Ester-SWNT

New applications of nitrile oxide 1,3-DC have been reported. Soluble, single-wall carbon nanotubes (SWNT) 32 functionalized with pentyl esters at the tips and pyridyl isoxazoline rings along the walls were prepared using pentyl ester-SWNT as dipolarophile. The complex... 

Electrochemical polymerization of pyrrole on an SWNT electrode using an aqueous HCl 0.5 M solution as electrolyte, resulted in deposition of a PPy film onto the SWNT layer leading to a composite with a bilayer structure, as demonstrated by Raman spectroscopy [112]. Anew method was developed by S.Cosner eta/, in 2008 [111] SWNTs were functionalized by electropolymerizable pyrrole groups following covalent and noncova-lent strategies. The covalent pyrrole grafting was carried out by ester formation between pyrrole alcohol and chemically oxidized SWNTs. The strong Ti-interactions between pyrene and SWNTs were exploited for the noncovalent adsorption of a new pyrene-pyrrole derivative on the pristine CNT surface. The pyrrole-ester-SWNTs were solubilized in THE and electropolymerized by controlled potential electrolysis at 0.95 V. The PPy/SWNT... 

Figure 22 (a) SWMT-ester, SWNT-C00-(CH2)it-CH3. (b) Ester from SWNT-COOH and PVA-VA. (c) Dendritic-type benzyi aicoboi ethers. Adapted with permission from Hirsch, A. Vostrowsky, 0. In Functional Molecular Nanostructures, Voi. 245,2005, pp 193. ... 

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],... 

Fig. 13.20 (a) Schematic diagram of the nanosensor. PSA-ABs are anchored to the NW/SWNT surface and function as specific recognition groups for PSA binding, (b) Reaction sequence for the modification of In203 NW i, deposition of 3-phosphonopropionic acid ii, DCC and A-hydroxysuccinimide activation Hi, PSA-AB incubation, (c) Reaction sequence for the modification of SWNT iV, deposition of 1-pyrenebutanoic acid succinimidyl ester V, PSA-AB incubation. Reprinted with permission from ref. [149]. Copyright (2005) American Chemical Society... 

Another interesting example of the use of o-QDM as diene was reported by Delgado et al. [69]. The first DA cycloaddition of o-QDM 58 to ester-functionalized single-wall carbon nanotubes (SWNT) 61 was performed in accordance with to Scheme 11.18. The authors showed that such DA reactions could be performed very efficiently in o-dichlorobenzene (o-DCB) under the action of microwave irradiation at 150 W for 45 min (Scheme 11.18). Conventional heating in o-DCB under reflux required 72 h and resulted in less conversion. 

As described above, cycloaddition reactions are among the most powerful for functionalization of fullerenes, and microwave irradiation has proven a very useful technique in this kind of chemistry. The reactivity of the walls of SWNTs should be similar to that of fullerenes - albeit significantly slower. It is therefore of interest to apply microwaves for lateral functionalization of SWNTs. The first such example of Diels-Alder addition to the lateral wall of a SWNT has been described [90], and involved use of microwaves as a source of energy (Scheme 21.24). Ester functionalized SWNT 69 [91] was reacted with o-quinodimethane 71, generated in situ from 4,5-benzo-l,2-oxathiin-2-oxide (70), under the action of microwave irradiation for 45 min. The reaction was also performed under classical heating conditions for 72 h in ODCB under reflux but under these conditions the NMR spectrum was indicative of very low conversion. 

In the specific case of nanotubes, biofunetionalization for enhanced compatibility has been an area of rapid growth during recent years (154). Several studies have focused on the binding of proteins to SWNT via noncovalent and covalent functionalization schemes. For example, Dai et al. (155) have adsorbed pyrene onto the side-walls of SWNT and then have made the succinimidyl ester group react with the amine groups in the lysine residues of the proteins to form covalent amide linkages. Similarly, MWNT have been functionalized with 4-hydroxynonenal to induce adsorption of the 4-hydroxynonenal antibody (156). 

The mechanical properties of SWNT reinforced polyurethane (PU) electrospun nanofibers were studied by Sen et al. (89). Stress-strain analysis showed that the tensile strength of the PU/SWNT nanofiber membrane was enhanced by 46% compared to pure PU nanofiber membrane. This value of tensile strength was further increased by 104% for ester functionalized PU/SWNT membranes because of the improved SWNT dispersion and the enhanced PU-SWNT interfacial interaction. 

As is shown in Section 3.3.2, biomolecules such as proteins and DNA bind to CNTs by nonspecific interactions. Dai and coworkers sought to develop a chemical method for the noncovalent functionalization of SWNTs with biomolecules.To this end, 1-pyrenebutanoic acid, succinimidyl ester was employed this molecule adsorbs irreversibly to the wall of pristine SWNTs in organic solvents such as A,A-dimethylformamide (DMF) or methanol. The pyrenyl group of 1-pyrenebutanoic acid, succinimidyl ester, which is aromatic, is known to strongly bind to the... 

Figure 8 1-Pyrenebutanoic acid, succinimidyl esta- (1) irreversibly adsorbs onto the sidewall of a SWNT via iTr-stacking. Amine groups on a protein react with the anchored succinimidyl ester to form amide bonds for protein immobilization. (Reproduced from Ref. 14. Amaican Chemical Society, 2001.)...

SWNT [2 + 1 ] Cycloadditions PEG di-azidocar-bonate ester Nitrene [55]... 

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