Carbon supramolecular complexes

Ali-Boucetta H, Al-Jamal KT, McCarthy D, Prato M, Bianco A, Kostarelos K (2008) Multiwalled carbon nanotube-doxorubicin supramolecular complexes for cancer therapeutics. Chem. Commun. 459—461. 

Figure 8.10 Soluble supramolecular complexes of carbon nanotubes, 0.01 M Na2S04, aqueous solution. Scan rate = 0.1 V/s T— 25°C working electrode is Pt disc (r — 0.05 cm). Potentials measured versus silver quasi-reference electrode (approximately —0.05 V versus SCE). Ref. 121, Reproduced by permission of the Royal Society of Chemistry.

FIGURE 2.2 Supramolecular nanostructures for light driven energy and electron transfer. This research is focused on rational design and study of self-assembled porphyrin, fullerene, and carbon nanotube bearing supramolecular complexes and nanostructures. 

The acceptor and donor strength of many functions besides fhose of fhe amide type have been characterized by the analysis of associations between simple molecules, such as, e.g., phenols and anilines, for which fhousands of experimental data exist, mosfly measured in chloroform or in carbon tetrachloride [94, 95]. Although these data are hampered by less well-defined structures compared to supramolecular complexes, they not only give a fairly consistent basis for the prediction of hydrogen-bonded associations but also can be used, e.g., for crown efher and cryptand complexes with alkali or ammonium ligands [32]. 

The rationale for the observed configuration (Scheme 3.29), is based on the X-ray structure of another a-carbamoyloxyorganolithium sparteine complex [185]. After deprotonation, the chelated supramolecular complex shown in the lower left is postulated. This structure contains an adamantane-like lithium-diamine chelate, and contains new stereocenters at the lithiated carbon and at lithium itself. Note that epimerization of the lithiated carbon would produce severe van der Waals repulsion between R and the lower piperidine ring, whereas epimerization at lithium produces a similarly unfavorable interaction between the same piperidine ring and the oxazolidine substituents. Thus, the carbamate is tailor-made for sparteine chelation of only one enantiomer of the a-carbamoyloxyorganolithium. These effects may provide thermodynamic stability to the illustrated isomer. To the extent these effects are felt in the transition state, they are also responsible for the stereoselectivity of the deprotonation. 

Figure 11. Tentative schematic illustration of the supramolecular complexes formed in acetonitrile and propylene carbonate. D is the coumarin donor and A the coumarin acceptor. The carbonyl groups of some propylene carbonate molecules are also shown. (Reproduced with permission from ref. 23. Copyright 1992 American Chemical Society).

The examples of DNA-based nanoactuators reviewed here demonstrate a wide variety of approaches and strategies for incorporation of controllable motions into DNA-based supramolecular complexes. This type of switchable molecular assembly will likely find future use in combination with other nanomaterials such as carbon nanotubes, metallic and semiconducting nanoparticles, and other electrically active components for construction of nanoelectronics for sensors applications, as one possible example. 

Ozoemena [125] performed the anodic oxidation and amperometric sensing of hydrazine using a glassy carbon electrode modified with a cobalt(ll) phthalocya-nine-cobalt(n) tetraphenylporphyrin (CoPc-(CoTPP)4) supramolecular complex. This amperometric sensor displayed excellent characteristics for the determination of hydrazine in 0.2 M NaOH at low overpotential (+100 mV vs. Ag/AgCl), with very fast amperometric response time (1 s), linear range of 10-230 pmol LT, limit of detection of 1 pmol L and sensitivity of 0.0157 pA L pmol . ... 

Ozoemena KI (2006) Anodic oxidation and amperometric sensing of hydrazine at a glassy carbon electrode modified with cobalt (II) phthalocyanine-cobalt (II) tetraphenylporphyrin (CoPc-(CoTPP)4) supramolecular complex. Sensors 6 874—891... 

Palkar, A., Kumbhar, A., Athans, A. J., 8c Echegoyen, L. (2008). Pyridyl-functionalized and water-soluble carbon nano onions First supramolecular complexes of carbon nano onions. Chemistry of Materials, 20,1685-1687. 

For the purposes of this review the criterion has been refined to include only those porphyrin complexes where there is direct structural or spectroscopic evidence for a metal-carbon interaction. This interaction will not, however, be limited to covalent bonds. The last decade has seen the rise in importance of supramolecular chemistry and non-covalent interactions, and a small set of examples involving porphyrin complexes will be included as the last section in the review. 

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