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Rod-shaped SU-101 catalysts exhibited a high HCOO− Faraday efficiency of 93.66% at −1.10 V vs. RHE due to the unique hexacoordinated Bi3+ site of SU-101.

A single stimulus leading to multiple responses is an essential function of many biological enzymatic reaction networks, which enable complex life activities. Owing to the lack of allosteric regulation of natural enzymes, it is challenging to duplicate a similar network using non-living chemicals. Herein, we report a nanozymatic cascade reaction network that demonstrates multiple responses of different modes and intensities upon a single H2O2 stimulus based on a single-atom nanozyme (Co-N-CNTs). Taking the two-electron cascade oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) as an example, the endogenous product H2O2 competitively inhibited substrates in the first one-electron oxidation at the Co-N4 active site on Co-N-CNTs, while accelerated the second one-electron oxidation under a micellar nanozyme. Using such a nanozymatic network, the feedback and feedforward regulation of product transformation were further applied to microfluidic flow reactors as a cell mimic. Owing to the unique varieties of response in intensities and modes, the proposed cell mimic demonstrated highly selective recognition and linear perception of H2O2 against over 20 interferences in a wide range of concentrations (0.01-100 mM), reminiscent of a primordial life-like process in mutable and harsh conditions.

Targeting tumor hydrogen peroxide (H

Innovative bimetallic materials provide more possibilities for further improving the performance of oxygen evolution reaction (OER) electrocatalysts. However, it is still a great challenge to rationally design bimetallic catalysts because there is not a practical way to decouple the factors influencing the intrinsic activity of active sites from others, thus hindering in-depth understanding of the mechanism. Herein, we provide a rational design of bimetallic Ni, Co two-dimensional polymer model OER catalyst. The well-defined architecture, identical density of active sites and monolayer characteristic allow us to decouple the intrinsic activity of active sites from other factors. The results confirmed that the relative position and local coordination environment has significant effect on the synergistic effect of the bimetallic centres. The highest electrocatalytic activity with the turnover frequency value up to 26.19 s

Bacterial vaginosis (BV) is the most common vaginal infection found in women in the world. Due to increasing drug-resistance of virulent pathogen such as Gardnerella vaginalis (G. vaginalis), more than half of BV patients suffer recurrence after antibotics treatment. Here, metastable iron sulfides (mFeS) act in a Gram-dependent manner to kill bacteria, with the ability to counteract resistant G. vaginalis for BV treatment. With screening of iron sulfide minerals, metastable Fe

Spinel oxides are promising low-cost catalysts with manifold and controllable physicochemical properties. Trial and error strategies cannot achieve the effective screening of high-performance spinel catalysts. Therefore, unraveling the structure–performance relationship is the foundation for their rational design. Herein, the effects of cations in tetrahedral and octahedral sites on the electronic structures of spinels were systematically investigated using GGA + U calculations based on ACr2O4 (A = Mn, Fe, Co, Ni, and Zn) and Zn/LiB2O4 (B = Cr, Mn, Fe, Co and Ni). The results indicate that the octahedrally coordinated B cations have notable influence on the electronic structures of spinels. The Jahn–Teller active ions Fe2+, Ni2+, Mn3+, Ni3+, Cr4+ and Fe4+ can remarkably reduce the band gaps of spinels and even change their electroconductibilities. These results will provide theoretical insights into the electronic properties of 3d transition metal spinels.

A peroxidase catalyzes the oxidation of a substrate with a peroxide. The search for peroxidase-like and other enzyme-like nanomaterials (called nanozymes) mainly relies on trial-and-error strategies, due to the lack of predictive descriptors. To fill this gap, here we investigate the occupancy of eg orbitals as a possible descriptor for the peroxidase-like activity of transition metal oxide (including perovskite oxide) nanozymes. Both experimental measurements and density functional theory calculations reveal a volcano relationship between the eg occupancy and nanozymes’ activity, with the highest peroxidase-like activities corresponding to eg occupancies of ~1.2. LaNiO3-δ, optimized based on the eg occupancy, exhibits an activity one to two orders of magnitude higher than that of other representative peroxidase-like nanozymes. This study shows that the eg occupancy is a predictive descriptor to guide the design of peroxidase-like nanozymes; in addition, it provides detailed insight into the catalytic mechanism of peroxidase-like nanozymes.

Graphene-based nanomaterials, including graphene oxide (GO) and reduced graphene oxide (rGO), play key roles in the nanozyme field. GO and rGO carrying various oxygen-containing functional groups, including epoxy, hydroxyl, ether, endoperoxide, carbonyl, carboxyl, and ester, have been reported to display peroxidase mimicking activities. However, the active center and the underlying mechanism responsible for its peroxidase mimicking activities still remain unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 as the model reaction, we investigate the possible catalytic mechanisms using DFT calculations. The results indicate that the carbonyl groups are the active centers. The activation of the C[double bond, length as m-dash]O bond is the key step in the catalytic cycle. The results will help realize the rational design of carbon-based nanozymes.

Nanozymes, the enzyme-mimicking nanomaterials, have been developed to overcome the low stability and high cost of natural enzymes. Unlike highly active and specific enzymes, however, the catalytic ...

The structural transformation and mechanical properties of fullerenes under high pressure have attracted a significant interest. However, the research data on the large-cage endohedral metallofulle...

A new Gd@C2v(9)-C82·2.5(S8)·0.5(CS2) co-crystal was prepared for the first time and characterized by single-crystal X-ray diffraction (XRD). The analysis clearly showed that, even though the C2v(9)-C82 cage is fully ordered, the endohedral Gd atoms are highly disordered. This result indicates the presence of highly delocalized endohedral Gd atoms, which has never been reported before. Density functional theory (DFT) calculations were used to rationalize the XRD results. The calculations reveal the presence of two local energy minima, a and b, with the latter existing as four conformers b1–b4. Whereas the energy difference between the two minima is calculated only ∼ 10 kcal/mol, their interconversion is almost impossible due to a high energy barrier, of up to 35.98 kcal/mol. This suggests the existence of multiple low-energy positions for the endohedral Gd atom. In addition, a remarkable electron transfer from the C2v(9)-C82 cage to the S8 moieties was demonstrated, which might result in a modified endohedral environment and further contribute to the occurrence of delocalized endohedral Gd atoms.

The opening of the five-membered ring is the essential step for phthalimide and its derivatives to be used as the reactants in many chemical synthetic routes. Reportedly, such ring opening follows the concerted mechanism in methanol solvent, which, however, has an unreasonably high energy barrier (36.3 kcal mol–1 at the M06-2X/6-311++G(d,p) level of theory). By density functional theory calculations, we report that this ring opening prefers the alternatively stepwise mechanism. The stepwise mechanism has a much lower energy barrier (21.0 kcal mol–1 at the same level of theory) and thus is much more completive than the concerted one. The stepwise mechanism should be considered as the dominant mechanism responsible for the phthalimide ring opening when studying the kinetics of the relevant synthetic reactions in the future.

Graphical Abstract ga1, The outbreak of SARS-coronavirus 2 (SARS-CoV2) has become a global health emergency. Although enormous efforts have been made, there is still no effective treatment against the new virus. Herein, a TiO2 supported single-atom nanozyme containing atomically dispersed Ag atoms (Ag-TiO2 SAN) is designed to serve as a highly efficient antiviral nanomaterial. Compared with traditional nano-TiO2 and Ag, Ag-TiO2 SAN exhibits higher adsorption (99.65%) of SARS-CoV2 pseudovirus. This adsorption ability is due to the interaction between SAN and receptor binding domain (RBD) of spike 1 protein of SARS-CoV2. Theoretical calculation and experimental evidences indicate that the Ag atoms of SAN strongly bind to cysteine and asparagine, which are the most abundant amino acids on the surface of spike 1 RBD. After binding to the virus, the SAN/virus complex is typically phagocytosed by macrophages and colocalized with lysosomes. Interestingly, Ag-TiO2 SAN possesses high peroxidase-like activity responsible for reactive oxygen species production under acid conditions. The highly acidic microenvironment of lysosomes could favor oxygen reduction reaction process to eliminate the virus. With hACE2 transgenic mice, Ag-TiO2 SAN showed efficient anti-SARS-CoV2 pseudovirus activity. In conclusion, Ag-TiO2 SAN is a promising nanomaterial to achieve effective antiviral effects for SARS-CoV2.

A biomimetic platelet based on assembling peptides initiates artificial coagulation for tumor therapy., Platelets play a critical role in the regulation of coagulation, one of the essential processes in life, attracting great attention. However, mimicking platelets for in vivo artificial coagulation is still a great challenge due to the complexity of the process. Here, we design platelet-like nanoparticles (pNPs) based on self-assembled peptides that initiate coagulation and form clots in blood vessels. The pNPs first bind specifically to a membrane glycoprotein (i.e., CD105) overexpressed on angiogenetic endothelial cells in the tumor site and simultaneously transform into activated platelet-like nanofibers (apNFs) through ligand-receptor interactions. Next, the apNFs expose more binding sites and recruit and activate additional pNPs, forming artificial clots in both phantom and animal models. The pNPs are proven to be safe in mice without systemic coagulation. The self-assembling peptides mimic platelets and achieve artificial coagulation in vivo, thus providing a promising therapeutic strategy for tumors.

Dioxygen activation with both cyclic (amino)(alkyl)carbenes and di(amino)carbenes at ambient temperature is described. Theoretical studies suggest that electron rearrangement from the doubly filled σ orbital of carbene carbon to its vacant p orbital through the π* antibonding orbital of 3O2 can be considered for Ccarbene-O bond formation.

Enzyme-mediated activation of prodrug in tumor cells is an attractive strategy for targeted cancer therapy. Of note, natural peroxidase and indole-3-acetic acid (IAA) have been shown as a promising enzyme-prodrug combination. However, insufficient endogenous peroxidase activity and the difficulty in selectively expressing exogenous peroxidase in tumor cells have severely limited its antitumor efficiency. The discovery of nanomaterials with peroxidase-like activity (nanozyme), particularly the metal-free nanozymes that possesses high stability and good biocompatibility, bring a new opportunity to overcome these challenges. Here, under the guidance of theoretical calculations, we developed a metal-free phosphorous and nitrogen dual-doped porous hollow carbon sphere nanozyme (PNCNzyme) with robust peroxidase-like activity in acidic environment. Based on this metal-free nanozyme, we developed a nanozyme-IAA activation strategy that activated IAA to produce abundant ROS and trigger tumor cell apoptosis. We also introduced folate (FA) onto the nanozyme to enhance its tumor targeting and endocytosis efficacy by tumor cells. Upon administrated to mice, the FA-PNCNzymes@IAA effectively accumulated in the xenografts derived from cervical cancer cells, catalyzed the production of ROS, and induced apoptosis. Taken together, these data demonstrate that the nanozyme-IAA combination is an effective enzyme-prodrug activation strategy for tumor targeted catalytic therapy.

Highest occupied molecular orbital–lowest unoccupied molecular orbital (H-L) energy gaps govern the chemical stabilities of molecules. Molecules with larger H-L gaps are more inert to chemical reactions and thus more experimentally separable. In this sense, H-L gaps play a more important role than energies of formation in determining the structures of the fullerenols that can be experimentally isolated. However, previous structural predictions for fullerenols are mainly based on energies. Recently, we proposed a rule of chemical stability for multiple addition products of fullerenes and endohedral metallofullerenes. In this study, we implement this rule into a computer program and use it to automatically determine large-energy-gap structures for C60 and C82 fullerenols. C60(OH)n (n = 12–48) and C2v(9)-C82(OH)x (x = 14–58) fullerenols have been studied using this program. All the structures determined have H-L gaps larger than those predicted previously. Some of the structures simultaneously have even more...

The empirical Clar model describes the π-electronic configurations for polycyclic aromatic hydrocarbons with closed-shell singlet ground states. However, it is not applicable to nanographenes (NGs), which usually have open-shell ground states. To model the π-electronic configurations of NGs, a new structural unit, radical half-sextet, was introduced. The modified Clar model can profoundly depict the π-electronic configurations for both nonmagnetic and magnetic NGs and thus can be used as the general model for NGs. The new model can precisely predict the favorable reaction patterns for NGs and can profoundly explain the already-known reactions of NGs.

The Lewis base stabilized borylenes and boryls are used to construct one dimension nanowires. Using the Lewis base (L) to coordinate sp2 borons, we constructed B5L5− cyclic compounds with six π-electrons. Then, using B5L5 and transition metals as building units, we further constructed half-sandwich and sandwich compounds. We found that the B5(CO)5 is the η5-ligand with stronger bonding affinity with Mn and Fe than the traditional cyclopentadiene. The calculated electronic band structures suggested that the constructed nanowire [VB5(CO)5FeB5(CO)5]∞ is an organic half-metal. The results may cast light on the future synthesis of boron-based metallocene-like molecules.

A peroxidase catalyzes the oxidation of a substrate with a peroxide. The search for peroxidase-like and other enzyme-like nanomaterials (called nanozymes) mainly relies on trial-and-error strategies, due to the lack of predictive descriptors. To fill this gap, here we investigate the occupancy of eg orbitals as a possible descriptor for the peroxidase-like activity of transition metal oxide (including perovskite oxide) nanozymes. Both experimental measurements and density functional theory calculations reveal a volcano relationship between the eg occupancy and nanozymes’ activity, with the highest peroxidase-like activities corresponding to eg occupancies of ~1.2. LaNiO3-δ, optimized based on the eg occupancy, exhibits an activity one to two orders of magnitude higher than that of other representative peroxidase-like nanozymes. This study shows that the eg occupancy is a predictive descriptor to guide the design of peroxidase-like nanozymes; in addition, it provides detailed insight into the catalytic mechanism of peroxidase-like nanozymes., The search for peroxidase-like as well as other enzyme-like nanozymes mainly relies on trial-and-error strategies, due to the lack of predictive descriptors. Here, the authors fill this gap by investigating the occupancy of eg orbitals as a possible descriptor for the peroxidase-like activity of transition metal oxide nanozymes

Chemical derivatives of fullerene and endohedral metallofullerenes (EMFs) not only keep some of the physicochemical properties of their parent molecules, but can also have water solubility and biocompatibility that are not owned by their parent molecules. These brilliant properties provide these materials potentials in biomedical applications. Here, we review the atomistic-level structural models for fullerene derivatives, and their applications as magnetic resonance imaging (MRI) contrast and cancer therapy agents. Because atomistic level structures are the base for their physicochemical properties, we first review the structural models of fullerene derivatives, which are applicable to fullerene derivatives synthesized in different conditions. Second, we review the widely explored applications of the Gd-containing EMF derivatives as the safe and efficient MRI contrast agents, thanks to their special geometries and electronic structures. Reportedly, fullerene-based materials, like Gd@C82(OH)22 nanoparticles, possess intrinsic antitumor activities. The recent advance in using fullerene derivatives for cancer therapy through different pathways, including photodynamic therapy (PDT), reactive oxygen species (ROS) scavenging, drug delivery, adjuvant activity for cancer vaccines, and reduction of the nutrient supply to tumor cells, are further summarized. Finally, we briefly discuss the challenges and perspectives for the future biomedical applications of fullerene derivatives.

The recent experimental realization of compound Tripp-B(CO)2 (denoted as 2a), where Tripp is 2,6-di(2,4,6-triisopropylphenyl)-phenyl), breaks through conventional knowledge that only transition metals can bind more than one CO to form multicarbonyl adducts. Compound 2a is stable in air but liberates CO under light. The B–CO bonds of 2a are considered to be similar to donor–acceptor bonds of transition metal complexes. To address the formation mechanism and chemical bonding of this novel type of boron compounds, we present a density functional theory study on the formation and photolysis of 2a and similar compounds. The results suggest that the formation of 2a is facile by three consecutive additions of CO to the terminal borylene metal complex, that is, the boron source of the synthesis. These CO additions can be practically accomplished via two different paths: CO direct addition and CO migration followed by addition. Such mechanisms can be excellently rationalized by the donor–acceptor bonding model of ...

Because of the lack of strong π-interaction in their bonds connecting building units, most of the metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs) achieved so far are insulators or wide-bandgap semiconductors. The design of metal-like frameworks based on known chemical components is a challenge. This work reports that aryl borons can be linked together through isocyanides to form stable and easily accessible low-dimensional boronic-organic frameworks (BOFs). Particularly, the boron atoms in the BOFs behave like transition metals, forming the combined σ-donation and π-backdonation bonds instead of the usual electron-sharing bonds with the isocyanide linkers. This peculiar bonding endows BOFs with semimetal and narrow-bandgap semiconductor features, which are different from MOFs and COFs and may be found to be useful in future nanoelectronics. The results open a door to integrating the knowledge of the donor–acceptor chemistry in the main group into materials science.

We report a facile synthesis of novel angularly fused bistetracene derivatives where two tetracene skeletons are cata-annulated at three benzene rings. Compared with previously described examples, our bistetracenes exhibit a narrower HOMO–LUMO gap but still exhibit high stability. Attempted synthesis of di-substituted bistetracene (BT-2TIPS) also led to unexpected triple (BT-3TIPS) and four-fold (BT-4TIPS) alkylsilylethynyl substitution. The photophysical, electrochemical and optical properties as well as the solid-state structure of these three bistetracene analogues are investigated. A charge carrier mobility up to 0.42 cm2 V−1 s−1 was determined based on field effect transistors.

Tumor necrosis factor-α (TNF-α) is a cell signalling protein involved in systemic inflammation in infectious and other malignant diseases. Physiologically, it plays an important role in regulating host defence, but its overexpression can lead to serious illnesses including cancer, autoimmune disease and inflammatory disease. Gadolinium-based metallofullerenols, e.g., Gd@C82(OH) x (x ≈ 22), are well known for their abundant biological activities with low toxicity experimentally and theoretically; however, their activity in direct TNF-α inhibition has not been explored. In this work, we investigated the inhibiting effects of four types of fullerene-based ligands: fullerenes, fullerenols, metallofullerenes, and metallofullerenols. We reported previously that fullerenes, metallofullerenes and their hydroxylated derivatives (fullerenols) can reside in the same pocket of the TNF-α dimer as that of SPD304-a known inhibitor of TNF-α [He et al. (2005) Science 310:1022, 18]. Ligand docking and binding free energy calculations suggest that, with a similar nonpolar interaction dominated binding pattern, the fullerene-based ligands, C60, C60(OH)12, Gd@C60, C82, C82(OH)12, Gd@C82, Gd@C82(OH)13 and Gd@C82(OH)21, have larger affinity than currently known inhibitors, and could be used to design novel inhibitors of TNF-α in the future. Graphical Abstract Fullerene-material/TNF-α.