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Lanthanide luminescent complexes are active and thriving in various research fields due to their unique optical properties, while optical materials across a wide spectral range and with multiple functions in one were rarely reported. In this work, a new class of Ln 3+ /Al 3+ metallacrowns (MCs) were constructed with excellent luminescence properties in both the visible and near-infrared regions, and the elaborate luminescence modulation can be achieved by doping with different Ln 3+ ions. Strikingly, the powder of LnMC was developed as a luminescent nanomaterial for the detection of latent fingerprints (LFPs), and even the third level details of fingerprints can be clearly recognized, which provides a reference for the identification of fingerprints in the field of criminal investigation. More importantly, TbMC and Tb 0.1 Sm 0.9 MC can be successfully used as luminescent thermometers with sensitivities of 2.51% °C -1 and 2.33% °C -1 , respectively, higher than most reported values. Meanwhile, TbMC was developed as a luminescent probe for Fe 3+ and 2,6-pyridinedicarboxylic acid (DPA) with low limits of detection (LOD) of 0.51 μM and 4.26 μM, respectively, representing the first example of MC with luminescence sensing. Also of note is that SmMC, Tb 0.1 Sm 0.9 MC and TbMC can be functionalized as luminescent inks and films due to their clear recognizable colours in the visible range, suggesting a new strategy for high-level anti-counterfeiting. In short, the LnMC luminescent material has wide application prospects in many fields, especially rare for multifunctional applications of small-molecule complexes with non-metal-organic frameworks., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The unique electronic nature of the 1,2,4,5-tetrazine or s -tetrazine (tz) ring has sparked tremendous scientific interest over the last few years. Tetrazines have found numerous applications, and their ability to coordinate to metal ions has opened the possibility of exploring their chemistry in both molecular systems and extended networks. The rich redox chemistry of s -tetrazines allows them to exchange electrons and switch between their dihydro (H 2 tz), neutral (tz), and radical (tz˙ - ) forms. Previous reports in the literature have observed electrochemically that a second electron can potentially be stored in the tetrazinyl ring and form a dianionic species. However, due to its extremely reactive nature, this has not been isolated before. Herein, the combination of strictly anhydrous and inert conditions, strong reducing agents, non-acidic solvents and most importantly blocking the accessibility of the nitrogen atoms by coordinating them to lanthanide ions allowed for the stabilization of a dianionic tetrazine in a lanthanocene complex. Three dinuclear metallocene complexes are reported, [(Cp* 2 Ln) 2 (tz˙ - )(THF) 2 ](BPh 4 ) (Ln = Y (1-Y); Cp* = pentamethylcyclopentadienyl; THF = tetrahydrofuran) and [(Cp* 2 Ln) 2 (tz 2- )(THF) 2 ]·2THF (Ln = Gd (2-Gd), or Y (2-Y)), which utilize the unsubstituted tz as the ligand. In 1-Ln, the tz ligand is reduced to the radical anion (tz˙ - ), while in 2-Ln, the tz ligand is in the -2 charge state. These complexes are the first structurally and physically characterized complexes bearing the dianion radical of an s -tetrazine. Detailed structural analysis, ab initio calculations, and physical characterization support that the tz 2- ligand is a closed-shell planar dianion with unique structural features vastly different from those of the tz, tz˙ - and H 2 tz species., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Molecular systems known as single-molecule magnets (SMMs) exhibit magnet-like behaviour of slow relaxation of the magnetisation and magnetic hysteresis and have potential application in high-density memory storage or quantum computing. Often, their intrinsic magnetic properties are plagued by low-energy molecular vibrations that lead to phonon-induced relaxation processes, however, there is no straightforward synthetic approach for molecular systems that would lead to a small amount of low-energy vibrations and low phonon density of states at the spin-resonance energies. In this work, we apply knowledge accumulated over the last decade in molecular magnetism to nanoparticles, incorporating Er 3+ ions in an ultrasmall sub-3 nm diamagnetic NaYF 4 nanoparticle (NP) and probing the slow relaxation dynamics intrinsic to the Er 3+ ion. Furthermore, by increasing the doping concentration, we also investigate the role of intraparticle interactions within the NP. The knowledge gained from this study is anticipated to enable better design of magnetically high-performance molecular and bulk magnets for a wide variety of applications, such as molecular electronics., (© 2024. The Author(s).)

Single-ion anisotropy is vital for the observation of Single-Molecule Magnet (SMM) properties (i.e., a slow dynamics of the magnetization) in lanthanide-based systems. In the case of europium, the occurrence of this phenomenon has been inhibited by the spin and orbital quantum numbers that give way to J = 0 in the trivalent state and the half-filled population of the 4f orbitals in the divalent state. Herein, by optimizing the local crystal field of a quasi-linear bis(silylamido) Eu II complex, the [Eu II (N{SiMePh 2 } 2 ) 2 ] SMM is described, providing an example of a europium complex exhibiting slow relaxation of its magnetization. This behavior is dominated by a thermally activated (Orbach-like) mechanism, with an effective energy barrier of approximately 8 K, determined by bulk magnetometry and electron paramagnetic resonance. Ab initio calculations confirm second-order spin-orbit coupling effects lead to non-negligible axial magnetic anisotropy, splitting the ground state multiplet into four Kramers doublets, thereby allowing for the observation of an Orbach-like relaxation at low temperatures., (© 2024. The Author(s).)

In this perspective, we provide an overview of the recent achievements in luminescent lanthanide-based molecular cluster-aggregates (MCAs) and illustrate why MCAs can be seen as the next generation of highly efficient optical materials. MCAs are high nuclearity compounds composed of rigid multinuclear metal cores encapsulated by organic ligands. The combination of high nuclearity and molecular structure makes MCAs an ideal class of compounds that can unify the properties of traditional nanoparticles and small molecules. By bridging the gap between both domains, MCAs intrinsically retain unique features with tremendous impacts on their optical properties. Although homometallic luminescent MCAs have been extensively studied since the late 1990s, it was only recently that heterometallic luminescent MCAs were pioneered as tunable luminescent materials. These heterometallic systems have shown tremendous impacts in areas such as anti-counterfeiting materials, luminescent thermometry, and molecular upconversion, thus representing a new generation of lanthanide-based optical materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Addition of [UI 2 (THF) 3 (μ-OMe)] 2 ·THF ( 2 ·THF) to THF solutions containing 6 equiv. of K[C 14 H 10 ] generates the heteroleptic dimeric complexes [K(18-crown-6)(THF) 2 ] 2 [U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)] 2 ·4THF ( 118C6 ·4THF) and {[K(THF) 3 ][U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)]} 2 ( 1THF ) upon crystallization of the products in THF in the presence or absence of 18-crown-6, respectively. Both 118C6 ·4THF and 1THF are thermally stable in the solid-state at room temperature; however, after crystallization, they become insoluble in THF or DME solutions and instead gradually decompose upon standing. X-ray diffraction analysis reveals 118C6 ·4THF and 1THF to be structurally similar, possessing uranium centres sandwiched between bent anthracenide ligands of mixed tetrahapto and hexahapto ligation modes. Yet, the two complexes are distinguished by the close contact potassium-arenide ion pairing that is seen in 1THF but absent in 118C6 ·4THF, which is observed to have a significant effect on the electronic characteristics of the two complexes. Structural analysis, SQUID magnetometry data, XANES spectral characterization, and computational analyses are generally consistent with U(iv) formal assignments for the metal centres in both 118C6 ·4THF and 1THF , though noticeable differences are detected between the two species. For instance, the effective magnetic moment of 1THF (3.74 μ B ) is significantly lower than that of 118C6 ·4THF (4.40 μ B ) at 300 K. Furthermore, the XANES data shows the U L III -edge absorption energy for 1THF to be 0.9 eV higher than that of 118C6 ·4THF, suggestive of more oxidized metal centres in the former. Of note, CASSCF calculations on the model complex {[U(η 6 -C 14 H 10 )(η 4 -C 14 H 10 )(μ-OMe)] 2 } 2- ( 1* ) shows highly polarized uranium-arenide interactions defined by π-type bonds where the metal contributions are primarily comprised by the 6d-orbitals (7.3 ± 0.6%) with minor participation from the 5f-orbitals (1.5 ± 0.5%). These unique complexes provide new insights into actinide-arenide bonding interactions and show the sensitivity of the electronic structures of the uranium atoms to coordination sphere effects., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The development and integration of Single-Molecule Magnets (SMMs) into molecular electronic devices continue to be an exciting challenge. In such potential devices, heat generation due to the electric current is a critical issue that has to be considered upon device fabrication. To read out accurately the temperature at the submicrometer spatial range, new multifunctional SMMs need to be developed. Herein, we present the first self-calibrated molecular thermometer with SMM properties, which provides an elegant avenue to address these issues. The employment of 2,2'-bipyrimidine and 1,1,1-trifluoroacetylacetonate ligands results in a dinuclear compound, [Dy 2 (bpm)(tfaa) 6 ], which exhibits slow relaxation of the magnetization along with remarkable photoluminescent properties. This combination allows the gaining of fundamental insight in the electronic properties of the compound and investigation of optomagnetic cross-effects (Zeeman effect). Importantly, spectral variations stemming from two distinct thermal-dependent mechanisms taking place at the molecular level are used to perform luminescence thermometry over the 5-398 K temperature range. Overall, these properties make the proposed system a unique molecular luminescent thermometer bearing SMM properties, which preserves its temperature self-monitoring capability even under applied magnetic fields., Competing Interests: The authors declare no competing financial interest.

We present a comprehensive investigation of the magnetic and optical properties of an ytterbium complex, which combines two desirable and practical features into a single molecular system. Based upon Yb III ions that promote near-infrared optical activity and a chemical backbone that is ideal for an in-depth understanding of the magnetic behaviour, we have designed a multifunctional opto-magnetic species that operates as a luminescent thermometer and as a single-molecule magnet (SMM). Our magnetic investigations, in conjunction with ab initio calculations, reveal one of the highest energy barriers reported for an Yb III -based complex. Moreover, we correlate this anisotropic barrier with the emission spectrum of the compound, wherein we provide a complete assignment of the energetic profile of the complex. Such studies lay the foundation for the design of exciting multi-faceted materials that are able to retain information at the single-molecule level and possess built-in thermal self-monitoring capabilities.

Understanding the self-assembly of cluster aggregates remains an important challenge in coordination chemistry. A chelating tetrazine-based ligand was employed to isolate an unprecedented tetranuclear Hg 4 complex exhibiting Hg I /Hg II mixed valence, which also contains metal-metal bonds. Single-crystal X-ray diffraction, X-ray photoelectron spectroscopy, solid-state nuclear magnetic resonance, and theoretical approaches (density functional theory) were employed to shed some light on the structure and self-assembly of this discrete molecule., Competing Interests: The authors declare no competing financial interest.

Food flows underpin the complex food supply chains that are prevalent in our increasingly globalized world. Recently, much effort has been devoted to evaluating the resources (e.g. water, carbon, nutrients) embodied in food trade. Now, research is needed to understand the scientific principles of the food commodity flows that underpin these virtual resource transfers. How do food flows vary with spatial scale? To address this question, we present an empirical analysis of food commodity flow networks across the full spectrum of spatial scales: global, national, and village. We discover properties of both scale invariance and scale dependence in food flow networks. The statistical distribution of node connectivity and mass flux are consistent across scales. Node connectivity follows a generalized exponential distribution, while node mass flux follows a Gamma distribution across scales. Similarly, the relationship between node connectivity and mass flux follows a power law across scales. However, the parameters of the distributions change with spatial scale. Mean node connectivity and mass flux increase with increasing scale. A core group of nodes exists at all scales, but node centrality increases as the spatial scale decreases, indicating that some households are more critical to village food exchanges than countries are to global trade. Remarkably, the structural network properties of food flows are consistent across spatial scales, indicating that a universal mechanism may underpin food exchange systems. In future research, this understanding can be used to develop theoretical models of food flow networks and to model food flows at resolutions for which empirical information is not available., Competing Interests: The authors have declared that no competing interests exist.

Binding sites are at the heart of all host-guest systems, whether biological or chemical. When considering binding sites that form covalent bonds with the guest, we generally envision a single, highly specific binding motif. Through single-crystal X-ray crystallography, the dynamic binding of a guest that displays a variety of covalent binding motifs in a single site of adsorption is directly observed for the first time. The stepwise crystallographic visualization of the incorporation of I 2 within a porous MOF is presented, wherein the preferred binding motifs throughout the uptake process are identified. The guest I 2 molecules initially bind with terminal iodide atoms of the framework to form [I 4 ] 2- units. However, as the adsorption progresses, the I 2 molecules are observed to form less energetically favorable I 3 - groups with the same framework iodide atoms, thereby allowing for more guest molecules to be chemisorbed. At near saturation, even more binding motifs are observed in the same pores, including both physisorbed and chemisorbed guest molecules. Herein, we present the successful identification of a unique set of host-guest interactions which will drive the improvement of high capacity iodine capture materials.

The preparation of η-cyclopentadienyl (η 5 -C 5 R 5 ), η-arene (η 6 -C 6 R 6 ), and η-cyclooctatetraenyl (η 8 -C 8 R 8 ) bridging motifs are common in organometallic chemistry; however, the synthetic preparation of η-cycloheptatrienyl (η 7 -C 7 R 7 ) bridging motifs has remained a synthetic challenge in 4f chemistry. To this end, we have developed a synthetic route towards a series of rare dinuclear organolanthanide inverse sandwich complexes containing the elusive η 7 -C 7 H 7 bridge. Herein, we present the structures and magnetic properties of the lanthanide inverse sandwich complexes [KLn 2 (C 7 H 7 )(N(SiMe 3 ) 2 ) 4 ] (Ln = Gd III ( 1 ), Dy III ( 2 ), Er III ( 3 )) and [K(THF) 2 Er 2 (C 7 H 7 )(N(SiMe 3 ) 2 ) 4 ] ( 4 ). These compounds are the first single-molecule magnets (SMMs) to feature this type of bridging motif. Furthermore, η 7 -C 7 H 7 was found to efficiently promote ferromagnetic exchange interactions between metal ions. Variable temperature dc magnetic susceptibility measurements and subsequent simulations give significant exchange constants of J = +1.384, +1.798, and +3.149 cm -1 and dipolar constants of J = -0.603, -0.601, and -0.475 cm -1 for compounds 2-4 , respectively. Frequency dependent ac susceptibility measurements under an applied static field resulted in the observation of dual relaxation processes, and brought forth a greater understanding of the intermolecularly driven process at high frequency. In particular, this type of analysis of compound 3 under 800 Oe elicited an energy barrier of U eff = 58 K. Ab initio calculations were performed in order to understand the nature of magnetic coupling and the origin of slow relaxation of magnetisation. Through these studies, the effect of the amido ancillary ligands on the magnetic axiality of the lanthanide ions was found to be competitive with the crystal field of the η 7 -C 7 H 7 π-electron cloud. Our findings suggest that the tunability of the dipolar and exchange components of the magnetic interactions lie within the dihedral angle imposed by the amido ligands, thus offering potential for the development of new exchange coupled lanthanide systems.

Single-molecule magnets (SMMs) that contain one spin centre (so-called single-ion magnets) theoretically represent the smallest possible unit for spin-based electronic devices. The realisation of this and related technologies, depends on first being able to design systems with sufficiently large energy barriers to magnetisation reversal, U eff , and secondly, on being able to organise these molecules into addressable arrays. In recent years, significant progress has been made towards the former goal - principally as a result of efforts which have been directed towards studying complexes based on highly anisotropic lanthanide ions, such as Tb(iii) and Dy(iii). Since 2013 however, and the remarkable report by Long and co-workers of a linear Fe(i) system exhibiting U eff = 325 K, single-ion systems of transition metals have undergone something of a renaissance in the literature. Not only do they have important lessons to teach us about anisotropy and relaxation dynamics in the quest to enhance U eff , the ability to create strongly coupled spin systems potentially offers access to a whole of host of 1, 2 and 3-dimensional materials with interesting structural and physical properties. This perspective summarises recent progress in this rapidly expanding sub-genre of molecular magnetism from the viewpoint of the synthetic chemist, with a particular focus on the lessons that have so far been learned from single-ion magnets of the d-block, and, the future research directions which we feel are likely to emerge in the coming years.

Vegetation has different adjustable properties for adaptation to its environment. Examples include stomatal conductance at short time scale (minutes), leaf area index and fine root distributions at longer time scales (days-months) and species composition and dominant growth forms at very long time scales (years-decades-centuries). As a result, the overall response of evapotranspiration to changes in environmental forcing may also change at different time scales. The vegetation optimality model simulates optimal adaptation to environmental conditions, based on the assumption that different vegetation properties are optimized to maximize the long-term net carbon profit, allowing for separation of different scales of adaptation, without the need for parametrization with observed responses. This paper discusses model simulations of vegetation responses to today's elevated atmospheric CO2 concentrations (eCO2) at different temporal scales and puts them in context with experimental evidence from free-air CO2 enrichment (FACE) experiments. Without any model tuning or calibration, the model reproduced general trends deduced from FACE experiments, but, contrary to the widespread expectation that eCO2 would generally decrease water use due to its leaf-scale effect on stomatal conductance, our results suggest that eCO2 may lead to unchanged or even increased vegetation water use in water-limited climates, accompanied by an increase in perennial vegetation cover., (Published by Oxford University Press on behalf of the Annals of Botany Company.)

Assisted colonization-the deliberate translocation of species from unsuitable to suitable regions-is a controversial management tool that aims to prevent the extinction of populations that are unable to migrate in response to climate change or to survive in situ. The identification of suitable translocation sites is therefore a pressing issue. Correlative species distribution models, which are based on occurrence data, are of limited use for site selection for species with historically restricted distributions. In contrast, mechanistic species distribution models hold considerable promise in selecting translocation sites. Here we integrate ecoenergetic and hydrological models to assess the longer-term suitability of the current habitat of one of the world's rarest chelonians, the Critically Endangered Western Swamp Tortoise (Psuedemydura umbrina). Our coupled model allows us to understand the interaction between thermal and hydric constraints on the foraging window of tortoises, based on hydrological projections of its current habitat. The process can then be repeated across a range of future climates to identify regions that would fall within the tortoise's thermodynamic niche. The predictions indicate that climate change will result in reduced hydroperiods for the tortoises. However, under some climate change scenarios, habitat suitability may remain stable or even improve due to increases in the heat budget. We discuss how our predictions can be integrated with energy budget models that can capture the consequences of these biophysical constraints on growth, reproduction and body condition.

The timing and magnitude of rainfall events are known to be dominant controls on pesticide migration into streams and groundwater, by triggering rapid flow processes, such as preferential flow and surface runoff. A better understanding of how regional differences in rainfall impact rapid leaching risk is required in order to match the scale at which water regulation occurs. We estimated the potential amount of rapid leaching, and the frequencies of these events in a case study of the southwest of Western Australia, for one soil type and a range of linearly sorbing, first order degrading chemicals. At the regional scale, those chemicals with moderate sorption and long half lives were the most susceptible to rapid transport within a year of application. Within the region, this susceptibility varied depending upon application time and seasonality in storm patterns. Those chemicals and areas with a high potential for rapid transport on average, also experience the greatest inter-annual variability in rapid leaching, as measured by the coefficient of variation. The timing and frequencies of rapid leaching events appeared to strongly relate to an area's relative susceptibility to rapid leaching. In the study region the results also suggested that frontal rainfall dominates rapid leaching along the western and southern coasts while convective thunderstorms play a greater role in the arid east., (2009 Elsevier B.V. All rights reserved.)

Prions are composed solely of an alternatively folded isoform of the prion protein (PrP), designated PrP(Sc). N-terminally truncated PrP(Sc), denoted PrP 27-30, retains infectivity and polymerizes into rods with the ultrastructural and tinctorial properties of amyloid. We report here that some polyoxometalates (POMs) favor polymerization of PrP 27-30 into prion rods, whereas other POMs promote assembly of the protein into 2D crystals. Antibodies reacting with epitopes in denatured PrP 27-30 also bound to 2D crystals treated with 3 M urea. These same antibodies did not bind to either native PrP(Sc) or untreated 2D crystals. By using small, spherical POMs with Keggin-type structures, the central heteroatom was found to determine whether prion rods or 2D crystals were preferentially formed. An example of a Keggin-type POM with a phosphorous heteroatom is the phosphotungstate anion (PTA). Both PTA and a Keggin-type POM with a silicon heteratom have low-charge densities and favor formation of prion rods. In contrast, POMs with boron or hydrogen heteroatoms exhibiting higher negative charges encouraged 2D crystal formation. The 2D crystals of PrP 27-30 produced by selective precipitation with POMs were larger and more well ordered than those obtained by sucrose gradient centrifugation. Our findings argue that the negative charge of Keggin-type POMs determines the quaternary structure adopted by PrP 27-30. The mechanism by which POMs function in competing prion polymerization pathways--one favoring 2D crystals and the other, amyloid fibrils--remains to be established.