[60]Fullerene−Pyrrolidine-N-oxides

Porous substrates as platforms for the nanostructuring of molecular magnets

This article highlights recent advances in the newly emerging field on the nanostructuration of molecular magnets using porous substrates.

Relative Stability of Empty Exohedral Fullerenes: π Delocalization versus Strain and Steric Hindrance

Predicting and understanding the relative stability of exohedral fullerenes is an important aspect of fullerene chemistry, since the experimentally formed structures do not generally follow the rules that govern addition reactions or the making of pristine fullerenes. First-principles theoretical calculations are of limited applicability due to the large number of possible isomeric forms, for example, more than 50 billion for C₆₀X₈. Here we propose a simple model, exclusively based on topological arguments, that allows one to predict the relative stability of exohedral fullerenes without the need for electronic structure calculations or geometry optimizations. The model incorporates the effects of π delocalization, cage strain, and steric hindrance. We show that the subtle interplay between these three factors is responsible for (i) the formation of non-IPR (isolated pentagon rule) exohedral fullerenes in contrast with their pristine fullerene counterparts, (ii) the appearance of more pentagon-pentagon adjacencies than predicted by the PAPR (pentagon-adjacency penalty rule), (iii) the changes in regioisomer stability due to the chemical nature of the addends, and (iv) the variations in fullerene cage stability with the progressive addition of chemical species.

A magnetoreception system constructed by a dysprosium metallofullerene and nitroxide radical

A site-specific magnetoreception system between Dy₃N@C₈₀ and nitroxide radical through spin-paramagnet interaction.

Controlling the magnetic properties of dysprosium metallofullerene within metal–organic frameworks

The hysteresis and quantum tunneling of magnetism for a metallofullerene DySc₂N@C₈₀ single-molecule magnet were modulated through trapping in MOF-177.

Molecular magnetic switch for a metallofullerene

The endohedral fullerenes lead to well-protected internal species by the fullerene cages, and even highly reactive radicals can be stabilized. However, the manipulation of the magnetic properties of these radicals from outside remains challenging. Here we report a system of a paramagnetic metallofullerene Sc₃C₂@C₈₀ connected to a nitroxide radical, to achieve the remote control of the magnetic properties of the metallofullerene. The remote nitroxide group serves as a magnetic switch for the electronic spin resonance (ESR) signals of Sc₃C₂@C₈₀ via spin–spin interactions. Briefly, the nitroxide radical group can ‘switch off’ the ESR signals of the Sc₃C₂@C₈₀ moiety. Moreover, the strength of spin–spin interactions between Sc₃C₂@C₈₀ and the nitroxide group can be manipulated by changing the distance between these two spin centres. In addition, the ESR signals of the Sc₃C₂@C₈₀ moiety can be switched on at low temperatures through weakened spin–lattice interactions.

Endohedral fullerenes are known to stabilize reactive radicals; however, the external magnetic manipulation of these species’ remains challenging. Here, the authors link a nitroxide radical to a paramagnetic fullerene system and are able to alter the spin behaviour of the fullerene via spin–spin interactions.

Theoretical investigation of an energetic fullerene derivative

A self-consistent estimation method for the thermochemical properties of N-methyl-3-(2',4',6'-trinitrobenzene)-fulleropyrrolidine (MTNBFP) is presented. This method is based on enthalpy of formation (Delta(f)H(m)(minus sign in circle)) and enthalpy of combustion obtained from BLYP/DNP calculations of the total energies and frequencies for MTNBFP. The enthalpy of formation was calculated by an optimized set of isodesmic reactions given the available experimental Delta(f)H(m)(minus sign in circle) of relative compounds. MTNBFP has a high enthalpy of formation, 2782.2 kJ/mol. Detonation velocity and detonation pressure were also presented in terms of Kamlet and Jacobs equations. Drop hammer impact sensitivity tests and blasting point per 5 s tests indicate MTNBFP may be a potential candidate primary explosive. To understand the test results well, we proposed a series of chemical reaction mechanisms and interpreted the relationship between impact sensitivity and electronic structures from the viewpoint of nitro group charge, electrostatic potential, and vibrational modes.

Stabilization of fulleropyrrolidine N-oxides through intrarotaxane hydrogen bonding

The chemical stabilization of labile fulleropyrrolidine N-oxides is achieved by encapsulation through intrarotaxane hydrogen bonding.