Synthesis, Photophysical and Supramolecular Properties of a π-Conjugated Molecular Crown Containing a Pentagonal Unit: A Model Compound for Fullerene C240

The total synthesis of carbon onions is a significant challenge in the fields of materials science and organic chemistry. To date, the synthesis of even a fragment of fullerene C240 and its smallest carbon onion C60@C240 remains poorly explored. Herein, we demonstrate a bottom-up strategy to produce a novel π-extended molecular crown-shaped molecule (MC3) containing curved pentagonal and hexagonal units. This molecular crown represents a curved model compound for fullerene C240 and is fully characterized by NMR, mass spectrometry, UV-vis absorption, and from its emission spectra. Its supramolecular host–guest interaction with fullerene C60 is also investigated. MC3 and C60@MC3 can potentially be employed as seeds or templates for the bottom-up synthesis of fullerene C240 and the carbon onion C60@C240, respectively.

Synthesis of Carbon Onion and Its Application as a Porous Carrier for Amorphous Drug Delivery

Given the great potential of porous carrier-based drug delivery for stabilising the amorphous form of drugs and enhancing dissolution profiles, this work is focussed on the synthesis and application of carbon onion or onion-like carbon (OLC) as a porous carrier for oral amorphous drug delivery, using paracetamol (PA) and ibuprofen (IBU) as model drugs. Annealing of nanodiamonds at 1100 °C produced OLC with a diamond core that exhibited low cytotoxicity on Caco-2 cells. Solution adsorption followed by centrifugation was used for drug loading and results indicated that the initial concentration of drug in the loading solution needs to be kept below 11.5% PA and 20.7% IBU to achieve complete amorphous loading. Also, no chemical interactions between the drug and OLC could be detected, indicating the safety of loading into OLC without changing the chemical nature of the drug. Drug release was complete in the presence of sodium dodecyl sulphate (SDS) and was faster compared to the pure crystalline drug, indicating the potential of OLC as an amorphous drug carrier.

Improved Electro-Grafting of Nitropyrene onto Onion-like Carbon via in Situ Electrochemical Reduction and Polymerization: Tailoring Redox Energy Density of the Supercapacitor Positive Electrode

<div>Herein, we report a improved method for the physical grafting of 1-nitropyrene (Pyr-NO2) onto highly graphitized carbon onion. This is achieved through a lowering of the onset potential of the pyrene polymerization via in situ reduction of the NO2 group. The additional redox activity pertaining to the reduced NO2 enables exceeding the faradaic capacity which is associated with the p-doping of the grafted pyrene backbone, as observed for pyrene, 1-aminopyrene, and unreduced Pyr-NO2. Theoretical calculations demonstrate the charge transfer and binding enthalpy capabilities of Pyr-NO2, which are significantly higher than those of the other two species, and which allow for improved p-stacking on the carbon surface. Upon 20 wt % grafting of Pyr-NO2, the capacity of the electrode jumps from 20 mAh g-1 electrode to 38 mAh g-1</div><div>electrode, which corresponds to 110 mAh g-1 per mass of Pyr-NO2 and the average potential is increased by 200 mV. Very interestingly, this high performance is also coupled with outstanding retention with respect to both the initial capacity for more than 4000 cycles, as well as the power characteristics, demonstrating the considerable advantages of employing the present in situ grafting technique.</div>

Improved Electro-Grafting of Nitropyrene onto Onion-like Carbon via in Situ Electrochemical Reduction and Polymerization: Tailoring Redox Energy Density of the Supercapacitor Positive Electrode

<div>Herein, we report a improved method for the physical grafting of 1-nitropyrene (Pyr-NO2) onto highly graphitized carbon onion. This is achieved through a lowering of the onset potential of the pyrene polymerization via in situ reduction of the NO2 group. The additional redox activity pertaining to the reduced NO2 enables exceeding the faradaic capacity which is associated with the p-doping of the grafted pyrene backbone, as observed for pyrene, 1-aminopyrene, and unreduced Pyr-NO2. Theoretical calculations demonstrate the charge transfer and binding enthalpy capabilities of Pyr-NO2, which are significantly higher than those of the other two species, and which allow for improved p-stacking on the carbon surface. Upon 20 wt % grafting of Pyr-NO2, the capacity of the electrode jumps from 20 mAh g-1 electrode to 38 mAh g-1</div><div>electrode, which corresponds to 110 mAh g-1 per mass of Pyr-NO2 and the average potential is increased by 200 mV. Very interestingly, this high performance is also coupled with outstanding retention with respect to both the initial capacity for more than 4000 cycles, as well as the power characteristics, demonstrating the considerable advantages of employing the present in situ grafting technique.</div>