The Covalent Functionalization of Surface-Supported Graphene: An Update.

In the last decade, the use of graphene supported on solid surfaces has broadened its scope and applications, and graphene has acquire a promising role as a major component of high-performance electronic devices. In this context, the chemical modification of graphene has become essential. In particular, covalent modification offers key benefits, including controllability, stability, and the facility to be integrated into manufacturing operations. In this Review, we critically comment on the latest advances in the covalent modification of supported graphene on substrates. We analyze the different chemical modifications with special attention to radical reactions. In this context, we review the latest achievements in reactivity control, tailoring electronic properties, and introducing active functionalities. Finally, we extended our analysis to other emerging 2D materials supported on surfaces, such as transition metal dichalcogenides, transition metal oxides, and elemental analogs of graphene.

The era of nano-bionic: 2D materials for wearable and implantable body sensors.

Nano-bionics have the potential of revolutionizing modern medicine. Among nano-bionic devices, body sensors allow to monitor in real-time the health of patients, to achieve personalized medicine, and even to restore or enhance human functions. The advent of two-dimensional (2D) materials is facilitating the manufacturing of miniaturized and ultrathin bioelectronics, that can be easily integrated in the human body. Their unique electronic properties allow to efficiently transduce physical and chemical stimuli into electric current. Their flexibility and nanometric thickness facilitate the adaption and adhesion to human body. The low opacity permits to obtain transparent devices. The good cellular adhesion and reduced cytotoxicity are advantageous for the integration of the devices in vivo. Herein we review the latest and more significant examples of 2D material-based sensors for health monitoring, describing their architectures, sensing mechanisms, advantages and, as well, the challenges and drawbacks that hampers their translation into commercial clinical devices.

Reactions of [60]Fullerene with Acetone under Basic Condition: Nucleophilic Ring Opening of the [5,6]-Cyclopropane in C60 and Formation of the Substituted Methano[60]Fulleroids.

The reactions of C60 with acetone were carried out under basic condition in the presence of 1.0 M TBAOH (tetra-n-butylammonium hydroxide) methanol solution and ArCH2Br (Ar = Ph or o-BrPh), where methano[60]fulleroids with a novel 1,1,4,9,9,25-configuration were obtained and structurally characterized by single crystal diffraction. The product was formed via the ring-opening reaction of the [5,6]-cyclopropane by the nucleophilic addition of MeO-, which is different from the reactions of other ketones reported previously.

Electrochemically controlled cleavage of imine bonds on a graphene platform: towards new electro-responsive hybrids for drug release.

Graphene-based materials are particularly suitable platforms for the development of new systems able to release drugs upon the application of controlled electrochemical stimuli. Herein, we report a new electro-responsive graphene carrier functionalised with aldehydes (as drug models) through imine-based linkers. We explore a new type of drug loading/release combination based on the formation of a covalent bond and its cleavage upon electrolysis. The new graphene-drug model hybrid is stable under physiological conditions and displays a fast drug release upon the application of low voltages.

Preparation of a C70 Bis-heterocyclic Derivative with High Chemio- and Regioselectivity.

C70 bis-heterocyclic derivative (1) bearing one oxazoline ring and one imidazoline ring with the 2 o'clock configuration is obtained with high chemio- and regioselectivity via the reaction of C70 with hydroxide and benzonitrile quenched with I2. Further study with benzylation experiment and theoretical calculations indicate that the oxazoline ring is the one first formed on the C70 cage, while the imidazoline ring is the one formed after the addition of I2 via a radical coupling reaction mechanism.

Reductive benzylation of singly bonded 1,2,4,15-C60 dimers with an oxazoline or imidazoline heterocycle: unexpected formation of 1,2,3,16-C60 adducts and insights into the reactivity of singly bonded C60 dimers.

Upon reduction, singly bonded 1,2,4,15-C60 dimers with an oxazoline or imidazoline heterocycle dissociate into monoanionic 1,2,4-C60 intermediates, which surprisingly leads to the formation of 1,2,3,16-C60 rather than 1,2,4,15-C60 adducts of the original configuration by further benzylation, even though the analogue of dibenzylated C60 oxazoline with a 1,2,4,15-configuration is stable and has been obtained. These results are corroborated by computational calculations, which rationalize the reaction and clarify the structure of the 1,2,3,16-C60 adducts, providing new insights into the intrinsic reactivity of singly bonded C60 dimers.

Reductive benzylation of C70 imidazoline with a bulky addend.

Reductive benzylation of C70 imidazolines bearing a bulky addend has been carried out under conditions similar to that reported for C60 analogues. However, different from the reaction of C60 analogues, the reaction of C70 imidazolines not only results in adducts with 1,2,3,16-configuration due to the steric effect, but also a considerable amount of dibenzylated and monobenzylated products with 1,2,3,4-configuration, demonstrating a reactivity difference between C60 and C70. Interestingly, the anions of the 1,2,3,16-C70 adduct are rather stable as shown by the electrochemical study, which is in contrast to the anions of 1,2,3,16-C60 counterparts, and can be rationalized by the electronic structure difference between C70 and C60 derivatives.

Reductive benzylation of C60 imidazoline with a bulky addend.

Reductive benzylation of C60 imidazoline with a bulky addend affords two 1,2,3,16-adducts (2 and 4) and one 1,2,3,4-adduct (3). Experimental and computational results indicate that the sterically favored 2 is more stable than the electronically favored 3. However, an opposite stability order is shown for the dianions of 2 and 3.

Hydroxide-initiated conversion of aromatic nitriles to imidazolines: fullerenes vs TCNE.

Transformation of aromatic nitriles to imidazolines has been achieved under basic conditions with the electron-deficient C60 and C70 fullerenes, but not with the electron-deficient olefin of tetracyanoethylene (TCNE). In situ UV-vis-NIR indicates that the ability of RC60(-) to undergo single-electron transfer (SET) to C60 is crucial for the reaction.

Aerobic oxidations of C60(2-) in the presence of PhCN and PhCH2CN: oxygenation versus dehydrogenation reactions.

Aerobic oxidations of dianionic C(60) were examined in PhCN and PhCH(2)CN, where dioxygen was activated to O(2)(•-) via the single-electron transfer from C(60)(2-) and underwent oxygenation and dehydrogenation reactions, respectively. Addition of PhCH(2)Br led to further benzylation for the oxygenated product but not for the dehydrogenated one, suggesting that the initial two negative charges were preserved for the intermediates of the oxygenation reaction but not for those of the dehydrogenation reaction.

Preparation and characterisation of an equatorial para-adduct of (PhCH2)HC70 from the reaction of C70(2-) with benzyl bromide and H2O: addition effects in the polar and equatorial regions of C70.

Benzyl(hydro)[70]fullerene regioisomers with the addends in both the equatorial and polar regions of C(70) have been prepared via the reaction of dianionic C(70) with benzyl bromide and H(2)O. HRMS, UV-vis, (1)H, (13)C, HMQC (heteronuclear multiple quantum coherence) and HMBC (heteronuclear multiple bond coherence) NMR characterisations have shown that the addition in the equatorial region of C(70) affords a new (PhCH(2))HC(70) regioisomer with para-positioned addends across a six-membered ring, which is different from the "polar" regioisomers where the addends have an ortho-addition pattern. (1)H NMR characterisations have shown a much stronger shielding effect for the addends in the equatorial region with respect to the counterparts in the polar region of C(70), while cyclic voltammetry study has shown a surprising positive shift for the first reduction potential of the equatorial regioisomer with respect to those of the polar regioisomer and pristine C(70), suggesting that the equatorial region of C(70) is rather electropositive than electronegative. D(2)O experiment has shown a significant difference of the deuterated product distribution between the equatorial and polar regioisomers, which can be justified by the different acidity of the (PhCH(2))HC(70) regioisomers. Computational calculations have been carried out to rationalize the formation of the C(70)HR regioisomers.