Peptide anchored Langmuir–Blodgett films of a fullerene amphiphile

Abstract

A new amphiphilic derivative of fullerene C 60 bearing an oligoglycyl tail (C 60 CHCOgly 2 OEt, 2) formed stable Langmuir floating films at the air-water interface. This occurred when the molecular assembly was stabilized by anchoring the amphiphilic C 60 's to the aqueous subphase, via hydrogen bonding interactions between a dipeptide (Gly-L-Leu) dissolved in the water subphase, and the oligoglycyl chain. The compression (y−A) isotherm of the Langmuir floating film constructed in such a way showed no hysteresis, was steep, and evidenced that the monolayer collapsed at a surface pressure yE65 mN m − 1 , thus confirming that the film was tightly packed, extremely stable, and rigid. A limiting area per molecule of 89.1 A , 2 was extrapolated, in agreement with the calculated cross-section area of the C 60 fullerene. On the contrary, when the dipeptide was absent and pure water was used as the subphase, the y −A isotherm yielded a limiting area B55 A , 2 which indicated the formation of multiple layers; moreover it showed significant hysteresis, the film was fragile, and it collapsed at y :50 mN m − 1 . Once anchored by the dipeptide, the floating monolayer of 2 could be transferred onto hydrophobic quartz, glass and silicon substrates, by successive vertical dipping cycles, each cycle made up of two down-strokes and two up-strokes, to yield the Langmuir-Blodgett film. Up to 200 down-and up-strokes could be repeated reproducibly, a noteworthy result for non-covalently assembled LB films of fullerenes. The transfer ratio was 1.0, except for the second down-stroke of each cycle that gave a transfer ratio of zero, making the sequence of successful transfers: D, U, U, (cleaning and spreading), D, U, U, (cleaning and spreading), and so on (D= down-stroke, U= up-stroke). The total number of deposited layers was therefore 150. X-ray diffraction spectra were registered and exhibited a peak, which was fitted by a Montecarlo method of simulation to obtain the distribution of the repeat unit responsible for scattering; such distribution, with thickness between 20 and 60 A , , was consistent with the size of the amphiphile and the transfer sequence. The UV-Vis spectra of the LB film exhibited the characteristic C 60 bands, and the absorption peaks in the 200-400 nm range were proportional to the number of layers, indicating that the deposition was reproducible and that the molecular environment of C 60 in each layer remained constant. © 2001 Elsevier Science B.V. All rights reserved.

Fabrication of Langmuir–Blodgett Film of a Fullerene Derivative with a Cyclic Peptide as an Anchor

“…To overcome these problems, chemical modifications of fullerenes are needed. A wide variety of fullerene derivatives have been synthesized by modification with various chemical species such as crown ethers ,– , polyhydroxylates , oligopeptides , , poly(ethylene glycol)s , hydrophilic porphyrins , , and so on . Polymers having fullerenes at the main or side chains , and dendrimers carrying fullerenes as the dendrons – have been reported as well.…”

Fabrication and Properties of Fullerodendron Thin Films

“…The formation of fullerene-derivative-modified SAMs has been achieved through the junction moiety of carboxyl derivative, organosilane, OsO 4 , or organosulfur. , On the other hand, the LB technique, the method that fabricates Langmuir films at the air/water interface and subsequently transfers those films onto a solid substrate, also allows controlling the structure of the films at a molecular level. Fullerene derivatives were functionalized by hydrophilic additives, such as poly(ethylene glycol), ,, polyhydroxylate, crown ether, and oligopeptide . Furthermore, the fullerene derivative, in which fullerene was incorporated into the branched moiety of dendron, was investigated as a LB-film-constituting material. ,, However, the construction of highly ordered thin films from dendron-including fullerene derivatives is still challenging investigations.…”