Impact of carboxylate ligation on the C-H activation reactivity of a non-heme Fe(IV)O complex: a computational investigation.

A comprehensive DFT investigation has been presented to predict how a carboxylate-rich macrocycle would affect the reactivity of a non-heme Fe(IV)O complex towards C-H activation. The popular non-heme iron oxo complex [FeIV(O)(N4Py)]2+, (N4Py = N,N-(bis(2-pyridyl)methyl)N-bis(2-pyridylmethyl)amine) (1), has been selected here as the primary compound. It is transformed to the compound [FeIV(O)(nBu-P2DA)], where nBu-P2DA = N-(1',1'-bis(2-pyridyl)pentyl)iminodiacetate (2) after the replacement of two pyridine donors of N4Py with carboxylate groups. Two other complexes, namely 3 and 4, have been predicted sequentially substituting nitrogen with the carboxylate groups. Ethylbenzene and dihydrotoluene were chosen as substrates. In terms of C-H activation reactivity, an interesting pattern emerges: as the carboxylate group becomes more equatorially enriched, the reactivity increases, following the trend 1 < 2 < 3 < 4. This also aligns with available experimental reports related to complexes 1 and 2. Fe(IV)O complexes exhibit two-state reactivity (triplet and quintet), whereas the quintet state is more favourable due to the stabilization of the transition states through exchange interactions involving a greater number of unpaired electrons. A detailed analysis of the factors influencing reactivity has been performed, including distortion energy (which decreases for the transition state with the addition of carboxylate groups), the triplet-quintet oxidant energy gap (which consistently decreases as carboxylate group enrichment increases), steric factors, and quantum mechanical tunneling. This investigation provides a detailed explanation of the observed outcomes and predicts the higher reactivity of carboxylate-enriched Fe(IV)O complexes. After potential experimental verification, this could lead to the development of new, optimal catalysts for C-H activation.

Ag+-Induced Supramolecular Polymers of Folic Acid: Reinforced by External Kosmotropic Anions Exhibiting Salting Out.

Introducing kosmotropic salts enhances protein stability and reduces solubility by withdrawing water from the protein surface, leading to 'salting out', a phenomenon we have mimicked in supramolecular polymers (SPs). Under the guidance of Ag+, folic acid (FA) self-assembled in water through slipped-stacking and hydrophobic interactions into elongated, robust one-dimensional SPs, resulting in thermo-stable supergels. The SPs exhibited temperature and dilution tolerance, attributed to the stability of the FA-Ag+ complex and its hydrophobic stacking. Importantly, FA-Ag+ SP's stability has been augmented by the kosmotropic anions, such as SO42-, strengthening hydrophobic interactions in the SP, evident from the enhanced J-band, causing improvement of gel's mechanical property. Interestingly, higher kosmotrope concentrations caused a significant decrease in SP's solubility, leading to precipitation of the reinforced SPs─a 'salting out' effect. Conversely, chaotropes like ClO4- slightly destabilized hydrophobic stacking and promoted an extended conformation of individual SP chain with enhanced solubility, resembling a 'salting in' effect.

Electron-donating and -withdrawing groups discriminate the fluorometric sensing of phosgene.

Phosgene, diphosgene, and chlorine are called choking agents due to their acute toxicity to the respiratory system by directly attacking through inhalation and causing acute hypoxia, asphyxia and death. For these reasons, small-molecule fluorescent probes have been developed for their detection to ensure public safety. In this regard, two thiophene-based chemodosimetric fluorescent probes TCAO ((Z)-3-(4-(dimethylamino)phenyl)thiophene-2-carbaldehyde oxime) and HMBT ((Z)-4-(2-((hydroxyimino)methyl)thiophen-3-yl)benzonitrile) were designed, synthesized and characterized using 1H-NMR, 13C NMR, FT-IR spectroscopy and HRMS methods. Probe TCAO exhibited higher selectivity and sensitivity for detecting phosgene than probe HMBT. The electron-donating group (EDG) and electron-withdrawing group (EWG) play a crucial role in detecting phosgene. TCAO, bearing EDG, exhibited a fluorescence 'turn-on' response by the NGP-assisted conversion of aldoxime to the cyano group in the presence of phosgene; whereas HMBT, bearing EWG, did not show any fluorometric response. Therefore, further studies were conducted on TCAO, and the quantum yield changed from Φ = 0.043 to Φ = 0.155 in the presence of phosgene. The limit of detection for TCAO was estimated to be as low as 51 nm. In addition, onsite monitoring for visual detection was performed using the easy-to-handle paper-strip method.

Hydrological modelling using SWAT for the assessment of streamflow dynamics in the Ganga River basin.

Growing concerns over water availability arise from the problems of population growth, rapid industrialization, and human interferences, necessitating accurate streamflow estimation at the river basin scale. It is extremely challenging to access stream flow data of a transboundary river at a spatio-temporal scale due to data unavailability caused by water conflicts for assessing the water availability.Primarily, this estimation is done using rainfall-runoff models. The present study addresses this challenge by applying the soil and water assessment tool (SWAT) for hydrological modelling, utilizing high-resolution geospatial inputs. Hydrological modelling using remote sensing and GIS (Geographic Information System) through this model is initiated to assess the water availability in the Ganga River basin at different locations. The outputs are calibrated and validated using the observed station data from Global Runoff Data Centre (GRDC). To check the performance of the model, Nash-Sutcliffe efficiency (NSE), percent bias (PBIAS), coefficient of determination (R2), and RSR efficacy measures are initiated in ten stations using the observed and simulated stream flow data. The R2 values of eight stations range from 0.82 to 0.93, reflecting the efficacy of the model in rainfall-runoff modelling. Moreover, the results obtained from this hydrological modelling can serve as valuable resources for water resource planners and geographers for future reference.

A density functional theory analysis of the C-H activation reactivity of iron(IV)-oxo complexes with an 'O' substituted tetramethylcyclam macrocycle.

In this article, we present a meticulous computational study to foresee the effect of an oxygen-rich macrocycle on the reactivity for C-H activation. For this study, a widely studied nonheme Fe(IV)O molecule with a TMC (1,4,8,11-tetramethyl 1,4,8,11-tetraazacyclotetradecane) macrocycle that is equatorially attached to four nitrogen atoms (designated as N4) and acetonitrile as an axial ligand has been taken into account. For the goal of hetero-substitution, step-by-step replacement of the N4 framework with O atoms, i.e., N4, N3O1, N2O2, N1O3, and O4 systems, has been considered, and dihydroanthracene (DHA) has been used as the substrate. In order to neutralise the system and prevent the self-interaction error in DFT, triflate counterions have also been included in the calculations. The study of the energetics of these C-H bond activation reactions and the potential energy surfaces mapped therefore reveal that the initial hydrogen abstraction, which is the rate-determining step, follows the two-state reactivity (TSR) pattern, which means that the originally excited quintet state falls lower in the transition state and the product. The reaction follows the hydrogen atom transfer (HAT) mechanism, as indicated by the spin density studies. The results revealed a fascinating reactivity order, in which the reactivity increases with the enrichment of the oxygen atom in the equatorial position, namely the order follows N4 < N3O1 < N2O2 < N1O3 < O4. The impacts of oxygen substitution on quantum mechanical tunneling and the H/D kinetic isotope effect have also been investigated. When analysing the causes of this reactivity pattern, a number of variables have been identified, including the reactant-like transition structure, spin density distribution, distortion energy, and energies of the electron acceptor orbital, i.e., the energy of the LUMO (σ*z2), which validate the obtained outcome. Our results also show very good agreement with earlier combined experimental and theoretical studies considering TMC and TMCO-type complexes. The DFT predictions reported here will undoubtedly encourage experimental research in this biomimetic field, as they provide an alternative with higher reactivity in which heteroatoms can be substituted for the traditional nitrogen atom.

A Phenanthrenequinone-Based Ratiometric Fluorescent Probe for Rapid Detection of Peroxynitrite with Imaging in Osteoblast Precursor Cells.

In the current situation, peroxynitrite (ONOO-) is drawing the increasing attention of researchers for its pivotal role in diverse pathological and physiological processes on grounds of robust oxidation and nitrification. Herein, we have successfully designed and synthesized a phenanthrenequinone benzyl borate-based chemosensor for fast and selective detection of ONOO-. The probe PTDP itself had an orange fluorescence, which was changed to strong blue fluorescence upon the addition of ONOO-, indicating the ratiometric response of the probe. This is so because of the cleavage of the benzyl boronate-protecting group of PTDP upon the addition of ONOO- with simultaneous releasing of pyridinyl-based chemosensor PPI. The PTDP showed outstanding performance in the various photophysical studies such as good selectivity, excellent sensitivity with a very low detection limit of 2.74 nM, and a very fast response time (<15 s). Furthermore, for practical applicability, it was successfully applied in the ratiometric detection of ONOO- in osteoblast precursor cells.

Experimental and computational investigation of the α-amylase catalyzed Friedel-Crafts reaction of isatin to access symmetrical and unsymmetrical 3,3',3''-trisindoles.

Trisindoles are of tremendous interest due to their wide range of biological activities. In this context, a number of methods have been reported in the past to synthesize 3,3',3''-trisindoles. However, most of the methods are only able to produce symmetrical 3,3',3''-trisindoles. Herein, we develop a sustainable and efficient approach to synthesize symmetrical as well as unsymmetrical 3,3',3''-trisindoles in a very selective manner using the α-amylase enzyme as a catalyst. Furthermore, various differently substituted isatin and indoles were used to prove the generality of the protocol and symmetrical or unsymmetrical 3,3',3''-trisindoles were obtained in 43-97% isolated yields. Next, a probable mechanism is proposed and investigated using molecular dynamics (MD) investigation to gain more insight into the role of residues available in the active site of the α-amylase enzyme. These studies revealed that Glu230, Lys209, and Asp206 in the active site of α-amylase play an important role in this catalysis. Moreover, the DFT studies suggested the formation of bisindole and alkylideneindolenine intermediates during the transformation. We synthesized four different biologically important 3,3',3''-trisindoles on a gram scale, which proved the robustness and scalability of this protocol.

High-valent nonheme Fe(IV)O/Ru(IV)O complexes catalyze C-H activation reactivity and hydrogen tunneling: a comparative DFT investigation.

A comprehensive density functional theory investigation has been presented towards the comparison of the C-H activation reactivity between high-valent iron-oxo and ruthenium-oxo complexes. A total of four compounds, e.g., [Ru(IV)O(tpy-dcbpy)] (1), [Fe(IV)O(tpy-dcbpy)] (1'), [Ru(IV)O(TMCS)] (2), and [Fe(IV)O(TMCS)] (2'), have been considered for this investigation. The macrocyclic ligand framework tpy(dcbpy) implies tpy = 2,2':6',2''-terpyridine, dcbpy = 5,5'-dicarboxy-2,2'-bipyridine, and TMCS is TMC with an axially tethered -SCH2CH2 group. Compounds 1 and 2' are experimentally synthesized standard complexes with Ru and Fe, whereas compounds 1' and 2 were considered to keep the macrocycle intact when switching the central metal atom. Three reactants including benzyl alcohol, ethyl benzene, and dihydroanthracene were selected as substrates for C-H activation. It is noteworthy to mention that Fe(IV)O complexes exhibit higher reactivity than those of their Ru(IV)O counterparts. Furthermore, regardless of the central metal, the complex featuring a tpy-dcbpy macrocycle demonstrates higher reactivity than that of TMCS. Here, a thorough analysis of the reactivity-controlling characteristics-such as spin state, steric factor, distortion energy, energy of the electron acceptor orbital, and quantum mechanical tunneling-was conducted. Fe(IV)O exhibits the exchanged enhanced two-state-reactivity with the quintet reactive state, whereas Ru(IV)O has only a triplet reactive state. Both the distortion energy and acceptor orbital energy are low in the case of Fe(IV)O supporting its higher reactivity. All the investigated C-H activation processes involve a significant contribution from hydrogen tunneling, which is more pronounced in the case of Ru, although it cannot alter the reactivity pattern. Furthermore, it has also been found that, independent of the central metal, aliphatic hydroxylation is always preferable to aromatic hydroxylation. Overall, this work is successful in establishing and investigating the cause of enzymes' natural preference for Fe over Ru as a cofactor for C-H activation enzymes.

Computational identification and exploration of novel FGFR tyrosine kinase inhibitors for the treatment of cholangiocarcinoma.

Tyrosine kinase inhibitors are a specific drug class revolutionizing cancer treatment. FGFR (Fibroblast Growth Factor Receptor) is a member of the receptor tyrosine kinase family that has been involved in various alterations which have been increasingly recognized as critical molecular drivers in cholangiocarcinoma, a malignant tumor originating from bile duct epithelial cells. The paper focuses on stepwise computational investigations for the discovery of novel inhibitors of FGFR using pharmacophore modeling, virtual screening, docking, ADMET analysis, molecular dynamics, and knowledge-based structure-activity relationship. To begin with, we have considered a library of 120314868 compounds from the ZINC 15 database through pharmacophore modeling, which was narrowed down to 110 having binding affinity >-8.0 kcal mol-1. The 110 compounds were analyzed using virtual screening and compared with the FDA-approved drug pemigatinib, which provided the 34 hits with binding affinities >-6.5 kcal mol-1. Finally, the top 4 hits were considered for docking, and ADMET property analysis for drug-likeness. MD and MM-GBSA analysis were performed to predict the binding free energy of these chemicals and determine their stability. To gain insight into the structure and binding interactions of these compounds, knowledge-based SAR analyses were performed using their electrostatic potential maps computed with DFT. Several techniques were employed to build improved inhibitors based on these SAR, and they were then analyzed utilizing ADMET, MD studies, and MM-GBSA analyses. Finally, the results suggested that the identified four compounds and developed inhibitors from this current work can be employed effectively as prospective FGFR inhibitors for treating Cholangiocarcinoma.Communicated by Ramaswamy H. Sarma.

N-Heterocyclic imino-catalyzed 1,4-regioselective azide-alkyne cycloaddition (AAC): a metal-free approach.

An unprecedented synthetic approach has been devised to efficiently synthesize regioselective 1,4-disubstituted 1,2,3-triazoles. This technique relies on the use of innovative metal-free highly basic N-heterocyclic imino catalysts. The experimental observations have been supported further by TD-DFT computational studies.

Divergent and Selective Synthesis of 3-Alkylidene Oxindoles Using Pd-Catalyzed Multicomponent Reaction.

Herein, a divergent and selective synthesis of (E)-3-alkylidene oxindole, which is a highly valuable framework due to its presence in biologically important molecules, via palladium-catalyzed multicomponent reaction of 3-diazo oxindole, isocyanide, and aniline has been developed. Further, the feasibility of the reaction was demonstrated by employing differently substituted 3-diazo oxindoles, isocyanides, and anilines as starting material and obtaining the corresponding products in 31-83% isolated yields. Besides, a plausible mechanism has been presented and further investigated using DFT calculations which suggest the formation of the Pd-carbene complex and ketenimine intermediate as the key step during the catalytic cycle.

A 'double locked' ratiometric fluorescent probe for detection of cysteine in a viscous system and its application in cancer cells.

Intracellular viscosity is a physicochemical property that regulates the consequences of several biological progressions. Cysteine (Cys) is an important signaling molecule that commands many cellular activities, such as antioxidant generation. Predicting that both may be interconnected with a diversity of pathological processes, their contemporaneous measurement would be valuable for studying the pathological ailment of cells. Herein, we have synthesized a 'double locked' probe, acrylic acid 6-[4-(2-benzothiazol-2-yl-2-cyano-vinyl)-phenyl]-naphthalen-2-yl ester (ABN) for the detection of Cys in a viscous medium and explored its application to living cells that were exposed to dexamethasone to regulate the intracellular viscosity level. ABN displayed a satisfactory ratiometric (blue to orange) fluorescence response in solution and in living cells when Cys and viscosity coexisted. A turn-on fluorescence signal was visualized when the probe was individually treated with Cys and glycerol (a standard viscosity source). Therefore, we propose that ABN is a fluorescent probe that permits the monitoring of variations in intracellular viscosity and Cys levels in a biological environment, and it can be utilized in innumerable cellular damage models.

Recent advances in transition metal-mediated trifluoromethylation reactions.

Fluorine compounds are known for their abundance in more than 20% of pharmaceutical and agrochemical products mainly due to the enhanced lipophilicity, metabolic stability and pharmacokinetic properties of organofluorides. Consequently, the last decade has seen enormous growth in the incorporation of a trifluoromethyl group into organic motifs. With due significance, this review aims to provide a complete picture of the transition metal-mediated construction of C(sp3, sp2, and sp)-CF3 bonds via C-H/X bond functionalization or addition processes in both aliphatic and aromatic hydrocarbons. Diversified reagents ranging from radical and electrophilic to nucleophilic trifluoromethylating agents and their respective mechanisms have been further deliberated in this comprehensive overview. The comprehensive coverage on this topic is expected to make this review unique and beneficial for further future applications enriching the community towards further improvements in the field of trifluoromethylation reactions, in turn improving the propensity towards further development of agrochemical drugs.

Role of "S" Substitution on C-H Activation Reactivity of Iron(IV)-Oxo Cyclam Complexes: a Computational Investigation.

A comprehensive density functional theory (DFT) investigation has been presented in this article to address the role of equatorial sulfur ligation in C-H activation. A non-heme iron-oxo compound with four nitrogen atoms constituting the equatorially connected macrocyclic framework (represented as N4) [Fe(IV)═O(THC)(CH3CN)]2+(THC = 1,4,8,11-tetrahydro1,4,8,11-tetraazacyclotetradecane) has been considered as the base compound. Other complexes have been anticipated by the sequential replacement of this nitrogen by sulfur, that is, N4, N3S1, N2S2, N1S3, and S4. Counterions, as always, have been considered to avoid the self-interaction error in DFT. Generally, the anti-conformers (with respect to equatorial N-H and Fe═O) turned out to be the most stable. It was found that with the enrichment of the equatorial sulfur atom, reactivity increases successively, that is, we get the trend N4 < N3S1 < N2S2 < N1S3 < S4. Our investigations have also verified the available experimental results where it has been reported that N2S2 is more reactive than N4 in their mixed conformation. In search of insights into this typical pattern of reactivity, the interplay of several factors has been recognized, such as the distortion energy which decreases for the transition states with the addition of sulfur; the spin density on the oxygen atom which increases implying that the radical character of abstractor increases on sulfur ligation; the energy of the electron acceptor orbital (the lowest unoccupied molecular orbital (σz2*)) which decreases continuously with the sulfur substitution; and the triplet-quintet oxidant energy gap which decreases consistently with S enrichment in the equatorial position. The computational predictions reported here, if further validated by experiments, will definitely encourage the synthesis of sulfur-ligated bio-inspired complexes instead of the ones constituting nitrogen exclusively.

Transition-metal-catalyzed C-H bond alkylation using olefins: recent advances and mechanistic aspects.

Transition metal catalysis has contributed immensely to C-C bond formation reactions over the last few decades, and alkylation is no exception. The superiority of such methodologies over traditional alkylation is evident from minimal reaction steps, shorter reaction times, and atom economy while also allowing control over regio- and stereo-selectivity. In particular, hydrocarbonation of alkenes has grabbed increased attention due its fundamental ability to effectively and selectively synthesise a wide range of industrially and pharmaceutically relevant moieties. This review attempts to provide a scientific viewpoint and a systematic analysis of the recent developments in transition-metal-catalyzed alkylation of various C-H bonds using simple and activated olefins. The key features and mechanistic studies involved in these transformations are described briefly.

A Dual Functional 2D MOF Exhibiting Rare Photosalient Effect as well as Selective Pd(II) Sensing in Aqueous Medium.

A Zn(II) based two-dimensional metal-organic framework (2D MOF) [Zn2(suc)2(4-nvp)2] (1) [H2suc = succinic acid and 4-nvp = 4-(1-naphthylvinyl)pyridine] exhibits a "photosalient effect" under UV light as well as sunlight along with the release of a stereoselective cyclobutane ligand, 1,3-bis(4'-pyridyl)-2,4-bis(naphthyl)cyclobutane (rctt-4-pncb). Photolysis of in situ generated MOF in solution also leads to the formation of rctt-4-pncb crystals. Interestingly, compound 1 shows a high selectivity for Pd(II) sensing in aqueous medium.

Effect of the substituent on C-H activation catalyzed by a non-heme Fe(IV)O complex: a computational investigation of reactivity and hydrogen tunneling.

Density functional theory investigations were performed to address the C-H activation reactivity and the influence of quantum mechanical tunneling catalyzed by a non-heme iron(IV)-oxo complex, namely [FeIVOdpaq-X]+, where the macrocyclic ligand dpaq represents {2-[bis(pyridine-2-yl-methyl)]amino-N-quinolin-8-yl-acetamido}. Counter ion and solvent corrections were incorporated in the computation to avoid self-interaction error. To find the impact of the indirectly linked substituents to the central metal atom, Fe, the macrocyclic ligand dpaq was substituted at the 5-position of its quinoline moiety represented as dpaq-X and the reactivity and hydrogen tunneling were compared with the parent ligand dpaq-H. Here, both electron-donating, e.g. -N(CH3)2 and -OMe, and electron-withdrawing, e.g. -NO2 and -SO2CF3, substituents compared to hydrogen were considered. The reactions displayed exchange interaction favouring two-state reactivity (TSR) as the S = 2 state was found for the excited state in the reactant, which crossed the S = 1 path (initially the ground state) during the progress of the reaction. This was further verified by the tunneling corrected kinetic isotope effect (KIE), which closely matched with the experiment (32) in the S = 2 state (22), whereas the S = 1 KIE (∼69) was found to be very far from that experimentally observed. More than 90% of all the C-H activation reactions proceeded through quantum mechanical tunneling even at room temperature. As the substituent group became more electron-donating, both the tunneling contributions and the kinetic isotope effect increased, which supported the anti-electrophilic tunneling control reactivity premise. The presented consequences may further expose the possibility for the rational design of metal-based catalysts with systematic ligand/substituent tuning that can be performed efficiently through quantum mechanical tunneling.

A Pd-catalyzed one-pot cascade consisting of C-C/C-O/N-N bond formation to access benzoxazine fused 1,2,3-triazoles.

A Pd-catalyzed one-pot cascade consisting of C-C/C-O/N-N bond formation to access clinically important fused 1,2,3-triazoles using N-aryl-α-(tosylhydrazone)acetamides with isocyanide has been developed. Besides, various substitutions on the N-aryl part of acetamides along with different isocyanides show good compatibility in this protocol. Next, two plausible mechanistic routes were proposed; however, one of the routes was more favourable which involved the formation of a benzoxazine ring first followed by the realization of a triazole ring. Additionally, the more favourable mechanistic route was investigated using DFT studies which suggests that the formations of a Pd(II)-isocyanide complex and α-diazoimino intermediates were key steps in the catalytic cycle.

Fabrication of self-assembled nanostructures for intracellular drug delivery from diphenylalanine analogues with rigid or flexible chemical linkers.

Self-assembly of molecular building blocks is a simple and useful approach to generate supramolecular structures with varied morphologies and functions. By studying the chemical properties of the building blocks and tuning the parameters of their self-assembly process, the resultant supramolecular assemblies can be optimized for the required downstream applications. To this end, in the present study we have designed and synthesized three different molecular building blocks composed of two diphenylalanine (FF) units connected to each other through three different linkers: ethylenediamine, succinic acid, or terephthalaldehyde. Under identical conditions, all the three building blocks self-assemble into supramolecular architectures with distinct morphologies. However, by varying the polarity of the self-assembly medium, the nature of the non-covalent interactions changes in such a way as to generate additional self-assembled structures unique to each building block. Utilizing microscopic and spectroscopic techniques, we characterized the morphological variety generated by each building block/linker combination. These data represent the first report analysing the diversity of nanostructures that can be generated from identical dipeptide-based molecular backbones simply by varying the chemical linker. We also demonstrate that the spherical assemblies and nanorod structures fabricated from these dipeptide/linker pairs can act as drug delivery systems. More specifically, the spherical assembly generated by two FF dipeptides linked via ethylenediamine and nanorods fabricated from terephthalaldehyde linked FF dipeptides were able to encapsulate the cancer chemotherapeutic agent doxorubicin (DOX) and chaperone the drug into cells. Thus, these supramolecular assemblies represent a new platform for the development of efficient and effective intracellular drug delivery systems.

Quantum-Dot-Mediated Controlled Synthesis of Dual Oxides of Molybdenum from MoS2 : Quantification of Supercapacitor Efficacy.

The versatile technological applications of molybdenum oxides requires the efficient synthesis of various stoichiometric molybdenum oxides. Thus, herein, a controlled method to synthesize both MoO3 and MoO2 from MoS2 via quantum dot intermediates is reported. Microscopic, spectroscopic, and X-ray studies corroborate the formation of orthorhombic α-MoO3 with a microbelt structure and monoclinic MoO2 nanoparticles that self-assemble into hollow tubes. Quantitative investigations into charge-storage kinetics reveal that MoO2 exhibits an excellent pseudocapacitive response up to a mass loading of 5 mg cm-2 with an areal capacity of 327.2 mC cm-2 at 5 mV s-1 , with 41.9 % retention at 100 mV s-1 . In contrast, above a mass loading of 0.5 mg cm-2 , the charge-storage nature of MoO3 electrodes switches from that of a supercapacitor to battery type. At a sweep rate of 50 mV s-1 , 87.2 % of the total charge is contributed by a capacitive response in a 1 mg cm-2 MoO2 electrode. The charge-storage kinetics of MoO3 and MoO2 reflect on the respective asymmetric supercapacitors. A MoO2 //graphite asymmetric supercapacitor holds an outstanding energy density of 341 mW h m-2 at a power density of 4949 mW m-2 and delivers an ultrahigh power density of 28140 mW m-2 with an energy density 142 mW h m-2 and energy efficiency of 87 %.