Abstract:C 60 molecules have been functionalized according to the Prato method with the short S-acetyl-protected chains. The redox properties of this fullerene derivative in the solution reveal reversible 1e reduction -oxidation steps similar to those of C 60 but shifted to more negative potentials. The in situ deprotected fullerenethioacetate compound forms a stable uniform electroactive monolayer on the (111) surface of gold with the most common diameter of the molecule in range 1.4 ± 0.2 nm. It undergoes both stepwi… Show more
“…2b); experimental conditions are given in ESI 4. † In line with previous studies, 17 the absence of a strong carbonyl stretching mode at 1687 cm À1 indicates that the sulfur-acetyl bond in TAT-TTF has been cleaved. However, an extra peak appears in the Reflection-Absorption Infrared (RAIR) spectrum at 2908 cm À1 that is assigned to the CH 3 stretching mode of an acetyl radical species.…”
A dihydro-TTF derivative with four acetyl-protected thiol ligands was synthesised and adsorbed on Au(111) under UHV conditions. Scanning Tunnelling Microscopy (STM) and Infrared (IR) spectroscopy show that self-organised structures are formed following annealing to 333 K, with each pair of bidentate thiolate ligands bonding to a single gold adatom in a S-Auad-S complex. Due to the lack of a direct orbital overlap between the dihydro-TTF moieties and the surface, relatively little charge transfer between TAT-TTF and the gold surface occurs.
“…2b); experimental conditions are given in ESI 4. † In line with previous studies, 17 the absence of a strong carbonyl stretching mode at 1687 cm À1 indicates that the sulfur-acetyl bond in TAT-TTF has been cleaved. However, an extra peak appears in the Reflection-Absorption Infrared (RAIR) spectrum at 2908 cm À1 that is assigned to the CH 3 stretching mode of an acetyl radical species.…”
A dihydro-TTF derivative with four acetyl-protected thiol ligands was synthesised and adsorbed on Au(111) under UHV conditions. Scanning Tunnelling Microscopy (STM) and Infrared (IR) spectroscopy show that self-organised structures are formed following annealing to 333 K, with each pair of bidentate thiolate ligands bonding to a single gold adatom in a S-Auad-S complex. Due to the lack of a direct orbital overlap between the dihydro-TTF moieties and the surface, relatively little charge transfer between TAT-TTF and the gold surface occurs.
“…As expected for its hexakis adduct, one main reduction signal is present in the corresponding CV curve (Zhang et al 2006). This signal was notably shifted toward negative potentials comparing to the values registered for pristine C 60 fullerene (Piotrowski et al 2013), allowing us to conclude that II has significantly lower electron accepting properties when compared to the unmodified C 60 core. Additional small peaks could probably be attributed to traces of fullerene derivatives with a lower number of functional groups.Fig.…”
C60TEMPO10 catalytic system linked to a microspherical gold support through a covalent S-Au bond was developed. The C60TEMPO10@Au composite catalyst had a particle size of 0.5–0.8 μm and was covered with the fullerenes derivative of 2.3 nm diameter bearing ten nitroxyl groups; the organic film showed up to 50 nm thickness. The catalytic composite allowed for the oxidation under mild conditions of various primary and secondary alcohols to the corresponding aldehyde and ketone analogues with efficiencies as high as 79–98%, thus giving values typical for homogeneous catalysis, while retaining at the same time all the advantages of heterogeneous catalysis, e.g., easy separation by filtration from the reaction mixture. The catalytic activity of the resulting system was studied by means of high pressure liquid chromatography. A redox mechanism was proposed for the process. In the catalytic cycle of the oxidation process, the TEMPO moiety was continuously regenerated in situ with an applied primary oxidant, for example, O2/Fe3+ system. The new intermediate composite components and the final catalyst were characterized by various spectroscopic methods and thermogravimetry.
Graphical abstractᅟ
Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-017-3857-z) contains supplementary material, which is available to authorized users.
“…Compounds 1-6 were synthesized according to the method previously reported in the literature 18 for the synthesis of compound 1, with a few variations introduced by us. 16 Compounds 7-12 were synthesized by adapting a simplied method used by us previously to synthesize 4-(S-acetylthiomethyl)benzaldehyde. 16 The preparation of compounds I-VI was accomplished using a modied Prato synthesis.…”
Section: Synthesismentioning
confidence: 99%
“…15 Recently, we demonstrated that thioester-functionalized fullerenes, which generally interact more weakly with the Au(111) surface than thiols, can be used to form SAMs. 16 In the present study, we have investigated the redox properties of fullerene derivatives containing an in situ formed thiol terminal group. Towards this goal, we synthesized a homologous series of new 6,4-(S-acetylthioalkyl)benzaldehydes that could be converted using a Prato reaction with fullerene-C 60 to a series of new alkylthiol-functionalized C 60 -fullerene derivatives (Fig.…”
A series of thioacetyl-functionalized fullerene-C 60 derivatives were synthesized using the Prato reaction of fullerene-C 60 with six different 4-(S-acetylthioalkyl)benzaldehydes. The structures of the synthesized compounds were characterized by FT-IR, 1 H NMR and ESI-MS techniques. The LUMO-HOMO band gaps, derived from DFT B3LYP/6-31G* calculations, for the azomethine ylides corresponding to each 4-(S-acetylthioalkyl)benzaldehyde and fullerene-C 60 were correlated with the efficiency of the Prato reaction. The compounds were deposited onto gold electrodes via self-assembly following an in situ deprotection procedure which transformed the thioacetyl-functionalized compounds into their thiolated derivatives. The redox properties of the C 60 derivatives in solution were characterized using Voltammetry. The LUMO-HOMO band gaps obtained from the electrochemical data were compared with the density functional theory (DFT) values for the optimized structures. The thioacetylfunctionalized C 60 derivatives were employed for the catalytic reduction of halogenated hydrocarbons. Following deprotection, they were also employed for the modification of gold substrates. The solvent dependent barrier properties of the thiolated fullerene films were investigated using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The topography of the C 60 derivative modified electrode was investigated using X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM), which confirmed stable modification of the Au support with a three dimensional (3D) film of worm-like fullerene aggregates.
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