It is well-known that the physical properties of SWNTs are closely correlated to their structures. SWNTs with controlled structures are, therefore, in great demand both for fundamental studies and technological applications. SWNTs other than the armchair and zigzag types are intrinsically chiral. Although their optical properties have been predicted theoretically, optical activity originating solely from carbon nanotubes has not been reported so far. We have found optically active SWNTs for the first time by preferentially extracting either (M)- or (P)-stereoisomers with chiral porphyrin dimers [1-6].
Reviews
X. Peng, F. Wang, A. F. M. M. Rahman, A. Bauri, and N. Komatsu,*"Optical Resolution of Single-Walled Carbon Nanotubes through Molecular Recognition with Chiral Diporphyrin Nanotweezers", Chem. Lett. (Highlight Review), 39 (10), 1022-1027 (2010).
N. Komatsu, and F. Wang, "A Comprehensive Review on Separation Methods and Techniques for Single-Walled Carbon Nanotubes", Materials (open access journal), 3 (7), 3818-3844 (2010).
N. Komatsu, "Sorting of Nanocarbon Materials (carbon nanotubes and nanodiamonds)", Powder Technology, 2 (11), 28-36 (2010).
N. Komatsu, "Novel and Practical Separation Processes for Fullerenes, Carbon Nanotubes and Nanodiamonds" J. Jpn. Petrol. Inst., 52 (3), 73-80 (2009).
N. Komatsu, "Sepaaration of Nanocarbons by Molecular Recognition", J. Incl. Phenom. Macrocycl. Chem., 61, 195-216 (2008) [highlighted at cover picture].
N. Komatsu, "Heterocyclic Supramolecular Chemistry of Fullerenes and Carbon Nanotubes" Topics in Heteroatom Chemistry; K. Matsumoto, Ed.; Springer: Heidelberg, Germany, pp 161-198 (2008).
Publication
[1] X. Peng, N. Komatsu,* S. Bhattacharya, T. Shimawaki, S. Aonuma, T. Kimura, A. Osuka, "Optically Active Single-Walled Carbon Nanotubes", Nature Nanotechnology, 2 (6), 361-365 (2007).
[2] X. Peng, N. Komatsu,* T. Kimura, A. Osuka, "Improved Optical Enrichment of SWNTs through Extraction with Chiral Nano-tweezers of 2,6-Pyridylene-bridged Diporphyrins", J. Am. Chem. Soc., 129, (51), 15947-15953 (2007).
[3] X. Peng, N. Komatsu,* T. Kimura, A. Osuka, "Simultaneous Enrichments of Optical Purity and (n, m) Abundance of SWNTs through Extraction with 3,6-Carbazolylene-Bridged Chiral Diporphyrin Nanotweezers", ACS Nano, 2 (10), 2045-2050 (2008).
[4] X. Peng, F. Wang, T. Kimura, N. Komatsu,* A. Osuka, "Optical Resolution and Diameter-Based Enrichment of Single-Walled Carbon Nanotubes through Simultaneous Recognition of Their Helicity and Diameter with Chiral Monoporphyrin", J. Phys. Chem. C., 113 (21), 9108-9113 (2009).
[5] F. Wang, K. Matsuda, A. F. M. M. Rahman, X. Peng, T. Kimura, and N. Komatsu,* "Simultaneous Discrimination of Handedness and Diameter of Single-Walled Carbon Nanotubes (SWNTs) with Chiral Diporphyrin Nanotweezers Leading to Enrichment of Single Enantiomer of (6,5)-SWNTs", J. Am. Chem. Soc., 132 (31), 10876-10881 (2010).
[6] A. F. M. M. Rahman, F. Wang, K. Matsuda, T. Kimura, and N. Komatsu,* "Diameter-based separation of single-walled carbon nanotubes through selective extraction with dipyrene nanotweezers" Chem. Sci., in press (DOI: 10.1039/c0sc00635a). [Highlighted at inside front cover]
Since the first observation of carbon nanotubes (CNTs) with transmission electron microscopy (TEM), it has been recognized that individual CNTs have a cylindrical shape and a strong propensity to form bundles. Also, CNT bundles are usually known to align in parallel or tangle to fabricate complex textures. However, other superstructures of CNTs, like rings and coils, attracted much attention due to their topologically interesting carbon structures at the curvatures and the potential for the characteristic properties especially in electromagnetic. In this context, we devised a very simple method for the isolation of circular single-walled carbon nanotubes by ultrasonic atomization, which has been utilized for concentration of alcohol, ketone and surfactant from their aqueous solutions. The sonoseparation process is applied for the first time to a solid-liquid heterogeneous system to obtain specific shape of the solid [7,8].
Publication
[7] N. Komatsu, "Isolation of Ring-shaped Single-Walled Carbon Nanotubes Using Ultrasonic Atomization", Ultrasonic Technology, 19 (5), 63-66 (2007).
[8] N. Komatsu,* T. Shimawaki, S. Aonuma and T. Kimura, "Ultrasonic Isolation of Toroidal Aggregates of Single-Walled Carbon Nanotubes" Carbon, 44 (10), 2091-2093 (2006).
Although quantum dots and carbon nanotubes have been developed as promising fluorescent probes in modern biotechnology, they always have considerable concerns about cytotoxicity and photobleaching. Quite recently, however, proton-implanted nanodiamond (ND) powder has been reported to be successfully employed as a fluorescent probe with no photobleaching and low cytotoxicity. This clearly shows the potential of ND powder as a molecular imaging agent. In continuation of our effort to develop an ND-based imaging probe, we found that powdered ND can be solubilized under physiological environment after appropriate organic surface functionalization [1,2], separated according to the size [1,3], and exhibits NMR signals in a solution phase [4,5].
Reviews
N. Komatsu, "Future of Carbon Materials in Biotechnology", New Diamond, 100, 68-70 (2011).
N. Komatsu, "Sorting of Nanocarbon Materials (carbon nanotubes and nanodiamonds)", Powder Technology, 2 (11), 28-36 (2010).
T. Takimoto, Y. Morita, N. Kadota, S. Aonuma, T. Kimura, and N. Komatsu, "Surface Functionalization and Size Separation of Nanodiamond Aiming at Medicinal Applications", Chemical Engineering, 54 (12), 947-951 (2009).
N. Komatsu, "Medical Applications of Nanodiamonds", Function & Materials, 29 (6), 23-29 (2009).
N. Komatsu, "Size Separation and Surface Functionalization of Nanodiamond Particles Aiming at Their Biomedical Applications ", J. Surf. Sci. Jpn., 30 (5), 273-278 (2009).
N. Komatsu, "Novel and Practical Separation Processes for Fullerenes, Carbon Nanotubes and Nanodiamonds" J. Jpn. Petrol. Inst., 52 (3), 73-80 (2009).
N. Komatsu, "Separation of Nanocarbons by Molecular Recognition" J. Incl. Phenom. Macrocycl. Chem., 61, 195-216 (2008) [highlighted at cover picture].
N. Komatsu, "Nanocarbon Science Aiming at Medicinal Applications", Chemical Engineering, 51 (12), 941-944 (2006).
N. Komatsu, "Diamond Technology", Diamond Industry Association Ed.; NGT Co., Chapter 9, 3-7 Medicinal Application of Diamonds, pp 683-687 (2007).
Publication
[1] L. Zhao, T. Takimoto, M. Ito, N. Kitagawa, T. Kimura, and N. Komatsu,* "Chromatographic Separation of Highly Soluble Diamond Nanoparticles Prepared by Polyglycerol Grafting" Angew. Chem. Int. Ed., 50 (6), 1388-1392 (2011) [highlighted at back cover]
[2] T. Takimoto, T. Chano, S. Shimizu, H. Okabe, M. Ito, M. Morita, T. Kimura, T. Inubushi, N. Komatsu, "Preparation of Fluorescent Diamond Nanoparticles Stably Dispersed under a Physiological Environment through Multi-Step Organic Transformations", Chem. Mater., 22 (11), 3462-3471 (2010).
[3] Y. Morita, T. Takimoto, H. Yamanaka, K. Kumekawa, S. Morino, S. Aonuma, T. Kimura, N. Komatsu,* "A Facile and Scalable Process for Size-Controllable Separation of Nanodiamond as Small as 4 nm", Small, 4 (12), 2154-2157 (2008).
[4] N. Komatsu,* N. Kadota, T. Kimura, E. Osawa, "Solution-phase 13C-NMR Spectroscopy of Detonation Nanodiamond", Chem. Lett. 36 (3), 398-399 (2007).
[5] N. Komatsu,* N. Kadota, T. Kimura, "Surface Modification of Nanodiamonds and the Influence to their Physical Properties", New Diamond, 83, 24-25 (2006).
We have investigated complex formation of fullerenes with flat pai-conjugated molecules of azulenes and porphyrins. Although they have unmatched shapes of the curved and flat surfaces, they showed very large binding constants of 103 - 105.
Although azulene is very small hydrocarbon consisting of only 10 carbons, it shows unexpectedly large binding constants to C60 and C70, which are larger than those of monoporphyrins and alternately conjugated aromatics. The energy-minimized structures reveal that the end-on structure of C70 is more stable than side-on, which may cause a similar affinity of azulene to C60 and C70 [1].
Although there exists a number of examples of porphyrin-based hosts for fullerenes, we investigated complexation behavior of porphyrin monomers and dimers for fullerenes in solution. All the porphyrins show large binding constants in the range of 103 - 104 M-1 and 104 - 105 M-1 for KC60 and KC70, respectively [1-5].
Reviews
N. Komatsu, "Sepaaration of Nanocarbons by Molecular Recognition", J. Incl. Phenom. Macrocycl. Chem., 61, 195-216 (2008).
N. Komatsu, "Heterocyclic Supramolecular Chemistry of Fullerenes and Carbon Nanotubes" Topics in Heteroatom Chemistry; K. Matsumoto, Ed.; Springer: Heidelberg, Germany, pp 161-198 (2008).
Publication
[1] S. Bhattacharya,* M. Hashimoto, A. Fujimoto, T. Kimura, H. Uno, and N. Komatsu,"Photophysical properties of a novel Ni(II)-Diporphyrin in Presence of Fullerenes: Insights from Experimental and Theoretical Studies", Spectrochimica Acta A, 70 (2), 416-424 (2008).
[2] S. Bhattacharya,* K. Tominaga, T. Kimura, H. Uno* and N. Komatsu* "A new metalloporphyrin dimer: effective and selective molecular tweezers for fullerenes" Chem. Phys. Lett., 433 (4-6), 395-402 (2007).
[3] S. Bhattacharya,* N. Ujihashi, S. Aonuma, T. Kimura, and N. Komatsu,*"Spectral and theoretical studies on effective and selective non-covalent interaction between tetrahexylporphyrins and fullerenes" Spectrochimica Acta A, 68 (3), 495-503 (2007).
[4] S. Bhattacharya,* T. Shimawaki, X. Peng, A. Ashokkumar, S. Aonuma, T. Kimura, and N. Komatsu,* "Spectroscopic and Theoritical Investigations on Effective and Selective Complexation between Porphyrins and Fullerenes" Chem. Phys. Lett., 430 (4-6), 435-442 (2006).
[5] S. Bhattacharya,* N. Komatsu, M. Banerjee, "p-Electronic Charge-Transfer Interactions in Supramolecular Complex Formation between Fullerenes and 5,10,15,20-Tetrahexylporphyrin" Chem. Phys. Lett., 406 (4-6), 509-518 (2005).
There was a great demand for more efficient purification method exploitable for large-scale production of pure fullerenes. Such situation of fullerene production led the author to explore practical purification method of fullerenes. Eventually, we developed a very fast, facile and inexpensive method for the purification of C60 and C70 by passing a solution of fullerene extract through thin layer of activated carbon, which is promising for industrial-scale production [6,7].
Reviews
N. Komatsu, "Sepaaration of Nanocarbons by Molecular Recognition", J. Incl. Phenom. Macrocycl. Chem., 61, 195-216 (2008).
N. Komatsu, "Purification of Fullerenes", Petrotech, 26(5), 373-378(2003).
Publication
[6] N. Komatsu,* N. Kadota, T. Kimura, Y. Kikuchi and M. Arikawa "Remarkable Improvement in Efficiency of Filtration Method for Fullerene Purification" Fullerenes, Nanotubes and Carbon Nanostructures, 15 (4), 217-226 (2007).
[7] N. Komatsu,* T. Ohe, and Kazumi Matsushige "A Highly Improved Method for Purification of Fullerenes Applicable to Large-scale Production" Carbon, 42, 163-167 (2004).
In 1997, we found bismuth bromide-catalyzed reductive coupling reactions. The ether forming reactions proceeded under neutral conditions in the presence of a catalytic amount of bismuth bromide, which worked more efficiently than other catalysts reported so far. Since such mild conditions are favorable for constructing labile linkages such as dibenzyl ethers, we applied these reactions to the synthesis of macrocyclic molecules with dibenzyl ether linkages such as oxacyclophanes and oxacalixarenes [8,9].
Although it was already known that homooxacalix[3]arenes and their dimers form stable complexes with C60 in solutions, we obtained more attractive result that p-halohomooxacalix[3]arenes preferentially precipitate C70 from solutions [8,10].
Reviews
N. Komatsu, "Sepaaration of Nanocarbons by Molecular Recognition", J. Incl. Phenom. Macrocycl. Chem., 61, 195-216 (2008).
Publications
[8] N. Komatsu,* "New Synthetic Route to Homooxacalix[n]arenes via Reductive Coupling of Diformylphenols" Tetrahedron Lett., 42(9), 1733-1736 (2001).
[9] N. Komatsu,* and T. Chishiro, "Serial Synthesis of Oxa[3.n]cyclopanes and Homooxacalix[n]arenes via Reductive Coupling of Arenedialdehydes, and Their X-ray Structures" J. Chem. Soc., Perkin Trans. 1, (13), 1532-1537 (2001).
[10] N. Komatsu,* "Preferential Precipitation of C70 over C60 with p-Halohomooxacalix[3]arenes" Org. Biomol. Chem., 1(1), 204-209 (2003).