Abstract Octaaryltetraazaporphyrins substituted at the para position of the peripheral benzene rings and containing group 14 elements (Si(IV), Ge(IV), and Sn(IV)) were synthesized and characterized, and their properties were compared specifically with those of a group 15 element (P). Tert-butyl or fluorine-substituted compounds exhibit the Q, CT, and Soret bands in ascending energy, and the position and intensity of the former two bands appear to change due to configuration interaction between their states. Consequently, strongly electron-donating diphenylamino-substituted compounds exhibited the CT, Q, and Soret bands in ascending energy. Among compounds with the same substituent, those containing elements situated at a higher level in the periodic table exhibited spectra with a stronger electron-withdrawing property. Namely, the Q and CT bands of the Si complex appeared at shorter wavelengths than those of the Ge and Sn compounds. The spectra of the Sn complexes resemble those of the P compound in terms of shape and position. Molecular orbital calculations broadly supported these observations. Single crystal X-ray diffraction analysis unambiguously elucidated two compounds containing tert-butyl substituents and Si or Sn to maintain a tetravalent, hexacoordinated metal representation.
Abstract Quantitative understanding of catalysis requires more than comparison of apparent activity. It begins by establishing whether a measured rate represents intrinsic surface chemistry or is influenced by mass transfer, heat transfer, reactor geometry, or catalyst evolution. Thermocatalysis developed a rigorous physical-chemistry framework for making this distinction and for describing intrinsic rates through microkinetic analysis, in which adsorption, surface reaction, desorption, coverage, and kinetically controlling elementary steps are evaluated using independently measurable parameters. In electrocatalysis, electrode potential introduces an independently controllable energetic variable, but measured current–potential behavior also contains contributions from solution resistance, diffusion, migration, local pH, bubble dynamics, and electrolyte speciation. Electrolyte engineering therefore treats intrinsic electrolyte properties as quantitative design variables, particularly at non-extreme pH with buffered systems. Photocatalysis extends the same quantitative logic by adding photon absorption, carrier generation, separation, transport, and interfacial charge transfer before surface catalytic turnover. Once local kinetic, thermodynamic, and transport properties are independently established, multiphysics simulation can predict spatial distributions, product yield, and reactor performance. Electron chemical potential serves as a useful connecting energetic coordinate, while the central methodology is the quantitative decomposition of apparent catalytic performance into elementary kinetics and transport.
Abstract ASP2397 is a siderophore-like cyclic hexapeptide with potent and rapid fungicidal activity against Aspergillus species. We report here its first total synthesis, enabled by an unprecedented one-pot chemoselective reduction of secondary N-benzyloxyamides that strictly preserves the fragile N–O bond. This transformation includes an Ir-catalyzed hydrosilylation with Et2SiH2, followed by NaBH3CN reduction of the resulting oxime derivatives in the presence of a carbamate protecting group and ester, providing efficient access to the non-canonical N-acetyl-N-hydroxyornithine (AhOrn) building block. The macrocycle was assembled via a solid-phase peptide synthesis (SPPS) and head-to-tail macrolactamization. A late-stage one-pot debenzylation/chelation protocol successfully furnished the Al3+-chelated ASP2397. The integrity of the synthesized macrocycle was unequivocally confirmed by its targeted antifungal activity, mirroring the natural product and providing the necessary chemical platform for future structure-activity relationship studies.
Abstract Sunlight is our largest energy resource, but it is diffuse and intermittent. Artificial photosynthesis aims to capture and store it in the chemical bonds of fuels. Among the possible approaches, photocatalysts built from light-absorbing semiconductors suspended in water are especially appealing for the simple system design and potential low cost, yet their practical use is still limited by low efficiency and the absence of scalable device architectures. This Account describes how our group has worked on these problems, by designing efficient visible-light-absorbing materials, improving charge utilization and rethinking the overall reaction system. We first designed visible-light-responsive photocatalysts, where cation doping and heteroanion substitution tune band and crystal structures in concert to broaden light absorption. An alternative route is to combine two photocatalysts in a Z-scheme system, mimicking the two-stage light reactions of natural photosynthesis. A key difficulty here is efficient electron transfer between the two photocatalysts. To address this, we developed scalable photocatalyst sheets in which a conductive layer mediates interparticle electron transport, setting a benchmark for photocatalytic water splitting. The same design also converts CO2 into carbon-based fuels when combined with molecular catalysts or living microorganisms. These advances move particulate photocatalysis a step closer to practical solar fuel production.
Abstract This Account highlights the transformative advances enabled by the world-first BL36XU beamline dedicated to in situ and operando characterization of metal nanoparticles and adsorbed species in polymer electrolyte fuel cells (PEFCs). While PEFCs hold great promise for sustainable energy conversion, they have not yet reached a level that makes them irreplaceable by alternative energy systems. To address this challenge, we developed complementary multimodal X-ray techniques including time-resolved QXAFS–XRD, HERFD-XANES–RIXS–XRD–QXAFS, same-view nano-XAFS–STEM/EDS, and 3D CT–XAFS, which provided unprecedented insights into critical issues such as spatially non-uniform performance, multi-element degradation mechanisms, and complex distribution–structure–activity–durability relationships of Pt-based electrocatalysts in PEFCs under operating conditions. Future perspectives emphasize simultaneous detection of light and heavy elements by combining hard X-rays with muonic X-rays. The advanced methodologies will drive the rational design of durable, cost-effective PEFCs for heavy-duty vehicles and establish a transferable paradigm for studying other electrochemical and heterogeneous catalytic systems.
Abstract Porous carbon-supported Cu–Co bimetallic catalysts (Cu–Co/NC) were synthesized from a Zn/Co bimetallic metal-organic framework (MOF) precursor and employed for peroxymonosulfate (PMS) activation toward tetracycline (TC) degradation. Among the prepared catalysts, Cu–Co/NC-1 exhibited the highest catalytic activity, achieving approximately 99% TC removal within 6 min with an apparent rate constant of 0.7831 min−1, which was 15.47 times higher than that of the NC/PMS system. Adsorption accounted for only 9.36% of TC removal during the 30 min pre-equilibration period, confirming that rapid TC elimination after PMS addition predominantly originated from catalytic oxidation. The catalyst maintained effective performance over a broad pH range and showed acceptable tolerance toward common coexisting anions. Quenching experiments and EPR analysis indicated that PMS activation proceeded through both radical and nonradical pathways involving SO4·−, ·OH, O2·−, and 1O2. The enhanced catalytic activity is attributed to the cooperative redox behavior of Cu and Co species, together with the contribution of oxygen-containing surface functionalities and the porous N-doped carbon framework. Furthermore, a Cu–Co/NC-1-loaded PTFE membrane reactor maintained high TC removal efficiency during 240 min of continuous operation, demonstrating the feasibility of continuous-flow catalytic degradation. This work provides a rational strategy for developing MOF-derived bimetallic carbon catalysts for PMS-based treatment of antibiotic contaminants.
Abstract π-Conjugated organic photoantenna ligands, such as bipyridine, are widely used to sensitize the luminescence of photoluminescent lanthanide ions (e.g. Eu3+ and Tb3+), whereas the photoantenna potential of minimal π-electronic systems remains largely unexplored. Here we report lanthanide metal–organic frameworks (MOFs, Ln = Eu, Gd, and Tb) constructed from isonicotinic acid (NA), one of the smallest π-electronic system ligands. Single-crystal X-ray diffraction analysis reveals tetranuclear Ln4O4 clusters with two distinct NA coordination modes and forms zeolite-like MOFs. Photophysical studies show that NA functions as an effective photoantenna, giving rise to excitation-wavelength-dependent ligand-centered emission in GdNA and efficient energy transfer to lanthanide ions in EuNA and TbNA. In particular, EuNA exhibits the excitation-dependent coexistence of ligand-centered and lanthanide-centered emissions, arising from coordination-mode-dependent energy relaxation pathways. These findings shed light on new aspects of the versatile luminescence control of cuboid-based lanthanide MOFs incorporating minimal π-electronic system ligands.
Abstract This work reviews recent progress in the microstructural and chemical design of materials for molten carbonate fuel cells (MCFCs), with emphasis on research conducted at the Faculty of Materials Science and Engineering, Warsaw University of Technology. The study demonstrates that the porous microstructure plays a decisive role in cell performance. Key parameters, including porosity, pore size distribution, tortuosity, constrictivity, and pore shape, strongly influence gas transport, electrolyte distribution, and electrochemical activity. The introduction of multimodal pore architectures and the use of both natural and synthetic porogens significantly enhanced power density by improving the electrolyte–gas interface and extending active reaction regions beyond the classical triple-phase boundary. Chemical modifications of cell components were found to improve durability and efficiency. Ceramic coatings, such as TiO2 and MgO, and composite TiO2/Ag layers reduced nickel dissolution rate from the cathode by up to 3 times while enhancing electrical performance. Furthermore, hybrid MCFC–SOFC systems incorporating oxygen-ion-conducting ceramics (SDC, YSZ) exhibited higher ionic conductivity. Computational modeling of porous microstructures, combined with experimental validation, provided insights into structure–property relationships and enabled the optimization of electrode design. Overall, the combined microstructural and chemical optimization offers an effective pathway to improve MCFC performance and durability.
Abstract In this paper, the discovery of the AZaphthalocyanine Unimolecular Layer (AZUL) catalyst, in which metal azaphthalocyanines are molecularly adsorbed on carbon, is summarized as a promising alternative to rare-metal catalysts. Also, this catalyst’s broad applicability to a wide range of electrochemical reactions and its implementation in practical energy devices are highlighted. Furthermore, the molecular adsorption concept is not limited to electrocatalysis but can be extended to other functional applications, such as enhancing the capacitance of supercapacitors. In addition, by combining AZUL catalysts with a recently developed electrolysis system employing regenerative redox mediators, both the overpotential required for electrolysis and the charge–discharge overpotential of zinc–air batteries can be dramatically reduced. Finally, the future prospects and potential directions for the further development of this emerging catalyst platform and its associated energy technologies are discussed.
Abstract We designed α(2,3)- and α(2,6)-sialylgalactose analogs bearing an exomethylene unit at C3 of sialic acid (3-exoSia) as a novel type of mechanism-based inhibitors of sialidases. Regio- and stereoselective substitution via vinylogous activation enabled the simultaneous construction of the 3-exomethylene moiety and the O-sialoside linkage. Both types of 3-exoSia disaccharides potently inhibit Clostridium perfringens sialidase NanI and selectively inhibit NEU2 among human sialidases, whereas the corresponding monosaccharide analog is inactive. These analogs initially work as competitive inhibitors, but are gradually cleaved as substrates to generate a reactive species that forms a covalent bond with sialidase.
Effective preparation and addition reactions of highly functionalized acetylides are described. While classical procedures with butyllithium or Grignard reagents often suffer from functional group limitations, the current procedure employs the turbo-Grignard reagent and bromoalkynes possessing epoxide, acetate, and chloride functional groups for acetylide formation. The addition reactions with the resulting acetylides proceeded in the presence of catalytic ZnCl2. This procedure is a promising alternative to classical approaches owing to its high functional group tolerance.
All-inorganic CsPbBr3 semi-transparent perovskite solar cells (PSCs) hold significant promise for optoelectronic applications. However, the performance improvement is hindered by challenges such as poor interfacial compatibility between the hole transport layer (HTL) and perovskite, limitations of conventional fabrication methods, and intrinsic defects in CsPbBr3. To address these issues, we propose a mild and efficient device fabrication strategy. Ultrapure water is introduced as a co-reactant in an atomic layer deposition (ALD) process to grow a nickel oxide (NiOX) HTL compatible with n-i-p structured devices. The hydroxyl groups derived from water molecules provide abundant adsorption sites, ensuring uniform and conformal film growth. By precisely controlling the water pulse duration, the Ni3+ content and work function of the NiOX layer can be finely tuned. Concurrently, a 2-phenylethylammonium bromide (PEABr) surface passivation layer deposited via ultrasonic spray coating effectively protects the CsPbBr3 from exposure to high-temperature water vapor during the ALD process. This passivation layer simultaneously replenishes Br- vacancies and passivates undercoordinated Pb2+ species at the perovskite surface. As a result, small-area CsPbBr3 PSCs fabricated using this strategy achieve a power conversion efficiency (PCE) of 7.00%, and large-area devices demonstrate an efficiency of 3.47%, highlighting the excellent scalability and application potential of this approach.
Abstract Multimetallic hydride clusters provide an excellent platform for the cooperative activation and transformation of small molecules under mild conditions. This account highlights our recent advances in the synthesis, reactivity, and mechanistic understanding of titanium-based hydride clusters capable of the cleavage and functionalization of N2. A trinuclear titanium heptahydride cluster exhibits remarkable reactivity, enabling stepwise N≡N bond reduction, cleavage, and hydrogenation without external reductants. Beyond N2 activation, the same cluster promotes unprecedented transformations of aromatic compounds, including C–C and C–N bond cleavage and carbon skeletal rearrangement of benzene and pyridines. Importantly, titanium hydride clusters mediate the direct hydroamination of simple alkenes with N2, affording alkylamines via C(sp2)–H and N–N bond cleavage followed by selective N–C bond formation. Expanded reactivity has further been realized using dititanium, chromium, and heterometallic hydride clusters, enabling N–X (X = H, B, Al, Si) bond formation, coupling reactions of N2 with α, β-unsaturated carbonyls or CO2, and N2 activation. Together, these findings establish multimetallic hydride frameworks as a promising platform for developing new molecular approaches to N2 fixation and the direct synthesis of value-added nitrogen-containing organic compounds.
Abstract Actinomycetes are ubiquitous in the environment and play crucial roles in soil and natural ecosystems. They are well known for producing a wide variety of secondary metabolites—chemical compounds that include antibiotics, pigments, and other pharmacologically active compounds—which have made significant contributions to medicine and industry. Secondary metabolites have traditionally been regarded as nonessential for microbial growth and survival. However, recent studies have revealed that these compounds play significant roles in the regulation of growth, differentiation, biological interactions, and stress responses in actinomycetes. For example, our research showed that actinomycetes produce a group of compounds known as heat shock metabolites when exposed to elevated temperatures. These metabolites contribute to growth under high-temperature conditions. Such findings indicate that secondary metabolites not only affect other organisms or the environment but also play key roles in the self-regulation and adaptive strategies of the producing microbes. This review summarizes current knowledge regarding how secondary metabolites produced by actinomycetes are functionally integrated into the organism's physiological processes, with the aim of providing insights useful to a broad scientific readership.
Electrocatalytic nitrate reduction is a sustainable alternative to the Haber-Bosch process, yet balancing activity with selectivity remains challenging. Herein, we developed a Fe-incorporated mesoporous UiO-66-NH2 (Fe-mUiO-66-NH2) catalyst using a hierarchical mesopore-confinement strategy. Structural analysis confirmed that the coral-like mesoporous architecture remains intact after Fe incorporation. XPS and electrochemical analyses show that the Fe sites within the mesoporous framework facilitate efficient charge transfer, which is key to the improved catalytic activity. Consequently, Fe-mUiO-66-NH2 achieves a superior ammonia yield rate of 160 mu mol h-1 cm-2 and a Faradaic efficiency of 75%, representing a significant improvement over the performance of the pristine MOF. This work demonstrates the synergy between efficient mass transport and optimized intrinsic activity, offering an effective strategy for high-efficiency nitrogen cycling.
Abstract This account focuses on the synthetic biology-based synthesis of biologically active terpenoids and meroterpenoids conducted in our laboratory. Particular emphasis is placed on the complete analysis of biosynthetic pathways and the mechanistic analysis of key transformation in the biosynthesis of individual natural products that are of academic and applied interest.
The one-step synthesis of 1,6-dihydro-3,4,9,10,15,16-R6-1,6,7,12,13,18-hexaazatrinaphthylene (R6HATN-H2: in R = H, HATN-H2) via the reaction of hexaketocyclohexane (HKC) with 1,2-phenylenediamine (PDA) was recently reported. In this study, the reaction mechanism, the optical absorption in the solid state, and the substituent effect (R = Me and Cl) are investigated. First, the reaction mechanism was examined through experiments and density functional theory (DFT) calculations. Rather than HATN, HKC and/or its condensates are hydrogenated by PDA. Moreover, to isolate HATN-H2 under air atmosphere, crystallization is required to inhibit its oxidation to HATN. Next, HATN-H2 showed an optical absorption at 667 nm in the solution, owing to its compact triangular donor/acceptor structure. Surprisingly, in the diffuse reflection of the crystal, a similar absorption was observed at 647 nm, but a different broad peak appeared at 810 to 1,010 nm. The latter peak is attributed to HATN-H* radicals on the crystal surface, based on electron spin resonance measurement and DFT calculation. The radicals remained very stable for a few years under air atmosphere. Finally, two derivatives, Me6HATN-H2 and Cl6HATN-H2, were synthesized via one-step synthesis. Single-crystal analysis showed columnar stacking structures. The dihydropyrazine units with two N-H groups are arranged in the opposite direction for Me6HATN-H2 and HATN-H2, but in the same direction for Cl6HATN-H2. The Me6HATN-H2 crystal showed a broad radical peak (770 to 960 nm) in the diffuse reflection, but no such peak was observed for Cl6HATN-H2. These differences in the crystal structure and the reflection absorbance are probably attributable to the Cl substituent.
Abstract This review summarizes recent advances in the synthesis, structure–activity relationships (SAR), and mode of action studies of marine-derived actin-depolymerizing macrolides, particularly aplyronines and mycalolides. Although these compounds have long been recognized as potent actin-targeting cytotoxins, recent chemical biology studies have revealed more complex mechanisms involving modulation of protein–protein interactions (PPIs) within the cytoskeleton. Synthetic efforts have enabled access to structurally diverse analogs, clarifying the distinct roles of the macrolactone and side-chain moieties in actin binding and cytotoxicity. Chemical probe development, including fluorescent, biotinylated, and photoaffinity-tagged derivatives, has facilitated the identification of tubulin as an additional target. Aplyronine A forms a heterotrimeric complex with actin and α/β-tubulin, acting as a molecular glue that destabilizes microtubules (MTs). In contrast, mycalolide C binds to tubulin independently of actin and enhances paclitaxel-induced MT assembly. Molecular modeling studies further support these distinct binding modes, revealing how these macrolides either disrupt or stabilize tubulin interactions. Collectively, these findings highlight the multiple functionalities of actin-binding macrolides as modulators of cytoskeletal PPIs and underscore their potential as lead compounds for the development of novel anticancer agents targeting MT dynamics.
Abstract The dithienophosphole (DTP) system has emerged as a remarkable structural motif in the field of organic materials, with pronounced electron-accepting properties due to its ease of synthetic accessibility, optoelectronic properties, and tunability through simple structural modifications. Since its introduction in 2004, this scaffold has been extensively elaborated by our group and others into a versatile platform for application-driven research. In this account, we delineate the multifaceted roles that DTPs have assumed across three principal research thrusts: a platform for promoting molecular self-assembly, Lewis acid sensing, and the engineering of chromophores featuring ambipolar redox behavior, which have collectively shaped the research in this area over the last decade.
Abstract The hydrodeoxygenation of oxygen-containing aliphatic compounds has emerged together with the concept of biomass refining. The hydrogenolysis of the C–O bond is a useful and central reaction for hydrodeoxygenation. There are two distinct approaches in C–O hydrogenolysis: an indirect multistep method (dehydrogenation–dehydration–hydrogenation and dehydration–hydrogenation routes) and direct C–O scission. The indirect route proceeds with conventional catalysts for C–O hydrogenolysis, such as Ru- and Cu-based ones. Catalysts for the direct C–O hydrogenolysis have been developed recently. In this review, the key to controlling selectivity in the hydrogenolysis of sterically hindered and unhindered C–O bonds is described for the cases of glycerol, erythritol, and 1,4-anhydroerythritol.
