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Preparation of the Self-Assembled T1 Nanofibril: T1 was synthesized by a solid-phase synthetic method based on Fmoc chemistry. The first amino acid Phe was loaded to Wang resin (substitution, 0.8 mmol g±1) by the preformed symmetrical anhydride method using N,N-dimethylaminopyridine as a catalyst. 2-(1H-Benzotriazol-1-yl)-1,1,3,3-tetramethyl uranium hexafluorophosphate/1hydroxy-benzotrizole (HBTU/HOBT) was employed as the coupling reagent. The peptide product was cleaved from the resin using K reagent (82.5 % TFA, 5 % thioanisole, 2.5 % ethanedithiol, 5 % phenol, and 5 % H2O), purified by RP-HPLC (Gilson Inc., France, zorbax C18 column, 9.4 ” 250 mm), and confirmed by MALDI-TOF mass spectrometry ([M+H]: observed 1562.0/ calc. 1558.7). Incubation of T1 in phosphate buffered saline (PBS) at 37 C for 2 weeks resulted in T1 fibril as confirmed by TEM. The TEM sample was prepared by transferring a colloidal solution of T1 fibril onto a TEM grid coated with a carbon film. After drying, the sample was stained with uranyl acetate. Preparation of Au Colloids: A Au colloidal solution was prepared according to the procedure described by Brown et al. [19]. 0.5 mL of a HAuCl4 solution (2 %) and 2 mL of a Na3citrate solution (38.8 mM) were added to 90 mL of H2O. After about 1 min stirring, 1 mL of freshly prepared NaBH4/Na3citrate aqueous solution (13 mg NaBH4 in 5 mL of a Na3citrate solution (38.8 mM)) was added. A transparent ruby-red colloidal solution formed immediately, which was stirred for a further 30 min and stored at 4 C. The pH value of the prepared Au colloidal solution was about 6. The UV-vis absorption spectrum of the Au sol exhibited a surface plasmon band at 522 nm. Assembly of Au Nanoparticles on T1 Fibril: The preformed Au nanoparticles were attached to the T1 fibril template by a simple procedure. A typical experiment involved adding 5 lL of T1 fibril colloidal solution into 0.5 mL of the Au colloidal solution. After keeping the mixture at 4 C for 24 h, a red precipitate appeared, indicating that Au nanoparticles had been attached onto the T1 fibrils. The precipitate was isolated by centrifuging at 4000 rpm for 30 min and then dispersed in H2O by ultrasonic treatment for several seconds. The obtained suspension was used in the preparation of TEM samples. To investigate the effect of pH on the structure of the Au nanoparticle assembly, the pH value of the obtained mixed colloidal solution was adjusted to pH 3.5, 4.5, 5.4, 6.5, and 9 by adding different amounts of a H3citrate solution (0.1 M) or a NaOH solution (0.1 M). Assembly of Pd Nanoparticles onto T1 Fibril: To assemble Pd nanoparticles, a different strategy was adopted. A saturated aqueous solution of PdCl2 was prepared by adding excessive amount of PdCl2 in ultra-pure water and then treating the mixture in an ultrasonic bath for 10 min. The mixture was centrifuged for 10 min at 4000 rpm to separate undissolved PdCl2. The obtained PdCl2 solution was mixed with the colloidal solution of T1 fibril in a ratio of 1:1 and then a five-fold excess of Na3citrate aqueous solution (0.001 M) was added to the mixture. After standing for several hours, the above mixture was exposed to hydrogen atmosphere for several hours. The color of the solution became yellow at the beginning, and then brown precipitate appeared, indicating that PdII had been reduced by hydrogen and the formed Pd nanoparticles were bound onto the T1 fibril template. Similarly, the produced precipitate was isolated by centrifuging and then re-suspended in H2O to prepare the TEM samples. In order to obtain a continuous nanowire of Pd nanoparticles, the process of adding the PdCl2 solution into the suspension of Pd-nanoparticle/T1-fibril complex and then reduction of PdII with hydrogen was repeated several times. Received: November 15, 2002 Final version: February 25, 2003

[11] R. S. Hegde, J. A. Mastrianni, M. R. Scott, K. A. DeFea, P. Tremblay, M. Torchia, S. J. DeArmond, S. B. Prusiner, V. R. Lingappa, Science 1998, 279, 827. [12] D. J. Selkoe, Science 1997, 275, 630. [13] C. Haass, P. J. Kahle, Nature 2000, 404, 341. [14] S. B. Prusiner, Science 1997, 278, 245. [15] R. W. Carrell, D. A. Lomas, Lancet 1997, 350, 134. [16] R. W.Carrell, B. Gooptu, Curr. Opin. Struct. Biol.1998, 8, 799. [17] D. M. Marini, W. Hwang, D. A. Laufferburger, A. Zhang, R. D. Kammar, Nano Lett. 2002, 2, 295. [18] J. De Mey, in Immunocytochemistry: Modern Methods and Application (Eds: J. Polak, S. Van Nooden), Wright-PSG, Bristol 1986. [19] K. R. Brown, D. G. Walter, M. J. Natan, Chem. Mater. 2000, 12, 306.

Stimulated Emission from a Needle-like Single Crystal of an End-Capped Fluorene/Phenylene Co-oligomer** By Xuhui Zhu, Denis Gindre, Nicolas Mercier,* Pierre Fr›re, and Jean-Michel Nunzi* Recent advances in optically pumped solid organic lasers have been achieved with a variety of semiconducting conjugated polymers[1±3] and dye-doped molecular solids as gain media[4,5] in thin (neat) films, triggered by the observation of lasing in a liquid solution of poly(2-methoxy-5-(2¢-ethylhexyloxy)-1,4-phenylene vinylene).[6] The fabrication of an organic diode laser is still a research target and only materials with large mobilities for both electrons and holes are serious candidates. On account of their high purity and their rigorously defined structure, high-quality molecular single crystals are more advantageous than polymers in this respect. Additionally, single crystals do not display grain boundary defects associated with solution-processed thin films (e.g., prepared by spin-coating) which may serve as carrier traps. Optically induced lasing from pure anthracene single crystals was reported as early as 1974.[7] Amplified spontaneous emission (ASE), which can be called a mirrorless laser emission, from one photopumped oligomeric single crystal was first evident in 1997, when observed by Fichou and co-workers[8] for an octylthiophene crystal. Later, other ASE experiments have been reported on conjugated oligomeric crystalline materials including an oligo(p-phenylenevinylene),[9] oligothiophene,[10]

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[1] C. M. Niemeyer, Angew. Chem. Int. Ed. 2001, 40, 4128. [2] M. Mertig, R. Kirsch, W. Pompe, H. Engelhardt, Eur. Phys. J. D 1999, 9, 45. [3] a) U. B. Slytr, P. Messner, D. Pum, M. Sara, Angew. Chem. Int. Ed. 1999, 38, 1034. b) W. Shenton, D. Pum, U. B. Sleytr, S. Mann, Nature 1997, 389, 585. c) W. Shenton, T. Douglas, M. Young, G. Stubbs, S. Mann, Adv. Mater. 1999, 11, 253. [4] M. Sastry, A. Kumar, S. Datar, C. V. Dharmadhikari, K. N. Ganesh, Appl. Phys. Lett. 2001, 78, 2943. [5] Y. Maeda, H. Tabata, T. Kawai, Appl. Phys. Lett. 2001, 79, 1181. [6] T. A. Taton, R. C. Mucic, C. A. Mirkin, R. L. Letsinger, J. Am. Chem. Soc. 2000, 122, 6305. [7] E. Dujardin, L.-B. Hsin, C. R. C. Wang, S. Mann, Chem. Commun. 2001, 1264. [8] E. Braun, Y. Eichen, U. Sivan, G. Ben-Yoseph, Nature 1998, 391, 775. [9] a) J. Richter, R. Seidel, R. Kirsch, M. Mertig, W. Pompe, J. Plaschke, H. K. Schackert, Adv. Mater. 2000, 12, 507. b) J. Richter, M. Mertig, W. Pompe, I. Monch, H. K. Schackert, Appl. Phys. Lett. 2001, 78, 536. [10] J. Hardy, G. Katrina, Science 1998, 282, 1075.

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[*] Dr. N. Mercier, Dr. X. Zhu, Prof. P. Fr›re Laboratoire IMMO, UMR-CNRS 6501 UniversitØ d'Angers 2 Bd Lavoisier, F-49045 Angers (France) E-mail: [email protected] Prof. J. M. Nunzi, Dr. D. Gindre Laboratoire POMA, UMR-CNRS 6136 UniversitØ d'Angers 2 Bd Lavoisier, F-49045 Angers (France) E-mail: [email protected] Dr. X. Zhu Institute of Advanced Materials and Technology Fudan University 220 Handan Rd, Shanghai 200433 (P.R. China)

[**] We thank the Pays de la Loire region for a post-doc fellowship to X. H. Z.

DOI: 10.1002/adma.200304816

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and a thiophene/phenylene co-oligomer[11,12] and also on melt-recrystallized oligomers.[13] Nevertheless, the number of ASE experiments on single crystals remains low, mainly as a result of the difficulty in obtaining crystals showing efficient luminescent properties. Molecular packing modes strongly affect solid-state photoluminescence. The incorporation of steric groups on the chromophore can ensure the emission properties by limiting the stacking of oligomers. In this communication we report on the crystal structure and preliminary results of optically induced ASE on a single crystal of a substituted fluorene/phenylene co-oligomer: 2,7-bis[4-(4¢-hydroxybiphenyl THP ether)]-9,9-diethylfluorene [THP = 2-(2H)-tetrahydropyran] (FP-THP). The hybrid oligomer FP-THP, consisting of 9,9-diethyl fluorene as the core and bulky THP moiety end-capped (bi)phenylene as the branch, embraces excellent solubility, photostability, and high photoluminescence efficiency in the single-crystalline state. On the other hand, the crystals, with sizes close to 2 mm ” 0.2 mm ” 0.2 mm, are peculiar in that their natural needle shape provides two-dimensional confinement in a waveguiding structure, and that the molecular orientation is naturally optimized for stimulated emission, the molecular axis being almost perpendicular to the needle axis. FP-THP is readily synthesized by Pd(PPh3)4-catalyzed cross-coupling reactions of 2,7-dibromo-9,9-diethylfluorene[14,15] and 4¢-hydroxybiphenyl-4-boronic acid THP ether, in aqueous alkali (Suzuki coupling, outlined in Fig. 1).[16] Protection of 4-bromo-4¢-hydroxy biphenyl was achieved by 3,4-dihydro-2H-pyran using pyridinium p-tolunesulfonate as the catalyst. Successive treatment of the as-protected bromide with butyllithium, trimethyl borate, and dilute NH4OAc afforded the desired boronic acid derivative in good yield.[17] Despite the acid-sensitivity of the THP groups, FP-THP is stable in non-acidic solution and in the solid state. Transparent well formed single crystals, typically approximately several millimeters long (Fig. 2), were easily obtained within a couple of days by slow vapour evaporation of diethyl ether into a CH2Cl2 solution of FP-THP.

Fig. 2. Photograph showing single crystals of FP-THP (upper) and ruler (mm unit, lower part).

FP-THP crystallizes in the Pbca space group, and the asymmetric unit contains one independent molecule, as shown in Figure 3. Disorder affects one THP group of the molecule, leading to the need to define two components (see Experimental). Bond lengths and angles are as expected. The confor-

Fig. 3. View of the of FP-THP molecule, and numbering of fluorene and phenyl planes. Disorder of one of the THP group is not shown. Ellipsoids are drawn at 30 % probability.

mation of the molecule can be described by dihedral angles between the central rigid fluorene and branched phenyl planes. Unlike the planar unsubstituted p-sexiphenylene,[18] FP-THP has significant twist among phenyl/phenyl (fluorene) rings (Table 1), as observed in other related structures.[19±21] Table 1. Dihedral angles between fluorene plane and phenyl planes, or between phenyl planes of a FP-THP molecule (see Fig. 3 for the numbering). Planes

Dihedral angles []

Fig. 1. Synthetic route to FP-THP. i) KOH aqueous solution (50 %), 2-bromoethyl, benzyltriethylammonium chloride, dimethylsulfoxide (95 %); ii) K2CO3 aqueous solution (2 M), Pd(PPh3)4, 4-hydoxybiphenyl-4-boronic acid THP ether, toluene and 1,2-dimethoxyethane (1:1) (30 %); iii) 3,4-dihydro-2H-pyran, p-toluenesulfonatepyridinium (Cat.), dichloromethane (84 %); iv) n-BuLi, tetrahydrofuran, ±100 C; v) B(OMe)3, ±90 C; vi) 10 % NH4Cl aqueous solution (70 %).

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1-2

1-3

1-4

1-5

2-5

3-4

30.6

35.0

81.2

44.3

13.7

45.4

The molecular packing, viewed along the a-axis, shows seemingly ªlayeredº molecules which actually shift from each other and form a long molecular axis extended in the direction along crystallographic c-axis, while the long crystal axis was found to be along the crystallographic a-axis (Fig. 4). This relative molecular orientation in the crystal makes it very suitable for self-waveguided emission along the needle axis.[22] The molecules are also arranged in such a way that the intermolecular aromatic interaction is effectively reduced with the nearest aromatic C´´´C contact larger than 3.5 Š. Such a molecular arrangement favours a high luminescence yield.[23]

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b)

a)

Fig. 4. a) Molecular packing (disorder of one of the THP end moieties in FP-THP not shown), and b) schematic representation of the molecular orientation in the crystal.

In the solid state, FP-THP absorbs with kmax at 355 nm, which is red-shifted by 12 nm compared to the absorption maximum in dilute CH2Cl2 solution. The optical density at 355 nm for a 0.1 mm thick crystal has been estimated to be 0.45 by using a 3x Nd:YAG laser. By excitation at the wavelength used in the stimulated emission experiments (k = 355 nm), FP-THP polycrystalline sample emits at 410 nm, with a 435 nm shoulder (Fig. 5b). The experimental set-up for the ASE experiments in a single crystal of FP-THP is shown in Figure 5a. The crystal was photo-pumped by a frequency tripled (3x) Nd:YAG laser (wavelength k = 355 nm) with 35 ps pulses at a repetition rate of 10 Hz. As our laser is TEM00 monomodal, by rotation of the 3x crystal, we can tune the energy of the pump and record the changes in the photoluminescence spectrum as a function of the excitation energy per pulse. The crystal was placed on a glass substrate and the excitation beam was in a horizontal plane, directed onto the crystal without focusing. The emitted light was collected with a 2 m long optical fiber along the long crystal axis, in a direction perpendicular to the excitation beam. The near-Gaussian beam diameter of the pump laser was 3 mm and the excited area of the crystals was about 1 mm ” 0.5 mm. Emitted light was collected by the optical fiber and then dispersed by an AVANTES AVS-S2000 spectrometer coupled to a 2048-element linear charge-coupled device array detector. The intensity of the pump beam was tuned from 120 to 700 lJ cm±2 pulse±1, i.e., approximately 0.6 to 3.5 lJ energy was directed onto the sample. In Figure 5b we can see the spectral narrowing of the emission at 410 nm for four excitation intensities. The spectrum obtained with low pump energy (120 lJ cm±2) is initially broad (> 100 nm). When the pump energy is increased, the peak intensity at 410 nm grows nonlinearly and its full width at half maximum (FWHM) decreases rapidly. For a pump intensity of 700 lJ cm±2, the FWHM is 1.5 nm, which is the resolution limit of our spectrometer. In summary, our synthetic, structural and photo-induced amplified spontaneous emission studies of 2,7-bis[4-(4¢-hydroxybiphenyl THP ether)]-9,9-diethylfluorene (FP-THP) demonstrated that the present hybrid approach is effective to afford molecules with excellent solubility, photostability, ease of fabrication of large and well-formed single crystals of millimeter size, and with efficient emission in single-crystal form. Work using single crystals of FP-THP to achieve distributed feedback

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a)

b)

Fig. 5. a) Experimental set-up for measurement of the emission spectra. The 3x beam is directed onto the crystal. The optical fiber is placed very close to one side of the needle-like crystals, perpendicular to the exciting beam. b) Gainnarrowed emission normalized spectra as a function of pump intensity for a single crystal of FP-THP. The crystal was photopumped with 35 ps pulses with repetition rate of 10 Hz at a wavelength of 355 nm. The spontaneous emission spectrum of a polycrystalline sample, recorded on a spectrofluorimeter, has been added.

(DFB) laser emission is underway.[24] Interestingly, such crystals should be well-suited for electrical pumping using the microgun technique developed by Molva and co-workers,[25] in which an array of micro-needles is used to inject electrons into a semiconductor crystal, thus overcoming junction and ohmic contact problems for large (> kA cm±2) current injection.

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All syntheses were performed under an inert N2 atmosphere. All samples were well characterized by 1H NMR spectroscopy on a Bruker Avance DRX 500 MHz spectrometer using solvent signals as internal references. UV-vis absorption spectra were recorded on a Lambda 2 Perkin±Elmer spectrometer. Fluorescence was recorded on a PTI spectrofluorimeter in dilute dichloromethane solution (HPLC grade) and on solution-cast films. Quantum yield (QY) in solution was measured using anthracene as the reference, dissolved in 95 % ethanol (spectral grade). The solution was degassed prior to the experiment and QY was found for FP-THP to be 0.60. 2,7-bis[4-(4¢-Hydroxybiphenyl THP ether)]-9,9-diethylfluorene (FP-THP): Yield: 0.24 g (30 %). m.p. 203 C. 1H NMR (500 MHz, CDCl3) d [ppm]: 0.43 (t, 6H), 1.54±2.04 (m, 12H), 2.14 (q, 4H), 3.63±3.66 (m, 2H), 3.93±3.98 (m, 2H), 5.50 (t, 2H), 7.16 (d, 4H), 7.58±7.67 (m, 10H), 7.74 (d, 4H), 7.80 (d, 4H). X-ray diffraction data were collected on a STOE-IPDS diffractometer using graphite-monochromated Mo Ka radiation (k = 0.71073 Š) at 293 K. FP-THP C102H100O8, MW 1453.82, orthorhombic, space group Pbca, a = 11.7774(4) Š, b = 17.546(1) Š, c = 39.150(2) Š, V = 8090.2(7) Š3, Z = 8, Dc = 1.194 g cm±3, l = 0.074 mm±1, crystal size 0.6 mm ” 0.15 mm ” 0.1 mm. 38 097 reflections were collected (2d < 48) giving 6237 independent reflections from which 2892 with I > 2r(I) were available for calculations. The structure was solved and refined using the Shelx97 package [26]. The attempts of structure resolution in acentric or centric space groups, revealed a positional disorder, or an unresolved superlattice structure, mainly for one THP group. The treatment of disorder (in the Pbca space group), for one THP group of the independent molecule, lead to define two cycles, the major component being, after refinement, 64 %. Thus, the molecules crystallize as (R,R) and (R,S) isomers together with centrosymmetrical ones (S,S) and (S,R). All hydrogen atoms were treated with a riding model. Positions and anisotropic motion parameters of all non-H atoms were refined by full-matrix least-squares routines against F2. Finally, refinements of the structure (547 variables) lead to R = 0.090, wR2= 0.26, G.O.F. = 1.01, residual electron density 0.63 eŠ±3. The crystal structure has been deposited at the Cambridge Crystallographic Data Centre and allocated the deposition number CCDC 200279.

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Received: January 2, 2003 Final version: January 31, 2003

[1] F. Hide, B. Schwartz, M. A. Diaz-Garcia, A. J. Heeger, Chem. Phys. Lett. 1996, 256, 424. [2] N. Tessler, G. J. Denton, R. H. Friend, Nature 1996, 382, 695. [3] M. D. McGehee, A. J. Heeger, Adv. Mater. 2000, 12, 1655. [4] V. G. Kozlov, S. R. Forrest, Curr. Opin. Solid State Mater. Sci. 1999, 4, 203. [5] A. Dodabalapur, M. Berggren, R. E. Slusher, Z. Bao, A. Timko, P. Schiotino, E. Laskowski, H. E. Katz, O. Nalamasu, IEEE J. Sel. Top. Quantum Electron. 1998, 4, 67. [6] D. Moses, Appl. Phys. Lett. 1992, 60, 3215. [7] O. S. Avanesjan, V. A. Benderskii, V. K. Brikenstein, V. L. Broude, L. I. Korshunov, A. G. Lavrushko, I. I. Tartakovskii, Mol. Cryst. Liq. Cryst. 1974, 29, 165. [8] D. Fichou, S. Delysse, J.-M. Nunzi, Adv. Mater. 1997, 9, 1178. [9] H. J. Brouwer, V. V. Krsnikov, T. A. Pham, R. E. Gill, P. F. van Hutten, G. Hadziioannou, Chem. Phys. 1998, 227, 65. [10] F. Garnier, G. Horowitz, P. Valat, F. Kouki, V. Wintgens, Appl. Phys. Lett. 1998, 72, 2087. [11] S. Hotta, M. Goto, Adv. Mater. 2002, 14, 498. [12] M. Nagawa, R Hibino, S. Hotta, H. Yanagi, M. Ichikawa, T. Koyama, Y. Taniguchi, Appl. Phys. Lett. 2002, 80, 544. [13] R. Hibino, M. Nagawa, S. Hotta, M. Ichikawa, T. Koyama, Y. Taniguchi, Adv. Mater. 2002, 14, 119. [14] B. A. Reinhardt, L. L. Brott, S. J. Clarson, A. C. Dillard, J. C. Bhatt, R. Kannan, Chem. Mater. 1998, 10, 1863. [15] E. P. Woo, M. Inbasekaran, W. Shiang, G. R. Roof, WO Patent 9 705 184, 1995. [16] N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457. [17] D. E. Cladingboel, Org. Process Res. Dev. 2000, 4, 153. [18] K. N. Baker, A. V. Fratini, T. Resch, H. C. Knachel, W. W. Adams, E. P. Socci, B. L. Farmer, Polymer 1993, 34, 1571. [19] G. Subramaniam, R. K. Gilpin, A. A. Pinkerton, Mol. Cryst. Liq. Cryst. 1992, 213, 229. [20] S. Destri, M. Pasini, C. Botta, W. Porzio, F. bertini, L. Marchiò, J. Mater. Chem. 2002, 12, 924. [21] K. T. Wong, Y. Y. Chien, R. T. Chen, C. F. Wang, Y. T. Lin, H. H. Chiang, P. Y. Hsieh, C. C. Wu, C. H. Chou, Y. O. Su, G. H. Lee, S. M. Peng, J. Am. Chem. Soc. 2002, 124, 11 576.

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[22] H. Yanagi, T. Morikawa, Appl. Phys. Lett. 1999, 75, 187. [23] J. Cornil, D. Beljonne, J.-P. Calbert, J.-L. Bredas, Adv. Mater. 2001, 13, 1053. [24] V. Dumarcher, L. Rocha, C. Denis, C. Fiorini, J.-M. Nunzi, F. Sobel, B. Sahraoui, D. Gindre, Pure Appl. Opt. 2000, 2, 279. [25] a) E. Molva, R. Accomo, G. Labrunie, J. Cibert, C. Bodin, Le Si Dang, G. Feuillet, Appl. Phys. Lett. 1993, 62, 796. b) D. Herve, R. Accomo, E. Molva, L. Vanzetti, J. J. Paggel, L. Sorba, A. Franciosi, Appl. Phys. Lett. 1995, 67, 2144. [26] SHELX97 (includes SHELXS97, SHELXL97, CIFTAB), Programs for Crystal Structure Analysis (Release 97-2), G. M. Sheldrick, Göttingen, Germany 1998.

Carbon-Nanotube-Templated Assembly of Rare-Earth Phthalocyanine Nanowires** By Lei Cao, Hong-Zheng Chen,* Han-Bo Zhou, Li Zhu, Jing-Zhi Sun, Xiao-Bin Zhang, Jun-Ming Xu, and Mang Wang* The remarkable optical, electrical, magnetic, and mechanical properties exhibited by carbon nanotubes (CNTs) have stimulated the development of novel CNT-based devices. Various applications of CNTs have been reported, such as fieldeffect transistors, full-color displays, chemical actuators, ultrafast optical switches, tips for scanning-probe microscopes, molecular computers, and so on.[1±6] However, great challenges must be overcome in order to make the potential applications into practical devices. Conventional methods only produce CNTs in the form of endless, highly tangled ropes. How to tailor the structure and aggregation of CNTs has currently become of broader interest. CNT-templated assembly of nanowires, the functionalization of the open ends, enrobing of the exterior walls, and encapsulating the interior cavities will create ways of fabricating novel one-dimensional (1D) hybrid materials.[7±12] A wide range of nanowires, made from materials including gold, copper, and platinum, has been synthesized.[13±15] Until now, however, most research work in the field has been related to metal compounds, and little has been published concerning the preparation of organic±inorganic hybrid nanowires. Dai and co-workers recently demonstrated that 1-pyrenebutanoic acid, succinimidyl ester, can be irreversibly adsorbed onto single-walled CNTs (SWCNTs), and that protein can be immobilized onto the functionalized SWCNTs, presenting us with opportunities for fabricating nanobiosensors.[8] Ajayan and co-workers prepared poly(meta-

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[*] Prof. H.-Z. Chen, Prof. M. Wang, L. Cao, H. B. Zhou, L. Zhu, Dr. J. Z. Sun Department of Polymer Science and Engineering, State Key Lab of Silicon Materials Zhejiang University Hangzhou 310 027 (China) E-mail: [email protected], [email protected] Prof. X. B. Zhang, J. M. Xu Department of Materials Science and Engineering Zhejiang University Hangzhou 310 027 (China)

[**] This work was supported by the National Natural Science Foundation of China (No.: 90 201 009).

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Experimental