Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Compression of a Flapping Mechanophore Accompanied by Thermal Void Collapse in a Crystalline Phase

Mechanical control of the molecular energy landscape is an important issue in modern materials science. Mechano­phores play a unique role in that the mechanical responses are induced against the activation barrier for intramolecular transformation with the aid of external forces. Here we report an unprecedented activation process of a flexible flapping mechano­phore. Namely, thermal void collapse in a crystalline phase triggers mechano­phore compression in a definite proportion. Unfavored conformational planarization of the flapping mechano­phore is compulsorily induced by packing force, leading to a total energy gain in crystal packing. Fluorescence chromism indicates extended π conjugation resulting from the mechano­phore compression, giving rise to an energy transfer from the unpressed to compressed conformers

Step-by-Step Fabrication of a Highly Oriented Crystalline Three-Dimensional Pillared-Layer-Type Metal–Organic Framework Thin Film Confirmed by Synchrotron X-ray Diffraction

Fabrication of a crystalline ordered thin film based on the porous metal–organic frameworks (MOFs) is one of the practical applications of the future functional nanomaterials. Here, we report the creation of a highly oriented three-dimensional (3-D) porous pillared-layer-type MOF thin film on a metal substrate using a step-by-step approach based on liquid-phase epitaxy. Synchrotron X-ray diffraction (XRD) study clearly indicates that the thin film is crystalline and its orientation is highly controlled in both horizontal and vertical directions relative to the substrate. This report provides the first confirmation of details of not only the crystallinity but also the orientation of 3-D MOF thin film using synchrotron XRD. Moreover, we also demonstrate its guest adsorption/desorption behavior by using <i>in situ</i> XRD measurements. The results presented here would promise useful insights for fabrication of MOF-based nanodevices in the future

Variable-Rung Design for a Mixed-Valence Two-Legged Ladder System Situated in a Dimensional Crossover Region

Ladder systems situated in a crossover from one dimensionality to two dimensionalities have been an attractive research target, because the physical properties, which are associated with dimensionality, are strongly dependent on the number of constituent legs. However, control of the intraladder configuration and electronic properties based on the substitution of structural components remain challenging tasks in materials science. On the other hand, structural design using coordination chemistry offers crucial advantages for architectural and electronic variations through substitutions of metal–organic building blocks. Here, we show the rational design and electronic properties of novel metal complex-based two-legged ladder compounds with several organic rung units: 4,4′-bipyridine, trans-1,4-diaminocyclohexane, and 4,4′-azopyridine. Single-crystal X-ray studies show that these two-legged ladder compounds are composed of halogen-bridged mixed-valence one-dimensional chains (MX chains) as their constituent legs. Depending on the molecular shape of the organic rung units, unique configurations of two-legged ladder lattices with periodic distortion of the legs are achieved. In addition, the electronic absorption spectra show that intervalence charge-transfer (IVCT) band gap of the two-legged ladder system increases with increasing degree of distortion of the leg. We have demonstrated for the first time that a two-legged ladder system shows a unique relationship between IVCT energy and the distortion parameter of the leg, as distinct from a single MX chain system. These systematic investigations, not only of configurations based on the rung variation but also of electronic states in metal–organic ladder system, provide the possibility for wide and rational tunings of physical and electronic properties of metal complex-based functional materials

Superprotonic Conductivity in a Highly Oriented Crystalline Metal–Organic Framework Nanofilm

The electrical properties of a highly oriented crystalline MOF nanofilm were studied. This nanofilm has low activation energy and a proton conductivity that is among the highest value reported for MOF materials. The study uncovered the reasons for the excellent performance of this nanofilm and revealed a new pathway for proton transport in MOF materials; besides the channels inside a MOF, the surface of the MOF nanocrystal can also dominate proton transport

Lithium Ion Diffusion in a Metal–Organic Framework Mediated by an Ionic Liquid

Metal–organic frameworks (MOFs) are desirable host materials to study and control the dynamics of molecules and ions such as lithium ions. We show the first study of a lithium ion-doped ionic liquid (IL) incorporated into a MOF and investigate its phase behavior and ionic conductivity. Moreover, for the first time, we have studied the dynamics of lithium ions in the micropores of the MOF in terms of the self-diffusion coefficient of the lithium ions. The IL was a mixture of EMI-TFSA (1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­amide) with LiTFSA (lithium bis­(trifluoromethylsulfonyl)­amide), and the MOF was ZIF-8 (Zn­(MeIM)₂; H­(MeIM) = 2-methylimidazole). The TFSA^– anions showed a gradual decrease of mobility in the micropores at low temperatures, which indicates the absence of the apparent freezing transition. The mobility of the Li⁺ cations showed a slightly steeper decrease than that of the TFSA^– anions at low temperature. The ionic conductivity of the (EMI_0.8Li_0.2)­TFSA in the micropores was 2 orders of magnitude lower than that of the bulk (EMI_0.8Li_0.2)­TFSA. However, the activation energy for the diffusion of lithium ions in the micropores of ZIF-8 was comparable with the bulk (EMI_0.8Li_0.2)­TFSA. These results suggest that the Li⁺ cations diffuse through the micropores via the exchange of the solvating TFSA^– anions, similar to the Grotthuss mechanism in proton conductivity