Unexpected Disparity in Photoinduced Reactions of C60 and C70 in Water with the Generation of O2•– or 1O2
Ontology highlight
ABSTRACT:
SUBMITTER: Liosi K
PROVIDER: S-EPMC8549049 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Ionic complexes between gold and C60 have been observed for the first time. Cations and anions of the type [Au(C60)2]+/- are shown to have particular stability. Calculations suggest that these ions adopt a C60-Au-C60 sandwich-like (dumbbell) structure, which is reminiscent of [XAuX]+/- ions previously observed for much smaller ligands. The [Au(C60)2]+/- ions can be regarded as Au(I) complexes, regardless of whether the net charge is positive or negative, but in both cases, the charge transfer between the Au and C60 is incomplete, most likely because of a covalent contribution to the Au-C60 binding. The C60-Au-C60 dumbbell structure represents a new architecture in fullerene chemistry that might be replicable in synthetic nanostructures.
| S-EPMC5964450 | biostudies-literature
Project description:An open-cage fullerene incorporating phosphorous ylid and carbonyl group moieties on the rim of the orifice can be filled with gases (H2 , He, Ne) in the solid state, and the cage opening then contracted in situ by raising the temperature to complete an intramolecular Wittig reaction, trapping the atom or molecule inside. Known transformations complete conversion of the product fullerene to C60 containing the endohedral species. As well as providing an improved synthesis of large quantities of 4 He@C60 , H2 @C60 , and D2 @C60 , the method allows the efficient incorporation of expensive gases such as HD and 3 He, to prepare HD@C60 and 3 He@C60 . The method also enables the first synthesis of Ne@C60 by molecular surgery, and its characterization by crystallography and 13 C NMR spectroscopy.
| S-EPMC8048630 | biostudies-literature
Project description:Perfluorocycloparaphenylenes (PFCPPs) are cycloparaphenylenes (CPPs) in which all hydrogen atoms have been replaced by fluorine atoms. Like CPPs, PFCPPs are highly strained, hoop-shaped π-conjugated molecules. In this article, we report a computational modeling of photoinduced electron transfer processes in the inclusion complex of PF[10]CPP with C60 fullerene. Its unique feature is the favorable electron transfer from C60 to the host molecule. The photooxidation of C60 is predicted to occur on a sub-nanosecond timescale. The PF[10]CPP⊃C60 dyad is the first nanoring-fullerene complex in which C60 acts as an electron donor in the photoinduced charge separation.
| S-EPMC9540460 | biostudies-literature
Project description:The antioxidant potential (capacity and activity) of aqueous fullerene dispersions (AFD) of non-functionalized C60, C70, and Gd@C82 endofullerene (in micromolar concentration range) was estimated based on chemiluminescence measurements of the model of luminol and generation of organic radicals by 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP). The antioxidant capacity was estimated by the TRAP method, from the concentration of half-suppression, and from the suppression area in the initial period. All three approaches agree and show that the antioxidant capacity of AFDs increased in the order Gd@C82 < C70 < C60. Mathematical modeling of the long-term kinetics data was used for antioxidant activity estimation. The effect of C60 and C70 is found to be quenching of the excited product of luminol with ABAP-generated radical and not an actual antioxidant effect; quenching constants differ insignificantly. Apart from quenching with a similar constant, the AFD of Gd@C82 exhibits actual antioxidant action. The antioxidant activity in Gd@C82 is 300-fold higher than quenching constants.
| S-EPMC8199091 | biostudies-literature
Project description:We report the first synthesis of 225Ac (t 1/2 = 10 days) endohedral fullerenes,225Ac@C60. The 225Ac@C60 was produced with a 12 ± 2% efficiency by applying an electrical arc discharge between a source of α-particle emitter 225Ac (∼1 mCi, electroplated on a Pt disk) and a thin coat of "preformed" C60 on an Al disk (C60 thickness of ∼0.25 mg/cm2). After formation by electrical arc discharge, the resulting radiofullerenes on the Al disk were dissolved in toluene under anaerobic conditions and converted to a malonate derivative using the Bingel reaction. Subsequent to repeated washings of the organic phase with dilute acidic solutions to remove exohedral 225Ac, ∼45% of 225Ac activity was retained in the organic phase, which resisted extraction into the aqueous phase. Failure to extract the 225Ac from the organic phase provided definitive evidence that the 225Ac is located inside of the fullerene. The formation of 225Ac@C60 was further confirmed using a classical hot-atom chemistry technique in which the organic phase containing purified endohedral 225Ac@C60 malonate was contacted with fresh dilute acid to repeatedly extract the ionic 4.8 m 221Fr and 45.6 m 213Bi activities (decay daughters of 225Ac), which were released by molecular disruption due to nuclear recoil. The result from the extraction experiments was further supported by a series of thin-layer chromatography and high-pressure liquid chromatography analysis of the organic phase containing 225Ac@C60 or 225Ac@C60 malonate. Taken together, studies show that, like polydentate chelators, single-wall fullerenes are not capable of retaining the 225Ac decay daughters.
| S-EPMC7594009 | biostudies-literature
Project description:The human body contains 60-70% water, depending on age. As a body fluid, it is not only a medium in which physical and chemical processes take place, but it is also one of the active mediators. Water is the richest substance with non-covalent hydrogen bonds. Water molecules, by themselves (in vacuum), are diamagnetic but when organized into clusters, they become diamagnetic or paramagnetic. Also, biomolecules (DNA, collagen, clathrin, and other proteins) have non-covalent hydrogen bonds in their structure. The interaction, as well as signal transmission, between water and biomolecules is achieved through the vibrations of covalent and non-covalent hydrogen bonds, which determine the state and dynamics of conformational changes in biomolecules. Disruptive conformational changes in biomolecules, cells, and tissues lead to their dysfunctionality, so they are a frequent cause of many disorders and diseases. For example, the rearrangement of hydrogen bonding due to mitochondrial disease mutation in cytochrome bc1 disturbs heme bH redox potential and spin state. In order to prevent and repair the dysfunctional conformational changes, a liquid substance was developed based on the second derivative of the C60 molecule (SD-C60), which has classical and quantum properties. The characterization of SD-C60 by UV-VIS-NIR, FTIR, TEM, and AFM/MFM was performed and it is shown that SD-C60 water layers generate vibrations with near-zero phase dispersion which are transmitted through Fibonacci's water chains to biomolecules. In comparison with previously published SD-C60 derivate (3HFWC, size until 10 nm, and 1-5 water layers), the improved formulation (3HFWC-W, size 10-25 nm, and 6-9 water layers) showed multiplied cytotoxic activity against melanoma cell lines of different aggressiveness. Apart from this, the mode of action was preserved and based on an induction of senescence rather than cell death. Importantly, high selectivity towards malignant phenotypes was detected. Observed effects can be ascribed to a machinery of hydrogen bonds, which are generated in SD-C60 and transmitted through water to biomolecules. This approach may open a new field in science and healthcare-a "water-based nanomedicine".
| S-EPMC10745578 | biostudies-literature
Project description:Helium is considered an almost ideal tagging atom for cold messenger spectroscopy experiments. Although helium is bound very weakly to the ionic molecule of interest, helium tags can lead to shifts and broadenings that we recorded near 963.5 nm in the electronic excitation spectrum of C60+ solvated with up to 100 helium atoms. Dedicated quantum calculations indicate that the inhomogeneous broadening is due to different binding energies of helium to the pentagonal and hexagonal faces of C60+, their dependence on the electronic state, and the numerous isomeric structures that become available for intermediate coverage. Similar isomeric effects can be expected for optical spectra of most larger molecules surrounded by nonabsorbing weakly bound solvent molecules, a situation encountered in many messenger-tagging spectroscopy experiments.
| S-EPMC5857924 | biostudies-literature
Project description:The donor-acceptor ability of frustrated Lewis pairs (FLPs) has led to widespread applications in organic synthesis. Single electron transfer from a donor Lewis base to an acceptor Lewis acid can generate a frustrated radical pair (FRP) depending on the substrate and energy required (thermal or photochemical) to promote an FLP into an FRP system. Herein, we report the Csp3-Csp cross-coupling reaction of aryl esters with terminal alkynes using the B(C6F5)3/Mes3P FLP. Significantly, when the 1-ethynyl-4-vinylbenzene substrate was employed, the exclusive formation of Csp3-Csp cross-coupled products was observed. However, when 1-ethynyl-2-vinylbenzene was employed, solvent-dependent site-selective Csp3-Csp or Csp3-Csp2 cross-coupling resulted. The nature of these reaction pathways and their selectivity has been investigated by extensive electron paramagnetic resonance (EPR) studies, kinetic studies, and density functional theory (DFT) calculations both to elucidate the mechanism of these coupling reactions and to explain the solvent-dependent site selectivity.
| S-EPMC8041292 | biostudies-literature
Project description:Aromatic amino acids such as l-tyrosine and l-tryptophan are deployed in natural systems to mediate electron transfer (ET) reactions. While tyrosine oxidation is always coupled to deprotonation (proton-coupled electron-transfer, PCET), both ET-only and PCET pathways can occur in the case of the tryptophan residue. In the present work, two novel conjugates 1 and 2, based on a SnIV tetraphenylporphyrin and SnIV octaethylporphyrin, respectively, as the chromophore/electron acceptor and l-tryptophan as electron/proton donor, have been prepared and thoroughly characterized by a combination of different techniques including single crystal X-ray analysis. The photophysical investigation of 1 and 2 in CH2 Cl2 in the presence of pyrrolidine as a base shows that different quenching mechanisms are operating upon visible-light excitation of the porphyrin component, namely photoinduced electron transfer and concerted proton electron transfer (CPET), depending on the chromophore identity and spin multiplicity of the excited state. The results are compared with those previously described for metal-mediated analogues featuring SnIV porphyrin chromophores and l-tyrosine as the redox active amino acid and well illustrate the peculiar role of l-tryptophan with respect to PCET.
| S-EPMC8252543 | biostudies-literature
Project description:A reliable synthesis of unstable and highly reactive BrO2 F is reported. This compound can be converted into BrO2 + SbF6 - , BrO2 + AsF6 - , and BrO2 + AsF6 - ?2?BrO2 F. The latter decomposes into mixed-valent Br3 O4 ?Br2 + AsF6 - with five-, three-, one-, and zero-valent bromine. BrO2 + H(SO3 CF3 )2 - is formed with HSO3 CF3 . Excess BrO2 F yields mixed-valent Br3 O6 + OSO3 CF3 - with five- and three-valent bromine. Reactions of BrO2 F and MoF5 in SO2 ClF or CH2 ClF result in Cl2 BrO6 + Mo3 O3 F13 - . The reaction of BrO2 F with (CF3 CO)2 O and NO2 produces O2 Br-O-CO-CF3 and the known NO2 + Br(ONO2 )2 - . All of these compounds are thermodynamically unstable.
| S-EPMC6973041 | biostudies-literature