Hirofumi Yoshikawa

Kwansei Gakuin University · Department of Materials Science

Recently, polymer electrolytes have been developed for high-performance and eco-friendly fuel cells. Among the candidates, eggshell membrane (ESM) has been promising because of its abundance to assemble various energy devices with low cost and its absorption ability of organic materials. In this work, we investigated fuel cells that included ESM-ab...

Recently, organic polysulfides have been synthesized as cathode active materials exceeding the battery performance of sulfur. However, the conventional organic polysulfides have exhibited capacities lower than the theoretical capacity of sulfur because the π-organic moieties do not conjugate with the sulfur chains. In this work, the organopolysulfi...

Two-dimensional Ag(I) coordination polymers containing a sulfur coordination atom, [Ag(tzdt)] n (KGF-24), and [Ag(tzdt)(TFA)] n (KGF-25) (Htzdt = 1,3-thiazolidine-2-thione, TFA = trifluoroacetate), were synthesized and characterized. Time-resolved microwave conductivity measurements and first-principles...

Nanohybrid materials comprising polyoxometalates (POMs) and nanocarbons have attracted considerable attention as electrode‐active materials for rechargeable lithium‐ion batteries (LIBs). These materials exhibit multiple multi‐electron redox reactions, resulting in an improved battery capacity. This study focuses on carbon nanohorns (CNHs) as a nano...

The synthesis of lanthanide metal-organic frameworks with terephthalate (Ln-BDC-MOFs) was investigated using a data-driven approach. Visually mapping the previously reported synthetic conditions suggested the existence of unexplored search spaces for novel Ln-BDC-MOFs. By focusing on the unexplored chemical reaction space, we successfully synthesiz...

The rapid evolution of electrical devices and the increasing demand for the supply of sustainable energy necessitate the development of high‐performance energy storage systems such as rechargeable and redox flow batteries. However, these batteries typically contain inorganic active materials, which exhibit several critical drawbacks hindering furth...

The rapid evolution of electrical devices and the increasing demand for the supply of sustainable energy necessitate the development of high‐performance energy storage systems such as rechargeable and redox flow batteries. However, these batteries typically contain inorganic active materials, which exhibit several critical drawbacks hindering furth...

Polymer electrolyte membrane fuel cells have recently attracted considerable attention as sustainable and eco-friendly electricity generation devices from the viewpoint of carbon neutrality. This study focuses on new discoveries related to the application of eggshell membranes to polymer electrolytes in the development of cheaper, more eco-friendly...

Invited for the cover of this issue are Daisuke Tanaka at Kwansei Gakuin University and co‐workers at Kwansei Gakuin University, Hokkaido University, Kyoto University, Japan and KU Leuven, Belgium. The image is a depiction of exploring the desired crystal by decision tree analysis. Read the full text of the article at 10.1002/chem.202102404. “We co...

Exploring the desired crystal by decision tree analysis. A decision tree uses digitized information to find the synthetic conditions for a new metal–organic framework that exhibits proton conductivity. More information on optimizing the synthesis can be found in the Full Paper by D. Tanaka et al. (DOI: 10.1002/chem.202102404).

Novel metal–organic frameworks containing lanthanide double‐layer‐based secondary building units (KGF‐3) were synthesized using machine learning (ML). Isolating pure KGF‐3 was challenging, and the synthesis was not reproducible because impurity phases were frequently obtained under the same synthetic conditions. Thus, dominant factors for the synth...

Crystal Engineering The machine‐learning‐assisted selective synthesis of semiconductive silver thiolate coordination polymers with segregated paths for holes and electrons is reported by Daisuke Tanaka et al. in their Research Article on page 23217.

Kristall‐Engineering Die durch maschinelles Lernen unterstützte Synthese von halbleitenden Silberthiolat‐Koordinationspolymeren mit segregierten Transportpfaden für Löcher und Elektronen wird von Daisuke Tanaka et al. im Forschungsartikel auf S. 23405 vorgestellt.

Coordination polymers (CPs) with infinite metal–S bond networks have unique electrical conductivities and optical properties, thus drawing attention. However, the development of new (−M−S−) n ‐structured CPs is hindered by their crystallization difficulty. Herein, we use machine learning to optimize the synthesis of trithiocyanuric acid (H 3 ttc)‐b...

Metal-organic frameworks (MOFs) and coordination polymers composed of thiolates as coordinating functional groups are interesting materials with unique optical and electronical properties. Herein, we report the preparation of KGF-4 and KGF-10, two Sn-MOF crystal structures with bonds between Sn and thiolate. KGF-10 was isolated as a pure phase and...

Coordination polymers (CPs) with infinite metal–S bond networks have unique electrical conductivities and optical properties, thus drawing attention. However, the development of new (−M−S−) n ‐structured CPs is hindered by their crystallization difficulty. Herein, we use machine learning to optimize the synthesis of trithiocyanuric acid (H 3 ttc)‐b...

A series of novel metal organic frameworks with lanthanide double-layer-based inorganic subnetworks (KGF-3) was synthesized assisted by machine learning. Pure KGF-3 was difficult to isolate in the initial screening experiments. The synthetic conditions were successfully optimized by extracting the dominant factors for KGF-3 synthesis using two mach...

A series of novel metal organic frameworks with lanthanide double-layer-based inorganic subnetworks (KGF-3) was synthesized assisted by machine learning. Pure KGF-3 was difficult to isolate in the initial screening experiments. The synthetic conditions were successfully optimized by extracting the dominant factors for KGF-3 synthesis using two mach...

The thermodynamic (PCN-222) and kinetic (PCN-224) products of porphyrinic Zr-metal–organic frameworks (MOFs) were synthesized via an anodic dissolution approach for the first time. To the best of our knowledge, this...

Coordination polymers with metal-sulfur (M-S) bonds in their nodes have interesting optical properties and can be used as photocatalysts for water splitting. A wide range of inorganic-organic hybrid materials with M-S bonds have been prepared in recent years. However, there is a dearth of structural information because of their low crystallinity, w...

A series of novel metal organic frameworks with lanthanide double-layer-based inorganic subnetworks (KGF-3) was synthesized assisted by machine learning. Pure KGF-3 was difficult to isolate in the initial screening experiments. The synthetic conditions were successfully optimized by extracting the dominant factors for KGF-3 synthesis using two mach...

Single‐atom catalysts (SACs) have been successfully used for various electrochemical reactions. The synthetic methods for different single metal atoms are specific, however; it is extremely challenging to develop a universal synthesis method for a large range of single‐atom metals. Herein, we report a comprehensive strategy to synthesize a full ran...

Universality in preparing samples with atomic metal dopants is vital to expand the diversity of single‐atom materials and their widespread applications. We provide a comprehensive library of single atoms for systematically investigating their different electrocatalytic behaviors in HER and RT Na‐S batteries. In particular, the tuning of single‐atom...

We synthesized four flexible interdigitated hydrophobic metal–organic frameworks that differ only in their centered metal ion and isostructural form, and showed water-adsorption properties that depended on the metal species. Crystallography...

To diversify metal-organic frameworks (MOFs), multi-component MOFs constructed from more than two kinds of bridging ligand have been actively investigated due to the high degree of design freedom afforded by the combination of multiple ligands. Predicting the synthesis conditions for such MOFs requires an understanding of the crystallization mechan...

Microfluidic systems are efficient tools for elucidating the non‐equilibrium state on the crystallization of multi‐component metal–organic frameworks (MOFs). The understanding of the crystallization mechanism makes it possible to predict the synthesis conditions. Based on the experimental analysis using microflow reactors, nonclassical crystallizat...

p>Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe³⁺), cobalt (Co³⁺), ruthenium (Ru<sup>3+</s...

The Cover Feature shows a porous inorganic/organic hybrid framework material to be used as a cathode for Li‐ion batteries. This material enables reversible electrochemical formation/cleavage of disulfide linkages in the framework. Based on this phenomenon, the battery can have a long‐life cycle, and it also can show significant battery capacities d...

Die kurze Synthese von schwefelangereichertem reduziertem Graphenoxid (S‐rGO) gelingt durch den Einsatz von Lawessons Reagenz. Polyoxometallat(POM)‐Cluster wurden auf der S‐rGO‐Oberfläche individuell immobilisiert, und eine Lithiumbatterie basierend auf dem POM und S‐rGO‐Komplex zeigte hohe Zyklenstabilität. Abstract The concise synthesis of sulfu...

We achieved concise synthesis of sulfur‐enriched graphene for battery applications. The direct treatment of graphene oxide (GO) with commercially available Lawesson’s reagent produced sulfur‐enriched‐reduced GO (S‐rGO). Various techniques, such as X‐ray photoelectron spectroscopy (XPS), confirmed the occurrence of both sulfur functionalization and...

Three porous and two nonporous disulfide‐ligand‐containing metal‐organic frameworks (DS‐MOFs) with various structural dimensionalities were used as cathode active materials in lithium batteries. Charge‐discharge performance examinations revealed that only porous DS‐MOF‐based batteries exhibited significant capacities close to theoretical values, wh...

Developing new cathode-active materials for rechargeable battery is important to fulfill the growing demands of energy transformation, storage, and utilization. Zeolitic transition metal oxides based on vanadomolybdate, constructed by pentagon metal-oxygen clusters as building blocks and metal ions as linkers in a trigonal symmetry, are good candid...

Recently, metal-organic frameworks (MOFs) composed of sulfur secondary building units (sulfur-SBUs) have attracted significant attention as unique electronic materials with high conductivities and photo- and electrocatalytic properties. Herein we report the crystal structure of KGF-1, an example of a Pb-MOF composed of three-dimensionally extended...

An electrochemical cell combining the energy storage characteristics of the chemical redox reaction and a physical capacitor effect presents advantages including high energy and power densities, and long durability. In this study, we prepared nanohybrid materials between polyoxometalate (POM) and porous carbon, which have different porous structure...

A new design strategy for high-performance organic cathode active materials for lithium-ion batteries is presented, which involves the assembly of redox-active organic molecules with a crystalline porous structure using mixed-stacked charge-transfer (CT) complexes. Hexahydroxytriphenylene was used as a donor molecule and 1,4,5,8,9,12-hexaazatriphen...

Li‐rich Mn‐based oxides (LRMO) are promising cathode materials to build next‐generation lithium‐ion batteries with high energy density exceeding 400 W h kg⁻¹. However, due to a lack of in‐depth understanding of oxygen redox chemistry in LRMO, voltage decay is not resolved thoroughly. Here, it is demonstrated that the oxygen redox chemistry could be...

Two interesting nona-cyanometalate-based coordination polymers (CPs) {[µ4-M(CN)9Mn2(dpo)2(DMF)4]·DMF}n (M = W 1, Mo 2) were obtained from the reaction of 2,5-di(4-pyridyl)-1,3,4-oxadiazole (dpo) and (Bu3NH)3[M(CN)8] (M = W, Mo) with Mn(NO3)2·6H2O in DMF solvent. It is noteworthy that the in-situ generated [M(CN)9]4– (M = W, Mo), the first nona-cyan...

Three octacyanometalate-based bimetallic coordination polymers (CPs), {[μ4-MV(CN)8][Co(DMF)4]2(ClO4)}n (M = W CP-1, Mo CP-2) and {[μ4-WIV(CN)8]Co2(azpy)4}n CP-3, were synthesized in the absence (for CPs 1 and 2) or presence (for CP-3) of auxiliary ligand 4,4’-azopyridine (azpy), respectively. CPs 1 and 2 exhibit the same three-dimensional (3D) poly...

Double [5]helicenes possessing two tetracoordinated boron atoms at the ring junctions were synthesized from glycine anhydride in three steps. The helicene with fluorine substituents on the boron atoms was employed as a cathode active material in a lithium battery to demonstrate moderate performance in the 1.8-3.5 V range with more than 63 mAh g-1 d...

The Front Cover shows an interdigitated metal–organic framework based on {[M(isophthalate)(4,4′‐bipyridine)]⋅solvent}n (M=Zn or Cd). Competition between ligands and solvent molecules influences crystal growth processes which is monitored using atomic force microscopy. More information can be found in the Communication by Y. Kamakura et al.

The front cover artwork is provided by the groups of Mr. Y. Kamakura, Prof. Dr. H. Yoshikawa and Prof. Dr. D. Tanaka (Kwansei Gakuin University, Japan) as well as Dr. N. Hosono, Ms. A. Terashima and Prof. Dr. S. Kitagawa (Institute for Integrated Cell‐Material Sciences (WPI‐iCeMS), Kyoto University Institute for Advanced Study (KUIAS), Japan). The...

Amorphous and crystalline MetfV10 electrodes for lithium ion batteries were prepared by mixing MetfV10 with different binders: polyvinylidenefluoride (PVDF) or polytetrafluoroethylene (PTFE). The amorphous MetfV10 cathode demonstrates a higher specific capacity than the crystalline cathode. The reaction mechanism was studied using in situ X-ray abs...

Metal‐organic frameworks (MOFs) containing two or more types of metal ions exhibit promising new functionalities. To precisely control the distribution of metal ions, the relationship between the crystal growth mechanism and the metal ion type is important, so we herein discuss the correlation between the crystal surface profiles and metal ions by...

Disulfide, which is a sub-group of organosulfides, has been studied as a promising cathode active material. Herein, to improve battery performance, we inserted disulfide into Cu-based metal organic framework (MOF) as a ligand. As a result, the disulfide inserted MOF exhibited a high capacity based on dual redox reactions of Cu ions and disulfide li...

Hydrazine-embedded heterocyclic compounds with dimeric dimethylacridine (1b), carbazole (2b), and phenothiazine (3b) skeletons were applied to cathode active materials of rechargeable lithium organic batteries, and the performance of the batteries was evaluated. The charge/discharge curves exhibited clear plateaus in the high voltage range of 3.3-3...

γ-phase LiV2O5, which shows superior electrochemical performance as cathode material in Li-ion batteries, was prepared by annealing the polyoxovanadate cluster Li7 [V15O36(CO3)]. The reaction mechanism was studied using operando X-ray absorption fine structure (XAFS), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS) analy...

The development of cathode-active material of Li battery is important for the current emerging energy transferring and saving problems. A stable crystalline microporous complex metal oxide based on Mo, V, and Bi is an active and suitable material for Li battery. High capacity (380 Ah/kg) and stable cycle performance are achieved. X-ray absorption n...

We successfully obtained a paramagnetic one-dimensional (1D) chain complex [{Ru2(O2CCH3)4}{Pt2(piam)2(NH3)4}2]n(PF6)4n·4nH2O (2; piam = pivalamidate) extended by metal-metal bonds. Compound 2 comprises two types of metal species, ruthenium and platinum, where an acetate-bridged dinuclear ruthenium complex (i.e., [Ru2]) and a pivalamidate-bridged pl...

A series of V-incorporated ε-Keggin polyoxometalate-based open framework materials, (NH4)1.8H10 [Zn3Mo11.9V0.1O40] ·6.5H2O, (NH4)1.8H10 [Zn2.7Mo11.6V0.7O40] ·6.5H2O, (NH4)1.8H7 [Zn2.6Mo11.2V1.2O40] ·6H2O, (NH4)2H14 [Mn2.4Mo12V0.2O40] ·5H2O, (NH4)2.2H12 [Mn2.2Mo11.9V0.7O40] ·5H2O, and (NH4)2.2H9 [Mn2.2Mo11.6V1.0O40] ·5H2O, is hydrothermally synthesi...

The tuning of the chemical composition of polyoxometalate (POM)-based open framework materials with the same structure, leading to a property change of the materials, is interesting. Here, we report the synthesis of a series of vanadium-incorporated, ϵ-Keggin polyoxometalate-based open framework materials by using a hydrothermal method. The resulti...

Metal-organic frameworks (MOFs) are well known for their application to various types of energy storage; nevertheless, their potential in electron storage has scarcely been investigated. Indeed, the synthetic strategy of MOFs towards the pseudocapactive materials is still absent due to the lack of a detailed insight into the solid-state redox proce...

The preparation of boron-doped nanocarbon scaffolds with well-defined structures is important for the understanding of the impact of boron doping on their properties and behavior at the molecular level. We recently succeeded in the synthesis of a structurally well-defined nanographene molecule, bearing two boron atoms at the central positions. In t...

Organic optoelectronic devices have received much attention in recent years, mainly owing to their flexibility and ease of fabrication. However, poor charge carrier mobilities of most organic materials and the strong binding energy of excitons pose significant design restrictions on such devices, which limit their performance for steady-state photo...

Three manganese–molybdenum/tungsten bimetallic coordination polymers, two 2D {{[μ4-M(CN)8]2[Mn(dmf)3]2[Mn(dmf)4]}·2DMF}n (M = W 1, Mo 2) and a 1D {{[μ4-Mo(CN)8][Mn(dmf)4]2}·(ClO4)}n (3), were constructed from the reaction of the (Bu3NH)3[M(CN)8] (M = W, Mo) and Mn(ClO4)2·6H2O molecular building blocks in DMF solvent in the presence (for 1 and 2) or...

By adopting a facile synthetic strategy, we obtained a microporous redox-active metal-organic framework (MOF), namely Cu(2,7-AQDC) (2,7-H2AQDC = 2,7-anthraquinonedicarboxylic acid) (1), and utilized it as a cathode active material in lithium batteries. With a voltage window of 4.0-1.7V, both metal clusters and anthraquinone groups in the ligands ex...

We performed electrochemical doping of Cl- ions to the x-form single crystals of a neutral pi radical LiPc, in which the structure consists of 1D stacking chains of LiPc and nanochannels parallel to them. It was found that the LiPc crystals on the working electrode were electrochemically oxidized in an acetonitrile solution of tetrabutylammonium ch...

We demonstrated that the performance of the polyoxometalate molecular cluster battery (POM-MCB) is significantly dependent on the weight ratio of POM in the cathodes; the discharge capacities per unit weight of POM decrease as the POM weight ratio increases. Operando XAFS and impedance measurements of the POM-MCBs with higher POM ratios revealed th...

The solid-state electrochemical reduction of magnetite (Fe3O4) nanoparticles was studied using a miniature Li battery that included Fe3O4 as a cathode active material. X-ray diffraction and absorption analyses clearly elucidated the relationship between the battery voltage and the chemical species reduced from Fe3O4. Upon discharging, the Fe3O4 nan...

Theoretical investigations are presented on the molecular and electronic structure changes of α-Keggin-type polyoxometalate (POM3-) clusters [PM12O40]3- (M = Mo, W) occurring towards reaching their super-reduced POM27- state during the discharging process in lithium-based molecular cluster batteries (MCBs). Density functional theory (DFT) was emplo...

magnified image Density functional theory calculations on the neutral [Mn 12 ] ⁰ molecular magnet and super‐reduced [Mn 12 ] 8– cluster were employed to investigate the experimental geometrical changes observed during discharging in a molecular cluster battery. It was found that for relevant low‐spin states the eight electrons added in [Mn 12 ] 8–...

A three-dimensional (3D) manganese–tungsten bimetallic coordination polymer (CP) {{[μ5-W(CN)8]2[Mn(HMTA)1.5]2[Mn(HMTA)(H2O)2]}·2H2O}n (CP-1) (HMTA = hexamethylenetetramine) is constructed by the reaction of the molecular building block [W(CN)8]3– and tetradentate bridging ligand HMTA with d5 transition metal ion Mn2+. CP-1 has been unambiguously co...

Although aromatic compounds occupy a central position in organic chemistry, antiaromatic compounds have demonstrated little practical utility. Herein we report the application of an antiaromatic compound as an electrode-active material in rechargeable batteries. The performance of dimesityl-substituted norcorrole nickel(II) complex (NiNC) as a cath...

Organic optoelectronic devices are usually driven by the electric field generated from an electrode potential difference or bias voltage. Although poled ferroelectric domains may produce oriented stray fields, few efforts have been made to utilize them for photocurrent generation in organic devices. Here we show that large net fields caused by inco...

A synergetic combination of a chemical redox reaction and a physical capacitor effect in one electrochemical cell is a promising route to realize both high-energy and high-power-density energy storage. In the present work, we studied the electrochemical properties of a nanohybrid system of polyoxometalate (POM) and graphene (RGO), in which individu...

Heterocyclic thiazyl radicals possess unique chemical and physical properties as building blocks for molecule-based conductors and magnetic materials. They do not need protecting groups on their molecular skeletons, and the lack of such substituents permits close packing in the solid state. Moreover, thiazyl radical solids often involve a multidime...

Aqueous solution was introduced into the self-assembly of water-insoluble (Bu3NH)3[M(CN)8] (M = W, Mo) and Mn(NO3)2·6H2O to afford two, three-dimensional (3D) coordination polymers (CPs), {[μ8-MV(CN)8MnII2(H2O)2(CH3OH)][NO3]}n (M = W 1, Mo 2), while polymer {[μ4-WV(CN)8MnII2(DMF)8](ClO4)}n (DMF = N,N-dimethylformamide) (3) was crystallized from the...

Rechargeable molecular-cluster batteries (MCBs) based on the manganese cluster complex [Mn12 O12 (CH3 CH2 C(CH3 )2 COO)16 (H2 O)4 ] ([Mn12]) that exhibited a capacity of approximately 200 A h kg(-1) in the battery voltage range of 4.0 to 2.0 V were developed. In these batteries, the capacity of approximately 100 A h kg(-1) in the range of 4.0-3.0 V...

Ferroelectricity is essential to many forms of current technology, ranging from sensors and actuators to optical or memory devices. In this circumstance, organic ferroelectrics are of particular importance because of their potential application in tomorrow's organic devices, and several pure organic ferroelectrics have been recently developed. Howe...

Supplementary Infomation

Seamless observation: Magnetic measurements in a solid-state electrochemical environment have been developed and applied to a mixed-valent chromium Prussian blue analogue (PBA) ferrimagnet. Battery cells containing PBA as a cathode active material were inserted into a SQUID and the PBA reduction during battery discharge was controlled. Magnetic cha...