Synthesis of Organic One-Dimensional Nanomaterials by Solid-Phase Reaction Huibiao Liu, ² Yuliang Li,* ,² Shengqiang Xiao, ² Haiyang Gan, ² Tonggang Jiu, ² Hongmei Li, ² Lei Jiang, ² Daoben Zhu,* ,² Dapeng Yu, ‡ Bin Xiang, ‡ and Yaofeng Chen ‡ Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China, and Department of Physics, Peking UniVersity, Beijing 100871, P.R. China Received June 16, 2003; E-mail: ylli@iccas.ac.cn During the past decade, the synthesis and functionalization of one-dimensional (1D) nanomaterials has become one of the most highly energized research areas. Because of their low dimensionality and high aspect of ratio, 1D nanomaterials possess highly unusual physical properties. Great efforts have been placed on the synthesis of 1D nanomaterials, and various methods 1-6 have been exploited. Most of studies concern metallic, 7 semiconductor 8 and other inorganic materials. 9 In contrast to inorganic materials, organic materials have peculiar electronic and optical properties. They are readily synthesized, show remarkable improvements on stability, and can be polyfunctionalized to allow for tailoring their optical, electronic, and chemical properties. There are some preparation methods available 10-12 for organic nanomaterials, such as recepi- tation, 10 evaporation, 11 and microemulsion. 12 However, the prepara- tion of organic 1D nanomaterials remains poorly studied, and only a few successful examples have been reported. 13 In recent studies, we have developed a novel and generic technique to fabricate the anthracene (AN) nanowires and perylene (PY) nanorods on the basis of solid-phase organic reactions under controlled reaction temperature, time, and argon gas flow rate. Solid- phase reaction of 9-anthracenecarboxylic acid (ACA) with CaO at 340 °C for 2 h, placed at the center of a quartz tube that was inserted in a horizontal tube furnace, resulted in wool-like products that formed on the surface of the copper wafer placed at the downstream end of the quartz tube. The full characterization data of the products indicates the typical characteristics of AN. The SEM image (Figure 1A) reveals that the products consist of a large quantity of wirelike nanostructures with lengths in the range of several to tens of micrometers, while their diameters are in the range of tens of nanometers to several micrometers. The aspect of ratio of the corresponding nanowires lies in the range of about 50-100. Figure 1B shows that the diameter of AN nanowires is about 410 nm. The surfaces of AN nanowires are clean and smooth. The nanowires are rather straight and have a uniform diameter along the entire length. TEM observations reveal that the geometrical shape of the AN nanostructures is a wire (Figure 1C,D). The diameter and length of the AN nanowires is in the range of 40 nm to 1.5 μm and 9-20 μm. The X-ray diffraction (XRD) patterns of the AN nanowires show it to be a monoclinic crystalline system. The stronger diffraction peak of the nanowires at (200) indicates a preferential orientation along the a axis and a quasi-one-dimensional shape, which is demonstrated by the TEM and SEM. The luminescence spectra of the AN nanowires during synthesis display differences from those of AN bulk crystasl (Figure 2A) which demonstrates the characteristics of AN monomer emission bands at 420 and 445 nm (attributed to the 0-0 band by D 1 and D 2 bands, respectively) and the excimer bands at 486 and 530 nm (attributed to the AN formed by two AN molecules overlapped each other with one benzene ring 14,15 ). The (100) direction of the anthracene crystal is known to be responsible for the D 2 band in the luminescence spectrum, whereas those in the (001) direction are responsible for the D 1 band. 16 However, the emission spectrum of AN nanowires show a sharp luminescence centered at 443 nm due to growth of orientation along the a axis. In the case of AN nanowires having larger diameters, the maximum peak position of the emission band is shifted to longer wavelength. Without the appearance of any broad band in the longer wavelength region (486 and 530 nm), it is suggested that there is scarcely any excimer 17,18 in the AN nanowires. It is also completely different from AN nanoparticles in which there are dual emissions, the monomer bands ² Chinese Academy of Sciences. ‡ Peking University. Figure 1. (A) Low magnification SEM image of the AN nanostructures to show the large quantity of nanowires. (B) SEM images of typical single AN nanowire. (C) Low magnification TEM image of the AN nanostructures to show the large quantity of nanowires. (D) TEM images of some typical AN nanowires. Figure 2. (A) The luminescence spectra of AN nanowires (solid line) and the bulk crystal of AN (dash line). (B) The luminescence spectra of PY nanorods (solid line) and the bulk crystal of PY (dash line). BATCH: ja9d53 USER: jld69 DIV: @xyv04/data1/CLS_pj/GRP_ja/JOB_i38/DIV_ja036697g DATE: August 12, 2003 Published on Web 00/00/0000 10.1021/ja036697g CCC: $25.00 © xxxx American Chemical Society J. AM. CHEM. SOC. XXXX, XXX, 9 A PAGE EST: 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67