Fullerene Monolayers

However, transfer of the monolayers to solid substrates was inefficient because of the small size of the hydrophilic anchor, which imparted a hydrophobic/hydrophilic imbalance. Accordingly, increasing the size of the hydrophilic anchor facilitated the formation of stable Langmuir films that could be transferred to sohd substrates with a transfer ratio of 1 (Nierengarten et al. 2001). Bayer s research group reported a related approach in which the fullerene was modified with carboxylate-terminated dendrons and alkyl chains (Maierhofer et al. 2000). This amphiphilic fullerene derivative formed stable monolayers that could be compressed and expanded without hysteresis (Fig. 11.46d Maierhofer et al. 2000). 

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Al-Jamal KT, Ramaswamy C, Florence AT. Supramolecular stmctures from dendrons and dendrimers. Adv Drug Deliv Rev 2005 57 2238-2270. 

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The growth of a well ordered fullerene monolayer, by means of molecular beam epitaxy, has been used for the controlled nucleation of single crystalline thin films. The quality and stability of molecular thin films has been shown... 

Guldi D M, Tian Y, Fendler J FI, Flungerbuhler FI and Asmus K-D 1996 Compression-dependent structural changes of functionalized fullerene monolayers J. Phys. Chem. 100 2753-8... 

W. Feng and B. Miller, Fullerene monolayer-modified porous Si. Synthesis and photoelectrochemistry, Electrochem. Solid-State Lett. 1(4), 172, 1998. 

In other materials synthesis applications, the utilization of the strong bonding of fullerenes to clean silicon surfaces, has led to the application of a monolayer... 

Compound 45 incorporates a fullerene acceptor and two substituted polythiophene-ethenyl tails it rectifies as an LS monolayer. Interestingly, it rectifies in one direction for smaller biases between 0 and 2.0 V, but in the reverse direction at higher biases, perhaps indicating a change in conduction mechanism, as discussed above. It also rectifies between A1 and Pb electrodes at 4.2 K (Fig. 22a) [108],... 

Honciuc A, Jaiswal A, Gong A, Ashworth K, Spangler CW, Peterson IR, Dalton LR, Metzger RM (2005) Current rectification in a Langmuir-Schaefer monolayer of fullerene-bis-[4-diphenylamino-4 -(N-ethyl-N-2 -ethyl)amino-l,4-diphenyl-l,3-butadiene] malonate between Au electrodes. J Phys Chem B109 857-871... 

Komatsu K (2005) The Mechanochemical Solid-State Reaction of Fullerenes. 254 185-206 Kriegisch V, Lambert C (2005) Self-Assembled Monolayers of Chromophores on Gold Surfaces. 258 257-313... 

Dendrimers have also been found useful in the construction of thin films containing isolated fullerenes [85, 86]. Such materials could eventually find practical application in sensors and/or optoelectronic devices [87]. Generally, monolayers prepared from C60 are ill-defined due to the aggregation tendency of fullerenes. The covalent attachement of C60 to bulky dendritic frameworks... 

The application of fullerene on the surfaces has an essential advantage in the studies with cell cultures as in this case we can obtain the maximum contact of cells with fullerene - cells adhere on the surface and colonize it as a confluent monolayer. That is the basic difference from the water-soluble complexes and micro-dispersed suspensions of fullerene C60. The pro-/antioxidant activities of fullerene were tested in chemical and biological systems. 

However, fullerene C60-modified surface is adequate for the adhesion and normal growth of cells in culture. Cells of the line MA-104 in the Eagle-MEM medium formed on fullerene film a normal monolayer. Cellular viability was assessed with the resazurin (Alamar Blue) reduction test. The dye resazurin is reduced by mitochondrial dehydrogenases of viable cells into the fluorescent product resorufin (maximum X = 530 nm, max X = 590 nm). The intensity of... 

Guldi DM, Hungerbuhler H, Asmus KD (1995) Stable monolayers and Langmuir-Blodgett films of functionalized fullerenes. J Phys Chem. 99 17673-17676. 

The structure of CNTs can be understood as sheets of graphene (i.e. monolayers of sp2 hybridized carbon, see Chapter 2) rolled-up into concentric cylinders. This results in the saturation of part of the dangling bonds of graphene and thus in a decrease of potential energy, which counterbalances strain energy induced by curvature and thus stabilizes the CNTs. Further stabilization can be achieved by saturating the dangling bonds at the tips of the tubes so that in most cases CNTs are terminated by fullerene caps. Consequently, the smallest stable fullerene, i.e. C60, which is - 0.7 nm in diameter, thus determines the diameter of the smallest CNT. The fullerene caps can be opened by chemical and heat treatment, as described in Section 1.5. 

The CgQ surface coverage was determined to be 2.0 10 mol cm . The monolayer can be further modified with monomeric amine reagents, which demonstrates the potential of the self-assembly process for growing three-dimensional fullerene structures. Different surfaces such as quartz. Si-oxide [105] or ITO [102] were coated with multilayers of fullerene up to stacks of 9 layers. An imidirectional electron transfer is possible across the fullerene mulhlayers [102]. Not only can multiple layers of fullerenes be connected to a certain surface but amino-functionalized can also serve as a linker between two different surfaces. 3-Aminopropyl-tethered glass plates could be linked via a Cgg layer to 3-aminopropyl covered zeolite crystals [106]. 

A benzo[18]crown-6 adduct (72) of Cgg (not shown) has been synthesized by the addition of the corresponding o-quinodimethane 71 in toluene [58]. The solubility of 72 in pro tic solvents such as MeOH strongly increases after the complexation of ions, as shown by extraction experiments. The combination of the crown ether and the fullerene moiety in 72 provides a highly amphiphilic character. This behavior allowed the preparation of Langmuir-Blodgett films of monolayers on mica of 72 and its complex. 

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