Depth profiling of polymer samples using Ga+ and C60+ ion beams

In this contribution, we focus on the use of C₆₀⁺ ions for depth profiling of model synthetic polymers: polystyrene (PS) and poly(methylmethacrylate) (PMMA). These polymers were spin coated on silicon wafers, and the obtained samples were depth‐profiled both with Ga⁺ ions and C₆₀⁺ ions. We observed an important yield enhancement for both polymers when C₆₀⁺ ions are used. More specifically, we discuss here the decrease in damage obtained with C₆₀, which is found to be very sensitive to the nature of the polymer. During the C₆₀⁺ sputtering of the PMMA layer, after an initial decrease, a steady state is observed in the secondary ion yield of characteristic fragments. In contrast, for PS, an exponential decrease is directly observed, leading to an initial disappearance cross section close to the value observed for Ga⁺. Though there is a significant loss of characteristic PS signal when sputtering with C₆₀⁺ ions beams, there are still significant enhancements in sputter yields when employing C₆₀⁺ as compared to Ga⁺. Copyright © 2008 John Wiley & Sons, Ltd.     

New approaches for the synthesis of hindered C60‐containing polyphosphazenes via functionalized intermediates

Two new approaches were developed to synthesize C₆₀‐containing polyphosphazenes. Accordingly, two new reactive macromolecular intermediates ( P4 and P8 ) were obtained from poly(dichlorophosphazene) by the direct nucleophilic substitution reaction. In one approach, a predesigned amimo end–functionalized polyphosphazene ( P4 ) was prepared and then reacted with C₆₀ molecules in chlorobenzene to yield C₆₀‐containing polyphosphazene; in the other approach, a polyphosphazene containing 4‐methyl phenoxy groups as side chains was first prepared, and then part of the 4‐methyl groups were converted to azidomethyl groups (in P8 ), which reacted with C₆₀ to yield C₆₀‐containing polyphosphazene. The polymers were characterized by ¹H NMR, ¹³C NMR, IR, and UV–visible spectra and by gel permeation chromatography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2877–2885, 2004     

Photosynthetic Antenna‐Reaction Center Mimicry with a Covalently Linked Monostyryl Boron‐Dipyrromethene–Aza‐Boron‐Dipyrromethene–C60 Triad

An efficient functional mimic of the photosynthetic antenna‐reaction center has been designed and synthesized. The model contains a near‐infrared‐absorbing aza‐boron‐dipyrromethene (ADP) that is connected to a monostyryl boron‐dipyrromethene (BDP) by a click reaction and to a fullerene (C₆₀) using the Prato reaction. The intramolecular photoinduced energy and electron‐transfer processes of this triad as well as the corresponding dyads BDP‐ADP and ADP‐C₆₀ have been studied with steady‐state and time‐resolved absorption and fluorescence spectroscopic methods in benzonitrile. Upon excitation, the BDP moiety of the triad is significantly quenched due to energy transfer to the ADP core, which subsequently transfers an electron to the fullerene unit. Cyclic and differential pulse voltammetric studies have revealed the redox states of the components, which allow estimation of the energies of the charge‐separated states. Such calculations show that electron transfer from the singlet excited ADP (¹ADP*) to C₆₀ yielding ADP^.+‐C₆₀^.? is energetically favorable. By using femtosecond laser flash photolysis, concrete evidence has been obtained for the occurrence of energy transfer from ¹BDP* to ADP in the dyad BDP‐ADP and electron transfer from ¹ADP* to C₆₀ in the dyad ADP‐C₆₀. Sequential energy and electron transfer have also been clearly observed in the triad BDP‐ADP‐C₆₀. By monitoring the rise of ADP emission, it has been found that the rate of energy transfer is fast (≈10¹¹ s^?1). The dynamics of electron transfer through ¹ADP* has also been studied by monitoring the formation of C₆₀ radical anion at 1000 nm. A fast charge‐separation process from ¹ADP* to C₆₀ has been detected, which gives the relatively long‐lived BDP‐ADP^.+C₆₀^.? with a lifetime of 1.47 ns. As shown by nanosecond transient absorption measurements, the charge‐separated state decays slowly to populate mainly the triplet state of ADP before returning to the ground state. These findings show that the dyads BDP‐ADP and ADP‐C₆₀, and the triad BDP‐ADP‐C₆₀ are interesting artificial analogues that can mimic the antenna and reaction center of the natural photosynthetic systems.     

C60‐Mediated Molecular Shape Sorting: Separation and Purification of Geometrical Isomers

A supramolecular crystallization‐based approach has been developed for the shape‐dependent separation of geometrical isomers under near‐ambient conditions. Difficulties to separate such isomers arise because of their very similar physical properties. The present approach relies on the ability of C₆₀ to preferentially form solvate crystals with molecules of a specific geometry. Subsequently, these molecules are released upon mild heating to regenerate pure C₆₀. By taking isomers of xylene and trimethylbenzene (TMB) as examples, we show that one of the isomers can be extracted from the rest with very high purity. To separate TMB isomers, a new C₆₀–1,3,5‐TMB solvate was developed, which led to the isolation of isomer purities greater than 99.6 %. Versatility, a low operating temperature of approximately 100 °C, a separation efficiency of more than 10 weight % of C₆₀ per cycle, and reagent recyclability makes this a promising molecular shape‐sorting approach.     

Almost Enclosed Buckyball Joints: Synthesis,Complex Formation,and Computational Simulations of Pentypticene‐Extended Tribenzotriquinacene

We report the synthesis of a tribenzotriquinacene‐based (TBTQ) receptor ( 3 ) for C₆₀ fullerene, which is extended by pentiptycene moieties to provide an almost enclosed concave ball bearing. The system serves as a model for a self‐assembling molecular rotor with a flexible and adapting stator. Unexpectedly, nuclear magnetic resonance spectroscopic investigations reveal a surprisingly low complex stability constant of K₁=213±37 M ^?1 for [C₆₀? 3 ], seemingly inconsistent with the previously reported TBTQ systems. Molecular dynamics (MD) simulations have been conducted for three different [C₆₀?TBTQ] complexes to resolve this. Because of the dominating dispersive interactions, the binding energies increase with the contact area between guest and host, however, only for rigid host structures. By means of free‐energy calculations with an explicit solvent model it can be shown that the novel flexible TBTQ receptor 3 binds weakly because of hampering entropic contributions.     

Stacking‐Layer‐Number Dependence of Water Adsorption in 3D Ordered Close‐Packed g‐C3N4 Nanosphere Arrays for Photocatalytic Hydrogen Evolution

Water adsorption capacity is a key factor to influence the photocatalytic H₂ evolution activity of polymeric g‐C₃N₄ . Herein, we report the synthesis of 3D ordered close‐packed g‐C₃N₄ nanosphere arrays (CNAs) that significantly enhance the water adsorption capacity. Through precisely controlling the average stacking‐layer number (ASLN) of the nanospheres in CNAs, we reveal an interesting stacking‐layer‐number dependence of water adsorption in the newly designed CNAs for accelerating the H₂ evolution reaction, which can be attributed to the differences in adsorption surface areas and adsorption sites endowed by the point‐defect cavities in sample CNAs.     

Energy‐Funneling‐Based Broadband Visible‐Light‐Absorbing Bodipy–C60 Triads and Tetrads as Dual Functional Heavy‐Atom‐Free Organic Triplet Photosensitizers for Photocatalytic Organic Reactions

C₆₀–bodipy triads and tetrads based on the energy‐funneling effect that show broadband absorption in the visible region have been prepared as novel triplet photosensitizers. The new photosensitizers contain two or three different light‐harvesting antennae associated with different absorption wavelengths, resulting in a broad absorption band (450–650 nm). The panchromatic excitation energy harvested by the bodipy moieties is funneled into a spin converter (C₆₀), thus ensuring intersystem crossing and population of the triplet state. Nanosecond time‐resolved transient absorption and spin density analysis indicated that the T₁ state is localized on either C₆₀ or the antennae, depending on the T₁ energy levels of the two entities. The antenna‐localized T₁ state shows a longer lifetime (τ_T=132.9 μs) than the C₆₀‐localized T₁ state (ca. 27.4 μs). We found that the C₆₀ triads and tetrads can be used as dual functional photocatalysts, that is, singlet oxygen (¹O₂) and superoxide radical anion (O₂ ^{. ?}) photosensitizers. In the photooxidation of naphthol to juglone, the ¹O₂ photosensitizing ability of the C₆₀ triad is a factor of 8.9 greater than the conventional triplet photosensitizers tetraphenylporphyrin and methylene blue. The C₆₀ dyads and triads were also used as photocatalysts for O₂ ^{. ?}‐mediated aerobic oxidation of aromatic boronic acids to produce phenols. The reaction times were greatly reduced compared with when [Ru(bpy)₃Cl₂] was used as photocatalyst. Our study of triplet photosensitizers has shown that broadband absorption in the visible spectral region and long‐lived triplet excited states can be useful for the design of new heavy‐atom‐free organic triplet photosensitizers and for the application of these triplet photosensitizers in photo‐organocatalysis.     

Fullerol–Titania Charge‐Transfer‐Mediated Photocatalysis Working under Visible Light

The development of visible‐light‐active photocatalysts is being investigated through various approaches. In this study, C₆₀‐based sensitized photocatalysis that works through the charge transfer (CT) mechanism is proposed and tested as a new approach. By employing the water‐soluble fullerol (C₆₀(OH)_x) instead of C₆₀, we demonstrate that the adsorbed fullerol activates TiO₂ under visible‐light irradiation through the “surface–complex CT” mechanism, which is largely absent in the C₆₀/TiO₂ system. Although fullerene and its derivatives have often been utilized in TiO₂‐based photochemical conversion systems as an electron transfer relay, their successful photocatalytic application as a visible‐light sensitizer of TiO₂ is not well established. Fullerol/TiO₂ exhibits marked visible photocatalytic activity not only for the redox conversion of 4‐chlorophenol, I^?, and Cr^VI, but also for H₂ production. The photoelectrode of fullerol/TiO₂ also generates an enhanced anodic photocurrent under visible light as compared with the electrodes of bare TiO₂ and C₆₀/TiO₂, which confirms that the visible‐light‐induced electron transfer from fullerol to TiO₂ is particularly enhanced. The surface complexation of fullerol/TiO₂ induced a visible absorption band around 400–500 nm, which was extinguished when the adsorption of fullerol was inhibited by fluorination of the surface of TiO₂. The transient absorption spectroscopic measurement gave an absorption spectrum ascribed to fullerol radical cations (fullerol^.+) the generation of which should be accompanied by the proposed CT. The theoretical calculation regarding the absorption spectra for the (TiO₂ cluster+fullerol) model also confirmed the proposed CT, which involves excitation from HOMO (fullerol) to LUMO (TiO₂ cluster) as the origin of the visible‐light absorption.     

Implications of Nitrogen Doping on Geometrical and Electronic Structure of the Fullerene Dimers

Because of its unsaturated bonds, C₆₀ is susceptible to polymerize into dimers. The implications of nitrogen doping on the geometrical and electronic structure of C₆₀ dimers have been ambiguous for years. A quarter‐century after the discovery of azafullerene dimer (C₅₉N)₂, we reported its single crystallographic structure in 2019. Herein, the unambiguous crystal structure information of (C₅₉N)₂ is elucidated specifically, revealing that the inter‐cage C—C single bond length of (C₅₉N)₂ is comparable with that of an ordinary C(sp³)‐C(sp³) single bond, and that the most stable conformer of (C₅₉N)₂ is gauche‐conformer with a dihedral angle of 66°. To amend the structural deviations, geometrical structure of (C₅₉N)₂ is optimized by a B3LYP‐D3BJ function, which is proved to be more consistent with its single crystal structure than those by the commonly used B3LYP function. Moreover, the calculation method is also suitable for other representative fullerene dimers, such as (C₆₀)₂ and its divalent anion. Additionally, the dissociation of (C₅₉N)₂ at 473 K under mass spectrometric conditions suggests the inter‐cage C—C bond is relatively weaker than an ordinary C—C single bond, which can be explained by the interaction energies of inter‐cages.     

Alkali‐Metal Trichloroacetates for Dichloromethylenation of Fullerenes: Nucleophilic Addition‐Substitution Route

The first experimental evidence that fullerenes react with alkali‐metal trichloroacetates through a nucleophilic addition‐substitution route, yielding dichloromethylenefullerenes as the final products, is reported. The intermediates, C₆₀(CCl₃)^? and C₇₀(CCl₃)^? anions, have been isolated in their protonated forms as ortho‐C₆₀(CCl₃)H, as well as three ortho and one para isomer of C₇₀(CCl₃)H. The structures were unambiguously determined by means of ¹H, ¹³C, and ¹H–¹³C HMBC NMR spectroscopy along with UV/Vis spectroscopy. The observed regiochemistry was analyzed with the aid of quantum chemical calculations. Conversion of the protonated compounds into the [6,6]‐closed C_60/70(CCl₂) cycloadducts under basic conditions can be effected only for the ortho isomers, whereas para‐C₇₀(CCl₃)H decomposes back into pristine C₇₀.     

Solubilization of C60 by micellization with a thermoresponsive block copolymer in water: Characterization,singlet oxygen generation,and DNA photocleavage

Water‐soluble diblock copolymer, poly(N‐isopropylacrylamide)‐block‐poly(N‐vinyl‐2‐pyrroridone) (PNIPAM_m‐b‐PNVP_n), was found to associate with fullerene (C₆₀), and thus C₆₀ can be solubilized in water. The 63C₆₀/PNIPAM_m‐b‐PNVP_n micelle formed a core‐shell micelle‐like aggregate comprising a C₆₀/PNVP hydrophobic core and a thermoresponsive PNIPAM shell. The C₆₀‐containing polymer micelle formation and its thermoresponsive behavior were characterized using light scattering and ¹H NMR techniques. The hydrodynamic radius (R_h) of the C₆₀‐bound polymer micelle increased with increasing temperature, which was ascribed to the hydrophobic association between dehydrated PNIPAM shells above lower critical solution temperature (LCST). ¹H NMR data suggest that the motion of the PNIPAM block is restricted above LCST due to the dehydration of the PNIPAM shell in water. The generation of singlet oxygen by photosensitization by the C₆₀‐bound polymer micelle was confirmed from photooxidation of 9,10‐anthracenedipropionic acid. Furthermore, DNA was found to be cleaved by visible light irradiation in the presence of the C₆₀‐bound polymer micelle. Therefore, there may be a hope for a pharmaceutical application of the C₆₀‐bound polymer micelle to cancer photodynamic therapy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Highly Crystalline Mesoporous C60 with Ordered Pores: A Class of Nanomaterials for Energy Applications

Highly ordered mesoporous C₆₀ with a well‐ordered porous structure and a high crystallinity is prepared through the nanohard templating method using a saturated solution of C₆₀ in 1‐chloronaphthalene (51 mg mL^?1) as a C₆₀ precursor and SBA‐15 as a hard template. The high solubility of C₆₀ in 1‐chloronaphthalene helps not only to encapsulate a huge amount of the C₆₀ into the mesopores of the template but also supports the oligomerization of C₆₀ and the formation of crystalline walls made of C₆₀. The obtained mesoporous C₆₀ exhibits a rod‐shaped morphology, a high specific surface area (680 m² g^?1), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C₆₀ offers high supercapacitive performance and a high selectivity to H₂O₂ production and methanol tolerance for ORR. This simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials.     

Calculations on the Nonlinear Second—Order Optical Polarizabilities for Series of Donor—C60 Molecules

IntroductionThebulkpreparation1ofC6 0 andC70 clusters(fullerenes)hasstimulatedawidevarietyofexperimentalandtheoreticalstudies .2 5Wehavesuccessfullyexaminedthestructures ,UV visiblespectraandthenonlinearthird orderopticalpolarizabilities (γ)ofC6 0 andC70 .6 ,7Byin troductionofsubstituents ,thecentrosymmetriesofC6 0 andC70 arebrokenandthesecond orderopticalnonlinearitiesareinduced .ThechargeseparationinsubstitutedC6 0whichleadstoenhancementofβvaluehasalsobeendis cussed .5Inrecentyears ,a…     

Unique Separation Behavior of a C60 Fullerene‐Bonded Silica Monolith Prepared by an Effective Thermal Coupling Agent

Herein, we report a newly developed C₆₀ fullerene‐bonded silica monolith in a capillary with unique retention behavior due to the structure of C₆₀ fullerene. N‐Hydroxysuccinimide (NHS)‐conjugated C₆₀ fullerene was successfully synthesized by a thermal coupling agent, perfluorophenyl azide (PFPA), and assigned by spectroscopic analyses. Then, NHS‐PFPA‐C₆₀ fullerene was attached onto the surface of a silica monolith in a capillary. The capillary provided specific separation ability for polycyclic aromatic hydrocarbons in liquid chromatography by an effective π–π interaction. Furthermore, corannulene, which has a hemispherical structure, was selectively retained in the capillary based on the specific structural recognition due to the spherical C₆₀ fullerene. This is the first report revealing the spherical recognition ability by C₆₀ fullerene in liquid chromatographic separation.     

Synthesis and Spectroscopic Properties of Phthalocyanine–[60]Fullerene Conjugates Connected Directly by Means of a Four‐Membered Ring

New covalently C₆₀‐conjugated phthalocyanine (Pc) analogues in which the Pc and C₆₀ components are connected by means of a four‐membered ring have been synthesized by taking advantage of a [2+2] cycloaddition reaction of C₆₀ with benzyne units generated from either a phthalocyanine derivative ( 8 ) or its precursor ( 1 ). The reaction of 1 with PhI(OAc)₂ and trifluoromethanesulfonic acid (TfOH) followed by the [2+2] cycloaddition of C₆₀ in the presence of tetra‐n‐butylammonium fluoride (TBAF) yielded the C₆₀‐substituted Pc precursor ( 3 ). Mixed condensation of 3 and 4,5‐dibutylsulfonylphthalonitrile ( 4 ) in a thermally promoted template reaction using a nickel salt successfully gave the Pc–C₆₀ conjugate ( 5 ). Results of mass spectrometry and ¹H and ¹³C NMR spectroscopy clearly indicate the formation of the anticipated Pc–C₆₀ conjugate. Direct coupling of C₆₀ with the Pc analogue that contained eight peripheral trimethylsilyl (TMS) groups ( 8 ) also proceeded successfully, such that mono and bis C₆₀‐adducts were detected by their mass, although the isolation of each derivative was difficult. The absorption and magnetic circular dichroism (MCD) spectra of 5 and the reference compound ( 7 ) differ from each other in the Q‐band region, thereby suggesting that the presence of the C₆₀ moiety affects the electronic structure of the conjugate. The reduction and oxidation potentials of 5 and 7 obtained by cyclic voltammetry are comparative, except for the C₆₀‐centered reduction couple at ?1.53 V versus Fc⁺/Fc in o‐dichlorobenzene (o‐DCB). A one‐electron reduction of 5 and 7 in tetrahydrofuran (THF) by using the sodium mirror technique results in the loss of band intensity in the Q‐band region, whereas the characteristic marker bands for Pc‐ring‐centered reduction appear at around 430, 600, and 900 nm for both compounds. The final spectral shapes of 5 and 7 upon the reduction resemble each other, thus indicating that no significant molecular orbital (MO) interactions between the C₆₀ and Pc units are present for the reduced species of 5 . In contrast, the oxidized species of 5 and 7 generated by the addition of NOBF₄ in CH₂Cl₂ show significantly different absorption spectra from each other. Whereas the broad bands at approximately 400–550 nm of 7 ⁺ are indicative of the cationic π‐radical species of metallo‐Pcs and can be assigned to a transition from a low‐lying MO to the half‐filled MO, no corresponding bands were observed for 5 ⁺. These spectral characteristics have been tentatively assigned to the delocalized occupied frontier MOs for 5 ⁺. The experimental results are broadly supported by DFT calculations.     

Facile Synthesis and Photophysical Properties of Sphere–Square Shape Amphiphiles Based on Porphyrin–[60]Fullerene Conjugates

Molecules constructed from a combination of zero‐dimensional ([60]fullerene (C₆₀)) and two‐dimensional (porphyrin (Por)) nanobuilding blocks represent an intriguing category of sphere–square “shape amphiphiles”. These sphere–square shape amphiphiles possess interesting optoelectronic properties. To efficiently synthesize a large variety of C₆₀–Por shape amphiphiles, a facile route based on Steglich esterification was developed. The synthetic strategy enables the preparation of hydroxy‐functionalized Por precursors ( 9 , 10 , 11 , 12 ) with high purity in a one‐pot procedure. All of the C₆₀–Por shape amphiphiles ( 1 , 2 , 3 , 4 , 5 ) can be readily synthesized in good yields through subsequent Steglich esterification with a highly soluble carboxylic acid derivative of methanofullerene ( 13 ). Photophysical studies indicated weak electronic coupling between the C₆₀ and Por moieties and suggest an edge‐to‐face alignment for the moieties. The fluorescence of electronically excited Por portions of each amphiphile was efficiently quenched, which was indicative of electron transfer from ¹Por to the C₆₀ group(s). Increasing the number of C₆₀ groups on the shape amphiphiles led to more pronounced quenching of the Por fluorescence, which indicated the potential for more effective generation of charge‐separated species, C₆₀^?.Por^+., from the photoexcited C₆₀–Por shape amphiphiles.     

A Tunable Cyclic Container: Guest‐Induced Conformational Switching,Efficient Guest Exchange,and Selective Isolation of C70 from a Fullerene Mixture

An adaptable cyclic porphyrin dimer with highly flexible linkers has been used as an artificial molecular container that can efficiently encapsulate various aromatic guests (TCNQ/C₆₀/C₇₀) through strong π–π interactions by adjusting its cavity size and conformation. The planar aromatic guest (TCNQ) can be easily and selectively exchanged with larger aromatic guests (C₆₀/C₇₀). During the guest‐exchange process, the two porphyrin rings switch their relative orientation according to the size and shape of the guests. This behavior of the cyclic container has been thoroughly investigated by using UV/Vis spectroscopy, NMR spectroscopy, and X‐ray crystal structure determination of the host–guest assemblies. The electrochemical and photophysical studies demonstrated the occurrence of photoinduced electron transfer from bisporphyrin to TCNQ/C₆₀/C₇₀ in the respective host–guest assemblies. The cyclic host can form complexes with C₆₀ and C₇₀ with association constants of (2.8±0.2)×10⁵ and (1.9±0.3)×10⁸ m ⁻¹, respectively; the latter value represents the highest binding affinity for C₇₀ reported so far for zinc(II) bisporphyrinic receptors. This high selectivity for the binding of C₇₀ versus C₆₀ allows the easy extraction and efficient isolation of C₇₀ from a C₆₀/C₇₀ fullerene mixture. Experimental evidence was substantiated by DFT calculations.     

NMR Properties of Polylithiated C60

Endohedral, ¹³C, ⁷Li, and nucleus‐independent (NICS) chemical shifts are reported for selected Li_nC₆₀ isomers (n = 6, 12, 18) at the GIAO (gauge‐including atomic orbitals)‐SCF/DZP//BP86/3–21G level. Li₆C₆₀ closely resembles C₆₀^6– in terms of NMR criteria for aromaticity, as evidenced by an exceptionally high endohedral shielding. In contrast, nonaromaticity is indicated for Li₁₂C₆₀, based on a positive endohedral chemical shift. NICS and δ(endo) values very similar to those of Li₁₂C₆₀ are obtained for Li₁₈C₆₀. According to population analysis, indeed the same number of electrons are transferred to the fullerene cage in both cases. Endohedral chemical shifts, accessible via ³He NMR of the corresponding endohedral helium compounds, could thus be a valuable indicator for the extent of reduction of the C₆₀ molecule. Energetic estimates suggest that in the bulk, Li₁₂C₆₀ should be unstable with respect to decomposition into Li₆C₆₀ and lithium metal.     

Nanoporous Carbon Tubes from Fullerene Crystals as the π‐Electron Carbon Source

Here we report the thermal conversion of one‐dimensional (1D) fullerene (C₆₀) single‐crystal nanorods and nanotubes to nanoporous carbon materials with retention of the initial 1D morphology. The 1D C₆₀ crystals are heated directly at very high temperature (up to 2000 °C) in vacuum, yielding a new family of nanoporous carbons having π‐electron conjugation within the sp²‐carbon robust frameworks. These new nanoporous carbon materials show excellent electrochemical capacitance and superior sensing properties for aromatic compounds compared to commercial activated carbons.     

Regulation of Glucose Oxidase Activity through Interaction with Fullerene Derivatives

The 2‐(hydroxymethyl)pyridine modified C₆₀ (PY‐C₆₀) and methoxydiglycol modified C₆₀ (MDG‐C₆₀) are synthesized using Bingel‐Hirsch reaction and characterized by nuclear magnetic resonance (NMR) and mass spectra. PY‐C₆₀ and MDG‐C₆₀ can bind to glucose oxidase (GOx) and quench the fluorescence of tryptophan (Trp) residue in GOx through static mechanism. The conformation of GOx is disturbed after formation of complex with these fullerene derivatives. Kinetic analysis indicates that PY‐C₆₀ and MDG‐C₆₀ may affect the catalytic activity of GOx with a partial mixed‐type inhibition mechanism. In the plasma glucose concentration range (3.6–5.2 mmol·L^?1), PY‐C₆₀ may significantly accelerate the catalytic velocity of GOx, however, MDG‐C₆₀ exerts almost no obvious change to the initial velocity of GOx, suggesting that elaborate design of molecular structure of fullerene derivative is very important for regulating the biological activity of fullerene‐enzyme complex.