Fullerene Encapsulation Research Articles

Molecular simulation on solubilization of fullerene C60 by C12E6 nonionic surfactants

ABSTRACT Coarse grained simulations were adopted to describe the encapsulation and dispersion of fullerene C 60 by hexaoxyethylene dodecyl ether (C 12 E 6 ) surfactants. The self-organised structures of C 12 E 6 molecules in water were captured and the characteristics of micelles composed of different number of C 12 E 6 molecules were analysed. We found that C 60 molecules alone or in clusters can spontaneously translate into the hydrophobic core of micelles. One monomeric C 60 can explore the hydrocarbon-chain region of the micelles with different sizes, and two different preferential locations of C 60 are observed. The small C 60 clusters can disaggregate after entering the micelle. Larger C 60 clusters can penetrate into the micelle as solid-like nanoparticles, although they are partially disaggregated. When investigating the self-assembly of C 12 E 6 surfactants and C 60 molecules, we found that it is very difficult to disperse C 60 in the micelle monomolecularly. At high molar ratio of C 12 E 6 /C 60 , colloidal nanoC 60 aggregates form with C 12 E 6 surfactants adsorbed on the surface. Our simulations provide an explanation for the different observations in fullerene solubilization in micellar solutions and give a guideline for further solubilization of pristine fullerene or small hydrophobic molecules with surfacant micelles, which is helpful for the design of new micelle-based delivery vehicles.

Continuum modelling of fullerene encapsulation inside two-section carbon and boron nitride nanotubes

Continuum modelling of fullerene encapsulation inside two-section carbon and boron nitride nanotubes

Multicomponent, Multicavity Metallacages That Contain Different Binding Sites for Allosteric Recognition.

The encapsulation of different guest molecules by their different recognition domains of proteins leads to selective binding, catalysis, and transportation. Synthetic hosts capable of selectively binding different guests in their different cavities to mimic the function of proteins are highly desirable but challenging. Here, we report three ladder-shaped, triple-cavity metallacages prepared by multicomponent coordination-driven self-assembly. Interestingly, the porphyrin-based metallacage is capable of heteroleptic encapsulation of fullerenes (C60 or C70) and coronene using its different cavities, allowing distinct allosteric recognition of coronene upon the addition of C60 or C70. Owing to the different binding affinities of the cavities, the metallacage hosts one C60 molecule in the central cavity and two coronene units in the side cavities, while encapsulating two C70 molecules in the side cavities and one coronene molecule in the central cavity. The rational design of multicavity assemblies that enable heteroleptic encapsulation and allosteric recognition will guide the further design of advanced supramolecular constructs with tunable recognition properties.

Reduction of thermal conductivity in carbon nanotubes by fullerene encapsulation from machine-learning molecular dynamics simulations

The carbon nano-peapod is a representative structure with interlayer van der Waals (vdW) interactions, in which encapsulated fullerene molecules play a critical role in modulating the transport properties of the carbon nanotubes (CNTs). In particular, their influence on the thermal transport characteristics has been the focal point of considerable attention. In this study, we trained an accurate machine learning potential for fullerene-encapsulated CNTs based on the efficient NEP model to investigate their thermal properties. Using equilibrium molecular dynamics simulation along with the spectral decomposition method for thermal conductivity, we find that the thermal conductivity of fullerene-encapsulated CNTs is roughly 55% lower than that of empty CNTs, aligning with experimental observations for CNT bundles with fullerene encapsulation [Kodama et al., Nat. Mater. 16, 892 (2017)]. The research suggests that weak vdW interactions between both the fullerene and CNTs, as well as between fullerene molecules themselves, hinder phonon propagation. The encapsulated fullerene contributes to an increase in phonon scattering within the CNTs, ultimately leading to a reduction in thermal conductivity. We utilized machine learning potential to investigate the structure of fullerene-encapsulated CNTs and their heat transport property. This approach provides valuable insights for performance research of complex systems featuring interlayer vdW interactions.

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages

AbstractChiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host–guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R‐PAC‐2, S‐PAC‐2 (with Br substituents) and R‐PAC‐3, S‐PAC‐3 (with CH3 substituents) enantiomers. PAC‐2, rather than PAC‐3, achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R‐PAC‐2, S‐PAC‐2 and fullerenes is confirmed by single‐crystal X‐ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face‐to‐face arene‐fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages.

Chiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host-guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R-PAC-2, S-PAC-2 (with Br substituents) and R-PAC-3, S-PAC-3 (with CH3 substituents) enantiomers. PAC-2, rather than PAC-3, achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R-PAC-2, S-PAC-2 and fullerenes is confirmed by single-crystal X-ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face-to-face arene-fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.

Unraveling the role of fullerene encapsulation driven CO2 capture in square pillared Bio-HOF under humid condition by advanced molecular simulation

Despite several interesting adsorbent materials, it is difficult to capture CO2 from point sources in industrial settings without removing humidity. Herein, we investigated the detailed adsorption of CO2 in the presence of humidity for a specifically designed material, which is known as Bio-Hydrogen bonded Organic Framework (Bio-HOFs). Specifically, the designed Bio-HOFs are made up of purine bases as organic ligands, supported with SiF6 pillar and connected via intermolecular hydrogen bonds. The strength of H-bonds in Bio-HOFs is screened with the aid of electron density measurement (Atom in Molecule) of optimized structure from advanced Density Functional Theory (DFT). Subsequently, Grand canonical Monte Carlo (GCMC) simulation was employed to estimate the CO2 uptake of Bio-HOFs and performed co-adsorptions in the presence of humidity at 298 K. Further, novel HOFs are envisaged by incorporating C60 fullerene to enhance zig-zag channels in Bio-HOFs. The resulting Bio-HOF@C60 further exhibits anomalous selectivity with higher values of screening parameters. In addition, the impact of the insertion of C60 fullerene in Bio-HOFs on the uptake of CO2 and the exceptional retention span of CO2 over N2 in SIFSIX-Cu-Adenine@C60 in the presence of humidity are highlighted.

Nanoscale Saturn Systems Based on C60/70 Bucky Ball and a Newly Designed [4]Cyclopara-1,2-diphenylethylene Hoop: A Strategy for Fullerene Encapsulation Release and Selective Recognition for C70.

A new carbonaceous nanohoop, [4]cyclopara-1,2-diphenylethylene ([4]CPDPE, composed by four 1,2-diphenylethylene units linked via the para of the phenyls), is designed together with two rational synthesis paths being proposed. The Saturn-like host-guest systems formed with the [4]CPDPE nanoring and fullerene C60/70 are explored using density functional theory calculations. The results evidence that the geometry mutual matching between [4]CPDPE and C60/70 is perfect, and the [4]CPDPE⊃C60/70 complexes could be formed spontaneously with high binding energies. Thermodynamic calculation results show that it essentially prefers to selectively recognize C70 over its smaller cousin C60. More interestingly, the [4]CPDPE nanoring could present the regular ring cylinder and the saddle shapes via configuration transformation between its all-trans form and all-cis form, so as to theoretically realize the fullerene encapsulation and release under photoirradiation. Furthermore, the 2:1 interaction structure ([4]CPDPE2⊃Dimer-C60) and properties are investigated. Additionally, the ultraviolet-visible (UV-vis) spectra are simulated, and host-guest noncovalent interaction (NCI) regions are investigated based on the electron density and reduced density gradient (RDG), which may be helpful for a deep understanding of the present designed systems in future.

Improving the molecular spin qubit performance in zirconium MOF composites by mechanochemical dilution and fullerene encapsulation.

Enlarging the quantum coherence times and gaining control over quantum effects in real systems are fundamental for developing quantum technologies. Molecular electron spin qubits are particularly promising candidates for realizing quantum information processing due to their modularity and tunability. Still, there is a constant search for tools to increase their quantum coherence times. Here we present how the mechanochemical introduction of active spin qubits in the form of 10% diluted copper(ii)-porphyrins in the diamagnetic PCN-223 and MOF-525 zirconium-MOF polymorph pair can be achieved. Furthermore, the encapsulation of fullerene during the MOF synthesis directs the process exclusively toward the rare PCN-223 framework with a controllable amount of fullerene in the framework channels. In addition to the templating role, the incorporation of fullerene increases the electron spin-lattice and phase-memory relaxation times, T1 and Tm. Besides decreasing the amount of nuclear spin-bearing solvent guests in the non-activated qubit frameworks, the observed improved relaxation times can be rationalized by modulating the phonon density of states upon fullerene encapsulation.

Modulation of thermal conductivity of single-walled carbon nanotubes by fullerene encapsulation: the effect of vacancy defects.

Single-walled carbon nanotubes (SWCNTs) possess extremely high thermal conductivity that benefits their application in high-performance electronic devices. The characteristic hollow configuration of SWCNTs is not favorable for the buckling stability of the structure, which is typically resolved by fullerene encapsulation in practice. To investigate the fullerene encapsulation effect on thermal conductivity, we perform molecular dynamics simulations to comparatively study the thermal conductivity of pure SWCNTs and fullerene encapsulated SWCNTs. We focus on disclosing the relationship between the vacancy defect and the fullerene encapsulation effect on thermal conductivity. It is quite interesting that vacancy defects weaken the coupling strength between the nanotube shell and the fullerene, especially for narrower SWCNTs (9, 9), which will considerably reduce the effect of fullerene encapsulation on the thermal conductivity of narrower SWCNTs. However, for thicker SWCNTs (10, 10) and (11, 11), vacancy defects have an ignorable effect on the coupling strength between the nanotube shell and the fullerene due to plenty of free space in thicker SWCNTs, so vacancy defects are not important for the fullerene encapsulation effect on the thermal conductivity of thicker SWCNTs. These findings shall be valuable for the application of SWCNTs in thermoelectric fields.

Rational Construction of Electrically Conductive Covalent Organic Frameworks through Encapsulating Fullerene via Donor-Acceptor Interaction.

A new kind of perylene-based 2D covalent organic framework (COF) is designed and synthesized based on the C2 + C2 topological diagram. The perylene-based COF is constructed via the condensation reaction using 2,5,8,11-tetrakis((4-formylphenyl) perylene (TFPPer) and 2,5,8,11-tetrakis(4-aminophenyl) perylene (TAPPer) as building blocks. The resulting TFPPer-TAPPer-COF features high crystallinity, excellent stability, intrinsic porosity, and an electron-rich skeleton. Significantly, the electrical performance of the COF can be enhanced through the encapsulation of fullerene (C60 ) into the 1D channels via donor-acceptor interaction. Compared to the pristine COF, the electrical conductivity of C60 @TFPPer-TAPPer-COF can be greatly increased from 8.98 × 10-8 to 1.59 × 10-5 S cm-1 , meanwhile the carrier mobility rises from 1.04 × 10-3 to 4.23 × 10-2 cm2 V-1 s-1 . The improvement in electrical performance stems from the strong donor-acceptor interaction between perylene and C60 . These results provide insights into the rational construction of conductive COFs through donor-acceptor interaction and demonstrate their great potential in related application fields.

Dramatically Enhanced Reactivity of Fullerenes and Tetrazine towards the Inverse-Electron-Demand Diels-Alder Reaction inside a Porous Porphyrinic Cage.

Inverse-electron-demand Diels-Alder reaction (IEDDA) between fullerenes and 1,2,4,5-tetrazine generally requires harsh conditions and long reaction times due to their strong electron-accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C60 /C70 )-tetrazine reaction inside a porous Zn-porphyrinic cage (Zn-PB) under sustainable conditions by installing a tetrazine-based axle (LA) via metal-ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene-tetrazine adducts. Furthermore, the C60 -tetrazine adduct is rearranged upon hydration to a bent-shaped C60 -pyrazoline adduct that can be released from the Zn-PB cavity in the presence of excess LA, thus catalyzing the formation of C60 -pyrazoline adduct inside Zn-PB without product inhibition.

Dramatically Enhanced Reactivity of Fullerenes and Tetrazine towards the Inverse‐Electron‐Demand Diels–Alder Reaction inside a Porous Porphyrinic Cage

AbstractInverse‐electron‐demand Diels–Alder reaction (IEDDA) between fullerenes and 1,2,4,5‐tetrazine generally requires harsh conditions and long reaction times due to their strong electron‐accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C60/C70)‐tetrazine reaction inside a porous Zn‐porphyrinic cage (Zn‐PB) under sustainable conditions by installing a tetrazine‐based axle (LA) via metal‐ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene‐tetrazine adducts. Furthermore, the C60‐tetrazine adduct is rearranged upon hydration to a bent‐shaped C60‐pyrazoline adduct that can be released from the Zn‐PB cavity in the presence of excess LA, thus catalyzing the formation of C60‐pyrazoline adduct inside Zn‐PB without product inhibition.

C–H⋯S Hydrogen Bond Assisted Supramolecular Encapsulation of Fullerenes with Nanobelts

C–H⋯S Hydrogen Bond Assisted Supramolecular Encapsulation of Fullerenes with Nanobelts

Effect of encapsulation of fullerene in semiconducting zigzagcarbon nanotubes on optical and thermoelectric properties

We study the optical and thermoelectric properties of carbon nanotubes (CNTs) with encapsulated C60 fullerene molecules. Using ab-initio methods, we calculate optical and thermoelectric paramters for CNT with fullerenes periodically located inside the nanotube at different distances from each other. Dependencies of these parameters on fullerene concentration and diameter of CNT are analyzed.

Strain-induced band modulation of thermal phonons in carbon nanotubes

We show that carbon nanopeapods are an ideal artificial superlattice to induce band modulation of thermal phonons. Based on spectral energy density analysis, we found that a periodic deformation in carbon nanotubes induced by fullerene encapsulation leads to zone folding of phonon dispersions up to near the maximum frequency. The zone-folding effect gives rise to phonon band gaps caused either by Bragg reflection or mode hybridization, and this reduces group velocity. This was quantified to play the leading role in reduction of thermal conductivity by the fullerene encapsulation. The strain modulation of thermal phonon bands opens a possibility to control material thermal conductivity.

Влияние инкапсуляции фуллеренов на оптические и термоэлектрические свойства углеродных нанотрубок

The hybrid systems based on the carbon nanotubes (CNT) and fullerenes (nanopipodes) are promising for applications in nanoelectronics. With insignificant variation of the CNT diameter the change of the fullerenes geometry takes place. The periodically located inside fullerenes represent a set of quantum points in the one-dimensional super-lattice. Using the variation of inside fullerenes it is possible to modulate the zone structure of the CNT – fullerene system and to control the electronic and phonon characteristics of nanopipodes. In the work the optical and thermoelectric properties of CNT with encapsulated molecules of C60 fullerene have been investigated. Using the first-principle methods the coefficients of absorption, optical conductivi-ty, thermal conductivity, thermoelectric figure of merit for CNT with fullerenes, periodically lo-cated inside the nanotubes at different distances from each other, have been calculated. It has been shown that with decreasing the distance between fullerenes the optical conductivity of CNT – C60 is suppressed at high frequencies. It has been determined that the conductance of the structures with fullerenes is less than the conductance of a clean tube, and approximately equal for considered distances (12.3 and 19.7 Å) between fullerenes. The CNT thermal conductivity due to the encapsulation of fullerenes considerably (3–4 times) decreases for the considered CNT (8.8) – C60 systems.

A self-assembled M2L2 truncated square and its application as a container for fullerenes.

An unprecedented bisthianthrene dipyridyl ligand was designed and synthesized for coordination driven self-assembly. The combination of this conformationally dynamic linker with a 90° convergent metal corner exclusively afforded a novel M2L2 truncated square-like metallamacrocycle. The single crystal X-ray structure reveals a belt-shaped geometry with a cavity diameter of ca. 13.7 Å. The breathable cavity and electron-rich thianthreno panels enable the highly efficient binding of the fullerenes C60 (Ka = 5.1 × 106 M-1) and C70 (Ka = 3.7 × 106 M-1). The encapsulation of C60 is fully confirmed by NMR, mass spectroscopy and single crystal X-ray diffraction analyses. The cyclic voltammograms further reveal that the truncated square is redox active. The strong binding affinity, adaptive complexation, and redox activity of the thianthrene-incorporated metallamacrocycle provide new insights into the design of supramolecular hosts.

SR-FTIR spectro-microscopic interaction study of biochemical changes in HeLa cells induced by Levan-C60, Pullulan-C60, and their cholesterol-derivatives

Objects of the present study are improved fullerene C60 drug carrier properties trough encapsulation by microbial polysaccharides, levan (LEV), pullulan (PUL), and their hydrophobized cholesterol-derivatives (CHL and CHP), that show better interaction with cancer cells. The zeta potential, polydispersity index, and the diameter of particles were determined, and their cytotoxicity against three cancer cell lines were tested. Biochemical changes in HeLa cells are analyzed by synchrotron radiation (SR) FTIR spectro-microscopy combined with the principal component analysis (PCA). The most significant changes occur in HeLa cells treated with LEV-C60 and correspond to the changes in the protein region, i.e. Amide I band, and the changes in the structure of lipid bodies and membrane fluidity are evident. The highest cytotoxicity was also induced by LEV-C60. In HeLa cells, cytotoxicity could not be strictly associated with biochemical changes in lipids, proteins and nucleic acids, but these findings are significant contribution to the study of the mechanism of interaction of C60-based nanoparticles with cellular biomolecules. In conclusion, LEV, PUL, CHL, and CHP enhanced fullerene C60 potential to be used as target drug delivery system with the ability to induce specific intracellular changes in HeLa cancer cells.

Theoretical Prediction on a Novel Reduction-Responsive Nanoring Having a Disulfide Group for Facile Encapsulation and Release of Fullerenes C60 and C70

In this work, a novel reduction-responsive disulfide bond-containing cycloparaphenylene nanoring molecule (DSCPP) with a pyriform shape has been designed. In addition, the interactions between the designed nanoring (host) and fullerenes C60 and C70 (guests) were investigated theoretically at the M06-2X/6-31G(d,p) and M06-L/MIDI! levels of theory. By analyzing geometric characteristics and host–guest binding energies, it is revealed that the designed DSCPP is an ideal host molecule of guests C60 and C70. DSCPP presents excellent elastic deformation during the encapsulation of C60 and C70. The high binding energies suggest that both DSCPP⊃C60 and DSCPP⊃C70 (∼92 and 118 kJ·mol–1 at the M06-2X/6-31G(d,p) level of theory) are stable host–guest complexes, and the guest C70 is more strongly encapsulated than C60 in the gas phase. The thermodynamic information indicates that the formation of the two host–guest complexes is thermodynamically spontaneous. In addition, the frontier molecular orbital (FMO) features and intermolecular weak interaction region between DSCPP and fullerenes gusts are discussed to further understand the structures and properties of the DSCPP⊃fullerene systems. Finally, the ring-opening mechanism of the DSCPP under reduction conditions is investigated.