Open-ended single-walled carbon nanotube

Water in well-characterized pores is a system of general interest because it serves as model system for the non-bulk or inhomogeneous water that is ubiquitous in biological and geological systems, as well as in nano-sfructured materials. Often confined or interfacial water is highly relevant to the properties and functions of entire systems, e.g., those in ion channels and clay minerals. X-ray diffraction studies show that water can fill the inner space of open-ended single-walled carbon nanotubes (SWCNTs) under ambient conditions and freezes into crystalline solids. These are often referred to as ice nanotubes . Ice stmctures in confined systems are characterized as stacked n-membered rings or equivalently as a rolled square-net sheet. The formation of the ice nanotubes in CNTs has also been observed by NMR, neutron diffraction, and vibrational spectroscopy studies. 

Rawat DS, Calbi MM, Migone AD. Equihbration time kinetics of gas adsoption on closed-and open-ended single-walled carbon nanotubes. 1 Phys Chem C 2007 111 12980-6. 

Holloway, A. F. ToghUl, K. Wildgoose, G. G. Compton, R. G. Ward, M. A. H. Tobias, G. Llewellyn, S. A. Ballesteros, B. Green, M. L. H. Crossley, A. 2008. Electrochemical opening of single-walled carbon nanotubes filled with metal halides and with closed ends. J. Phys. Chem. C, 112, 10389-10397. 

The amine function served also as the starting point for the first covalent linkage of Pcs to single-walled carbon nanotubes (SWNTs) [94], The pipes with open-end and surface-bound acyl chloride moieties were used to prepare the Pc-SWNTs system by amide-bond formation (Fig. 14). Accordingly, statistical reaction of 4-aminophthalonitrile with 4-tcr/-bu(yIph111alonitrile in the presence of zinc ions delivered the monoamino Pc that was then employed in the conjugation with the acid chloride modified carbon nanotubes (CNTs). Here, it should also be mentioned that other functions have been applied to the covalent modification of CNTs, i.e., amide [95], ester [96,97], or click chemistry [98],... 

Figure 3 Carbon-based architectures (a) Cgo, the prototype fullerene, (b) open-ended and (c) closed single-walled carbon nanotubes, (d) multilayered graphene.

Hwang YG, Lee YH, Adsorption of HjO molecules at the open ends of single walled carbon nanotubes. Journal of the Korean Physical Society, 2003. 42 S267-S271. 

Wanbayor, R., Ruangpornvisuti, V. (2008). Theoretical study of adsorption of C1-C3 alkoxides on various cap-ended and open-ended armchair (5,5) single-walled carbon nanotubes. Carbon, 46,12-18. 

The filling control approach has even been applied to some nanophase materials. For example, the onset of metallicity has been observed in individual alkali metal-doped single-walled zigzag carbon nanotubes. Zigzag nanotubes are semiconductors with a band gap around 0.6 eV. Using tubes that are (presumably) open on each end, it has been observed that upon vapor phase intercalation of potassium into the interior of the nanotube, electrons are donated to the empty conduction band, thereby raising the Fermi level and inducing metallic behavior (Bockrath, 1999). 

A principal distinction can be made between single-walled nanotubes (SWNT) and multiwalled nanotubes (MWNT). Both classes comprise species of most different diameters and lengths. Besides dimensions, it is also the way the graphene layer is rolled up to be a tube that dominantly influences the properties of the resulting materials. Furthermore, there may or may not be caps at the tubes ends, the respective structures then are called closed or open carbon nanotubes. The structural features of single-walled nanotubes will be discussed first in the following before the concept shall be extended to the multiwalled variants then. 

With those things in mind, a single-wall, (10,10) nanotube capped with a C5, hemifiillerene dome was used as the probe tip for all the simulations discussed here. (For a more detailed explanation of the cap structure see Harrison et al (35).) The nanotube contains 870 carbon atoms, has a diameter of approximately 14 A, and has a length from base to the end of the cap of approximately 53 A. To satisfy the valence requirements of carbon, the carbon atoms at the open end of the tube are hydrogen terminated. A total of 11040 atoms were used to simulate the C,3 monolayer and the diamond substrate. 

FIGURE 13.7 Preparation and characterization of single-walled nanotube (SWNT) forest formed by metal-assisted deposition of oxidized, shortened SWNTs. (a) Schematic representation of SWNT forest preparation. Shortened, open-ended SWNTs with carboxyl-functionalized ends are produced by oxidation of SWNTs. A suspension of SWNTs is introduced to a metal surface functionalized with iron hydroxides. An SWNT forest results as SWNTs vertically align via self-assembly. (Part a adapted with permission from Chattopadhyay, D., Galeska, I., and Papadimitrakopoulos, F., Metal-assisted organization of shortened carbon nanotubes in monolayer and multilayer forest assemblies, J. Am. Chem. Soc., 123,9451-9452,2001. Copyright 2001 American Chemical Society.) Cyclic voltammograms (scan rate 300 mV s ) of (b) SWNT forest electrodes in pH 5.5 buffer with and without 0.2 mM HjOj. (Continued)... 

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