Kunihisa Sugimoto

Solid-state magnetic properties of thiaporphyrin Cu ^II ion pairs can be controlled by the assembly mode: dimer-based packing induces antiferromagnetic behaviour, whereas charge-by-charge assembly does not.

Small-molecule sorption by porous metal–organic frameworks has attracted considerable attention but remains largely unexplored in nonporous crystals composed of discrete metal complexes. Here, we report cyanoborate-bridged cubane-type tetranuclear ruthenium complexes, [Ru4(Cp)4{BR(CN)3}4] (R = F (1), Me (2), H (3)), as adaptive crystalline hosts for volatile organic compounds (VOCs). Recrystallization of 1 from solvents with widely varying polarities, sizes, and shapes afforded solvate crystals containing one to three guest molecules per cubane unit. The guest molecules were accommodated around the shallow concave faces of the cubane units, and the packing structures were classified into three types largely governed by guest size and shape. The desolvated solid of 1 reversibly sorbed various VOC vapors, with the sorption amounts largely consistent with the solvent contents of the corresponding solvate crystals, indicating guest-dependent rearrangement of the intermolecular packing. Complexes 2 and 3 exhibited substituent-dependent CH2Cl2 sorption–desorption behavior. Although 1 showed only very limited N2 and H2 uptake at 77 K, it exhibited appreciable low-temperature CO2 uptake. These results expand the scope of adaptive crystalline hosts to discrete metal-complex systems with rigid, three-dimensionally shaped molecular units.

FeOOH has emerged as a promising earth‐abundant catalyst for water oxidation, with activity comparable to that of precious‐metal oxides such as IrO ₂ and RuO ₂ under optimal conditions. Herein, we systematically investigate the effect of crystal structure on water oxidation activity using four FeOOH polymorphs (α, β, γ, and δ) under identical conditions. We demonstrate that the catalytic performance strongly depends on the crystal structure, with higher surface hydrophilicity leading to enhanced water oxidation activity. The same structure‐dependent trend is observed under both electrochemical and photochemical conditions, indicating that the intrinsic catalytic properties of FeOOH govern the reaction irrespective of the reaction mode. Density functional theory calculations reveal that the adsorption energy for H ₂ O on FeOOH surfaces correlates well with the experimentally observed activity, with δ‐FeOOH exhibiting the highest performance. These findings identify interfacial hydrophilicity as a key descriptor for water oxidation on FeOOH polymorphs and provide design guidelines for the development of efficient, earth‐abundant water oxidation catalysts.

The temperature and pressure dependence of the crystal structures and photophysical properties of three crystalline polymorphs of imidoylamidinato Pt(II) complexes exhibiting green luminescence (UG form, main phase), yellow luminescence (UY form), and orange luminescence (UO form) under ambient temperature and pressure were investigated. While the UG and UO forms did not show phase transitions in the temperature range of 300–90 K and below 6.5 GPa (UG) or 3.2 GPa (UO), the UY form exhibited inverse symmetry breaking induced by temperature and pressure. Based on observations of temperature- and pressure-induced phase transition processes using single-crystal X-ray diffraction and optical microscopy, these phase transitions were confirmed to proceed in a single-crystal to single-crystal manner via a twinning deformation process, in which multiple structural domains corresponding to different phases coexisted simultaneously within individual crystal particles during the transformation. It was revealed that, in the UY form, the strength of the interaction between BF₄^– ions and complex cations changes with temperature and pressure. This triggers a phase transition by inducing alterations in the arrangement of complex cations and counter-anions. In terms of contracting the crystal lattice, the effects of cooling and pressurization are similar. However, observing different luminescence behaviors in the UO and UY forms under temperature and pressure changes revealed that temperature and pressure do not necessarily have consistent effects on the stability of the excited state.

Photocatalytic overall water splitting holds great promise for sustainable hydrogen production. For overall water splitting performed by one-step excitation, both the hydrogen evolution and oxygen evolution reactions are hindered kinetically; hence, it is necessary to employ site-selective modification of photocatalysts with hydrogen-evolving and oxygen-evolving cocatalysts. However, critical challenges remain, including the need for cumbersome, multi-step photodeposition processes and durable blocking layers to inhibit the reverse reactions. Here we find a conductive, two-dimensional metal–organic framework to serve as a simple, multifunctional cocatalyst. We loaded this framework on SrTiO₃:Al, an overall water-splitting photocatalyst, using a one-step self-assembly method. The framework cocatalyst promoted steady photocatalysis with an apparent quantum efficiency of 31.5% at 350 nm, free from the reverse reaction even without blocking layers. We proposed the operational principles for the cocatalyst activity using spectroscopic, electrochemical and theoretical analyses. This two-dimensional metal–organic framework offers an all-in-one approach for designing efficient and practical one-step excitation overall water-splitting systems. The alternative text for this image may have been generated using AI.

Two cocrystals were obtained using C ₇₀ and a Ni-porphyrin derivative: a porous one featuring one-dimensional channels, and a nonporous one. High-pressure single-crystal X-ray diffraction clarified their pressure resistivity.

Supramolecular systems exhibit collective functions that emerge from the hierarchical assembly of individual molecular building blocks. Metal-organic polyhedra (MOPs) are a class of functional supramolecular architectures with well-defined molecular geometry and an intrinsic cavity. In recent years, considerable progress has been made in assembling MOPs into extended networks to create porous solids. However, most reported MOP assemblies are limited to three-dimensional networks, which, owing to their high-dimensional connectivity, hinder effective stress dissipation and render them brittle under mechanical stress. Here, we report the one-dimensional (1D) self-assembly of MOPs into supramolecular polymeric aerogels that combine permanent microporosity with exceptional mechanical flexibility. The reaction between amino acid-functionalized naphthalenediimide (NDI) linkers and copper salts led to the synthesis of octahedral copper-based MOPs, followed by their spontaneous self-assembly to form supramolecular gels. The corresponding aerogels converted from the gels possessed uniform 1D fibrillar networks (14.8 ± 2.2 nm in width) with intrinsic microporosity derived from individual MOP cavities. The aerogel endured 87% compressive strain without fracture, demonstrating distinct ductility. Furthermore, these fibrils in the supramolecular gels were converted to crystals after 2 weeks. Single-crystal X-ray diffraction revealed that MOPs are arranged via face-to-face interaction between octahedral MOPs to form a 1D helical chain structure. An analysis of the self-assembly process using Hansen solubility parameters unveiled that solvent conditions with high polarity and low dispersion interaction drive the formation of anisotropic assemblies. This work provides a new strategy for tailoring the mechanical properties of supramolecular materials through dimensional control of their assemblies.

Meltable organic–inorganic hybrid semiconductors are attractive for their potential for melt‐based processing. Although meltable semiconducting metal halide perovskites have been extensively studied, meltable semiconducting coordination polymers (CPs) remain scarce, despite their excellent structural designability and the tunability of their optoelectronic properties. We report a new family of meltable semiconductive Pb(II) benzenethiolate CPs bearing long alkyl chains, formulated as [Pb(SPhOC ₆ ) ₂ ] _n ( KGF‐34(C6) ; HSPhOC ₆ = 4‐hexyloxybenzenethiol). For comparison, we also synthesized the classical analogue [Pb(SC ₆ ) ₂ ] _n ( KGF‐59(C6) ; HSC ₆ = 1‐hexanethiol). Single‐crystal X‐ray diffraction analyses revealed that both KGF‐34(C6) and KGF‐59(C6) adopt 2D architectures, albeit with distinct inorganic (–Pb–S–) _n networks. A comprehensive characterization of the semiconducting properties, combined with first‐principles calculations, revealed that KGF‐34(C6) exhibits significantly higher photoconductivity, a narrower band gap, and a larger band dispersion than KGF‐59(C6) , attributable to differences in their inorganic (–Pb–S–) _n network structures. Furthermore, both KGF‐34(C6) and KGF‐59(C6) exhibit multiple phase transitions, including melting and liquid crystalline formation, enabling the fabrication of optoelectronic devices via melt processing. Notably, this is the first report of meltable semiconducting CPs comprising benzenethiol‐derived ligands. These findings offer a rational design strategy for developing melt‐processable semiconductive materials based on metal–benzenethiolate CPs.

Meltable organic–inorganic hybrid semiconductors are attractive for their potential for melt‐based processing. Although meltable semiconducting metal halide perovskites have been extensively studied, meltable semiconducting coordination polymers (CPs) remain scarce, despite their excellent structural designability and the tunability of their optoelectronic properties. We report a new family of meltable semiconductive Pb(II) benzenethiolate CPs bearing long alkyl chains, formulated as [Pb(SPhOC ₆ ) ₂ ] _n ( KGF‐34(C6) ; HSPhOC ₆ = 4‐hexyloxybenzenethiol). For comparison, we also synthesized the classical analogue [Pb(SC ₆ ) ₂ ] _n ( KGF‐59(C6) ; HSC ₆ = 1‐hexanethiol). Single‐crystal X‐ray diffraction analyses revealed that both KGF‐34(C6) and KGF‐59(C6) adopt 2D architectures, albeit with distinct inorganic (–Pb–S–) _n networks. A comprehensive characterization of the semiconducting properties, combined with first‐principles calculations, revealed that KGF‐34(C6) exhibits significantly higher photoconductivity, a narrower band gap, and a larger band dispersion than KGF‐59(C6) , attributable to differences in their inorganic (–Pb–S–) _n network structures. Furthermore, both KGF‐34(C6) and KGF‐59(C6) exhibit multiple phase transitions, including melting and liquid crystalline formation, enabling the fabrication of optoelectronic devices via melt processing. Notably, this is the first report of meltable semiconducting CPs comprising benzenethiol‐derived ligands. These findings offer a rational design strategy for developing melt‐processable semiconductive materials based on metal–benzenethiolate CPs.