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Two new salts of a mononuclear tripodal Fe(II) complex were prepared, using ClO 4 - and Cl - . The ClO 4 - sample (1) remained HS at low temperatures, similar to the previously reported BF 4 - analogue. Crystallising with the Cl - anion (2) led to a markedly different crystal packing arrangement, and engendered SCO activity. This has been correlated to the lower crystal packing density in 2 and the coordination complex conformational differences arising due to the packing motifs of 1 and 2. Further, solvent ordering effects have been proposed to facilitate spin transition behaviour in 2.

Discrete spin crossover (SCO) heteronuclear cages are a rare class of materials which have potential use in next-generation molecular transport and catalysis. Previous investigations of cubic cage [Fe 8 Pd 6 L 8 ] 28+ constructed using semi-rigid metalloligands, found that Fe II centers of the cage did not undergo spin transition. In this work, substitution of the secondary metal center at the face of the cage resulted in SCO behavior, evidenced by magnetic susceptibility, Mössbauer spectroscopy and single crystal X-ray diffraction. Structural comparisons of these two cages shed light on the possible interplay of inter- and intramolecular interactions associated with SCO in the Ni II analogue, 1 ([Fe 8 Ni 6 L 8 (CH 3 CN) 12 ] 28+ ). The distorted octahedral coordination environment, as well as the occupation of the CH 3 CN in the Ni II axial positions of 1, prevented close packing of cages observed in the Pd II analogue. This led to offset, distant packing arrangements whereby important areas within the cage underwent dramatic structural changes with the exhibition of SCO., (© 2022 Wiley-VCH GmbH.)

Ensuring continuous and sustainable lithium supply requires the development of highly efficient separation processes such as LLE (liquid-liquid extraction) for both primary sources and certain waste streams. In this work, 4-phosphoryl pyrazolones are used in an efficient pH-controlled stepwise separation of Li + from Ca 2+ , Mg 2+ , Na + and K + . The factors affecting LLE process, such as the substitution pattern of the extractant, diluent/water distribution, co-ligand, pH, and speciation of the metal complexes involved, were systematically investigated. The maximum extraction efficiency of Li + at pH 6.0 was 94 % when Mg 2+ and Ca 2+ were previously separated at pH<5.0, proving that the separation of these ions is possible by simply modulating the pH of the aqueous phase. Our study points a way to separation of lithium from acid brine or from spent lithium ion battery leaching solutions, which supports the future supply of lithium in a more environmentally friendly and sustainable manner., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Highly selective rare-earth separation has become increasingly important due to the indispensable role of these elements in various cutting-edge technologies including clean energy. However, the similar physicochemical properties of rare-earth elements (REEs) render their separation very challenging, and the development of new selective receptors for these elements is potentially of very considerable economic and environmental importance. Herein, we report the development of a series of 4-phosphoryl pyrazolone receptors for the selective separation of trivalent lanthanum, europium, and ytterbium as the representatives of light, middle, and heavy REEs, respectively. X-ray crystallography studies were employed to obtain solid-state structures across 11 of the resulting complexes, allowing comparative structure-function relationships to be probed, including the effect of lanthanide contraction that occurs along the series from lanthanum to europium to ytterbium and which potentially provides a basis for REE ion separation. In addition, the influence of ligand structure and lipophilicity on lanthanide binding and selectivity was systematically investigated via n -octanol/water distribution and liquid-liquid extraction (LLE) studies. Corresponding stoichiometry relationships between solid and solution states were well established using slope analyses. The results provide new insights into some fundamental lanthanide coordination chemistry from a separation perspective and establish 4-phosphoryl pyrazolone derivatives as potential practical extraction reagents for the selective separation of REEs in the future.

We present five new dinuclear triple helicate compounds of types [Mn 2 L 3 ](ClO 4 ) 4 , [Co 2 L 3 ](BF 4 ) 4 , [Ni 2 L 3 ](BF 4 ) 4 , [Cu 2 L 3 ](BF 4 ) 4 , and [Zn 2 L 3 ](BF 4 ) 4 , where L is a previously reported semi-rigid ligand incorporating two α-diimine primary donor groups and two secondary 4-pyridyl donor groups. All complexes have been characterized in both solution and the solid state. Single crystal X-ray diffraction studies were used to probe the variation in the respective helical structures as the coordinated metal ion was altered, including the effect on the orientations of the secondary binding domains. The influence of the metal ion size, the spin state in the case of Fe(II), and the presence of Jahn-Teller distortions on the overall helical structure has been investigated. These results form a basis for the design and construction of new large metallosupramolecular architectures which manifest properties associated with the constituent helical metalloligand units.

Herein, we report an efficient proton exchange membrane formed from a synergistic combination of graphene oxide (GO) and oxidized single-walled carbon nanotube (CNTOX) by the freeze-drying route that gives rise to enhanced fuel cell power density. At 25 °C and 100% relative humidity (RH), the 3DGO-CNTOX hybrid shows remarkably high out-of-plane and in-plane proton conductivities of 6.64×10 -2 and 5.08 S cm -1 , respectively. Additionally, the measured performance using prepared films as proton conduction membranes in a proton exchange membrane fuel cell (PEMFC) exhibited a peak power density of 117.21 mW cm -2 . The high performance of these films can be ascribed to the freeze-dried-driven structural morphology of 3DGO-CNTOX that facilitates higher water retention capacity as well as the synergistic strengthening effect between GO and CNTOX with a highly interconnected proton conduction network. The current results imply that the new 3DGO-CNTOX hybrid material has potential for wide application as a proton exchange membrane., (© 2022 Wiley-VCH GmbH.)

The development of efficient proton conductors that are capable of high power density, sufficient mechanical strength, and reduced gas permeability is challenging. Herein, we report the development of a series of aromatic sulfonic acid/graphene oxide hybrid membranes incorporating benzene sulfonic acid (BS), naphthalene sulfonic acid (NS), naphthalene disulfonic acid (DS) or pyrene sulfonic acid (PS) using a facile freeze dried method. For out-of-plane proton conductivity, the 3DGO-BS and 3DGO-NS yielded proton conductivities of 4.4×10 -2  S cm -1 and 3.1×10 -2  S cm -1 , respectively; this represents a two-times higher value than that which occurs for three dimensional graphene oxide (3DGO). Additionally, the respective prepared films as membranes in a proton exchange membrane fuel cell (PEMFC) show maximum power density of 98.76 mW cm -2 for 3DGO-NS while it is 92.75 mW cm -2 for 3DGO-BS which are close to double that obtained for 3DGO (50 mW cm -2 )., (© 2022 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)

Reaction of 1,3,4,6-tetra- O -acetyl- N -(2-hydroxy)-naphthylidene glucosamine (HL(Ac)) with uranyl acetate in ethanol leads to formation of dinuclear [(UO 2 ) 2 (L) 2 ] (1). In a second step 1 is quantitatively transferred into the trinuclear oxo-bridged complex [(UO 2 ) 3 (μ 3 -O)(L) 3 ] 2- (2 2- ) via deprotonation and coordination of a water molecule. This transformation was followed by NMR and UV/Vis spectroscopy and it proved possible to selectively introduce 18 O into the μ 3 -bridge.

Magnetoelectric (ME) materials exhibiting coupled electric and magnetic properties are of significant interest because of their potential use in memory storage devices, new sensors, or low-consumption devices. Herein, we report a new category of ME material that shows liquid crystal (LC), ferroelectric (FE), and field-induced single molecule magnet (SMM) behaviors. Co(II) complex incorporating alkyl chains of type [Co(3C 16 -bzimpy) 2 ](BF 4 ) 2 (1; 3C 16 -bzimpy=2,2'-(4-hexadecyloxy-2,6-diyl)bis(1-hexadecyl-1H-benzo[d]imidazole)) displayed a chiral smectic C mesophase in the temperature range 321 K-458 K, in which distinct FE behavior was observed, with a remnant polarization (88.3 nC cm -2 ). Complex 1 also exhibited field-induced slow magnetic relaxation behavior that reflects the large magnetic anisotropy of the Co(II) center. Furthermore, the dielectric property of 1 was able to be tuned by an external magnetic field occurring from both spin-lattice coupling and molecular orientational variation. Clearly, this multifunctional compound, combining LC, FE, and SMM properties, represents an entry to the development of a range of next-generation ME materials., (© 2021 Wiley-VCH GmbH.)

Effective receptors for the separation of Li + from a mixture with other alkali metal ions under mild conditions remains an important challenge that could benefit from new approaches. In this study, it is demonstrated that the 4-phosphoryl pyrazolones, HL 2 -HL 4 , in the presence of the typical industrial organophosphorus co-ligands tributylphosphine oxide (TBPO), tributylphosphate (TBP) and trioctylphosphine oxide (TOPO), are able to selectively recognise and extract lithium ions from aqueous solution. Structural investigations in solution as well as in the solid state reveal the existence of a series of multinuclear Li + complexes that include dimers (TBPO, TBP) as well as rarely observed trimers (TOPO) and represent the first clear evidence for the synergistic role of the co-ligands in the extraction process. Our findings are supported by detailed NMR, MS and extraction studies. Liquid-liquid extraction in the presence of TOPO revealed an unprecedented high Li + extraction efficiency (78 %) for HL 4 compared to the use of the industrially employed acylpyrazolone HL 1 (15 %) and benzoyl-1,1,1-trifluoroacetone (52 %) extractants. In addition, a high selectivity for Li + over Na + , K + and Cs + under mild conditions (pH ∼8.2) confirms that HL 2 -HL 4 represent a new class of ligands that are very effective extractants for use in lithium separation., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The interlayer spaces in two dimensional (2D) layered materials such as graphene, metal oxides and metal chalcogenides can be used in a number of roles that include the trapping of gases, for ion transfer and for water purification applications. In such spaces, "inner" pressure occurs on guest species enclosed between the layers and its variation can, in principal, be used for precisely controlling particular guest properties. In this study, a mixture of two 2D materials including graphene oxide (GO) and nickel hydroxide (Ni(OH) 2 ), was employed to yield an anisotropic GO-Ni(OH) 2 hybrid 2D sheet. The inner pressure associated with this material was able to be tuned by reduction of the GO (to yield rGO) and this in turn was shown to affect the magnetic behaviour of Ni(OH) 2 . The ferromagnetic transition temperature ( T c ) for Ni(OH) 2 decreases as the interlayer distance became shorter, which is opposite to the behaviour observed for the application of hydrostatic pressure to the hybrid sheet. The uniaxial pressure affecting the interlayer of the 2D material, and generated by the reduction of GO to rGO, has the potential to not only influence the behaviour of a range of magnetic materials, but also individual properties of other types of functional materials.

The rapid transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-driven infection signifies an ultimate challenge to global health, and the development of effective strategies for preventing and/or mitigating its effects are of the utmost importance. In the current study, an in-depth investigation for the understanding of the SARS-CoV-2 inactivation route using graphene oxide (GO) is presented. We focus on the antiviral effect of GO nanosheets on three SARS-CoV-2 strains: Wuhan, B.1.1.7 (U.K. variant), and P.1 (Brazilian variant). Plaque assay and real-time reverse transcription - polymerase chain reaction (RT-PCR) showed that 50 and 98% of the virus in a supernatant could be cleared following incubation with GO (100 μg/mL) for 1 and 60 min, respectively. Transmission electron microscopy (TEM) analysis and protein (spike (S) and nucleocapsid (N) proteins) decomposition evaluation confirm a two-step virus inactivation mechanism that includes (i) adsorption of the positively charged spike of SARS-CoV-2 on the negatively charged GO surface and (ii) neutralization/inactivation of the SARS-CoV-2 on the surface of GO through decomposition of the viral protein. As the interaction of S protein with human angiotensin-converting enzyme 2 (ACE2) is required for SARS-CoV-2 to enter into human cells, the damage to the S protein using GO makes it a potential candidate for use in contributing to the inhibition of the worldwide spread of SARS-CoV-2. Specifically, our findings provide the potential for the construction of an effective anti-SARS-CoV-2 face mask using a GO nanosheet, which could contribute greatly to preventing the spread of the virus. In addition, as the effect of surface contamination can be severe in the spreading of SARS-CoV-2, the development of efficient anti-SARS-CoV-2 protective surfaces/coatings based on GO nanosheets could play a significant role in controlling the spread of the virus through the utilization of GO-based nonwoven cloths, filters, and so on., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

The reaction of UO 2 (OAc) 2  ⋅ 2H 2 O with the biologically inspired ligand 2-salicylidene glucosamine (H 2 L 1 ) results in the formation of the anionic trinuclear uranyl complex [(UO 2 ) 3 (μ 3 -O)(L 1 ) 3 ] 2- (1 2- ), which was isolated in good yield as its Cs-salt, [Cs] 2 1. Recrystallization of [Cs] 2 1 in the presence of 18-crown-6 led to formation of a neutral ion pair of type [M(18-crown-6)] 2 1, which was also obtained for the alkali metal ions Rb + and K + (M=Cs, Rb, K). The related ligand, 2-(2-hydroxy-1-naphthylidene) glucosamine (H 2 L 2 ) in a similar procedure with Cs + gave the corresponding complex [Cs(18-crown-6)] 2 [(UO 2 ) 3 (μ 3 -O)(L 2 ) 3 ([Cs(18-crown-6)] 2 2). From X-ray investigations, the [(UO 2 ) 3 O(L n ) 3 ] 2- anion (n=1, 2) in each complex is a discrete trinuclear uranyl species that coordinates to the alkali metal ion via three uranyl oxygen atoms. The coordination behavior of H 2 L 1 and H 2 L 2 towards UO 2 2+ was investigated by NMR, UV/Vis spectroscopy and mass spectrometry, revealing the in situ formation of the 1 2- and 2 2- dianions in solution., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The magnetic properties and structural aspects of the 1-D cobalt(ii) complexes, [Co(pyterpy)Cl2]·2H2O (1·2H2O; pyterpy = 4'-(4'''-pyridyl)-2,2':6',2''-terpyridine) and [Co(pyethyterpy)Cl2]·2H2O (2·2H2O; pyethyterpy = 4'-((4'''-pyridyl)ethynyl)-2,2':6',2''-terpyridine) are reported. In each complex the central cobalt(ii) ion displays an octahedral coordination environment composed of three nitrogen donors from the terpyridine moiety, a nitrogen donor from a pyridyl group and two chloride ligands which occupy the axial sites. 1·2H2O exhibits abrupt spin-crossover (SCO) behaviour (T1/2↓ = 218 K; T1/2↑ = 227 K) along with a thermal hysteresis loop, while 2·2H2O and the dehydrated species 1 and 2 exhibit high-spin (HS) states at 2-300 K as well as field-induced single-molecule magnet (SMM) behaviour attributed to the presence of magnetic anisotropic HS cobalt(ii) species (S = 3/2). 1·2H2O exhibited reversible desorption/resorption of its two water molecules, revealing reversible switching between SCO and SMM behaviour triggered by the dehydration/rehydration processes. Single crystal X-ray structural analyses revealed that 1·2H2O crystalizes in the orthorhombic space group Pcca while 2 and 2·2H2O crystallize in the monoclinic space group P2/n. Each of the 1-D chains formed by 1·2H2O in the solid state are bridged by hydrogen bonds between water molecules and chloride groups to form a 2-D layered structure. The water molecules bridging 1-D chains in 1·2H2O interact with the chloride ligands occupying the axial positions, complementing the effect of Jahn-Teller distortion and contributing to the abrupt SCO behaviour and associated stabilization of the LS state.

Ferroelectric spin crossover (SCO) behavior is demonstrated to occur in the cobalt(II) complex, [Co(FPh-terpy) 2 ](BPh 4 ) 2 ⋅3ac (1⋅3 ac; FPh-terpy=4'-((3-fluorophenyl)ethynyl)-2,2':6',2''-terpyridine) and is dependent on the degree of 180° flip-flop motion of the ligand's polar fluorophenyl ring. Single crystal X-ray structures at several temperatures confirmed the flip-flop motion of fluorobenzene ring and also gave evidence for the SCO behavior with the latter behavior also confirmed by magnetic susceptibility measurements. The molecular motion of the fluorobenzene ring was also revealed using solid-state 19 F NMR spectroscopy. Thus the SCO behavior is accompanied by the flip-flop motion of the fluorobenzene ring, leading to destabilization of the low spin cobalt(II) state; with the magnitude of rotation able to be controlled by an electric field. This first example of spin-state conversion being dependent on the molecular motion of a ligand-appended fluorobenzene ring in a SCO cobalt(II) compound provides new insight for the design of a new category of molecule-based magnetoelectric materials., (© 2021 Wiley-VCH GmbH.)

Soft materials represented by polymers, liquid crystals, and colloids are a class of materials that exhibit a variety of unique functionalities which derive from their non-rigid structures. In particular, soft metal complexes incorporating flexible long alkyl chains in their structures have been shown to display synergy between the structural dynamics of the long alkyl chain moieties and the electron dynamics occurring at the metal centre. This review presents a discussion of such soft metal complexes with a focus on spin crossover (SCO) behaviours that are associated with a structural phase transition, including a liquid crystal (LC) transition, arising from the flexible natures of the respective complexes. We also discuss how to fabricate soft materials based on SCO complexes.

The synthesis of [M(dimphen)(NCS) 2 ] (1; M = Fe II ), (2; M = Co II ), (3; M = Mn II ) and [Fe(dimphen)(NCSe) 2 ] (4), where dimphen = [1,2-bis(9-methyl-1,10-phenanthrolin-2-yl)ethane], are reported. The crystal packing structures of 1-3, show intermolecular π-π stacking and NCSSCN interactions. The complex 1 shows ferromagnetic interaction, and the complex 2 displays single-molecular magnet behaviour.

The development of molecule-based switchable materials remains an important challenge in the field of molecular science. Achievement of a structural phase transition induced by adsorption/desorption of guest molecules in spin crossover (SCO) Co(II) compounds is of significant interest because of the possibility that the spin state of the magnetic anisotropic high-spin (HS, S = 3/2) and low-spin (LS, S = 1/2) states can be switched via the induced changes in associated intermolecular interactions. In this study, we demonstrated a reversible magnetic switching associated with spin state conversion, along with a single-crystal to single-crystal (SCSC) phase transition induced by dehydration/rehydration. [Co(terpy) 2 ](BF 4 ) 2 ·H 2 O ( 1 ·H 2 O; terpy = 2,2':6',2''-terpyridine) assembles in the solid state via π-π and CH-π interactions involving adjacent terpyridine cores along the ab direction to form two-dimensional (2D) layered domains. 1 ·H 2 O exhibits gradual and incomplete SCO, from fully HS to ca. 0.5 HS, and the field-induced single-molecule magnet (SMM) behavior attributed to the presence of the anisotropic partial high-spin Co(II) species. 1 ·H 2 O undergoes a SCSC transformation accompanied by a change from the tetragonal space group I 4 1 / a to P 4 2 / n via a dehydration process. Dehydrated 1 exhibits a reverse thermal hysteresis behavior ( T 1/2↑ = 287 K; T 1/2↓ = 270 K) in the gradual SCO region from fully HS to ca. 0.5 HS, followed by an ordinary thermal hysteresis ( T ' 1/2↑ = 195 K; T ' 1/2↓ = 155 K) to fully LS Co(II). A temperature-dependent single-crystal X-ray structural analysis revealed that the reverse hysteresis can be attributed to an order/disorder structural phase transition of the BF 4 - anions involving a symmetry breaking to yield the monoclinic space group P 2 1 / n and orbital (angular momentum) transition ( L T). Both the SCSC phase transition and magnetic behavior are switchable by dehydration/rehydration processes; thus 1 again adsorbs water at room temperature to give both the original structure and its magnetic behavior.

Preferential formation of cis - or trans -palladium(II) complexes controlled via the exocyclic binding sites embedded in dithiamacrocycles ( L 1 = -S(CH 2 ) 2 S-; L 2 = -S(CH 2 ) 2 O(CH 2 ) 2 S-) is reported. From the reaction with K 2 PdCl 4 , the shorter sulfur-to-sulfur separation in L 1 preferentially leads to the formation of cis -[Pd( L 1 )Cl 2 ] ( 1 ), while L 2 , incorporating a larger sulfur-to-sulfur separation, coordinates in a trans fashion to form a cyclic dimer, trans -[Pd 2 ( L 2 ) 2 Cl 4 ] ( 2 ). The observed results illustrate the possibility for the controlled formation of cis/trans square-planar complexes through binding-site design. When palladium(II) acetate was substituted for K 2 PdCl 4 in the above reaction, L 1 gave no product, while L 2 resulted in the formation of a unique tripalladium(II) complex, [Pd 3 ( L 2 )(CH 3 C(═N)OC(═N)CH 3 )(CH 3 COO) 4 ] ( 3 ), in which three Pd II atoms are linked by acetimidic anhydride, CH 3 C(═N)OC(═N)CH 3 , derived from the acetonitrile solvent employed. In the 1 H NMR spectrum for 3 , specific methylene signals for methylene protons adjacent to S donors exhibit large complexation-induced splitting of the geminal proton signals into axial and equatorial proton peaks, thus indicating magnetically nonequivalent geminal protons that reflect the restricted conformation of the metallabicycle.

Vapor-induced crystal to crystal transformation between non-polar [Fe(sap)(acac)(sol)] (H 2 sap = 2-salicylideneaminophenol, acac = acethylacetate, sol = MeOH, pyridine) and polar [Fe(sap)(acac)(DMSO)] was demonstrated. It provides an example of switchable ferroelectric behaviour attributted to the structural phase transition triggered by solvent vapour.

The formation of plastic or brittle organic crystals of salen derivatives that depend on the solvents employed for crystallization is demonstrated. Large yellow crystals (ranging from mm to cm size) of ten different salen derivatives were obtained and investigated. Among them, (bis(2-hydroxyacetophenone)ethylenediimine) 2, which was recrystallized from dichloromethane, tetrahydrofuran or chloroform, exhibited plastic deformation behaviour when mechanical force was applied to the (001) face. In contrast, when 2 was recrystallized from benzene, brittle crystals were obtained. Face indexing confirmed that different crystal faces were obtained by depending on the solvent employed for recrystallization, which leads to either flexible (plastic) or brittle crystals. Photoluminescence with a band maximum at 510 nm and thermochromism related to tautomerism between OH and NH forms were also investigated, and indicate that 2 is a flexible organic single-crystal material with multifunctional properties., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Recently, non-crystalline coordination materials have been shown to represent a versatile class of functional materials. However, such materials incorporating metal complex clusters have remained largely unexplored. Herein, we demonstrate that a luminescent tetranuclear ReV cluster melts at 489 K, with the cluster structure being maintained in the corresponding supercooled ionic liquid phase.

CO 2 -responsive spin-state conversion between high-spin (HS) and low-spin (LS) states at room temperature was achieved in a monomeric cobalt(II) complex. A neutral cobalt(II) complex, [Co II (COO-terpy) 2 ]⋅4 H 2 O (1⋅4 H 2 O), stably formed cavities generated via π-π stacking motifs and hydrogen bond networks, resulting in the accommodation of four water molecules. Crystalline 1⋅4 H 2 O transformed to solvent-free 1 without loss of porosity by heating to 420 K. Compound 1 exhibited a selective CO 2 adsorption via a gate-open type of the structural modification. Furthermore, the HS/LS transition temperature (T 1/2 ) was able to be tuned by the CO 2 pressure over a wide temperature range. Unlike 1 exhibits the HS state at 290 K, the CO 2 -accomodated form 1⊃CO 2 (P CO 2 =110 kPa) was stabilized in the LS state at 290 K, probably caused by a chemical pressure effect by CO 2 accommodation, which provides reversible spin-state conversion by introducing/evacuating CO 2 gas into/from 1., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A hexagonal cobalt(ii) metallacycle and its "lipid packaged" derivatives, [Co 6 (R-bisterpy) 6 ]X 12 (R = H, OC 16 H 33 , OC 27 H 55 ; X = BF 4 , C 12 -Glu), have been synthesized and characterized. The compounds incorporating BF 4 - anions formed sphere-like aggregates while the compounds with C 12 -Glu lipid anions gave double-layered honeycomb architectures composed of hexagonal stacked tubular structures, which exhibit spin crossover behaviour.

Ion conduction through graphene oxide (GO) nanosheets that is pH-switchable between H + (in acid) and OH - (in base) ions is demonstrated. This finding is the first observation of this type for ion conductive materials and demonstrates an example of stimuli-driven ion-conduction switching.

Two-dimensional Hofmann-type coordination polymers of type Mn(H 2 O) 2 [Pd(CN) 4 ]· x H 2 O ( 1· x H 2 O ; x = 0, 1, and 4), Mn(H 2 O)(MeOH)[Pd(CN) 4 ]·2MeOH ( 2·2MeOH ), and Mn(MeOH) 2 [Pd(CN) 4 ]·MeOH ( 3·MeOH ) have been synthesized. The homosolvent-bound 1·4H 2 O , 1·H 2 O , and 3·MeOH polymers consist of undulating layer structures, whereas the structure of heterosolvent-bound 2·2MeOH consists of "Janus-like" flat layers in which water-bound and MeOH-bound-sides are present. 1·4H 2 O and 1·H 2 O exhibited anisotropic two-dimensional thermal expansions involving structural transformations of the undulating layers; one layer axis expands while the other contracts. 2·2MeOH exhibits anisotropic thermal expansion in which the flat layers shift sideways as the temperature is increased, with colossal interlayer expansion occurring (α c = +200 MK -1 over 140-180 K, α c = +165 MK -1 over 200-280 K). 3·MeOH also showed colossal interlayer expansion (α c = +216 MK -1 ) together with expansion of the undulating layers.

The self-assembly of a mixed-spin [Fe 4 L 6 ] 8+ tetrahedral cage is reported. The cage undergoes temperature induced spin-crossover with a 29 K hystereisis. Variable temperature X-ray photoelectron spectroscopy (VT-XPS), combined with SQUID data, allowed differentiation between the surface and bulk magnetic properties.

A homochiral one-dimensional (1D) Mn(iii) coordination polymer [MnL] n (1) was synthesised employing the N 3 O-donor tetradentate ligand (L = 2-hydroxy-N-[2-[[(2-aminophenyl)methylene]amino]-2-methylpropyl]-benzamide). The X-ray structure of 1 and its magnetic properties were investigated in detail. The crystal structure of 1 shows a homochiral helical arrangement in which spontaneous resolution has occurred, despite the ligand being achiral. Magnetic characterization revealed an antiferromagnetic interaction between manganese(iii) ions (J = -2.48 cm -1 , g = 1.96) that leads to an antiferromagnetic spin-ordering phase transition at T N ≈ 7 K. Noteworthily, 1 exhibits weak ferromagnetism with a relatively large coercive field of 3.0 kOe based on the spin canting, indicating the formation of a homochiral weak ferromagnet.

Control of ion arrangements in ionic liquids represents a major challenge owing to the presence of the predominant coulombic interactions between cationic and anionic ion species that forms the coulombic ordering. Here, water-induced ion rearrangement in a room-temperature ionic liquid (RT-IL) metal complex, (1-ethyl-3-methylimidazolium) 2 [MnN(CN) 4 ], is demonstrated through coordinative interactions between anions. Solidification occurred, which was associated with the formation of a "separated" structure consisting of cation columns and anionic cyanide-bridged one-dimensional coordination polymers. The energy diagram is in accord with the resultant RT-IL incorporating mononuclear [MnN(CN) 4 ] 2- molecules being a kinetic phase stabilized by inter-ion repulsions of the anionic divalent metal complex moieties. Water acts to decrease the coulombic interactions, including repulsion, giving rise to breaking of the coulombic ordering arising from coordination bond formation in the IL phase., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The behavior of single-ion magnets (SIMs) that reflects large distortions of their coordination environments caused by the packing of long alkyl chains for two Co(II) complexes of the type [Co(C n -terpy) 2 ](BF 4 ) 2 (C n -terpy = 4'-alkoxy-2,2':6',2″-terpyridine; n = 10 (1), 16 (2)) is reported. 1·2MeOH, which features a highly distorted octahedral high-spin Co(II) center, exhibits field-induced slow magnetic relaxation under an applied dc field of 1000 Oe. Further detailed analysis of the relaxation process indicated the prevalence of the Raman process at low temperature. Surprisingly, 2 shows a reverse spin transition (rST) and also exhibits remarkable field-induced SIM behavior, revealing the presence of magnetic anisotropy for this high-spin Co(II) species that is triggered by a structural phase transition. We present here the first examples of the coexistence of field-induced slow magnetic relaxation and rST associated with structural phase transitions involving long-alkyl-chain conformational changes from gauche to anti. These results indicate the prospect of inducing SIM properties in other distorted high-spin Co(II) species bearing long alkyl chains.

The 2D coordination polymers, [Mn(salen)]2[PtII(CN)4]1-x[PtIV(CN)4(I2)]x (salen = N,N'-ethylenebis(salicylideneaminato), x = 0.18 (1), 0.45 (2), 0.85 (3)), have been synthesized via consecutive oxidative additions of iodine to the 2D undulating layers in [Mn(salen)]2[PtII(CN)4]. The presence of I-Pt-I chains perpendicular to the layers and the inhomogeneity of individual I-Pt-I sites were demonstrated. The I-Pt-I chains in 3 give rise to an absorption band involving the excitation that arises from an antibonding nature orbital to the corresponding bonding nature orbital between iodides in the I-Pt-I bridging units. Moreover, variable-temperature X-ray powder diffraction patterns and Raman spectra for 1 and 2 indicate that some I-Pt-I sites display different vibrational energies that are associated with the contraction of the zigzag 2D layers.