Metal ions influence the self-assembly behavior of crystallization solvents within low-dimensional coordination polymers, thereby determining pore geometry and (ir)reversibility. In this study, we investigate two isomorphous one-dimensional (1D) chain compounds, {[Mn(2,2 '-bpy)(CA)]& centerdot;2EtOH} (1) and {[Zn(2,2 '-bpy)(CA)]& centerdot;5H2O} (2) (2,2 '-bpy = 2,2 '-bipyridine; CA2- = chloranilate), crystallized from the same EtOH/H2O mixed solvent. Notably, these compounds selectively incorporate EtOH in 1 and H2O in 2 as continuous hydrogen-bonded "molecular pillars." Single-crystal X-ray diffraction analysis revealed pi-stacked -M-(mu 2-CA)-M- chain columns that form molecular-pillar-stabilized 1D channels. Thermal and vacuum desolvation induced an irreversible transformation to a distinct phase, and resoaking in the original solvent failed to restore the initial diffraction pattern. Attenuated total reflectance infrared analysis using an area-normalized band ratio confirmed the selective attenuation of guest bands after desolvation with limited recovery upon resoaking. Combined thermogravimetric analysis and differential scanning calorimetry further quantified guest-retention energetics, yielding Delta H per guest of approximately 20 kJ mol-1 for EtOH in 1 and 5 kJ mol-1 for H2O in 2. Gas and vapor sorption measurements exhibited negligible uptake after activation, consistent with pore collapse in the guest-free state. These findings establish crystallization solvents as integral structural components that dictate metastable porosity and irreversible structural fixation in 1D coordination polymers.

Herein, a free Cu complex, K2[Cu(maleonitriledithiolate)2], and an inclusion Cu complex, K2{[Cu(maleonitriledithiolate)2]@(beta-cyclodextrin)2}, were synthesised and characterised. Single-crystal X-ray diffraction revealed that the inclusion complex consisted of [Cu(maleonitriledithiolate)2]2- as a guest and two beta-cyclodextrins as a host. The structure of the guest fragment, [Cu(maleonitriledithiolate)2]2-, was essentially the same in the two complexes. The shortest Cu - Cu distance in the free complex and the inclusion complex was 6.91 and 15.5 & Aring;, respectively. Hyperfine splitting was observed in the electron paramagnetic resonance spectrum of the inclusion complex (g// = 2.090, g perpendicular to = 2.025, A// = 448 MHz, A perpendicular to = 108 MHz), whereas the free complex showed no hyperfine splitting (g// = 2.083, g perpendicular to = 2.025). The difference was attributed to the isolation of the Cu(II) ion included in the beta-cyclodextrins from other Cu ions. The association of host-guest in the solution-state and electrochemical behaviour were also investigated.

Diarylmaleimides are promising organic dyes owing to their structural simplicity and the tunability of their electronic structures through aryl substitution. Herein, we designed and synthesized pyridine‐linked diarylmaleimide dimers 1–3 bearing thiophene chains. The pyridine unit imparts proton responsiveness, whereas the length of the thiophene chains controls the electron‐donating ability. To evaluate the effect of the number of maleimide frameworks, h1, a half‐structure of 1, was also synthesized. Comparison of the absorption and fluorescence spectra of 1–3 with those of h1 revealed that the maleimide dimer framework enhances light‐harvesting efficiency and induces larger Stokes shifts. Extending the π‐conjugation through thiophene rings led to redshifted absorption and fluorescence bands, accompanied by increased molar absorption coefficients. As part of their proton‐responsive behavior, acid titration induced larger absorption spectral changes in 1–3 than those observed for h1. Notably, the absorption band of protonated 3 extended into the near‐infrared region. According to 1H NMR analysis and density functional theory (DFT) calculations, 1 exhibited structure‐specific proton responsiveness, involving a conformation in which both the pyridine nitrogen atom and an imide carbonyl oxygen atom participate in proton capture. Additionally, 1–3 displayed viscosity‐dependent fluorescence arising from the restriction of molecular motions.

Prussian blue analogues (PBAs), a class of microporous crystalline coordination frameworks, are long known for their diverse properties in porosity, magnetic, charge transport, catalysis, optics, and more. Versatile structural composition and the ability to control defect ordering through synthetic conditions offer opportunities to manipulate the functionality in the crystalline state. However, developments in Prussian blue analogues (PBAs) have primarily revolved around the ordered crystalline state, and the glassy state of PBAs has not yet been explored. Here we report the discovery of a disordered glassy state of the PBA via mechanically induced crystal–glass transformation. We found the preservation of metal–ligand–metal connectivity, confirming the short-range order and semiconductor behaviour, exhibiting an electronic conductivity value of 0.31 mS cm−1 at 50 ˚C. Mechanical-induced glass transformation also triggers changes in electronic states, where electroneutrality is compensated by introducing unconventional CN− vacancies. Partial disorders and ligand vacancies in recrystallized PBA give rise to an enhanced porosity, inaccessible in the crystalline parent. The present work also established a correlation between the mechanical stress required to initiate crystal–glass transformation and intrinsic mechanical properties, which are controlled by the vacancy/defect content, the presence of interstitial water, and the overall composition of PBAs.

Spin qubits are among the most promising candidates for quantum information processing and sensing technologies. Their potential to function even at elevated temperatures makes them particularly attractive for future devices. However, while extensive studies have been carried out on S = 1/2 systems, high-spin complexes remain much less explored as spin qubit platforms. In this study, we prepared a Zn(II)-based MOF, [CH6N3][Zn(HCOO)3], doped with trace amounts of Mn(II) ions (S = 5/2, 0.2, and 0.02 mol%). Magnetic measurements under static fields revealed slow relaxation phenomena dominated by direct and Raman-like processes. Importantly, Q-band pulsed ESR confirmed quantum coherence between MS = ±1/2 sublevels, achieving phase memory times (T2) up to 5.4 µs at 10 K, which is significantly longer than those reported in other Mn(II)-based systems. Rabi nutation experiments verified coherent spin control and multilevel transitions, while Wigner matrix analysis revealed reorientation of the nuclear quantization axis during spin flips. Notably, coherence persisted above 150 K, attributed to the stabilization provided in the MOF's hydrogen-bonded lattice. This work represents the first demonstration of high-spin Mn(II) qubits with measurable coherence at elevated temperatures, underscoring MOFs as versatile and tunable platforms for advancing quantum materials and molecular spin-based technologies.

Thieno[2,3-h]isoquinoline-based aromatic imide was designed as a fundamental scaffold to modify the electronic structure of aromatic imides. Utilizing the reactivity of the thiophene unit, methoxyphenyl and N,N-dimethylaminophenyl groups were introduced into the scaffold (1 and 2, respectively), and their optical and electrochemical properties were investigated. 1 and 2 exhibited solvent-dependent fluorescence, showing linear correlations between their emission maxima and the solvent polarity parameter ET(30). 2 displayed greater sensitivity to solvent polarity than 1, owing to the stronger electron-donating nature of the dimethylamino group relative to the methoxy group. Protonation of the pyridine units in 1 and 2 led to the formation of pyridinium ions, resulting in red-shifted absorption bands. Further protonation of the dimethylamino group in 2 disrupted the donor-acceptor electronic structure, leading to blue-shifted absorption and fluorescence bands. These findings highlight the potential of the thieno[2,3-h]isoquinoline-based aromatic imide scaffold as a versatile platform for modulating the electronic structure of the aromatic imides via diverse aryl substitutions and protonation.

It is expected that single-molecule magnets (SMMs) containing Lanthanoids play an important role in high-density magnetic devices. In this work, we synthesized new conductive Ln(III) SMMs, (TMTSF)4[Ln(NCS)6](CH3CN)2(CH2Cl2)0.5 (H2O)0.5 (TMTSF = (tetramethyltetraselenafulvalene), Ln(III) = Dy (1) and Tb (2)), which have organic TMTSF pi donors as the conducting part. The crystal structure has high symmetry, and lanthanoid complexes form a lattice-like structure with the TMTSF donor. [Ln(NCS)6]3- forms a distorted octahedron due to SSe contact with the TMTSF. The compound undergoes fast magnetic relaxation in the low-temperature region, and its relaxation time tau is almost independent of the temperature. The change in rate is nearly linear. The compounds show semiconductive behavior and a weak magnetoresistance effect at ambient and high pressure at the low temperatures.

Emerging microporous hydrogen-bonded organic frameworks (HOFs) are expected to overcome water shortages owing to their potential in harvesting and releasing water at low energies.

Co(II) was doped into the diamagnetic one-dimensional framework of bis(dimethylglyoximato) Ni(II) and Pd(II) complexes [Ni/PdII(Hdmg)2] (Hdmg = dimethylglyoximate anion) (hereafter referred to as Co@Ni and Co@Pd samples) to study magnetic properties as a potential spin qubit. In a previous report of electron paramagnetic resonance (EPR) spectroscopy of this compound prepared using the same doping strategy in the Ni matrix, a spectrum assigned to S = 1/2 Co(II) with gx = 2.58, gy = 2.26 gz = 1.98 was observed. The relatively large gx value, compared to those typically observed in [Co(Hdmg)2Bx] complexes (B = Lewis base ligand, x = 1 or 2), which fall within the ranges gx = 2.1-2.4, gy = 2.0-2.2 and gz ≈ 2.01, led to the interpretation of this species to be Co(Hdmg)2 with an extremely axial interaction. However, our EPR analysis, combined with SQUID (superconducting quantum interference device) and XANES (X-ray absorption near-edge structure) analyses, revealed that the previously identified species are μ-O bridged dimers: [Co(Hdmg)(μ-Hdmg)]2 and [Co(Hdmg)(μ-Hdmg)][Ni/Pd(Hdmg)(μ-Hdmg)]. Furthermore, our liquid-helium temperature EPR spectra revealed a Co species with much greater axial g anisotropy (gx = 4.75 gy,z ≈ 0.75 for Co@Ni and gx = 4.2 gy,z ≈ 1.33 for Co@Pd). We assign this species to the truly planar Co(Hdmg)2 with negligibly weak axial interaction, which might have been overlooked in previous EPR studies.

Metal compounds with S = 1/2 coordination-frameworks have been emerging as new powerful qubit candidates. In this study, we have reported the CN-based coordination framework TMA(2)[KCo1-xFex(CN)(6)] to be a qubit. We explored the magnetization dynamics and spin coherence of the magnetic dilution of the S = 1/2 Fe(iii) complex TMA(2)[KFe(CN)(6)] (TMA = tetramethylammonium) in its Co(iii)-based diamagnetic analogue TMA(2)[KCo(CN)(6)]. Alternating-current (AC) susceptibility data illustrate a slow magnetic relaxation upon applying a field of 0.1 T, which follows the phonon-bottleneck relaxation mechanism along with the Raman process. A magnetic relaxation time (tau) of 0.3 s (2% Fe) was realized at 1.8 K. Moreover, pulsed EPR data reveal a coherence duration of 1 mu s (0.1% Fe) at 4 K with successful observation of Rabi oscillation at 4 K and 13 K (2% Fe) using MW pulses with variable irradiation-field strengths. The overall results indicate that TMA(2)[KCo1-xFex(CN)(6)] represents a promising qubit candidate, as it is capable of being placed in any superposition of the two distinct M-s states (M-s = +1/2 and M-s = -1/2).

In this article, we investigate the encapsulation of K2[Ni(maleonitriledithiolate)2] (1) within a host molecule, β-cyclodextrin (β-CD), via single-crystal X-ray analysis. An inclusion complex, K2{[Ni(maleonitriledithiolate)2]@(β-CD)2} (2), was constructed from 1 and two β-CDs. The anion guest Ni complex included a host cavity, constructed using two β-CDs, and the Ni atom of the anion was located between the two hydrophilic primary rims. Ultraviolet-visible absorption spectroscopy revealed that inclusion complex 2 exhibited a 2:1 (host:guest) stoichiometry in the solution, which is consistent with the result obtained from X-ray crystallography. The association of the host and guest occurred in two steps, and the association constants for the first and second steps were 1.1(7) × 104 and 1.8(5) × 104 mol−1 dm3, respectively. The catalytic behavior of 1 and 2 was investigated for electrochemical hydrogen production in the aqueous solution of an acetate buffer (pH = 4.72). During the catalytic reaction, inclusion complex 2 was observed to have a better catalytic reaction rate than 1. The study findings provide insights into the effects of the encapsulation of guest molecules within host structures.

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The exchange bias effect is pivotal in semiconductor technology, particularly for magnetic recording and spin valve devices. However, conventional materials that rely on interfaces present manufacturing challenges. This study focuses on the exchange bias effect in bulk materials without interfaces. A novel magnetic material, Cd2FeOsO6, was synthesized, exhibiting a strong exchange bias effect at low-cooling magnetic fields. This study offers insights into materials with pronounced exchange bias and a unique mechanism. Cd2FeOsO6 demonstrates ferrimagnetic ordering and hard magnetism below 285 K. Notably, a substantial 10 kOe exchange bias arises with a weak 80 Oe magnetic field. This effect is likely due to partial ordering and strong spin-orbit coupling of the ligand of Os. These findings highlight the potential of double perovskite materials for notable exchange bias effects at room temperature with modest cooling fields. Leveraging 5d element properties advances bulk materials with enhanced exchange bias traits.

Quasi-one-dimensional (1D) compounds are suitable models to develop future nanodevices. The critical issue is that most of the several hundred reported 1D compounds adopt parallel arrangements. Here, we report the first example of an orthogonal grade-separated arrangement of the halogen-bridged metal complex (MX-Chain) [PtII(en)2][PtIVCl2(en)2][FeIIICl5]2, abbreviated as [Pt(en)2Cl][FeIIICl5] (en = ethylenediamine), which is the first example of that arrangement of molecular single chains. The space group and topology are coincidentally same as alchemists' gold, Hg3-delta AsF6, which aligns as atomic single chains. This molecular nanostructure is very rare and valuable as a three-dimensional (3D) nanowiring model. The hydrogen bond network found in [Pt(en)2Cl][FeIIICl5] represents a new strategy for making such nanostructures. The structural and optical relationships are similar to those of typical Pt(II)/Pt(IV) mixed valent MX-Chains in charge-density-wave (CDW) states. Polarized Raman spectra strongly supported the presence of orthogonal grade-separated chains in CDW states. Thus, this work proved the concept of molecular single-chain grade-separated nanowiring.

In this study, we successfully synthesized the double perovskite oxide Cd2FeReO6 by using a high-temperature and high-pressure method. The crystal structure was confirmed to belong to the P2(1)/n space group, exhibiting approximately 68% ordering of Fe3+ and Re5+ ions at the perovskite B-site with the remaining regions showing antisite disorder. The measured Curie temperature of Cd2FeReO6 was 460 K, slightly lower than expected but still significantly above room temperature. Remarkably, Cd2FeReO6 displayed a remarkable low-field butterfly type tunneling magnetoresistance of -23% (-37% between the lowest and the largest values) at 5 K and 90 kOe, the highest among the A(2)FeReO(6) (A = Ca, Sr, Pb, Ba) family. First-principles calculations provided insight into the origin of this observed magnetoresistance behavior, revealing Cd2FeReO6's half-metallic ferrimagnetic nature. This research extends our understanding of the double perovskite family and emphasizes its potential significance in the domains of spintronics and materials science. The exploration of differing magnetoresistance behaviors between Cd2FeReO6 and Ca2FeReO6, along with the influence of antisite disorder in Cd2FeReO6, opens intriguing avenues for further research.

Inclusion structures incorporating more than one guest molecule are elusive because confinement alters their molecular properties. We report the solid-state characterization of an inclusion complex comprising two γ-cyclodextrins and two [Cu(2-pyridinemethanolate)(2-pyridinemethanol)]PF6 units. Quantum calculation reveals that interfragment charge transfer occurs. The confined Cu fragment and the unincluded "linear chain [Cu(2-pyridinemethanolate)(2-pyridinemethanol)]PF6" exhibit different properties.

The combination of single-ion magnets (SIMs) and metal-organic frameworks (MOFs) is expected to produce new quantum materials. The principal issue to be solved in this regard is the development of new strategies for the synthesis of SIM-MOFs. This work demonstrates a new simple strategy for the synthesis of SIM-MOFs where a diamagnetic MOF is used as the framework into which the SIM sites are doped. 1, 0.5, and 0.2 mol% of the Co(II) ions are doped into the Zn(II) sites of [CH6N3][Zn-II(HCOO)(3)]. The doped Co(II) sites in the MOFs perform as SIM with a positive D term of zero-field splitting. The longest magnetic relaxation time is 150 ms (0.2 mol% Co) at 1.8 K under a static field of 0.1 T. Temperature dependency of the relaxation time suggests suppressing magnetic relaxation by reduction of spin-spin interaction upon doping in the rigid framework. Thus, this work represents a proof of concept for the creation of a single-ion doped magnet in the MOF. This simple synthetic strategy will be widely applied for the creation of quantum magnetic materials.

Reaction of M(OAc)2·xH2O (M, x = Zn, 2 and Co, 4), 1,4-dihydro-5,6-dicyano-2,3-pyrazinedione (H2CN2pyzdione), and pyrazine (pyz) affords two compounds of the same molecular formula {[M(H2O)6][M(CN2pyzdione)2(pyz)]·6H2O}n (M = Zn for 1 and Co for 2) in which discrete units of [M(H2O)6]2+ are linked to one-dimensional chains of [M(CN2pyzdione)2(pyz)]2– via multiple O–H···O hydrogen-bonding interactions and M2+-bound H2O molecules in [M(H2O)6]2+ also serve as linkers of hydrogen-bonded interstitial H2O molecules. Remarkably, 1 crystallizes in the monoclinic crystal system, the similar crystal system and unit cell parameters as 2, but with a space group distinct from 1 and 2, i.e., 1 is the noncentrosymmetric space group C2, whereas 2 is the centrosymmetric space group C2/m. This polar structure for 1 is induced by the presence of alternating arrangements of distinguishable two axial Zn–N bonds within [Zn(CN2pyzdione)2(pyz)]2– chains. Indeed, solid-state circular dichroism spectra of 1 exhibit significant Cotton effects, as evidenced by the polar space group C2. Moreover, these Cotton effects show clear temperature-dependence depending on contents of H2O molecules of 1.

Prussian blue analogues (PBAs) are archetypes of microporous coordination polymers/metal-organic frameworks whose versatile composition allows for diverse functionalities. However, developments in PBAs have centred solely on their crystalline state, and the glassy state of PBAs has not been explored. Here we describe the preparation of the glassy state of PBAs via a mechanically induced crystal-to-glass transformation and explore their properties. The preservation of short-range metal-ligand-metal connectivity is confirmed, enabling the framework-based functionality and semiconductivity in the glass. The transformation also generates unconventional CN- vacancies, followed by the reduction of metal sites. This leads to significant porosity enhancement in recrystallised PBA, enabled by further accessibility of isolated micropores. Finally, mechanical stability under stress for successful vitrification is correlated to defect contents and interstitial water. Our results demonstrate how mechanochemistry provides opportunities to explore glassy states of molecular framework materials in which the stable liquid state is absent.

This study explored the thermochromic behavior of [(mu 2-6-methyl-2-pyridinemethanolate)2{Cu(6-methyl-2pyridinemethanol)}2](PF6)2. The complexes show no significant variation between 296 K and 100 K according to a single-crystal X-ray crystallographic investigation. The occupancy of the triplet at 300 K and 100 K is 55% and 16.9%, respectively based on magnetic susceptibility. Photographs of the complex at different temperatures and quantum calculation exhibit that the thermochromic behavior is induced by the alteration of spin state between triplet and singlet.