks transferred from the hexagonal lattice to the lamellar structure introducing chiral side chains as substituent groups. In the racemic compound, the hydroxyl groups may randomly interact, and the part of the hydrogen bonding between hydroxyl groups acts as a linkage between the phthalocyanine stacks. As a result of the intercolumnar hydrogen bonding, the phthalocyanine stacks assemble to form the hexagonal lattice. On the other hand, the chirality of the diol unit controls the direction of hydrogen bonding among hydroxyl groups. The regularity of the hydrogen-bonding direction results in the helical arrangement of the phthalocyanine rings. We found the X-ray reflection peak at 0.26 nm for (S)-CuPc(OH)16 as shown in Figure 5. This peak occurrence corresponds to the regular packing of the diol units. Shimizu et al. have reported that the molecular distance between hydrogen bonding hydroxyl oxygens in the crystal structure of 1-glucosamide bolaamphiphiles was ca. 0.28 nm.46,47 The observed reflection peak is almost consistent with this value. The polymeric hydrogen bonding between diol units may be formed within the phthalocyanine stack, contributing to the formation of the helical arrangement. The helical arrangement will induce the distance separating of phthalocyanine stacks, and alter the intercolumnar structure. Nolte et al. reported the helical arrangement of optically active phthalocyanines and proposed three types of helical structures.36,37 The X-ray reflection of the stacking distance was only observed at 0.34 nm, and the CD spectra of (S)-CuPc(OH)16 implied that the dipoles of the phthalocyanine rings were arranged in the form of a left-handed helix. From these observations, we propose the helical structure represented in Scheme 2. However, the X-ray reflection did not provide information on the pitch of the helix in (S)-CuPc(OH)16. Phthalocyanine rings align and rotate along the columnar axis.48 The morphology of the aggregate was examined by TEM. Samples were prepared by casting thin films of (rac)-ZnPc(OH)16, (rac)-CuPc(OH)16, and (S)-CuPc(OH)16 from aqueous solutions onto a carbon-coated grid. Both aggregates (46) Masuda, M.; Shimizu, T. Chem. Commun. 1996, 1057-1058. (47) Shimizu, T.; Masuda, M. J. Am. Chem. Soc. 1997, 119, 28122818. (48) Maltheˆte, J.; Jacques, J.; Tinh, N. H.; Destrade, C. Nature 1982, 298, 46-48.
2082
Langmuir, Vol. 16, No. 5, 2000
Kimura et al.
Scheme 2. Speculated Pathways for the Formation of Fibrous Assemblies
Conclusion
Figure 6. Transmission electron micrographs of fibrous assemblies made of (a) (rac)-CuPc(OH)16 and (b) (S)-CuPc(OH)16 (bar ) 400 nm).
of (rac)-CuPc(OH)16 and (S)-CuPc(OH)16 produced good contrast without staining, and the fibrous aggregates were observed with 10-40 nm widths (Figure 6). (S)-CuPc(OH)16 gave thin fibers compared with (rac)-CuPc(OH)16. However, the solution of (rac)-ZnPc(OH)16 did not produce the TEM image under the same experimental conditions. This difference between copper and zinc complexes agrees with UV-vis and viscosity studies. Judging from the CPK molecular model, the axis of the phthalocyanine molecule is about 2.0 nm. The observed width of fibrous aggregates implies that the fibrous aggregates are made up by the assembly of numerous phthalocyanine stacks. From this TEM image, we may conclude that the amphiphilic copper phthalocyanines self-assemble in an aqueous solution to produce fibrous aggregates.
We have demonstrated that the amphiphilic copper phthalocyanine complex can form fibrous aggregates through a spontaneous self-assembly processes. The aggregate of optically active (S)-CuPc(OH)16 has a unique helical structure. The mechanistic pathways of the assembly processes were postulated as Scheme 2. Large network structures with energy and electron conducting groups as metallophthalocyanine will open new possibilities for the constructions of molecular devices. We summarize our results as follows: (1) The central metal of phthalocyanine is an important factor in the formation of the columnar structure. (2) The racemic mixture of amphiphilic copper phthalocyanine assembles spontaneously to the two-dimensional hexagonal lattice of phthalocyanine stacks. (3) The helical arrangement of phthalocyanine rings occurs in the optically active copper phthalocyanine. (4) The chirality of the side chain affects the intercolumnar structure of phthalocyanine stacks. Acknowledgment. This research was supported by Grant-in-Aid for COE research “Advanced Fiber/Textile Science and Technology” from the Ministry of Education, Science, Sports, and Culture of Japan (#10CE2003). Supporting Information Available: Synthesis and characterization of new compounds. See any current masthead page for Web access instructions. LA990801J
