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We report enhanced proton conductivity promoted by a structural phase transition of MFM-504(Cu)-DMF to MFM-504(Cu)-MeOH and to MFM-504(Cu)-OH via ligand substitution upon exposure to MeOH and H 2 O vapors, respectively. MFM-504(Cu)-DMF can be synthesized by the solvothermal reaction of Cu(NO 3 ) 2 ·3H 2 O and the flexible zwitterionic ligand, imidazolium-1,3-bis(methylenedicarboxylate) (imidc - ), to afford a unique layered interwoven network structure. MFM-504(Cu)-OH shows a proton conductivity of 5.01 × 10 -4 S cm -1 at 80 °C and 99% relative humidity (RH) with an activation energy ( E a ) of 0.80 eV, indicating a vehicle mechanism within MFM-504(Cu)-OH., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Rare-earth metal-organic frameworks (RE-MOFs) formed in the presence of fluoride donors are a group of complex and applicable MOFs. Determining structural complexity is crucial in applying such MOFs and has been achieved to uncover framework disorders in the important fcu framework topology MOF, Y-ndc- fcu -MOF ( 1 ). 1 is found to contain F - groups disordered over the μ 3 -face-capping sites in its secondary building unit (SBU) and framework distortions upon sorption of different guest molecules. The favored location of the guests is within the octahedral cage of 1 where they interact with the Y 3+ centers. The size, shape, and interactions of the different guests lead to subtle distortions within the SBU and adoption of specific orientations of the naphthalene group of the 1,4-naphthalenedicarboxylate framework linkers. The sorption of DMF (l) /H 2 O (l) lowers the symmetry from cubic Fm 3̅ m (for MeOH (l) , N 2(g) , CO 2(g or l) ) to cubic Pa 3̅ (for DMF (l) /H 2 O (l) ) symmetry with retention of the fcu topology, and conversion between the Pa 3̅ and Fm 3̅ m structures is induced by solvent exchange. Such disorder and sorption locations and transformation are important considerations during the optimization and application of MOFs for sorption-based technologies.

Mono- and bis-salen functionalised [2]rotaxanes have been synthesised from the esterification of [2]rotaxanes containing phenol-terminated threads (salen=N,N'-bis(salicylidene)ethylenediamine). The [2]rotaxanes have general formula [RH][Cr 7 NiF 8 (O 2 C t Bu) 16 ], where [RH] + is a thread with a central secondary ammonium site that templates a [Cr 7 NiF 8 (O 2 C t Bu) 16 ] - ring. The threads are terminated at one or both ends by carboxylic acid functionalised salen groups. The {M(salen)} groups can be free-base [M=(H + ) 2 ] or metallated [M=Cu 2+ , Ni 2+ , (VO) 2+ ]. The [2]rotaxanes have been characterised by single crystal XRD and solid- and solution-state EPR spectroscopy. Where two paramagnetic M ions are involved [M=Cu 2+ and/or (VO) 2+ ] the [2]rotaxanes contain three electron spin S= 1 / 2 ${{ 1/2 }}$ centres, since the {Cr 7 Ni} ring has an S= 1 / 2 ${{ 1/2 }}$ ground state which is well isolated at low temperatures. These three-spin [2]rotaxanes have been characterised in solution by pulsed dipolar EPR spectroscopies (DEER, also known as PELDOR, and RIDME). The M⋅⋅⋅M and M⋅⋅⋅{Cr 7 Ni} interactions measured are consistent with dipolar interactions and also with the distances from single crystal XRD. The authors declare no competing financial interest., (© 2024 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN) 2 Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and cationic Δ/Λ-Rh(SiN)2[BAr4F] unsaturated complexes, wherein rhodium(III) is coordinated to two inert silylquinoline ligands in a propeller-like arrangement.

We report the synthesis of a right-handed (Δ-stereochemistry of strand crossings) trefoil knot from a single molecular strand containing three pyrazine-2,5-dicarboxamide units adjacent to point-chiral centers and six pyridine moieties. The oligomeric ligand strand folds into an overhand (open-trefoil) knot through the assistance of coordinatively dynamic Co(II) "chaperones" that drive the formation of a three-metal-ion circular helicate. The entangled structure is kinetically locked by oxidation to Co(III) and covalently captured by ring-closing olefin metathesis to generate a trefoil knot of single topological handedness. The stereochemistry of the strand crossings in the metal-coordinated overhand knot is governed by the stereochemistry of the point-chiral carbon centers in the ligand strand. The overhand and trefoil knots were characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Removal of the metal ions from the knot, followed by hydrogenation of the alkene, yielded the wholly organic trefoil knot. The metal-free knot and parent ligand were investigated by circular dichroism (CD) spectroscopy. The CD spectra indicate that the topological stereochemistry of the knot has a greater effect on the asymmetry of the chromophore environment than do the point-chiral centers of the strand.

Two novel Ce(III) metal organic frameworks (MOFs) with formulas [Ce(5Meip)(H-5Meip)] n GR-MOF-17 and [CeCl(5Meip)(DMF)] n GR-MOF-18 (5Meip = 5-methylisophthalate, DMF = N , N -dimethylformamide) have been synthesized, forming 3-dimensional frameworks. Magnetic measurements show that both compounds present field-induced slow magnetic relaxation under a small applied dc field. For GR-MOF-17, the temperature dependence of relaxation times is best described by a Raman mechanism, whereas for GR-MOF-18, relaxation occurs through a combination of Raman and local-mode pathways. Moreover, when avoiding short Ce⋯Ce interactions by magnetic dilution in GR-MOF-17@La and GR-MOF-18@La, only the local-mode mechanism is responsible for magnetic relaxation. Photophysical studies show the occurrence of ligand-centred luminescence in both compounds and phosphorescence emission at low temperature for GR-MOF-17.

The paramagnetism of f-block ions has been exploited in chiral shift reagents and magnetic resonance imaging, but these applications tend to focus on 1 H NMR shifts as paramagnetic broadening makes less sensitive nuclei more difficult to study. Here we report a solution and solid-state (ss) 29 Si NMR study of an isostructural series of locally D 3 h -symmetric early f-block metal(III) tris -hypersilanide complexes, [M{Si(SiMe 3 ) 3 } 3 (THF) 2 ] ( 1-M ; M = La, Ce, Pr, Nd, U); 1-M were also characterized by single crystal and powder X-ray diffraction, EPR, ATR-IR, and UV-vis-NIR spectroscopies, SQUID magnetometry, and elemental analysis. Only one SiMe 3 signal was observed in the 29 Si ssNMR spectra of 1-M , while two SiMe 3 signals were seen in solution 29 Si NMR spectra of 1-La and 1-Ce . This is attributed to dynamic averaging of the SiMe 3 groups in 1-M in the solid state due to free rotation of the M-Si bonds and dissociation of THF from 1-M in solution to give the locally C 3 v -symmetric complexes [M{Si(SiMe 3 ) 3 } 3 (THF) n ] ( n = 0 or 1), which show restricted rotation of M-Si bonds on the NMR time scale. Density functional theory and complete active space self-consistent field spin-orbit calculations were performed on 1-M and desolvated solution species to model paramagnetic NMR shifts. We find excellent agreement of experimental 29 Si NMR data for diamagnetic 1-La , suggesting n = 1 in solution and reasonable agreement of calculated paramagnetic shifts of SiMe 3 groups for 1-M (M = Pr and Nd); the NMR shifts for metal-bound 29 Si nuclei could only be reproduced for diamagnetic 1-La , showing the current limitations of pNMR calculations for larger nuclei., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In the design of dynamic supramolecular systems used in molecular machines, it is important to understand the binding preferences between the macrocycle and stations along the thread. Here, we apply 1 H NMR spectroscopy to investigate the relative stabilities of a series of linear alkylammonium templated pseudorotaxanes with the general formula [H 2 NRR'][Cr 7 CoF 8 (O 2 CCH 2 t Bu) 16 ] by exchanging the cation in solution. Our results show that the pseudorotaxanes are able to exchange threads via a dissociative mechanism. The position of equilibrium is dependent upon the ammonium cation and solvent used. Short chain primary ammonium cations are shown to be far less favourable macrocycle stations than secondary ammonium cations. Collision-induced dissociation mass spectrometry (CID-MS) has been used to look at disassembly of the pseudorotaxanes in a solvent-free environment and stability trends compared to those in acetone-d6. The energy needed to induce 50 % of the precursor ion loss (E 50 ) is used and shows a similar trend to the equilibria measured by NMR. The relative stabilities of these hybrid inorganic-organic pseudo-rotaxanes are different to those of host-guest compounds involving crown ethers and this may be valuable for the design of molecular machines., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Versatile, efficient and robust (pre)catalysts are pivotal in accelerating the discovery and optimization of chemical reactions, shaping diverse synthetic fields such as cross-coupling, C-H functionalization and polymer chemistry. Yet, their scarcity in certain domains has hindered the advancement and adoption of new applications. Here we present a highly reactive air- and moisture-stable ruthenium precatalyst [( t BuCN) 5 Ru(H 2 O)](BF 4 ) 2 , featuring a key exchangeable water ligand. This versatile precatalyst drives an array of transformations, including late-stage C(sp 2 )-H arylation, primary/secondary alkylation, methylation, hydrogen/deuterium exchange, C(sp 3 )-H oxidation, alkene isomerization and oxidative cleavage, consistently outperforming conventionally used ruthenium (pre)catalysts. The generality and applicability of this precatalyst is exemplified through the potential for rapid screening and optimization of photocatalytic reactions with a suite of in situ generated ruthenium photocatalysts containing hitherto unknown complexes, and through the rapid discovery of reactivities previously unreported for ruthenium. The diverse applicability observed is suggestive of a generic platform for reaction simplification and accelerated synthetic discovery that will enable broader applicability and accessibility to state-of-the-art ruthenium catalysis., (© 2024. The Author(s).)

A three-dimensional heterobimetallic porous structure with the formula {[Y 3.5 Tb 1.5 L 6 (OH) 3 (H 2 O) 1.5 (DMF) 1.5 ] n ·1.5H 2 O·DMF} n (L = 3-amino-4-hydroxybenzoate) ( Y/Tb-MOF ) has been synthesized and characterized by single crystal and powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS), electrophoretic mobility, and Fourier transform infrared (FTIR) spectroscopy. The structure presents two metal environments: a bioaugmented isosceles wedge (mm2) MO 8 and a tricapped trigonal prism (-6m2) MN 3 O 6 . These configurations facilitate the creation of channels with a diameter of 10.7 Å, enabling its utilization as an active catalyst where the heterobimetallic nature of the assembly will be explored. This mixed-metal metal-organic framework has been tested in the cycloaddition of epoxides with carbon dioxide as well as in the cyanosilylation and hydroboration reactions of carbonylic substrates. Additionally, a monometallic Tb-MOF analogue has been synthesized for comparative evaluation of their catalytic performances. Both the mixed metal and monometallic variants exhibit outstanding activity in the cyanosilylation and hydroboration of carbonyls and in the synthesis of carbonates under CO 2 pressure. However, only the latter exhibits high recyclability., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

A new family of six complexes based on 5-nitropicolinic acid (5-npic) and transition metals has been obtained: [M(5-npic) 2 ] n (M II = Mn (1) and Cd (2)), [Cu(5-npic) 2 ] n (3), and [M(5-npic) 2 (H 2 O) 2 ] (M II = Co (4), Ni (5), and Zn (6)), which display 1D, 2D, and mononuclear structures, respectively, thanks to different coordination modes of 5-npic. After their physicochemical characterization by single-crystal X-ray diffraction (SCXRD), elemental analyses (EA), and spectroscopic techniques, quantum chemical calculations using Time-Dependent Density Functional Theory (TD-DFT) were performed to further study the luminescence properties of compounds 2 and 6. The potential anticancer activity of all complexes was tested against three tumor cell lines, B16-F10, HT29, and HepG2, which are models widely used for studying melanoma, colon cancer, and liver cancer, respectively. The best results were found for compounds 2 and 4 against B16-F10 (IC 50 = 26.94 and 45.10 μg mL -1 , respectively). In addition, anti-inflammatory studies using RAW 264.7 cells exhibited promising activity for 2, 3, and 6 (IC 50 NO = 5.38, 24.10, and 17.63 μg mL -1 , respectively). This multidisciplinary study points to complex 2, based on Cd II , as a promising anticancer and anti-inflammatory material.

The decamethyldysprosocenium cation, [Dy(Cp*) 2 ] + (Cp* = {C 5 Me 5 }), was a target single-molecule magnet (SMM) prior to the isolation of larger dysprosocenium cations, which have recently shown magnetic memory effects up to 80 K. However, the relatively short Dy···Cp* centroid distances of [Dy(Cp*) 2 ] + , together with the reduced resonance of its vibrational modes with electronic states compared to larger dysprosocenium cations, could lead to more favorable SMM behavior. Here, we report the synthesis and magnetic properties of a series of solvated adducts containing bis-halobenzene decamethyldysprosocenium cations, namely [Dy(Cp*) 2 (PhX-κ- X ) 2 ][Al{OC(CF 3 ) 3 } 4 ] (X = F or Cl) and [Dy(Cp*) 2 (C 6 H 4 F 2 -κ 2 - F , F )(C 6 H 4 F 2 -κ- F )][Al{OC(CF 3 ) 3 } 4 ]. These complexes were prepared by the sequential reaction of [Dy(Cp*) 2 (μ-BH 4 )] ∞ with allylmagnesium chloride and [NEt 3 H][Al{OC(CF 3 ) 3 } 4 ], followed by recrystallization from parent halobenzenes. The complexes were characterized by powder and single crystal X-ray diffraction, NMR and ATR-IR spectroscopy, elemental analysis, and SQUID magnetometry; experimental data were rationalized by a combination of density functional theory and ab initio calculations. We find that bis-halobenzene adducts of the [Dy(Cp*) 2 ] + cation exhibit highly bent Cp*···Dy···Cp* angles; these cations are also susceptible to decomposition by C-X (X = F, Cl, Br) activation and displacement of halobenzenes by O-donor ligands. The effective energy barrier to reversal of magnetization measured for [Dy(Cp*) 2 (PhF-κ- F ) 2 ][Al{OC(CF 3 ) 3 } 4 ] (930(6) cm -1 ) sets a new record for SMMs containing {Dy(Cp*) 2 } fragments, though all SMM parameters are lower than would be predicted for an isolated [Dy(Cp*) 2 ] + cation, as expected due to transverse ligand fields introduced by halobenzenes and the large deviation of the Cp*···Dy···Cp* angle from linearity promoting magnetic relaxation.

Dysprosium complexes with strong axial crystal fields are promising candidates for single-molecule magnets (SMMs), which could be used for high-density data storage. Isolated dysprosocenium cations, [Dy(Cp R ) 2 ] + (Cp R = substituted cyclopentadienyl), have recently shown magnetic hysteresis (a memory effect) above the temperature of liquid nitrogen. Synthetic efforts have focused on reducing strong transverse ligand fields in these systems as they are known to enhance magnetic relaxation by spin-phonon mechanisms. Here we show that equatorial coordination of the halobenzenes PhX (X = F, Cl, Br) and o -C 6 H 4 F 2 to the cation of a recently reported dysprosocenium complex [Dy(Cp ttt )(Cp*)][Al{OC(CF 3 ) 3 } 4 ] (Cp ttt = C 5 H 2 t Bu 3 -1,2,4; Cp* = C 5 Me 5 ) reduces magnetic hysteresis temperatures compared to that of the parent cation. We find that this is due to increased effectiveness of both one- (Orbach) and two-phonon (Raman) relaxation mechanisms, which correlate with the electronegativity and number of interactions with the halide despite κ 1 -coordination of a single halobenzene having a minimal effect on the metrical parameters of [Dy(Cp ttt )(Cp*)(PhX-κ 1 - X )] + cations vs the isolated [Dy(Cp ttt )(Cp*)] + cation. We observe unusual divergent behavior of relaxation rates at low temperatures in [Dy(Cp ttt )(Cp*)(PhX)][Al{OC(CF 3 ) 3 } 4 ], which we attribute to a phonon bottleneck effect. We find that, despite the transverse fields introduced by the monohalobenzenes in these cations, the interactions are sufficiently weak that the effective barriers to magnetization reversal remain above 1000 cm -1 , being only ca . 100 cm -1 lower than for the parent complex, [Dy(Cp ttt )(Cp*)][Al{OC(CF 3 ) 3 } 4 ].

Optimization of active sites and stability under irradiation are important targets for sorbent materials that might be used for iodine (I 2 ) storage. Herein, we report the direct observation of I 2 binding in a series of Cu(II)-based isostructural metal-organic frameworks, MFM-170, MFM-172, MFM-174, NJU-Bai20, and NJU-Bai21, incorporating various functional groups (-H, -CH 3 , - NH 2 , -C≡C-, and -CONH-, respectively). MFM-170 shows a reversible uptake of 3.37 g g -1 and a high packing density of 4.41 g cm -3 for physiosorbed I 2 . The incorporation of -NH 2 and -C≡C- moieties in MFM-174 and NJU-Bai20, respectively, enhances the binding of I 2 , affording uptakes of up to 3.91 g g -1 . In addition, an exceptional I 2 packing density of 4.83 g cm -3 is achieved in MFM-174, comparable to that of solid iodine (4.93 g cm -3 ). In situ crystallographic studies show the formation of a range of supramolecular and chemical interactions [I···N, I···H 2 N] and [I···C≡C, I-C═C-I] between -NH 2 , -C≡C- sites, respectively, and adsorbed I 2 molecules. These observations have been confirmed via a combination of solid-state nuclear magnetic resonance, X-ray photoelectron, and Raman spectroscopies. Importantly, γ-irradiation confirmed the ultraresistance of MFM-170, MFM-174, and NJU-Bai20 suggesting their potential as efficient sorbents for cleanup of radioactive waste.

To date, only a small number of chemistries and chemical fueling strategies have been successfully used to operate artificial molecular motors. Here, we report the 360° directionally biased rotation of phenyl groups about a C-C bond, driven by a stepwise Appel reaction sequence. The motor molecule consists of a biaryl-embedded phosphine oxide and phenol, in which full rotation around the biaryl bond is blocked by the P-O oxygen atom on the rotor being too bulky to pass the oxygen atom on the stator. Treatment with SOCl 2 forms a cyclic oxyphosphonium salt (removing the oxygen atom of the phosphine oxide), temporarily linking the rotor with the stator. Conformational exchange via ring flipping then allows the rotor and stator to twist back and forth past the previous limit of rotation. Subsequently, the ring opening of the tethered intermediate with a chiral alcohol occurs preferentially through a nucleophilic attack on one face. Thus, the original phosphine oxide is reformed with net directional rotation about the biaryl bond over the course of the two-step reaction sequence. Each repetition of SOCl 2 -chiral alcohol additions generates another directionally biased rotation. Using the same reaction sequence on a derivative of the motor molecule that forms atropisomers rather than fully rotating 360° results in enantioenrichment, suggesting that, on average, the motor molecule rotates in the "wrong" direction once every three fueling cycles. The interconversion of phosphine oxides and cyclic oxyphosphonium groups to form temporary tethers that enable a rotational barrier to be overcome directionally adds to the strategies available for generating chemically fueled kinetic asymmetry in molecular systems.

Monomeric [Co(SDZ) 2 phen] (1) and [Co(SDZ)(bq)Cl] (2) complexes (SDZ = sulfadiazine, phen = 1,10-phenanthroline, and bq = 2,2'-biquinoline) have been synthesized and characterized. X-ray diffraction studies indicate that SDZ acts as a bidentate ligand coordinating through the sulfonamide and the pyrimidine N atoms in both compounds. In complex 1, the coordination sphere consists of two SDZ ligands and a bis-chelating phen ligand, giving rise to a CoN 6 coordination sphere. On the other hand, 2 has a CoN 4 Cl core, with two N-atoms from SDZ and two from the bq ligand. Both compounds have been studied by dc and ac magnetometry and shown to display slow magnetic relaxation under an optimum external dc field (1 kOe) at low temperatures. Moreover, compound 2 displays long range magnetic ordering provided by spin-canted antiferromagnetism, which has been characterized by further field-dependent magnetic susceptibility measurements, FC/ZFC curves, hysteresis loops and frequency-independent ac curves. The signs of the calculated D parameters, positive in 1 and negative in 2, have been rationalized according to the two lowest-lying transitions in the orbital energy diagrams derived from ab initio ligand field theory (AILFT). In a subsequent attempt to reveal the possible hidden zero-field SMM behaviour, Ni(II)-based 3 and Co(II)-doped Ni(II)-based (with a Ni : Co ratio of 0.9 : 0.1) heterometallic compound 2Ni were synthesized.

Rare-earth (RE) metal-organic frameworks (MOFs) synthesized in the presence of fluorine-donating modulators or linkers are an important new subset of functional MOFs. However, the exact nature of the RE a X b core of the molecular building block (MBB) of the MOF, where X is a μ 2 or 3 -bridging group, remains unclear. Investigation of one of the archetypal members of this family with the stable fcu framework topology, Y-fum- fcu -MOF ( 1 ), using a combination of experimental techniques, including high-field (20 T) solid-state nuclear magnetic resonance spectroscopy, has determined two sources of framework disorder involving the μ 3 -X face-capping group of the MBB and the fumarate (fum) linker. The core of the MBB of 1 is shown to contain a mixture of μ 3 -F - and (OH) - groups with preferential occupation at the crystallographically different face-capping sites that result in different internally lined framework tetrahedral cages. The fum linker is also found to display a disordered arrangement involving bridging- or chelating-bridging bis-bidentate modes over the fum linker positions without influencing the MBB orientation. This linker disorder will, upon activation, result in the creation of Y 3+ ions with potentially one or two additional uncoordinated sites possessing differing degrees of Lewis acidity. Crystallographically determined host-guest relationships for simple sorbates demonstrate the favored sorption sites for N 2 , CO 2 , and CS 2 molecules that reflect the chemical nature of both the framework and the sorbate species with the structural partitioning of the μ 3 -groups apparent in determining the favored sorption site of CS 2 . The two types of disorder found within 1 demonstrate the complexity of fluoride-containing RE-MOFs and highlight the possibility to tune this and other frameworks to contain different proportions and segregations of μ 3 -face-capping groups and degrees of linker disorder for specifically tailored applications., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The isolation of formally two-coordinate lanthanide (Ln) complexes is synthetically challenging, due to predominantly ionic Ln bonding regimes favoring high coordination numbers. In 2015, it was predicted that a near-linear dysprosium bis(amide) cation [Dy{N(Si i Pr 3 ) 2 } 2 ] + could provide a single-molecule magnet (SMM) with an energy barrier to magnetic reversal ( U eff ) of up to 2600 K, a 3-fold increase of the record U eff for a Dy SMM at the time; this work showed a potential route to SMMs that can provide high-density data storage at higher temperatures. However, synthetic routes to a Dy complex containing only two monodentate ligands have not previously been realized. Here, we report the synthesis of the target bent dysprosium bis(amide) complex, [Dy{N(Si i Pr 3 ) 2 } 2 ][Al{OC(CF 3 ) 3 } 4 ] ( 1-Dy ), together with the diamagnetic yttrium analogue. We find U eff = 950 ± 30 K for 1-Dy , which is much lower than the predicted values for idealized linear two-coordinate Dy(III) cations. Ab initio calculations of the static electronic structure disagree with the experimentally determined height of the U eff barrier, thus magnetic relaxation is faster than expected based on magnetic anisotropy alone. We propose that this is due to enhanced spin-phonon coupling arising from the flexibility of the Dy coordination sphere, in accord with ligand vibrations being of equal importance to magnetic anisotropy in the design of high-temperature SMMs.

The thermostable four-coordinate divalent lanthanide (Ln) bis-amidinate complexes [Ln(Piso) 2 ] (Ln = Tb, Dy; Piso = {(NDipp) 2 C t Bu}, Dipp = C 6 H 3 i Pr 2 -2,6) were prepared by the reduction of parent five-coordinate Ln(III) precursors [Ln(Piso) 2 I] (Ln = Tb, Dy) with KC 8 ; halide abstraction of [Ln(Piso) 2 I] with [H(SiEt 3 ) 2 ][B(C 6 F 5 )] gave the respective Ln(III) complexes [Ln(Piso) 2 ][B(C 6 F 5 )]. All complexes were characterized by X-ray diffraction, ICP-MS, elemental analysis, SQUID magnetometry, UV-vis-NIR, ATR-IR, NMR, and EPR spectroscopy and ab initio CASSCF-SO calculations. These data consistently show that [Ln(Piso) 2 ] formally exhibit Ln(II) centers with 4f n 5d z 2 1 (Ln = Tb, n = 8; Dy, n = 9) valence electron configurations. We show that simple assignments of the f-d coupling to either L - S or J - s schemes are an oversimplification, especially in the presence of significant crystal field splitting. The coordination geometry of [Ln(Piso) 2 ] is intermediate between square planar and tetrahedral. Projecting from the quaternary carbon atoms of the CN 2 ligand backbones shows near-linear C···Ln···C arrangements. This results in strong axial ligand fields to give effective energy barriers to magnetic reversal of 1920(91) K for the Tb(II) analogue and 1964(48) K for Dy(II), the highest values observed for mononuclear Ln(II) single-molecule magnets, eclipsing 1738 K for [Tb(C 5 i Pr 5 ) 2 ]. We tentatively attribute the fast zero-field magnetic relaxation for these complexes at low temperatures to transverse fields, resulting in considerable mixing of m J states.

A synthetic strategy is demonstrated to prepare two distinct trimers of antiferromagnetically coupled {Cr 7 Ni} rings, substantially varying the magnetic interactions between the spin centres. The interactions were studied using multi-frequency cw EPR: in a trimer linked via non-covalent H-bonding interactions no measurable interaction between rings was seen, while in a trimer linked via iso-nicotinate groups isotropic and anisotropic exchange interactions of +0.42 and -0.8 GHz, respectively, were observed. The latter are the same as those for a simpler hetero-dimer system, showing how the spin-spin interactions can be built in a predictable and modular manner in these systems., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Here we report the synthesis and structural characterization of four [7]rotaxanes formed by coordinating hybrid inorganic-organic [2]rotaxanes to a central {Ni 12 } core. X-ray single crystal diffraction demonstrate that [7]rotaxanes are formed, with a range of conformations in the crystal. Small angle X-ray scattering supported by molecular dynamic simulations demonstrates that the large molecules are stable in solution and also show that the conformers present in solution are not those found in the crystal. Pulsed EPR spectroscopy show that phase memory times for the {Cr 7 Ni} rings, which have been proposed as qubits, are reduced but not dramatically by the presence of the {Ni 12 } cage., Competing Interests: The authors declare no competing financial interest., (This journal is © the Partner Organisations.)

Isolated dysprosocenium cations, [Dy(Cp R ) 2 ] + (Cp R = substituted cyclopentadienyl), have recently been shown to exhibit superior single-molecule magnet (SMM) properties over closely related complexes with equatorially bound ligands. However, gauging the crossover point at which the Cp R substituents are large enough to prevent equatorial ligand binding, but small enough to approach the metal closely and generate strong crystal field splitting has required laborious synthetic optimization. We therefore created the computer program AtomAccess to predict the accessibility of a metal binding site and its ability to accommodate additional ligands. Here, we apply AtomAccess to identify the crossover point for equatorial coordination in [Dy(Cp R ) 2 ] + cations in silico and hence predict a cation that is at the cusp of stability without equatorial interactions, viz., [Dy(Cp ttt )(Cp*)] + (Cp ttt = C 5 H 2 t Bu 3 -1,2,4, Cp* = C 5 Me 5 ). Upon synthesizing this cation, we found that it crystallizes as either a contact ion-pair, [Dy(Cp ttt )(Cp*){Al[OC(CF 3 ) 3 ] 4 -κ-F}], or separated ion-pair polymorph, [Dy(Cp ttt )(Cp*)][Al{OC(CF 3 ) 3 } 4 ]·C 6 H 6 . Upon characterizing these complexes, together with their precursors, yttrium and yttrium-doped analogues, we find that the contact ion-pair shows inferior SMM properties to the separated ion-pair, as expected, due to faster Raman and quantum tunneling of magnetization relaxation processes, while the Orbach region is relatively unaffected. The experimental verification of the predicted crossover point for equatorial coordination in this work tests the limitations of the use of AtomAccess as a predictive tool and also indicates that the application of this type of program shows considerable potential to boost efficiency in exploratory synthetic chemistry.

The study of sub-valent Group 2 chemistry is a relatively new research field, being established in 2007 with the report of the first Mg(I) dimers. These species are stabilized by the formation of a Mg-Mg covalent bond; however, the extension of this chemistry to heavier alkaline earth (AE) metals has been frustrated by significant synthetic challenges, primarily associated with the instability of heavy AE-AE interactions. Here we present a new blueprint for the stabilization of heavy AE(I) complexes, based upon the reduction of AE(II) precursors with planar coordination geometries. We report the synthesis and structural characterisation of homoleptic trigonal planar AE(II) complexes of the monodentate amides {N(SiMe 3 ) 2 } - and {N(Mes)(SiMe 3 )} - . DFT calculations showed that the LUMOs of these complexes all show some d-character for AE = Ca-Ba. DFT analysis of the square planar Sr(II) complex [Sr{N(SiMe 3 ) 2 }(dioxane) 2 ] ∞ revealed analogous frontier orbital d-character. AE(I) complexes that could be accessed by reduction of these AE(II) precursors were modelled computationally, revealing exergonic formation in all cases. Crucially, NBO calculations show that some d-character is preserved in the SOMO of theoretical AE(I) products upon reduction, showing that d-orbitals could play a crucial role in achieving stable heavy AE(I) complexes., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Proton-exchange membrane fuel cells enable the portable utilization of hydrogen (H 2 ) as an energy resource. Current electrolytic materials have limitation, and there is an urgent need to develop new materials showing especially high proton conductivity. Here, we report the ultra-fast proton conduction in a novel metal-organic framework, MFM-808, which adopts an unprecedented topology and a unique structure consisting of two-dimensional layers of {Zr 6 }-clusters. By replacing the bridging formate with sulfate ligands within {Zr 6 }-layers, the modified MFM-808-SO 4 exhibits an exceptional proton conductivity of 0.21 S·cm -1 at 85 °C and 99% relative humidity. Modeling by molecular dynamics confirms that proton transfer is promoted by an efficient two-dimensional conducting network assembled by sulfate-{Zr 6 }-layers. MFM-808-SO 4 also possesses excellent photocatalytic activity for water splitting to produce H 2 , paving a new pathway to achieve a renewable hydrogen-energy cycle.

A core feature of covalent organic frameworks (COFs) is crystallinity, but current crystallization processes rely substantially on trial and error, chemical intuition and large-scale screening, which typically require harsh conditions and low levels of supersaturation, hampering the controlled synthesis of single-crystal COFs, particularly on large scales. Here we report a strategy to produce single-crystal imine-linked COFs in aqueous solutions under ambient conditions using amphiphilic amino-acid derivatives with long hydrophobic chains. We propose that these amphiphilic molecules self-assemble into micelles that serve as dynamic barriers to separate monomers in aqueous solution (nodes) and hydrophobic compartments of the micelles (linkers), thereby regulating the polymerization and crystallization processes. Disordered polyimines were obtained in the micelle, which were then converted into crystals in a step-by-step fashion. Five different three-dimensional COFs and a two-dimensional COF were obtained as single crystals on the gram scale, with yields of 92% and above., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

We repeat the earliest claimed [2]catenane synthesis, reported by Wasserman over 60 years ago, in order to ascertain whether or not a nontemplate, statistical synthesis by acyloin macrocyclization does indeed form mechanically interlocked rings. The lack of direct experimental evidence for Wasserman's catenane has led to it being described as a "prophetic compound", a technical term used in patents for claimed molecules that have not yet been synthesized. Contemporary synthetic methods were used to reconstruct Wasserman's deuterium-labeled macrocycle and other building blocks on the 10-100 g reaction scale necessary to generate, in principle, ∼1 mg of catenane. Modern spectrometric and spectroscopic tools and chemical techniques (including tandem mass spectrometry, deuterium nuclear magnetic resonance (NMR) spectroscopy, and fluorescent tag labeling) were brought to bear in an effort to detect, isolate, and prove the structure of a putative [2]catenane consisting of a 34-membered cyclic hydrocarbon mechanically linked with a 34-membered cyclic α-hydroxyketone.

Challenges for the development of efficacious new superbases include their ease of synthesis, chemical stability, and high basicity, while minimizing nucleophilicity is important for reducing unwanted side reactions. Here, we introduce a new family of organic superbases, compact amine-crown ether rotaxanes, which show desirable characteristics in all these respects. Metal-free active template synthesis provides access to a range of rotaxanes with as little as three atoms between the stoppering groups, locking the location of a small crown ether (21C7 and 24C8 derivatives) over the amine group of the axle. The forced proximity of the interlocked protophilic components results in p K a H + values as high as 32.2 in acetonitrile, which is up to 13 p K a H + units greater than the p K a H + values of the non-interlocked components, and brings the free base rotaxanes into the basicity realm of phosphazene superbases. The rotaxane superbases are generally chemically stable and, in a model reaction for superbases, eliminate HBr from a primary alkyl bromide with complete selectivity for deprotonation over alkylation. Their modest size, ease of synthesis, high basicity, low nucleophilicity, and, in the best cases, rapid substrate deprotonation kinetics and excellent hydrolytic stability make compact amine-crown ether rotaxane superbases intriguing candidates for potential applications in synthesis and supramolecular and materials chemistry.

Despite being known for decades, the solution-state molecular chemistry of heptapnictogen ([Pn 7 ] 3- ; Pn = P, As) clusters is not well established. Here we study heavy element derivatives of tetrel functionalized heptapnictogen clusters towards heteroallene capture, specifically isocyanates, an isothiocyanate and CO 2 are probed. Clusters (Me 3 Ge) 3 P 7 (1), (Et 3 Ge) 3 P 7 (2), ( n Bu 3 Sn) 3 P 7 (3), and (Me 3 Si) 3 As 7 (4) were all found to capture isocyanates between all three of their tetrel-pnictogen bonds. In the case of phenyl isocyanate insertion, tetrel coordination at the isocyanate nitrogen atoms is preferred, while in the case of p -toluenesulfonyl isocyanate insertion, tetrel coordination at oxygen is preferred. Furthermore, the reaction of (Me 3 Si) 3 P 7 with CO 2 gave NMR spectra consistent with the capture of the greenhouse gas. Heteroallene insertion at these clusters was also studied using density functional theory.

The first fully characterized boron-functionalized heptaphosphide Zintl cluster, [(BBN)P 7 ] 2- ([ 1 ] 2- ), is synthesized by dehydrocoupling [HP 7 ] 2- . Dehydrocoupling is a previously unprecedented reaction pathway to functionalize Zintl clusters. [Na(18-c-6)] 2 [ 1 ] was employed as a transition metal-free catalyst for the hydroboration of aldehydes and ketones. Moreover, the greenhouse gas carbon dioxide (CO 2 ) was efficiently and selectively reduced to methoxyborane. This work represents the first examples of Zintl catalysis where the transformation is transition metal-free and where the cluster is noninnocent.

Isolating metal-organic cage structures which incorporate more than one distinct ligand has been challenging due to competing pressures from narcissistic and social sorting phenomena. Here we report the first example of exclusive formation of a single tetrahedral product from a reaction mixture containing two different bidentate ligands. Exclusive formation of the tetrahedron, which incorporates one unique metal vertex, relies on a triamine to orientate the heteroditopic ligand. Inclusion of perchlorate counterions during the self-assembly process is also found to be a requirement if social sorting is to be avoided. The C 3 -symmetric structure is characterised by HR-MS, NMR spectroscopy and X-ray crystallography, and provides proof of principle for use of heteroditopic ligands in classical M 4 L 6 supramolecular structures, opening exciting possibilities for their use in separation, storage and catalysis applications.

Autonomous chemically fueled molecular machines that function through information ratchet mechanisms underpin the nonequilibrium processes that sustain life. These biomolecular motors have evolved to be well-suited to the tasks they perform. Synthetic systems that function through similar mechanisms have recently been developed, and their minimalist structures enable the influence of structural changes on machine performance to be assessed. Here, we probe the effect of changes in the fuel and barrier-forming species on the nonequilibrium operation of a carbodiimide-fueled rotaxane-based information ratchet. We examine the machine's ability to catalyze the fuel-to-waste reaction and harness energy from it to drive directional displacement of the macrocycle. These characteristics are intrinsically linked to the speed, force, power, and efficiency of the ratchet output. We find that, just as for biomolecular motors and macroscopic machinery, optimization of one feature (such as speed) can compromise other features (such as the force that can be generated by the ratchet). Balancing speed, power, efficiency, and directionality will likely prove important when developing artificial molecular motors for particular applications.

We report a new class of synthetic molecular pumps that use a stepwise information ratchet mechanism to achieve the kinetic gating required to sequester their macrocyclic substrates from bulk solution. Threading occurs as a result of active template reactions between the pump terminus amine and an acyl electrophile, whereby the bond-forming reaction is accelerated through the cavity of a crown ether. Carboxylation of the resulting amide results in displacement of the ring to the collection region of the thread. Conversion of the carbamate to a phenolic ester provides an intermediate rotaxane suitable for further pumping cycles. In this way rings can be ratcheted onto a thread from one or both ends of appropriately designed molecular pumps. Each pumping cycle results in one additional ring being added to the thread per terminus acyl group. The absence of pseudorotaxane states ensures that no dethreading of intermediates occurs during the pump operation. This facilitates the loading of different macrocycles in any chosen sequence, illustrated by the pump-mediated synthesis of a [4]rotaxane containing three different macrocycles as a single sequence isomer. A [5]rotaxane synthesized using a dual-opening transamidation pump was structurally characterized by single-crystal X-ray diffraction, revealing a series of stabilizing CH···O interactions between the crown ethers and the polyethylene glycol catchment region of the thread.

Carbene-metal-amides (CMAs) are an emerging class of photoemitters based on a linear donor-linker-acceptor arrangement. They exhibit high flexibility about the carbene-metal and metal-amide bonds, leading to a conformational freedom which has a strong influence on their photophysical properties. Herein we report CMA complexes with (1) nearly coplanar, (2) twisted, (3) tilted, and (4) tilt-twisted orientations between donor and acceptor ligands and illustrate the influence of preferred ground-state conformations on both the luminescence quantum yields and excited-state lifetimes. The performance is found to be optimum for structures with partially twisted and/or tilted conformations, resulting in radiative rates exceeding 1 × 10 6 s -1 . Although the metal atoms make only small contributions to HOMOs and LUMOs, they provide sufficient spin-orbit coupling between the low-lying excited states to reduce the excited-state lifetimes down to 500 ns. At the same time, high photoluminescence quantum yields are maintained for a strongly tilted emitter in a host matrix. Proof-of-concept organic light-emitting diodes (OLEDs) based on these new emitter designs were fabricated, with a maximum external quantum efficiency (EQE) of 19.1% with low device roll-off efficiency. Transient electroluminescence studies indicate that molecular design concepts for new CMA emitters can be successfully translated into the OLED device., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Understanding the structural and chemical changes that reactive metal-organic frameworks (MOFs) undergo is crucial for the development of new efficient catalysts for electrochemical reduction of CO 2 . Here, we describe three Bi(iii) materials, MFM-220, MFM-221 and MFM-222, which are constructed from the same ligand (biphenyl-3,3',5,5'-tetracarboxylic acid) but which show distinct porosity with solvent-accessible voids of 49.6%, 33.6% and 0%, respectively. We report the first study of the impact of porosity of MOFs on their evolution as electrocatalysts. A Faradaic efficiency of 90.4% at -1.1 V vs. RHE (reversible hydrogen electrode) is observed for formate production over an electrode decorated with MFM-220-p, formed from MFM-220 on application of an external potential in the presence of 0.1 M KHCO 3 electrolyte. In situ electron paramagnetic resonance spectroscopy confirms the presence of ·COOH radicals as a reaction intermediate, with an observed stable and consistent Faradaic efficiency and current density for production of formate by electrolysis over 5 h. This study emphasises the significant role of porosity of MOFs as they react and evolve during electroreduction of CO 2 to generate value-added chemicals., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, n Bu; Tptm = {C(S-C 5 H 4 N) 3 } - ) and [AE(Tptm)(N'')] (AE = Mg-Ba; N'' = {N(SiMe 3 ) 2 } - ) were targeted from the reaction of HTptm with R 2 Mg or [AE(N'') 2 ] 2 . Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ 3 C , N , N -C{Bu}{S-C 5 H 4 N} 2 )(μ-S-C 5 H 4 N)} 2 ] (1) and [{Mg(κ 3 C , N , N -C{Me}{S-C 5 H 4 N} 2 )(μ-OSiMe 3 )} 2 ] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N'')] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)( n Bu)] (1m') system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.

Herein, we report the synthesis of a series of heteroleptic magnesium complexes stabilized with the scorpionate ligand tris(2-pyridylthio)methanide (Tptm). The compounds of the general formula [Mg(Tptm)(X)] ( 1-X ; X = Cl, Br, I) were obtained via protonolysis reaction between the proligand and selected Grignard reagents. Attempts to isolate the potassium derivative K(Tptm) lead to decomposition of Tptm and formation of the alkene (C 5 H 4 N-S) 2 C=C(C 5 H 4 N-S) 2 , and this degradation was also modelled using DFT methods. Compound 1-I was treated with K(CH 2 Ph), affording the degradation product [Mg(Bptm) 2 ] ( 2 ; Bptm = {CH(S-C 5 NH 3 ) 2 } - ). We analyzed and quantified the steric properties of the Tptm ligand using the structural information of the compounds obtained in this study paired with buried volume calculations, also adding the structural data of HTptm and its CF 3 -substituted congener (HTptm CF3 ). These studies highlight the highly flexible nature of this ligand scaffold and its ability to stabilize various coordination motifs and geometries, which is a highly desirable feature in the design of novel organometallic reagents and catalysts.

Polymer beads have been used as the core of magnetic particles for around twenty years. Here we report studies to attach polymetallic complexes to polymer beads for the first time, producing beads of around 115 microns diameter that are attached to 10 14 hybrid inorganic-organic [2]rotaxanes. The bead is then formally a [10 14 ] rotaxane. The number of complexes attached is counted by EPR spectroscopy after including TEMPO radicals within the thread of the hybrid [2]rotaxanes., (© 2022. The Author(s).)

Despite being known for decades the chemical reactivity of homoatomic seven-atom phosphorus clusters towards small molecules remains largely unexplored. Here, we report that neutral tris(silyl) functionalised heptaphosphane (P 7 (SiR 3 ) 3 ) cages are capable of heteroallene capture between the P-Si bonds of the cluster. A range of isocyanates and an isothiocyanate were investigated. In the case of isocyanates, silyl bonding at oxygen or nitrogen is regioselectively directed by the functional group on the isocyanate and substituents on the silyl moiety. Above all, we find that captured isothiocyanate molecules can be exchanged for isocyanate molecules, indicative of small molecule catch and release. Small molecule catch and release at these Zintl-derived clusters reveals their potential application as chemical storage materials or as reusable probes., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Self-assembly and characterisation of a supramolecular trigonal bipyramidal iron cage containing an [Fe III (μ 2 -F) 6 (Fe II ) 3 ] 3+ star motif at its core is reported. The complex can be formed in a one step reaction using an heterotopic ligand that supports site-specific incorporation of iron in three distinct electronic configurations: low-spin Fe II , high-spin Fe II and high-spin Fe III , with iron(II) tetrafluoroborate as the source of the bridging fluorides. Formation of a μ 2 -F bridged mixed-valence Fe II -Fe III star is unprecedented. The peripheral high-spin Fe II centres of the mixed-valence tetranuclear star incorporated in the iron cage are highly anisotropic and engage in F-mediated antiferromagnetic exchange with the central Fe III ion.

Manganese(II) xanthate complexes of the form [Mn(S 2 COR) 2 (TMEDA)], where TMEDA = tetramethylethylenediamine and R = methyl ( 1 ), ethyl ( 2 ), n -propyl ( 3 ), n -butyl ( 4 ), n -pentyl ( 5 ), n -hexyl ( 6 ), and n -octyl ( 7 ), have been synthesized and structures elucidated using single-crystal X-ray diffraction. Complexes 1 - 7 were used as molecular precursors to synthesize manganese sulfide (MnS). Olelyamine-capped nanocrystals have been produced via hot injection, while the doctor blading followed by thermolysis yielded thick films. Free-standing polycrystalline powders of MnS are produced by direct thermolysis of precursor powders. All thermolysis techniques produced cubic MnS, as confirmed by powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. Magnetic measurements reveal that the α-MnS nanocrystals exhibit ferromagnetic behavior with a large coercive field strength ( e.g., 0.723 kOe for 6.8 nm nanocrystals)., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

With the recent increase in research into ferroelectric, anti-ferroelectric and piezoelectric materials, studying the solid-state properties in situ under applied electric fields is vital in understanding the underlying processes. Where this behaviour is the result of atomic displacements, crystallographic insight has an important role. This work presents a sample environment designed to apply an electric field to single-crystal samples in situ on the small-molecule single-crystal diffraction beamline I19, Diamond Light Source (UK). The configuration and operation of the cell is described as well as its application to studies of a proton-transfer colour-change material., (© Lucy K. Saunders et al. 2021.)

Gold(i) bridged dimeric and trimeric structures of a ground state spin S = 1/2 heterometallic {Cr 7 Ni} wheel have been prepared and studied by continuous wave (CW) and pulsed wave EPR spectrometry. The {Cr 7 Ni} relaxation time constants (T 1 and T m ) show rates matching well with previous observations. Four pulse Double Electron Resonance (DEER) studies suggest presence of more than one conformations. Small Angle X-ray Scattering (SAXS) in conjunction with Molecular Dynamic (MD) Simulations were performed to look at the possible conformations in solution. In line with DEER results, simulation data further indicated more flexible molecular geometry in solution than the one in solid state.

Although circular helicates can be assembled with a range of labile transition-metal centers, solely "chiral-at-metal" examples (i.e., systems without chiral ligands) and heterometallic (i.e., mixed metal systems, racemic or chiral) circular helicates both remain unexplored. Here, we report on the enantioselective synthesis of a heterometallic (Ir 2 Zn 4 ) hexameric circular helicate and its elaboration into the corresponding triply interlocked Star of David [2]catenane. The relative inertness of Ir(III) enables enantiospecific synthesis of the hexameric circular helicate using chiral-at-metal building blocks. The resulting Star of David [2]catenane, which is a chiral 6-2-1 link, is formed as a single topological enantiomer. The X-ray crystal structure of the (Ir 2 Zn 4 )-catenane shows each of the two 95-atom-long macrocycles entwined around the six metal octahedral metal ions and each other, forming a triply interlocked circular double helix. Two PF 6 - anions reside above and below the central cavity. The Star of David [2]catenane, both with and without coordinated Zn(II) ions, retains the photophysical properties characteristic of cyclometalated Ir(III) complexes. The synthetic strategy opens up new research directions and opportunities for the assembly of other chiral knots, links, and heterometallic circular helicates.

MFM-722(Pb)-DMA undergoes a single-crystal-to-single-crystal (SCSC) transformation to give MFM-722(Pb)-H2O via ligand substitution upon exposure to water vapour. In situ single crystal impedance spectroscopy reveals an increase in proton conductivity due to this structural transition, with MFM-722(Pb)-H2O showing a proton conductivity of 6.61 × 10-4 S cm-1 at 50 °C and 98% RH. The low activation energy (Ea = 0.21 eV) indicates that the proton conduction follows a Grotthuss mechanism.

The length and constitution of spacers linking three 2,6-pyridinedicarboxamide units in a molecular strand influence the tightness of the resulting overhand (open-trefoil) knot that the strand folds into in the presence of lanthanide(iii) ions. The use of β-hairpin forming motifs as linkers enables a metal-coordinated pseudopeptide with a knotted tertiary structure to be generated. The resulting pseudopeptide knot has one of the highest backbone-to-crossing ratios (BCR)-a measure of knot tightness (a high value corresponding to looseness)-for a synthetic molecular knot to date. Preorganization in the crossing-free turn section of the knot affects aromatic stacking interactions close to the crossing region. The metal-coordinated pseudopeptide knot is compared to overhand knots with other linkers of varying tightness and turn preorganization, and the entangled architectures characterized by NMR spectroscopy, ESI-MS, CD spectroscopy and, in one case, X-ray crystallography. The results show how it is possible to program specific conformational properties into different key regions of synthetic molecular knots, opening the way to systems where knotting can be systematically incorporated into peptide-like chains through design., Competing Interests: The authors declare no conflicts of interests., (This journal is © The Royal Society of Chemistry.)

Reduction of copper(ii) chloride using sodium ascorbate in the presence of pure sodium 5-nitro-tetrazolate (NaNT) forms copper(i) 5-nitrotetrazolate - a known initiatory explosive (DBX-1) - and the novel mixed-ligand copper(i) chloride 5-nitrotetrazolate coordination polymer Cu3Cl(N4C-NO2)2, as well as mixtures of both. The reaction is controlled by the presence of seed crystals and transition metal compounds other than CuCl2. Cu3Cl(N4C-NO2)2 is obtained as a wine-red, air stable, water-insoluble, crystalline and highly sensitive explosive material with a greater crystal density, lower thermal stability and a higher sensitivity toward hydrolysis and shock than DBX-1. Efforts to obtain the stable and pure starting material are improved by crystallisation of NaNT as a tetrahydrate. Cu3Cl(N4C-NO2)2 and Na(H2O)4(NT) were characterised by single crystal and powder XRD, IR spectroscopy, magnetic and thermal measaurements, elemental analysis, particle size measurements, mass spectrometry, and by drop weight testing.

Four 3d-4f hetero-polymetallic complexes [Fe 2 Ln 2 ((OCH 2 ) 3 CR) 2 (O 2 C t Bu) 6 (H 2 O) 4 ] (where Ln = La ( 1 and 2 ) and Gd ( 3 and 4 ); and R = Me ( 1 and 3 ) and Et ( 2 and 4 )) are synthesized and analyzed using elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and SQUID magnetometry. Crystal structures are obtained for both methyl derivatives and show that the complexes are isostructural and adopt a defective dicubane topology. The four heavy metals are connected with two alkoxide bridges. These four precursors are used as single-source precursors to prepare rare-earth orthoferrite pervoskites of the form LnFeO 3 . Thermal decomposition in a ceramic boat in a tube furnace gives orthorhombic LnFeO 3 powders using optimized temperatures and decomposition times: LaFeO 3 formed at 650 °C over 30 min, whereas GdFeO 3 formed at 750 °C over 18 h. These materials are structurally characterized using powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray map spectroscopy, and SQUID magnetometry. EDX spectroscopy mapping reveals a homogeneous spatial distribution of elements for all four materials consistent with LnFeO 3 . Magnetic measurements on complexes 1 - 4 confirm the presence of weak antiferromagnetic coupling between the central Fe(III) ions of the clusters and negligible ferromagnetic interaction with peripheral Gd(III) ions in 3 and 4 . Zero-field-cooled and field-cooled measurements of magnetization of LaFeO 3 and GdFeO 3 in the solid-state suggest that both materials are ferromagnetic, and both materials show open magnetic hysteresis loops at 5 and 300 K, with M sat higher than previously reported for these nanomaterials. We conclude that this is a new and facile low temperature route to these important magnetic materials that is potentially universal, limited only by what metals can be programmed into the precursor complexes.

The synthesis, structures, and properties of [4]- and [3]-rotaxane complexes are reported where [2]-rotaxanes, formed from heterometallic {Cr 7 Ni} rings, are bound to a fluoride-centered {CrNi 2 } triangle. The compounds have been characterized by single-crystal X-ray diffraction and have the formulas [CrNi 2 (F)(O 2 C t Bu) 6 ]{( B H)[Cr 7 NiF 8 (O 2 C t Bu) 16 ]} 3 ( 3 ) and [CrNi 2 (F)(O 2 C t Bu) 6 (THF)]{( B H)[Cr 7 NiF 8 (O 2 C t Bu) 16 ]} 2 ( 4 ), where B = py-CH 2 CH 2 NHCH 2 C 6 H 4 SCH 3 . The [4]-rotaxane 3 is an isosceles triangle of three [2]-rotaxanes bound to the central triangle while the [3]-rotaxane 4 contains only two [2]-rotaxanes bound to the central triangle. Studies of the behavior of 3 and 4 in solution by small-angle X-ray scattering and atomistic molecular dynamic simulations show that the structure of 3 is similar to that found in the crystal but that 4 has a different conformation to the crystal. Continuous wave and pulsed electron paramagnetic resonance spectroscopy was used to study the structures present and demonstrate that in frozen solutions (at 5 K) 4 forms more extended molecules than 3 and with a wider range of conformations.