A new chain complex is reported, containing ten CrIII and four NiII paramagnetic centres. The structure is terminated by NiII ions bound to 1,4,7,10-tetrazaacyclododecane (cyclen) with the chain forming through Cr...Ni and Cr...Cr edges bridged by fluoride and pivalate ligands. At the centre of the chain are two NiII sites bridged by oxalate (ox) giving a chain of formula [{Ni(cyclen)}2Cr10Ni2(ox)F14(O2CtBu)22]. The oxalate appears to have formed in situ from atmospheric CO2. Magnetic and EPR studies suggest either an S = 1 ground state with significant zero-field splitting or an S = 0 ground state with a low-lying S = 1 excited state.

Carbon–carbon (C–C) coupling reactions are fundamental transformations in modern synthetic chemistry that are traditionally dominated by platinum group metal (PGM) catalysts. The scarcity, cost and toxicity of PGMs have inspired the quest for more sustainable alternatives. Alkaline earth (AE) metals have attracted a lot of interest due to their high earth abundance, though their applications in CC coupling reactions remain underdeveloped as a result of the limited redox chemistry of these metals. AE-electrides could offer a new strategy to fully unlock AE-mediated C–C coupling, owing to their higher accessibility with respect to low oxidation state complexes, and strong reducing power. Here we show how the pseudo-linear barium amidinate complex [Ba(L)2] (1-Ba, L = {C(Cy)(NDipp)2}–, Dipp = 2,6-diisopropylphenyl, Cy = cyclohexyl) was converted into the room-temperature-stable electride (RoSE) {K2[Ba(L)2]∙2e–} (2) via mechanochemical methods. The formation of an electride was confirmed via pulsed EPR studies that reveal magnetic communication between anionic electrons and ligand and metal spin-active nuclei (1H, 14N and 135,137Ba). Compound 2 activates arenes and performs

A new heterometallic ring, [Me4N][(Me4N)2Cr5Ni3F8(BTFB)16] (BTFB = 3,5-bis(trifluoromethyl)benzoate) is reported, templated about tetramethylammonium (Me4N)+. This ring features five Cr(III) centers and three Ni(II) centers at the vertices of an octagon. Each edge of the octagon is bridged by internal fluoride and two external BTFB ligands. In the crystal structure, two of the three ammonium cations are at the center of the octagonal ring, while the third cation is outside. X-ray single crystal diffraction does not distinguish between five possible isomers, but a single isomer, with nickel sites at the 1, 3, and 6 positions of the octagon, can be deduced by a combination of collision-induced dissociation mass spectrometry (CID-MS), and EPR spectroscopy and magnetometry, which show a ground state spin of 1/2. The same reaction carried out with cobalt(II) or zinc(II) in place of nickel(II) leads to ordered [(Me4N)2Cr6M2F8(BTFB)16] (M = Co or Zn) in which the divalent metals are placed at the 1,5-positions in the metal octagon.

Electron Paramagnetic Resonance (EPR) spectroscopy is a cornerstone analytical technique in the physical and life sciences. The UK’s EPSRC-funded National Research Facility for EPR Spectroscopy (EPR NRF) at The University of Manchester supports national academic and industrial users, yet the environmental sustainability of such high-throughput, energy-intensive research infrastructures remains largely unassessed. This study includes a first-of-it-kind cradle-to-grave life cycle assessment (LCA), using the eighteen environmental impact indicators from ReCiPe 2016, to quantify the environmental impacts of NRF operations. Inventory data covers material and energy consumption, cryogen use, waste generation, and travel by staff. Results show that impacts are dominated by the operational phase, with higher-frequency spectrometer platforms driving substantially greater electricity demand and material-intensive components, such as magnet power supplies, identified as key hotspots. Embedding life cycle thinking within facility management demonstrates how sustainability principles can align technical performance with environmental responsibility. The approach provides a replicable model for other large-scale laboratories, contributing to the decarbonisation and circularisation of research infrastructures through collaboration with instrument manufacturers and the wider EPR community. To further enhance sustainability performance, potentially three circularity-oriented interventions are going to be implemented as the project develops: retrofitting obsolete cryogenic systems to extend service life and reduce embodied emissions, enabling remote monitoring and automation to minimise travel and equipment standby losses, and adopting robotic sample handling to enhance experimental throughput and resource efficiency.

ABSTRACT A new heterometallic ring, [Me 4 N][(Me 4 N) 2 Cr 5 Ni 3 F 8 (BTFB) 16 ] (BTFB = 3,5‐bis(trifluoromethyl)benzoate) is reported, templated about tetramethylammonium (Me 4 N) + . This ring features five Cr(III) centers and three Ni(II) centers at the vertices of an octagon. Each edge of the octagon is bridged by internal fluoride and two external BTFB ligands. In the crystal structure, two of the three ammonium cations are at the center of the octagonal ring, while the third cation is outside. X‐ray single crystal diffraction does not distinguish between five possible isomers, but a single isomer, with nickel sites at the 1, 3, and 6 positions of the octagon, can be deduced by a combination of collision‐induced dissociation mass spectrometry (CID‐MS), and EPR spectroscopy and magnetometry, which show a ground state spin of 1 / 2 . The same reaction carried out with cobalt(II) or zinc(II) in place of nickel(II) leads to ordered [(Me 4 N) 2 Cr 6 M 2 F 8 (BTFB) 16 ] (M = Co or Zn) in which the divalent metals are placed at the 1,5‐positions in the metal octagon.

Lanthanide complexes continue to gain significant interest in molecular quantum science due to their rich electronic structures, which can be engineered to support protected spin states relevant for quantum technologies. Carefully tailored ligand fields can give rise to avoided level crossings between crystal-field perturbed states, which may reduce sensitivity to magnetic field fluctuations. Motivated by this, we investigate an axially compressed pseudo-D6h symmetry air-stable macrocyclic Tb(III) complex [TbIII(LN6)(Ph3SiO)2]+ using ab initio calculations, magnetic and EPR measurements. The axially compressed, pseudo-D6h symmetry imposes a ground state that is predominantly composed of mJ = ±6 for the oblate J = 6 Tb(III) ion, with small admixtures from lower |mJ⟩ components. We investigate the hexagonal vs nonhexagonal transverse crystal field contributions to the tunneling gap, calculating different models by selecting from the ab initio crystal field parameters. Our calculations predict a small tunneling gap, ≈1 GHz, and we test this prediction experimentally using multifrequency EPR on La(III)-diluted powder samples. Our EPR results are consistent with the possibility of a low-energy (several GHz) tunneling gap. The Gd(III) analog [GdIII(LN6)(Ph3SiO)2]+ provides an orbital-quenched comparison, and its magnetic data and EPR spectra are well described using the axial zero-field splitting parameter D, demonstrating experimentally the largely axial ligand field in this pseudo-D6h environment.

Three heterometallic rings, [Pr2NH2][(Pr2NH2)Cr6IIIM2IIF8(BTFB)16] (M is Ni, Co, or Zn, BTFBH = 3,5-bis(trifluoromethyl)benzoic acid) are reported, templated about a di-n-propylammonium cation. The ring contains six Cr(III) ions and two M(II) ions at the corners of an octagon, with the divalent metal ions disordered around the ring. Each edge of the octagon is bridged by a fluoride and two bridging BTFB- ligands. One of the two ammonium cations in the crystal structure is located at the center of the octagonal ring, and the other outside the ring. Two divalent metals in the ring lead to the presence of isomers, which can be seen in the magnetic and EPR studies for MII = Ni or Zn, and 19F-NMR spectra for MII = Co. The data are interpreted as resulting from an approximately 50:50 mixture of isomers, where the divalent ions are at the 1,5 and 1,2 positions in the ring. A different reaction was pursued, which gave [(Pr2NH2)][Cr7IIIMIIF8(BTFB)16] rings; these could not be fully characterized by crystallography but their formation is confirmed by elemental analysis, mass spectrometry, NMR spectroscopy (for M = Co), magnetic studies, and EPR spectroscopy (for M = Ni, Zn).

Quantum-confined nanoclusters can be described by the jellium model, which emphasizes closed-shell electron configurations, but an open-shell variation with jellium aromaticity has been proposed. Such clusters are termed superatoms because they behave like an atom, and they exhibit unusual properties. Superatoms feature metal-metal bonding; hence, since their discovery 40 years ago, superatoms have exclusively involved main group or transition metals, with actinides only considered computationally as dopants owing to actinide-actinide bonding being exceedingly rare. Here we report trithorium nanoclusters exhibiting three-centre-one-electron actinide-actinide bonding. Experimental and computational analysis demonstrates Robin-Day Class III 6d-orbital valence delocalization in these clusters. These S = 1/2 clusters are paramagnetic, but in external applied magnetic fields they exhibit exalted diamagnetism, evidencing actinide open-shell jellium aromaticity superatom character. Exalted diamagnetism is not normally associated with a single unpaired electron, but with a 1S1 magic number, the valence delocalization enables exalted diamagnetism, which is aromaticity, via superatom ring currents.

This study identifies a distinct free radical signature in a D. melanogaster model of Parkinson’s Disease, successfully differentiating Pink1-deficient flies from wild-type controls. This insight was achieved using a robust quantum sensing methodology for the selective detection of free radicals in biological systems. Our approach utilizes optically detected magnetic resonance (ODMR) and magnetic modulation (MM) protocols with nanodiamond nitrogen-vacancy (NV) centres. Selective identification is achieved using the spin probe TEMPOL, a cell-permeable superoxide dismutase 2 (SOD2) mimic that initially quenches the photoluminescence signal. Upon scavenging free radicals like hydroxyl and superoxide, TEMPOL is converted to a diamagnetic adduct, restoring the contrast and thus enabling quantitative detection. The approach was first validated in a chemical system with radical generation confirmed by electron paramagnetic resonance (EPR) spectroscopy. It was then demonstrated across biological scales, from isolated mitochondria and whole glioblastoma cells to the Drosophila model. In these studies, high-resolution respirometry revealed distinct free radical signatures, and findings were compared with NV T1 relaxometry. This work provides new biophysical insight into mitochondrial dysfunction, demonstrating a distinct free radical signature in a neurodegeneration model and connecting it to specific metabolic states. ### Competing Interest Statement The authors have declared no competing interest. Royal Academy of Engineering, CiET-2223-102 European Research Council, 683108 Biotechnology and Biological Sciences Research Council, https://ror.org/00cwqg982, BB/T012226/1 Engineering and Physical Sciences Research Council, EP/W012226/1, EP/S033181/1, EP/V035231/1, EP/X034623/1

Herein we present a series of room-temperature stable, structurally analogous rare-earth complexes of the form [M(NHAriPr6)2] (M = Sc, Y, La, Sm, Eu, Tm, Yb; NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}). All seven complexes contain formal M(II) ions with close M···arene contacts. The Sc(II) and La(II) complexes display an open-book deformation (ca. 11–13°) of one metal-bound arene, while for Y(II) there are two symmetry-equivalent Y···arene interactions with smaller deformations (ca. 7°). In the case of Sc(II), Y(II), and La(II), quantum chemical calculations reveal the delocalization of a metal d-electron from M(II) into ligand π-orbitals forming δ-bonding interactions. In the case of Y(II), EPR and UV-Vis-NIR spectroscopies combined with quantum chemical calculations show a structural change in solution to the single-open-book deformation structure in common with Sc(II) and La(II). While the Sm(II), Eu(II), Tm(II), and Yb(II) complexes retain similar close M···arene contacts, their 4fn+1 valence electron configurations do not lead to δ-bonding interactions; however, NMR studies of diamagnetic 4f14 Yb(II) reveal 171Yb···1H coupling to arene ring-protons at room temperature and show that the M···arene interaction is preserved in solution across a wide temperature range. These complexes represent a rare structurally analogous M(II) series which extends from the group 3 elements into the lanthanide series and includes an extremely rare neutral formal Sc(II) complex.

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When studying hazardous materials such as spent nuclear fuel (SNF), the minimisation of sample volumes is essential, together with the use of chemically-similar surrogates where possible. For example, the bulk behaviour of urania (UO2) can be mimicked by appropriately-engineered thin films of sufficient thickness, and inactive materials such as ceria (CeO2) can be used to study the effects within radioactive systems used to fuel nuclear fission. However, thin film properties are sensitive to the preparative method, many of which require the use of highly toxic precursors and specialised apparatus (e.g., chemical vapour deposition). To address this, we present the development of a flexible, tuneable, scalable method for the preparation of thin-film CeO2 SIMFUEL models with a thickness of ≈5 μm. The effects of γ irradiation (up to 100 kGy) and dopants including trivalent lanthanides (Ln3+) and simulant ε-particles on the structure and long-term leaching of these systems under SNF storage conditions were explored, alongside the context of this within further work. It was found that the sensitivity of CeO2 films to reduction upon irradiation, particularly in the presence of simulant ε-particles, resulted in increased leaching of Ce (as CeIII), while trivalent lanthanides (Nd3+ and Eu3+) had a minimal effect on Ce leaching.

Although several Run+ (n = 2 or 3) complexes have been reported to be excellent biomimetics for the water oxidation process of photosystem II, investigation and spectroscopic characterization of the reactive intermediates such as [Ru-IV/V & boxH;O](n+) involved in the catalytic process are not only scarce but also a daunting task. Here, we report a catalyst [Ru-III(L)(PPh3)(H2O)](+) (2) found to show electrochemical water oxidation efficiency with a considerably low overpotential of 195 mV compared to other Run+ water oxidation catalysts reported in the nonaqueous media. Besides, the Schiff base ligand (L) employed in this study facilitates the stabilization of a [LRuV & boxH;O](+) species. By the use of multispectroscopic techniques (spectroelectrochemistry, electron paramagnetic resonance, and resonance Raman), we have shed light on the electronic structure of the elusive [LRuV & boxH;O](+) species. Based on the experimental results, a plausible intermolecular radical coupling (I2M) mechanism is proposed, which is corroborated by theoretical calculations.

Landmark advances in rare earth (RE) chemistry have shown that divalent complexes can be isolated with non-Aufbau 4f n {5d/6s}1 electron configurations, facilitating remarkable bonding motifs and magnetic properties. We report a series of divalent bis-tethered arene complexes, [RE(NHAriPr6 )2] (2RE; RE = Sc, Y, La, Sm, Eu, Tm, Yb; NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}). Fluid solution EPR spectroscopy gives g iso < 2.002 for 2Sc, 2Y, and 2La, consistent with formal nd1 configurations, calculations reveal metal-arene δ-bonding via mixing of nd(x 2-y 2) valence electrons into arene π* orbitals. Experimental and calculated EPR and UV-Vis-NIR spectroscopic properties for 2Y show that minor structural changes markedly alter the metal d(x 2-y 2) contribution to the SOMO. This contrasts 4f n {5d/6s}1 complexes where the valence d-based electron resides in a non-bonding orbital. Complexes 2Sm, 2Eu, 2Tm, and 2Yb contain highly-localised 4f n+1 ions with no appreciable metal-arene bonding by density functional calculations. These results show that the physicochemical properties of divalent rare earth arene complexes with both formal nd1 and 4f n+1 configurations are nuanced, may be controlled through ligand modification, and require a multi-pronged experimental and theoretical approach to fully rationalise.

During the last decade, there has been an increasing interest in the rationalisation of how structural changes stabilise (or destabilise) diradical systems. Demonstrated herein is that indolocarbazole (ICz) diradicals, substituted with dicyanomethylene (DCM) groups, are useful motifs for dynamic covalent chemistry by self-assembling from isolated monomers to cyclophane structures. The comparison of ICz-based systems substituted with DCM groups in para- or meta-positions (p-ICz-CN and m-ICz-CN) and their short-chain carbazole analogues (p-Cz-CN and m-Cz-CN) may identify new potential design strategies for stimuli-responsive materials. The principal objectives of this investigation are the elucidation of (i) the connection between diradical character and the cyclophane stability, (ii) the spatial disposition of the cyclophane structures, (iii) the monomer/cyclophane interconversion both in solution and solid state in response to external stimuli and (iv) the impact that the different pi-conjugation and electronic communication between the DCM terminals exerts on the electronic adsorption of the diradicals and their redox behavior. The spontaneous nature of the cyclophane structure is supported by the negative relative Gibbs free energies calculated at 298 K and experimentally by UV-Vis and Raman spectroscopy of the initial yellow solid powder. The conversion to monomeric species having diradical character was demonstrated by variable-temperature (VT) EPR, UV-Vis, Raman and IR measurements, resulting in appreciable chromic changes. In addition, electrochemical oxidation and reduction convert the cyclophane dimer (m-ICz-CN)2 to the monomer monocations and dianions, respectively. This research demonstrates how the chemical reactivity and physical properties of pi-conjugated diradicals can be effectively tuned by subtle changes in their chemical structures.

The magnetic properties of a 2D layered material consisting of high-spin Co2+ complexes, [Co(NH3NH2)(2)(H2O)(2)Cl-2]Cl-2 (CoHyd(2)Cl(4)), have been extensively characterized using electron paramagnetic resonance, magnetic susceptibility, and low-temperature heat capacity measurements. Electron paramagnetic resonance spectroscopy studies suggest that below 50 K, the J = 3/2 orbital triplet state of Co is gradually depopulated in favor of the J = 1/2 spin state, which is dominant below 20 K. In light of this, the magnetic susceptibility has been fitted with a two-level model, indicating that the interactions in this material are much weaker than previously thought. This two-level model is unable to fit the data at low temperatures and, combined with electron paramagnetic resonance spectroscopy, suggests that ferromagnetic interactions between Co2+ cations in the J = 1/2 state become significant approaching 2 K. Heat capacity measurements suggest the emergence of a long-range ordered state below 246 mK, which neutron diffraction confirms to be ferromagnetic.

A new calcium-based Room temperature Stable Electride (RoSE), K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] (2), is successfully synthesized from the reaction of a calcium tris-amide, [Ca{N(Mes)(SiMe3)}3K] (1) (Mes = 2,4,6-trimethylphenyl), with potassium under mechanochemical treatment. The dimeric structure of K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] is calculated using ab initio random structure searching (AIRSS) methods. This shows the existence of highly localized anionic electrons (e-) and suggests poor electrical conductance, as confirmed via electroconductivity measurements. The two anionic electrons in 2 are strongly antiferromagnetically coupled, thus in agreement with the largely diamagnetic response from magnetometry. Reaction of 2 with pyridine affords 4,4'-bipyridine, while reaction with benzene gives C-H activation and formation of a calcium hydride complex, [K(η6-C6H6)4][{Ca[N(Mes)(SiMe3)](H)}2K3] (3). Computational DFT analysis reveals the crucial role played by the ligand framework in the stabilization of this new Ca-hydride complex.

Landmark advances in rare earth (RE) chemistry have shown that formally divalent complexes can be isolated with non-Aufbau 4fn5d(dz2)1 or 4fn{5d/6s}1 electron configurations, which facilitate novel bonding motifs and phenomenal magnetic properties. We report an unprecedented series of divalent bis-tethered arene complexes, [RE(NHAriPr6)2] (2RE; RE = Sc, Y, La, Sm, Eu, Tm, Yb; NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}), where 2Sc, 2Y, and 2La show metal-arene δ-bonding via nd(x2-y2)- and π* orbital mixing, while 2Sm, 2Eu, 2Tm, and 2Yb contain 4fn+1 ions without δ-bonds. Fluid solution EPR spectroscopy gives giso = 1.9995, 1.998, 1.989 for 2Sc, 2Y, and 2La, respectively, consistent with formal nd1 configurations, while metal hyperfine interactions suggest extensive delocalisation. Solution and crystalline phase EPR and UV-Vis-NIR spectroscopy for 2Y show incongruities due to minor structural changes between these phases that markedly alter the metal 4d(x2-y2) character to the SOMO (22% vs 12%, respectively). In contrast to existing 4fn5d(dz2)1 or 4fn{5d/6s}1 complexes where the valence d-based electron resides in a non-bonding orbital, the sensitivity of 2Y to its local environment suggests RE(II) arene δ-bonding represents a hitherto unexplored opportunity to tune the electronic structure properties of nd1 rare earth ions.

Metal–Organic Framework (MOF)-derived TiO2, synthesised through the calcination of MIL-125-NH2, is investigated for its potential as a CO2 photoreduction catalyst. The effect of the reaction parameters: irradiance, temperature and partial pressure of water was investigated. Using a two-level design of experiments, we were able to evaluate the influence of each parameter and their potential interactions on the reaction products, specifically the production of CO and CH4. It was found that, for the explored range, the only statistically significant parameter is temperature, with an increase in temperature being correlated to enhanced production of both CO and CH4. Over the range of experimental settings explored, the MOF-derived TiO2 displays high selectivity towards CO (98%), with only a small amount of CH4 (2%) being produced. This is notable when compared to other state-of-the-art TiO2 based CO2 photoreduction catalysts, which often showcase lower selectivity. The MOF-derived TiO2 was found to have a peak production rate of 8.9 × 10−4 μmol cm−2 h−1 (2.6 μmol g−1 h−1) and 2.6 × 10−5 μmol cm−2 h−1 (0.10 μmol g−1 h−1) for CO and CH4, respectively. A comparison is made to commercial TiO2, P25 (Degussa), which was shown to have a similar activity towards CO production, 3.4 × 10−3 μmol cm−2 h−1 (5.9 μmol g−1 h−1), but a lower selectivity preference for CO (3 : 1 CH4 : CO) than the MOF-derived TiO2 material developed here. This paper showcases the potential for MIL-125-NH2 derived TiO2 to be further developed as a highly selective CO2 photoreduction catalyst for CO production.

We report the synthesis and structural characterization of a series of heterometallic rings templated via alkylammonium or imidazolium cations. The template and preference of each metal's coordination geometry can control the structure of heterometallic compounds, leading to octa-, nona-, deca-, dodeca-, and tetradeca-metallic rings. The compounds were characterized by single-crystal X-ray diffraction, elemental analysis, magnetometry, and EPR measurements. Magnetic measurements show that the exchange coupling between metal centres is antiferromagnetic. EPR spectroscopy shows that the spectra of {Cr7Zn} and {Cr9Zn} have S = 3/2 ground states, while the spectra of {Cr12Zn2} and {Cr8Zn} are consistent with S = 1 and 2 excited states. The EPR spectra of {(ImidH)-Cr6Zn2}, {(1-MeImH)-Cr8Zn2}, and {(1,2-diMeImH)-Cr8Zn2} include a combination of linkage isomers. The results on these related compounds allow us to examine the transferability of magnetic parameters between compounds.