We herein demonstrate the synthesis of a pair of enantiomerically pure Yb complexes by post-functionalisation of the parent Yb complex condensation with an enantiomerically pure chiral amine. The enantiomeric pair is structurally characterised by single crystal and powder X-ray diffraction, showing that it crystalises in the 222 Sohncke space group with Flack parameters close to zero, which confirms their enantiopurity. Circular Dichroism (CD) and absorption spectroscopies in the NIR reveal sharp F → F f-f transitions, with values up to 0.07, indicating a chiral environment for the ytterbium centre. Furthermore, a dynamic mechanism with mixing of ligand states is shown to contribute to the CD intensity. X-band pulse Electron Paramagnetic Resonance spectroscopy, on a magnetically dilute single crystal containing 1% of Yb complexes within the isostructural Y diamagnetic host, reveals a phase memory time, , of the electronic spin of 600 ns and that it can be coherently manipulated by microwave pulses, as evidenced by Rabi nutations.

The design of -platinum(ii) complexes marked a significant turning point in the development of unconventional anticancer metallodrugs. Compared to cisplatin, these complexes induce distinctly different cellular responses and are often active against cisplatin-resistant cell lines. In this study, we synthesized and fully characterized two new Pt(ii) complexes, introducing one acetate (OCOCH) ligand (x) into the -PtXX' axis, where X' is either acetate or chlorido. We evaluated their cytotoxicity across a panel of malignant (Capan-1, B16, MCF7, HCT-116, CT26 and P31) and non-malignant (HaCaT, HUVEC, BEC, and MCF10A) cell lines, finding that the complex with only one acetate to a chlorido group is more active and selective than the complex with two acetates (X = X'). Furthermore, the two complexes differ from cisplatin in their cellular uptake route as well as mode of action by inducing cancer cell death non-DNA-associated mechanisms.

The -1,2-CBH carborane is a recognized 3D aromatic icosahedral building block, with an electron distribution governed by the outer hydridic BH and acidic CH vertices. We attached the carborane cage to a peptidomimetic scaffold to generate an active-site inhibitor of SmCB1, a protease drug target in the Schistosoma pathogen. The carborane-tagged compound exhibited superior inhibitor affinity and bioactivity compared to its conventional 2D aromatic phenyl analog. Quantum mechanical computations, based on the crystal structure of the protease-inhibitor complex, revealed that the carborane tag contributed to inhibitor binding not only through nonpolar interactions but also a key hydrogen bond between its CH vertex and a negatively charged residue in the binding site. This interaction, driven by the large dipole moment of the carborane cage, resulted in a more favorable energy contribution than that of the phenyl group in the 2D analog. The carborane pharmacophore boosted affinity for SmCB1 and conferred specific anti-schistosomal activity, highlighting its potential in protein ligand design.

A strategy for the development of new vanadium-based drugs is the preparation of complexes that target proteins and bear molecules involved in the cellular metabolism as ligands, like α-hydroxycarboxylic acids. Based on these premises, this study explores the solution behaviour of the dioxidovanadium(V) complex of malic acid, Cs[V O(mal)]·2HO, and its interaction with the model protein lysozyme (HEWL) at room and at physiological temperature using V nuclear magnetic resonance (NMR), electrospray ionisation-mass spectrometry (ESI-MS) and X-ray crystallography. The results show the coexistence in aqueous solution of various molecular species containing two or ten V centres. In solution these species are formed regardless of the presence of HEWL, while at 37 °C the formation of [V O] (V) is precluded when the protein is present. Crystallographic data reveal that, when protein crystals are incubated with the V compound at room temperature (25 °C) and at pH 4.0, [VO], [V O(mal)], [V O] and [V O] are bound to the protein, while at 37 °C, under the same conditions, only [VO] interacts with HEWL. [V O] can bind the protein both covalently (as [V O] ion) and non-covalently. Whereas the transformation of [V O(mal)] to [V O(mal)] is expected on the basis of thermodynamic considerations, the formation of V and of the V-HEWL adduct is not easily predictable. Docking calculations confirm the experimental results and highlight the role of protein-protein interaction in the stabilization of the revealed adduct. This study demonstrates that vanadium compounds can undergo transformation in solution, giving rise to species that interact with proteins through several binding modes and stabilization mechanisms.

Metal-organic frameworks (MOFs) are a versatile class of porous coordination materials that have found widespread application in various fields, particularly as heterogeneous catalysts. Due to the modular nature and molecular tunability of the metal node-linker coordination in MOFs, they are considered competent hosts for secondary materials in their extensive pore channels. Modifications of the metal nodes or ligand functionalisation in MOFs can improve the anchoring ability of nanoparticles, effectively enhance the nanoparticles' stability, and mitigate the inherent nature of nanoparticles to aggregate. In this review, the synthetic strategies ("ship-in bottle", "bottle-around-ship", and one-pot) and novel characterisation techniques of nanoparticle-MOF (NP-MOF) composites are discussed in detail. The precise determination of nanoparticle-MOF coordination is crucial to shed light on the structure-activity relationships of the catalytic composites. Recognising the synergistic properties of MOFs and metallic nanoparticles, we also explore recent advancements in NP-MOF composites with a special focus on zirconium-based MOFs for catalytic applications within the last five years. Therefore, we aim to aid the reader in evaluating the up-to-date and state-of-the-art advancements concerning the chemistry of nanoparticles and MOFs as catalysts, acting as a path for future learning and optimisations.

Lanthanide chelates and copper-free 'click' chemistry have important uses for targeted molecular imaging and therapeutic strategies. Herein, we report the complexation of lanthanides to a tetrazine-functionalised DO3A macrocyclic chelator and the tetrazine-TCO ligation between the lanthanide(DO3A-tetrazine) complexes and a TCO-PEG-functionalised rhodamine as a model agent. The luminescent and magnetic properties of the resultant dual-modal conjugates are described. The tetrazine moiety was found to sensitise terbium luminescence, resulting in a 'turn-off' effect upon its transformation to the dihydropyridazine linker, with the rhodamine moiety then dominating the fluorescence emissions. The relaxivities of Gd(DO3A-tetrazine) and Gd(DO3A-PEG-rhodamine) were found to be similar to [Gd(DOTA)] (Dotarem®). As a proof-of-concept test, the click conjugates were delivered to mice brains using the combination of focused ultrasound and microbubbles, with neuron uptake of the probes observed.

Here we report on one-dimensional nano objects of formula [Yb(hfac)(-or -Ant-C8)] where the Ant-C8 moiety refers to enantiopure - and -twistacenes decorated at positions 2,6 with 4-pyridyl-ethynyl units and helically locked into an end-to-end twist by an octyl tether. The crystal structure analysis reveals intertwined 1D nano-chains featuring two crystallographically independent Yb(iii) ions. Under applied magnetic fields these systems show slow relaxation of the magnetization. The optical properties show the expected contributions of the F ← F electronic transition of the Yb(iii) ions split by the crystal field. Magnetic field and temperature dependent Magneto-Chiral Dichroism (MChD) studies reveal contributions of opposite sign and similar intensity for the two crystallographically independent ions that cancel out for the 0-0' and 0-2' absorptions but not for the 0-1'. These findings, supported by theoretical calculations, demonstrate the important role of the structural arrangement of MChD-active ions when designing chiral magneto-optical materials responsive to light and magnetic fields.

Mass cytometry with antibodies labelled with stable metal isotopes enables both sensitive imaging and the quantification of protein expression in biological samples. Typically, these specimens are exposed to a panel of labelled antibodies , after sample collection. Here, we have developed a rhodium-labelled immunoconjugate of the HER2-targeted therapeutic IgG1 antibody, trastuzumab, and evaluated its biodistribution using mass cytometry techniques. A Rh complex of a macrobicyclic sarcophagine (sar, 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) chelator was appended with a dibromopyridazinedione (DBPD), to produce a novel disulfide bond labelling molecule, "Rh-sar-DBPD". Rh-sar-DBPD was site-specifically conjugated to trastuzumab its four native solvent-accessible disulfide bonds, to yield a near homogeneous, well-defined and stable pyridazinedione (PD) immunoconjugate, Rh-sar-PD-trastuzumab, in which four Rh-sar-PD groups were attached per molecule of trastuzumab. Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were then applied to measure Rh content, as a proxy for Rh-sar-PD-trastuzumab accumulation, in and studies. ICP-MS studies indicated HER2-mediated uptake of Rh-sar-PD-trastuzumab in HER2-expressing breast cancer cells, with LA-ICP-MS images showing intercellular heterogeneity in Rh-sar-PD-trastuzumab uptake. To study the biodistribution of Rh-sar-PD-trastuzumab, female NSG mice bearing orthotopic HCC1954 breast cancer tumours were administered the immunoconjugate. Quantitative ICP-MS of Rh signal in dissected tissues indicated receptor-specific HER2-mediated uptake in tumours, as well as accumulation in the spleen and liver. Finally, LA-ICP-MS imaging analysis of tumour and ovary tissue sections showed heterogeneous uptake in HER2-expressing HCC1954 tumour cells and follicular granulosa cells of the ovaries, which are known to express growth factor receptors. To the best of our knowledge, this is the first report in which both ICP-MS and LA-ICP-MS have been used on tissue exposed to a metal-tagged antibody , enabling quantification of the biodistribution of the novel immunoconjugate, Rh-sar-PD-trastuzumab, in a murine model of breast cancer.

The anticancer platinum complex oxaliplatin exerts its activity through DNA damage and immune-stimulatory mechanisms, but is associated with adverse treatment side effects. Platinum(iv) complexes represent a promising prodrug strategy to improve tolerability and to enhance antitumor efficacy attachment of additional bioactive ligands or tumor-targeting moieties. In the present study, oxaliplatin(iv) complexes containing immune-stimulatory STING agonists SR-717 or MSA-2 were synthesized and their biological properties were studied. Whereas the Pt-SR-717 compound was fast reduced, Pt-MSA-2 complexes displayed significantly higher reductive stability reflected by low cytotoxicity. Although the platinum(iv) complexes activated interferon regulatory factor (IRF) and NF-κB signaling pathways less effectively compared to the free STING agonists, reducing conditions elevated cytotoxicity and STING downstream signaling, particularly for MSA-2-containing prodrugs. Rapid albumin binding of a maleimide-containing Pt-MSA-2 derivative resulted in elevated plasma levels, prolonged blood circulation, and enhanced tumor accumulation of platinum in CT-26 tumor-bearing mice. The Pt-MSA-2 complexes triggered immune activation and cytokine secretion without hematotoxicity usually associated with free oxaliplatin. The albumin-targeted Pt-MSA-2 drug significantly inhibited tumor growth after intravenous application, while the non-maleimide complex was effective only when applied peritumorally. However, the effects were not enhanced compared to mono-treatment with oxaliplatin or MSA-2, indicating a lack of synergism between the two simultaneously released agents. Our results demonstrate that oxaliplatin(iv) complexes represent a valuable strategy for enhanced tumor-targeting and adverse effect reduction, but question the simultaneous release of STING agonists and free oxaliplatin as a potent strategy towards synergistic antineoplastic activity.

We report the synthesis of dianionic OCO-supported NHC and MIC complexes of molybdenum and tungsten with the general formula (OCO)MO (OCO = bis-phenolate benzimidazolylidene M = Mo (1-Mo), bis-phenolate triazolylidene M = Mo (2-Mo), M = W (2-W) and bis-phenolate imidazolylidene, M = Mo (3-Mo), W (3-W)). These complexes are tested in the catalytic deoxygenation of nitroarenes using pinacol as a sacrificial oxygen atom acceptor/reducing agent to examine the influence of the carbene and the metal centre in this transformation. The results show that the molybdenum-based triazolylidene complex 2-Mo is by far the most active catalyst, and TOFs of up to 270 h are observed, while the tungsten analogues are basically inactive. Mechanistic studies suggest that the superiority of the triazolylidene-based complex 2-Mo is a result of a highly stable metal carbene bond, strongly exceeding the stability of the other NHC complexes 1-Mo and 3-Mo. This is proven by the structural isolation of a triazolylidene pinacolate complex (5-Mo) that can be thermally converted to a μ-oxodimolybdenum(V) complex 7-Mo. The latter complex is very oxophilic and stoichiometrically deoxygenates nitro- and nitrosoarenes at room temperature. In contrast, azoarenes are not reductively cleaved by 7-Mo, suggesting direct deoxygenation of the nitroarenes to the corresponding anilines with nitrosoarenes as intermediates. In summary, this work showcases the superior influence of MIC donors on the catalytic properties of early transition metal complexes.

Platinum chemotherapy is part of every second anticancer treatment regimen. However, its application is limited by severe side effects and drug resistance. The combination of platinum-based chemotherapeutics with EGFR inhibitors has shown remarkable synergism in clinical treatment. To enhance the tolerability of this combination, we designed a novel multi-action oxaliplatin-based platinum(iv) complex with an EGFR-inhibiting moiety (KP2749). KP2749 releases two independent cytotoxic agents upon reduction: oxaliplatin and the EGFR inhibitor KP2187, which was selected for its strong intrinsic fluorescence that became quenched upon complexation to metal ions. In particular, KP2749 demonstrated high stability and specific KP2187 release, with quenched fluorescent properties in its intact form, facilitating the investigation of its intracellular reduction. Notably, by exploiting its fluorescence, we demonstrated that intact KP2749 itself exhibited EGFR-inhibitory properties. Furthermore, subsequent experiments indicated that our complex was able to overcome resistance to oxaliplatin and EGFR inhibitors and in xenograft models . These effects were not only based on EGFR inhibition and DNA damage, but also improved cellular drug uptake. Finally, docking analysis confirmed that the intact KP2749 complex had EGFR-binding properties, which were different from free KP2187. Consequently, these data suggested that the coordination of EGFR inhibitors to metal cores (like platinum) allow the fine-tuning of their EGFR-targeting properties. In conclusion, this study not only presents a new potential anticancer drug but also offers a novel fluorescent tool to study the intracellular drug release kinetics of platinum(iv) complexes.

Phenylacetylene is a detrimental impurity in the polymerisation of styrene, capable of poisoning catalysts even at ppm levels and significantly degrading the quality of polystyrene. The semi-hydrogenation of phenylacetylene to styrene instead of ethylbenzene is, therefore, an important industrial process. We report a novel cerium(iv)-based metal-organic framework (denoted as Ce-bptc), which comprises {Ce} clusters bridged by biphenyl-3,3',5,5'-tetracarboxylate linkers. Ce-bptc serves as an ideal support for palladium nanoparticles and the Pd@Ce-bptc catalyst demonstrates excellent catalytic performance for semi-hydrogenation of phenylacetylene, achieving a selectivity of 93% towards styrene on full conversion under ambient conditions with excellent reusability. synchrotron X-ray powder diffraction and electron paramagnetic resonance spectroscopy reveal the binding domains of phenylacetylene within Ce-bptc, and details of the reaction mechanism are discussed.

Organoiridium picolinamidate complexes are promising for intracellular applications because of their biocompatibility, activity in living systems, and ease of derivatization. To shield their metal centers from inhibition by biological nucleophiles (e.g., glutathione), attempts were made to increase the steric bulk of the supporting -(2,6-R-phenyl)picolinamidate ligand. It was found that when R = H () or methyl (), the ligand adopts -coordination to iridium, whereas when R = isopropyl () or phenyl (), ,-coordination was observed. Based on experimental measurements and density functional theory calculations, it was revealed that the carbon chemical shift of the C(O)NR group can be used as a diagnostic handle to distinguish between the - and ,-isomers in solution. Computational studies indicate that the former is favored thermodynamically but the latter is preferred when the R group is overly bulky. Complexes - exhibit differences in lipophilicity, cellular uptake, cytotoxicity, and the propensity to generate reactive oxygen species in living cells. Reaction studies showed that / are more efficient than / in promoting the reduction of aldehydes to alcohols via transfer hydrogenation but both isomer types were susceptible to catalyst poisoning by glutathione. This work has led to new insights into structural isomerism in organoiridium picolinamidate complexes and suggests that steric tuning alone is insufficient to protect the Ir center from poisoning by biological nucleophiles.

By reacting a 3,6-ditriazolyl-2,5-dihydroxybenzoquinone (HtrzAn) anilato linker with Ln ions (Ln = Dy, Tb, Ho), two different series of polymorphs, formulated as [Ln(trzAn)(HO)] ·10HO (Dy, 1a; Tb, 2a, Ho, 3a) and [Ln(trzAn)(HO)] ·7HO (Dy, 1b, Tb, 2b, Ho, 3b) have been obtained. In these series the two Dy-coordination networks (1a and 1b) and the Tb-coordination polymer (2b) show a Single Ion Magnet (SIM) behavior. 1-3a MOFs show reversible structural flexibility upon removal of a coordinated water molecule from a distorted hexagonal 2D framework to a distorted 3,6-brickwall rectangular 3D structure in [Ln(trzAn)(HO)] ·2HO (Dy, 1a_des; Tb, 2a_des, Ho, 3a_des) involving shrinkage/expansion of the hexagonal-rectangular networks. Noteworthy, 2b represents the first example of a Tb-anilate-based coordination polymer showing SIM behaviour to date and the best SIM properties within the polymorphs. Theoretical investigation CASSCF calculations supports this behavior, since 2b shows less mixing between the states of the ground state among all the studied complexes.

The transmembrane protein known as the mitochondrial calcium uniporter (MCU) mediates the influx of calcium ions (Ca) into the mitochondrial matrix. An overload of mitochondrial Ca ( Ca) is directly linked to damaging effects in pathological conditions. Therefore, inhibitors of the MCU are important chemical biology tools and therapeutic agents. Here, two new analogues of previously reported Ru- and Os-based MCU inhibitors Ru265 and Os245, of the general formula [(CHCO)M(NH)(μ-N)M(NH)(OCCH)](CFSO), where M = Ru (1) or Os (2), are reported. These analogues bear adamantane functional groups, which were installed to act as guests for the host molecule cucurbit-[7]-uril (CB[7]). These complexes were characterized and analyzed for their efficiency as guests for CB[7]. As shown through a variety of spectroscopic techniques, each adamantane ligand is encapsulated into one CB[7], affording a supramolecular complex of 1 : 2 stoichiometry. The biological effects of these compounds in the presence and absence of two equiv. CB[7] were assessed. Both complexes 1 and 2 exhibit enhanced cellular uptake compared to the parent compounds Ru265 and Os245, and their uptake is increased further in the presence of CB[7]. Compared to Ru265 and Os245, 1 and 2 are less potent as Ca uptake inhibitors in permeabilized cell models. However, in intact cell systems, 1 and 2 inhibit the MCU at concentrations as low as 1 μM, marking an advantage over Ru265 and Os245 which require an order of magnitude higher doses for similar biological effects. The presence of CB[7] did not affect the inhibitory properties of 1 and 2. Experiments in primary cortical neurons showed that 1 and 2 can elicit protective effects against oxygen-glucose deprivation at lower doses than those required for Ru265 or Os245. At low concentrations, the protective effects of 1 were modulated by CB[7], suggesting that supramolecular complex formation can play a role in these biological conditions. The biocompatibility of 1 was investigated in mice. The intraperitoneal administration of these compounds and their CB[7] complexes led to time-dependent induction of seizures with no protective effects elicited by CB[7]. This work demonstrates the potential for supramolecular interactions in the development of MCU inhibitors.

Multifunctional optical materials can be realized by combining stimuli-responsive photoluminescence (PL), , optical thermometry, with non-linear optical (NLO) effects, such as second-harmonic generation (SHG). We report a novel approach towards SHG-active luminescent thermometers achieved by constructing unique iridium(iii) complexes, -[Ir(CN)(,-pinppy)] (,-pinppy = (,)-2-phenyl-4,5-pinenopyridine), bearing both a chiral 2-phenylpyridine derivative and cyanido ligands, the latter enabling the formation of a series of molecular materials: (TBA)[Ir(CN)(,-pinppy)]·2MeCN (1) (TBA = tetrabutylammonium) and (Bu-DABCO)[Ir(CN)(,-pinppy)](i)·MeCN (2) (Bu-DABCO = 1-(-butyl)-1,4-diazabicyclo-[2.2.2]octan-1-ium) hybrid salts, (TBA){[La(NO)(HO)][Ir(CN)(,-pinppy)]} (3) square molecules, and {[La(NO)(dmf)][Ir(CN)(,-pinppy)]}·MeCN (4) coordination chains. Thanks to the chiral pinene group, 1-4 crystallize in non-centrosymmetric space groups leading to SHG activity, while the N,C-coordination of ppy-type ligands to Ir(iii) centers generates visible charge-transfer (CT) photoluminescence. The PL characteristics are distinctly temperature-dependent which was utilized in achieving ratiometric optical thermometry below 220 K. The PL phenomena were rationalized by DFT/TD-DFT calculations indicating an MLCT-type of the emission in obtained Ir(iii) complexes with the rich vibronic structure providing a few emission bands that variously depend on temperature due to the role of thermally activated vibrations. As these crucial vibrational modes depend on the crystal lattice, the thermometry performance differs within 1-4 being the most efficient in 4 while the SHG is by far the best also for 4. This proves that pinene-functionalized cyclometalated dicyanidoiridates(iii) are great prerequisites for tunable PL-NLO conjunction with the most effective multifunctionality ensured by the insertion of these anions into bimetallic frameworks.

While platinum-based chemotherapeutic agents have established themselves as indispensable components of anticancer therapy, they are accompanied by a variety of side effects and the rapid occurrence of drug resistance. A promising strategy to address these challenges is the use of platinum(iv) prodrugs, which remain inert until they reach the tumor tissue, thereby mitigating detrimental effects on healthy cells. Typically, platinum drugs are part of combination therapy settings. Consequently, a very elegant strategy is the development of platinum(iv) prodrugs bearing a second, clinically relevant therapeutic in axial position. In the present study, we focused on gemcitabine as an approved antimetabolite, which is highly synergistic with platinum drugs. In addition, to increase plasma half-life and facilitate tumor-specific accumulation, an albumin-binding maleimide moiety was attached. Our investigations revealed that maleimide-cisplatin(iv)-gemcitabine complexes cannot carry sufficient amounts of gemcitabine to induce a significant effect . Consequently, we designed a carboplatin(iv) analog, that can be applied at much higher doses. Remarkably, this novel analog demonstrated impressive results, characterized by significant improvements in overall survival. Notably, these encouraging results could also be transferred to an xenograft model with acquired gemcitabine resistance, indicating the high potential of this approach.

Platinum-based fuel cell electrocatalysts are structured on a nano level in order to extend their active surface area and maximize the utilization of precious and scarce platinum. Their performance is dictated by the atomic arrangement of their surface layers atoms structure-property relationships. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) are the preferred methods for characterizing these catalysts, due to their capacity to achieve local atomic-level resolutions. Size, morphology, strain and local composition are just some of the properties of Pt-based nanostructures that can be obtained by (S)TEM. Furthermore, advanced methods of (S)TEM are able to provide insights into the quasi-, or even operando stability of these nanostructures. In this review, we present state-of-the-art applications of (S)TEM in the investigation and interpretation of structure-activity and structure-stability relationships.

We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)] as charge neutral electronic qubits based on vanadyl complexes ( = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CHCl/toluene solution, which evidence the usual hyperfine coupling with the V nucleus ( = 7/2) and an additional superhyperfine interaction with the = 1/2 nucleus of the Pt isotope (natural abundance 34%). DFT calculations ascribe the spin density delocalization on the Pt ion to a combination of π and pathways, with the former representing the predominant channel. Spin relaxation measurements in frozen CDCl/toluene- solution between 90 and 10 K yield values (1-6 μs in 1 and 2-11 μs in 2) which compare favorably with those of known vanadyl-based qubits in similar matrices. Coherent spin manipulations indeed prove possible at 70 K, as shown by the observation of Rabi oscillations in nutation experiments. The results indicate that the heavy Group 10 metal ion is not detrimental to the coherence properties of the vanadyl moiety and that Pt-VO lanterns can be used as robust spin-coherent building blocks in materials science and quantum technologies.

Design strategies for molecular thermometers by magnetic resonance are essential for enabling new noninvasive means of temperature mapping for disease diagnoses and treatments. Herein we demonstrate a new design strategy for thermometry based on chemical control of the vibrational partition function. To do so, we performed variable-temperature Co NMR investigations of four air-stable Co(iii) complexes: Co(accp) (1), Co(bzac) (2), Co(Bu-acac) (3), and Co(acac) (4) (accp = 2-acetylcyclopentanonate; bzac = benzoylacetonate; Bu-acac = 2,2,6,6-tetramethyl-3,5-heptanedionate and acac = acetylacetonate). We discovered Co chemical shift temperature sensitivity (Δ/Δ) values of 3.50(2), 3.39(3), 1.63(3), and 2.83(1) ppm °C for 1-4, respectively, at 100 mM concentration. The values observed for 1 and 2 are new records for sensitivity for low-spin Co(iii) complexes. We propose that the observed heightened sensitivities for 1 and 2 are intimately tied to the asymmetry of the accp and bzac ligands the acac and Bu-acac ligands, which enables a larger number of low-energy Raman-active vibrational modes to contribute to the observed Δ/Δ values.

Here we report the synthesis and structural characterization of four [7]rotaxanes formed by coordinating hybrid inorganic-organic [2]rotaxanes to a central {Ni} 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 {CrNi} rings, which have been proposed as qubits, are reduced but not dramatically by the presence of the {Ni} cage.