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G-quadruplex (G4) DNAzymes with peroxidase activities hold potential for applications in biosensing. While these nanozymes are easy to assemble, they are not as efficient as natural peroxidase enzymes. Several approaches are being used to better understand the structural basis of their reaction mechanisms, with a view to designing constructs with improved catalytic activities. Spermine alters the structures and enhances the activities of some G4 DNAzymes. The reported effect of spermine in shifting the conformation of some G4 DNAzymes from antiparallel to parallel has not been tested on multimeric G4 DNAzymes. In this study, we examined the effects of spermine on the catalytic activities of multivalent constructs of Bcl2, c-MYC, PS2.M, and PS5.M. Our findings show that spermine significantly improved the peroxidase activity of PS2.M, an antiparallel G4 DNAzyme, while there was no significant effect on c-MYC, which already exists in a parallel conformation. The addition of spermine led to a substantial increase in the initial velocity of PS2.M and its multimeric form, enhancing it by approximately twofold. Therefore, spermine enhancement offers promise in expanding the range of DNAzymes available for use as biosensing tools.

The human gut microbiota (HGM) is a complex ecosystem subtly dependent on the interplay between hundreds of bacterial species and numerous metabolites. Dietary phenols, whether ingested (e.g., plant-derived guaiacol, mequinol, or resveratrol) or products of bacterial fermentation (e.g., p -cresol), have been attributed with influencing bacterial growth and host health. They are cleared by phase II metabolism, one form utilizing β-d-glucuronidation, but encounter bacterially derived glucuronidases capable of hydrolyzing them to release their phenolic and glucuronic acid moieties with potential effects on host cells or the surrounding bacterial population. Tools to enable the detailed study of their activity are currently lacking. Syntheses of β-d-glucuronides from methyl 1,2,3,4 tetra-acetyl β-d-glucopyranosyluronate by direct glycosylation with 2-, 3-, or 4-methoxy- and 4-fluorophenol acceptors employing trimethylsilyl triflate catalysis are reported. Yields (methoxy series) were modest. An improved route from methyl 1,2,3,4-tetra-acetyl β-d-glucopyranosyluronate via selective anomeric deprotection ( N -methyl piperazine) and conversion to an α-trichloroacetimidate glycosyl donor was employed. Coupling with 2- and 3-methoxyphenol acceptors and deprotection provided 2- and 3-methoxyphenyl β-d-glucuronides in 2-fold improved overall yield. These naturally occurring methoxyphenyl glucuronides augment available model substrates of dietary glucuronides, which include 3- and 4'-linked resveratrol. The use of model glucuronides as substrates was illustrated in studies of β-d-glucuronidase activity employing cell lysates of 9 species of HGM ( Bacteroidetes ), revealing distinct outcomes. Contrasting effects on bacterial growth were also observed between the free phenolic components, their respective glucuronides, and glucuronic acid. The glucuronide of 4-fluorophenol provided sensitive and background-free detection of β-glucuronidase activity using 19 F NMR., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The longitudinal and transverse nuclear magnetic resonance relaxivity dispersion (NMRD) of 1 H in water induced by the paramagnetic relaxation enhancement (PRE) of dissolved lanthanide ions (Ln 3+ ) can become very strong. Longitudinal and transverse 1 H NMRD for Gd 3+ , Dy 3+ , Er 3+ and Ho 3+ were measured from 20 MHz/0.47 T to 1382 MHz/32.5 T, which extended previous studies by a factor of more than two in the frequency range. For the NMRD above 800 MHz, we used a resistive magnet, which exhibits reduced field homogeneity and stability in comparison to superconducting and permanent NMR magnets. These drawbacks were addressed by dedicated NMRD methods. In a comparison of NMRD measurements between 800 MHz and 950 MHz performed in both superconducting and resistive magnets, it was found that the longitudinal relaxivities were almost identical. However, the magnetic field fluctuations of the resistive magnet strongly perturbed the transverse relaxation. The longitudinal NMRDs are consistent with previous work up to 600 MHz. The transverse NMRD nearly scales with the longitudinal one with a factor close to one. The data can be interpreted within a PRE model that comprises the dipolar hyperfine interactions between the 1 H and the paramagnetic ions, as well as a Curie spin contribution that is dominant at high magnetic fields for Dy 3+ , Er 3+ and Ho 3+ . Our findings provide a solid methodological basis and valuable quantitative insights for future high-frequency NMRD studies, enhancing the measurement accuracy and applicability of PRE models for paramagnetic ions in aqueous solutions.

Aim: Circulating maternal MicroRNA (miRNA) is a promising source of biomarkers for antenatal diagnostics. NanoString nCounter is a popular global screening tool due to its simplicity and ease of use, but there is a lack of standardisation in analysis methods. We examined the effect of user-defined variables upon reported changes in maternal blood miRNA during pregnancy., Methods: Total RNA was prepared from the maternal blood of pregnant and control rats. miRNA expression was profiled using Nanostring nCounter. Raw count data were processed using nSolver using different combinations of normalisation and background correction methods as well as various background thresholds. A panel of 14 candidates in which changes were supported by multiple analysis workflows was selected for validation by RT-qPCR. We then reverse-engineered the nSolver analysis to gain further insight., Results: Thirty-one putative differentially expressed miRNAs were identified by nSolver. However, each analysis workflow produced a different set of reported biomarkers and none of them was common to all analysis methods. Four miRNAs with known roles in pregnancy (miR-183, miR-196c, miR-431, miR-450a) were validated. No single nSolver analysis workflow could successfully identify all four validated changes. Reverse engineering revealed errors in nSolver data processing which compound the inherent problems associated with background correction and normalisation., Conclusion: Our results suggest that user-defined variables greatly influence the output of the assay. This highlights the need for standardised nSolver data analysis methods and detailed reporting of these methods. We suggest that investigators in the future should not rely on a single analysis method to identify changes and should always validate screening results., Competing Interests: All authors declared that there are no conflicts of interest., (© The Author(s) 2024.)

Polyoxometalates (POM) are anionic oxoclusters of early transition metals that are of great interest for a variety of applications, including the development of sensors and catalysts. A crucial step in the use of POM in functional materials is the production of composites that can be further processed into complex materials, e.g. by printing on different substrates. In this work, we present an immobilization approach for POMs that involves two key processes: first, the stable encapsulation of POMs in the pores of mesoporous silica nanoparticles (MSPs) and, second, the formation of microstructured arrays with these POM-loaded nanoparticles. Specifically, we have developed a strategy that leads to water-stable, POM-loaded mesoporous silica that can be covalently linked to alkene-bearing surfaces by amine-Michael addition and patterned into microarrays by scanning probe lithography (SPL). The immobilization strategy presented facilitates the printing of hybrid POM-loaded nanomaterials onto different surfaces and provides a versatile method for the fabrication of POM-based composites. Importantly, POM-loaded MSPs are useful in applications such as microfluidic systems and sensors that require frequent washing. Overall, this method is a promising way to produce surface-printed POM arrays that can be used for a wide range of applications., (© 2024. The Author(s).)

The [Gd 8 (opch) 8 (CO 3 ) 4 (H 2 O) 8 ]·4H 2 O·10MeCN coordination cluster ( 1 ) crystallises in P1¯. The Gd 8 core is held together by four bridging carbonates derived from atmospheric CO 2 as well as the carboxyhydrazonyl oxygens of the 2-hydroxy-3-methoxybenzylidenepyrazine-2-carbohydrazide (H 2 opch) Schiff base ligands. The magnetic measurements show that the Gd III ions are effectively uncoupled as seen from the low Weiss constant of 0.05 K needed to fit the inverse susceptibility to the Curie-Weiss law. Furthermore, the magnetisation data are consistent with the Brillouin function for eight independent Gd III ions. These features lead to a magnetocaloric effect with a high efficiency which is 89% of the theoretical maximum value.

Complexes of lanthanide(iii) ions (Ln) with tetraazacyclododecane- N , N ', N '', N '''-tetraacetate (DOTA) are a benchmark in the field of magnetism due to their well-investigated and sometimes surprising features. Ab initio calculations suggest that the ninth ligand, an axial water molecule, is key in defining the magnetic properties because it breaks the potential C 4 symmetry of the resulting complexes. In this paper, we experimentally isolate the role of the water molecule by excluding it from the metal coordination sphere without altering the chemical structure of the ligand. Our complexes are therefore designed to be geometrically tetragonal and strict crystallographic symmetry is achieved by exploiting a combination of solution ionic strength and solid state packing effects. A thorough multitechnique approach has been used to unravel the electronic structure and magnetic anisotropy of the complexes. Moreover, the geometry enhancement allows us to predict, using only one angle obtained from the crystal structure, the ground state composition of all the studied derivatives (Ln = Tb to Yb). Therefore, these systems also provide an excellent platform to test the validity and limitations of the ab initio methods. Our combined experimental and theoretical investigation proves that the water molecule is indeed key in defining the magnetic anisotropy and the slow relaxation of these complexes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

[(2-{[6-(1,3-Benzo-thia-zol-2-yl)pyridin-2-yl]carbonyl-aza-nid-yl}phen-yl)sulf-anido]nickel(II), [Ni(C 19 H 11 N 3 OS 2 )], crystallizes in the centrosymmetric monoclinic space group P 2 1 / n with one mol-ecule in the asymmetric unit. The expected ligand, a bis-Schiff base derived from pyridine-2,6-dicarbaldehyde and 2-amino-thio-phenol, had modified in situ in a both unexpected and unsymmetrical fashion. One arm had cyclized to form a benzo[ d ]thia-zol-2-yl functionality, while the imine linkage of the second arm had oxidized to an amide group. The geometry about the central Ni II atom is distorted square-planar N 3 S. The mol-ecules form supra-molecular face-to-face dimers via rather strong π-π stacking inter-actions, with these dimers then linked into chains via pairwise C-H⋯O inter-actions., (© Al-Zeidaneen et al. 2023.)

Prenatal diagnosis of congenital disease improves clinical outcomes; however, as many as 50% of congenital heart disease cases are missed by current ultrasound screening methods. This indicates a need for improved screening technology. Extracellular vesicles (EVs) have attracted enormous interest in recent years for their potential in diagnostics. EVs mediate endocrine signalling in health and disease and are known to regulate aspects of embryonic development. Here, we critically evaluate recent evidence suggesting that EVs released from the foetus are able to cross the placenta and enter the maternal circulation. Furthermore, EVs from the mother appear to be transported in the reverse direction, whilst the placenta itself acts as a source of EVs. Experimental work utilising rodent models employing either transgenically encoded reporters or application of fluorescent tracking dyes provide convincing evidence of foetal-maternal crosstalk. This is supported by clinical data demonstrating expression of placental-origin EVs in maternal blood, as well as limited evidence for the presence of foetal-origin EVs. Together, this work raises the possibility that foetal EVs present in maternal blood could be used for the diagnosis of congenital disease. We discuss the challenges faced by researchers in translating these basic science findings into a clinical non-invasive prenatal test., (© 2022. The Author(s).)

In situ metal-templated (hydrazone) condensation also called subcomponent self-assembly of 4,6-dihydrazino-pyrimidine, o -vanillin and dysprosium ions resulted in the formation of discrete hexa- or dodecanuclear metallosupramolecular Dy 6 (L) 6 or Dy 12 (L) 8 aggregates resulting from second-order template effects of the base and the lanthanide counterions used in these processes. XRD analysis revealed unique circular helical or tetragonal bipyramid architectures in which the bis(hydrazone) ligand L adopts different conformations and shows remarkable differences in its mode of metal coordination. While a molecule of trimethylamine acts as a secondary template that fills the void of the Dy 6 (L) 6 assembly, sodium ions take on this role for the formation of heterobimetallic Dy 12 (L) 8 by occupying vacant coordination sites, thus demonstrating that these processes can be steered in different directions upon subtle changes of reaction conditions. Furthermore, Dy 6 (L) 6 shows an interesting spin-relaxation energy barrier of 435 K, which is amongst the largest values within multinuclear lanthanide single-molecular magnets., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

We present a combined experimental and theoretical study of the ultrafast transient absorption spectroscopy results of a {Ni 2 Dy 2 }-compound in DMF, which can be considered as a prototypic molecule for single molecule magnets. We apply state-of-the-art ab initio quantum chemistry to quantitatively describe the optical properties of an inorganic complex system comprising ten atoms to form the chromophoric unit, which is further stabilized by surrounding ligands. Two different basis sets are used for the calculations to specifically identify two dominant peaks in the ground state. Furthermore, we theoretically propagate the compound's correlated many-body wavefunction under the influence of a laser pulse as well as relaxation processes and compare against the time-resolved absorption spectra. The experimental data can be described with a time constant of several hundreds of femtoseconds attributed to vibrational relaxation and trapping into states localized within the band gap. A second time constant is ascribed to the excited state while trap states show lifetimes on a longer timescale. The theoretical propagation is performed with the density-matrix formalism and the Lindblad superoperator, which couples the system to a thermal bath, allowing us to extract relaxation times from first principles., (© 2021 The Authors. Published by Wiley-VCH GmbH.)

The current trend for ultra-high-field magnetic resonance imaging (MRI) technologies opens up new routes in clinical diagnostic imaging as well as in material imaging applications. MRI selectivity is further improved by using contrast agents (CAs), which enhance the image contrast and improve specificity by the paramagnetic relaxation enhancement (PRE) mechanism. Generally, the efficacy of a CA at a given magnetic field is measured by its longitudinal and transverse relaxivities r 1 and r 2 , i.e., the longitudinal and transverse relaxation rates T 1 -1 and T 2 -1 normalized to CA concentration. However, even though basic NMR sensitivity and resolution become better in stronger fields, r 1 of classic CA generally decreases, which often causes a reduction of the image contrast. In this regard, there is a growing interest in the development of new contrast agents that would be suitable to work at higher magnetic fields. One of the strategies to increase imaging contrast at high magnetic field is to inspect other paramagnetic ions than the commonly used Gd(III)-based CAs. For lanthanides, the magnetic moment can be higher than that of the isotropic Gd(III) ion. In addition, the symmetry of electronic ground state influences the PRE properties of a compound apart from diverse correlation times. In this work, PRE of water 1 H has been investigated over a wide range of magnetic fields for aqueous solutions of the lanthanide containing polyoxometalates [Dy III (H 2 O) 4 GeW 11 O 39 ] 5- ( Dy-W 11 ), [Er III (H 2 O) 3 GeW 11 O 39 ] 5- ( Er-W 11 ) and [{Er III (H 2 O)(CH 3 COO)(P 2 W 17 O 61 )} 2 ] 16- ( Er 2 -W 34 ) over a wide range of frequencies from 20 MHz to 1.4 GHz. Their relaxivities r 1 and r 2 increase with increasing applied fields. These results indicate that the three chosen POM systems are potential candidates for contrast agents, especially at high magnetic fields.

Mesothelioma is a cancer that typically originates in the pleura of the lungs. It rapidly invades the surrounding tissues, causing pain and shortness of breath. We compared cell lines injected either subcutaneously or intrapleurally and found that only the latter resulted in invasive and rapid growth. Pleural tumors displayed a transcriptional signature consistent with increased activity of nuclear receptors PPARα and PPARγ and with an increased abundance of endogenous PPAR-activating ligands. We found that chemical probe GW6471 is a potent, dual PPARα/γ antagonist with anti-invasive and anti-proliferative activity in vitro . However, administration of GW6471 at doses that provided sustained plasma exposure levels sufficient for inhibition of PPARα/γ transcriptional activity did not result in significant anti-mesothelioma activity in mice. Lastly, we demonstrate that the in vitro anti-tumor effect of GW6471 is off-target. We conclude that dual PPARα/γ antagonism alone is not a viable treatment modality for mesothelioma., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

The incidence of tickborne diseases in the United States is increasing; reported cases more than doubled from >22,000 in 2004 to >48,000 in 2016 (1). Ticks are responsible for approximately 95% of all locally acquired vectorborne diseases reported by states and the District of Columbia, with Lyme disease accounting for >80% of those cases (2). After a tick bite, persons might seek care at an emergency department (ED) for tick removal and to receive postexposure prophylaxis, which has been shown to effectively prevent Lyme disease when taken within 72 hours of a high-risk bite (3). Using data from CDC's National Syndromic Surveillance Program (NSSP), investigators examined ED tick bite visits during January 2017-December 2019 by sex, age group, U.S. region, and seasonality. During this 36-month period, 149,364 ED tick bite visits were identified. Mean cumulative incidence was 49 ED tick bite visits per 100,000 ED visits overall; incidence was highest in the Northeast (110 per 100,000 ED visits). The seasonal distribution of ED tick bite visits was bimodal: the larger peak occurred during the spring and early summer, and the smaller peak occurred in the fall. This pattern aligns with the seasonality of a known and abundant human-biter, the blacklegged tick, Ixodes scapularis (4). Compared with other age groups, pediatric patients aged 0-9 years accounted for the highest number and incidence of ED tick bite visits; incidence was higher among male patients than among females. Tick bites are not monitored by current surveillance systems because a tick bite is an event that in and of itself is not a reportable condition to health departments. Syndromic surveillance of ED tick bite visits can provide timely information that might predict temporal and geographic risk for exposure to tickborne diseases and guide actionable public health messaging such as avoiding tick habitats, wearing repellent consistently when outdoors, and performing regular tick checks during times of increased tick bite risk., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

The potential use of bis(methylene)bis(5-bromo-2-hydroxylsalicyloylhydrazone) as a multifunctional fluorescence sensor for Cu 2+ , Ni 2+ , Co 2+ and Fe 2+ ions was investigated. The optical behaviour shows an increase in an absorption band at 408 nm which can be ascribed to the d-d transition (UV-vis) of the metal ions and a concomitant decrease in fluorescence intensity at 507 nm. The crystallographic analysis shows the binding site of the sensor to two Cu 2+ ions and confirms the stoichiometry of 1 : 2 (ligand to metal) which is in good agreement with a Job plot analysis. Furthermore the Cu 2+ -complex catalyses A3 coupling reactions at 1 mol% catalytic loading; chiral propargylamine derivatives were obtained in high yield after 24 h reaction time under ambient conditions., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

We report the synthesis and magnetic properties of three new nine-membered Fe(III)-Dy(III) cyclic coordination clusters (CCCs), with a core motif of [Fe 6 Dy 3 (μ-OMe) 9 (vanox) 6 (X-benz) 6 ] where the benzoate ligands are substituted in the para-position with X = F ( 1 ), Cl ( 2 ), Br ( 3 ). Single crystal X-ray diffraction structure analyses show that for the smaller fluorine or chlorine substituents the resulting structures exhibit an isostructural Fe 6 Dy 3 core, whilst the 4-bromobenzoate ligand leads to structural distortions which affect the dynamic magnetic behavior. The magnetic susceptibility and magnetization of 1 - 3 were investigated and show similar behavior in the dc (direct current) magnetic data. Additional ac (alternating current) magnetic measurements show that all compounds exhibit frequency-dependent and temperature-dependent signals in the in-phase and out-of-phase component of the susceptibility and can therefore be described as field-induced SMMs. The fluoro-substituted benzoate cluster 1 shows a magnetic behavior closely similar to that of the corresponding unsubstituted Fe 6 Dy 3 cluster, with U eff = 21.3 K within the Orbach process. By increasing the size of the substituent toward 4-chlorobenzoate within 2 , an increase of the energy barrier to U eff = 36.1 K was observed. While the energy barrier becomes higher from 1 to 2 , highlighting that the introduction of different substituents on the benzoate ligand in the para -position has an impact on the magnetic properties, cluster 3 shows a significantly different SMM behavior where U eff is reduced in the Orbach regime to only 4.9 K., (Copyright © 2020 Kühne, Anson and Powell.)

The first dinuclear and trinuclear chromium(III) and dinuclear vanadium(III) complexes of N 4 - R -substituted-3,5-di(2-pyridyl)-1,2,4-triazole ( Rdpt ) ligands have been prepared by solvothermal complexations under inert atmospheres, and characterized. The reactions of Cr III and V III with adpt ( R = amino) resulted in deamination of the ligand and yielded the dinuclear doubly-triazolate bridged complexes [ V 2 III ( dpt - ) 2 Cl 4 ] ( 1 ) and [ Cr 2 III ( dpt - ) 2 Cl 4 ] ( 2 ). In the case of the Cr III complex 2 this bridging results in a rare example of ferromagnetic coupling for a dinuclear Cr III compound. DFT studies confirm that in 2 the ferromagnetic coupling pathways dominate over the antiferromagnetic pathways, whereas in 1 the reverse occurs, consistent with the observed overall antiferromagnetic coupling in that case. It was also found that the use of different additives in the reaction allows the nuclearity of the Cr III product to be manipulated, giving either the dinuclear system, or the first example of a trinuclear circular helicate for a Rdpt complex, [ Cr 3 III ( dpt ) 3 Cl 6 ]·1¾MeCN·¼DCM ( 3 ). Reaction of N 4 - pydpt (R = 4-pyridyl) with V III led to an unusual shift of the pyridyl substituent from N 4 to N 1 of the triazole, forming the ligand isomer N 1 - pydpt , and giving a dinuclear doubly-triazole bridged complex, [ V 2 III ( N 1 - pydpt ) 2 Cl 6 ]·2MeCN ( 4 ). Reaction with Cr III results in loss of the 4-pyridyl ring and a mixture of the di- and trinuclear complexes, 2 and 3 . Interestingly, partial oxidation of the V III in dinuclear complex 4 to vanadyl V IV =O was identified by crystallographic analysis of partially oxidized single crystals, [(V IV O) 0.84 (V III ) 1.16 ( N 1 - pydpt ) 2 Cl 5.16 ]·0.84H 2 O·1.16MeCN ( 5 )., (Copyright © 2020 Rinck, Kitchen, Carter, Lan, Anson, Fink, Brooker and Powell.)

The level of cancer biomarkers in cells, tissues or body fluids can be used for the prediction of the presence of cancer or can even indicate the stage of the disease. Alpha-fetoprotein (AFP) is the most commonly used biomarker for early screening and diagnosis of hepatocellular carcinoma (HCC). Here, a combination of three techniques (click chemistry, the biotin-streptavidin-biotin sandwich strategy and the use of antigen-antibody interactions) were combined to implement a sensitive fluorescent immunosensor for AFP detection. Three types of functionalized glasses (dibenzocyclooctyne- (DBCO-), thiol- and epoxy-terminated surfaces) were biotinylated by employing the respective adequate click chemistry counterparts (biotin-thiol or biotin-azide for the first class, biotin-maleimide or biotin-DBCO for the second class and biotin-amine or biotin-thiol for the third class). The anti-AFP antibody was immobilized on the surfaces via a biotin-streptavidin-biotin sandwich technique. To evaluate the sensing performance of the differently prepared surfaces, fluorescently labeled AFP was spotted onto them via microchannel cantilever spotting (µCS). Based on the fluorescence measurements, the optimal microarray design was found and its sensitivity was determined., (Copyright © 2019, Dadfar et al.; licensee Beilstein-Institut.)

Tetranuclear chiral Cu(ii)-Schiff-base complexes S-1 and R-1, were synthesised using enantiomerically pure ( S )-(H 2 vanPheol) and ( R )-(H 2 vanPheol) ligands respectively in the ratio of 1 : 1 of Cu(NO 3 ) 2 to ( S / R )-(H 2 vanPheol) in MeOH at room temperature. A pair of polynuclear chiral Cu(ii)-cluster complexes were characterized using single-crystal X-ray diffraction, elemental analysis, infrared and CD spectroscopy. The results revealed the importance of these chiral ligands encouraging the arrangement of copper metal in non-centrosymmetric polar packing. The potential of the novel [Cu 4 ( S / R -vanPheol) 2 ( S / R -HvanPheol) 2 (CH 3 OH) 2 ](NO 3 ) 2 complexes as biologically active compounds was assessed in particular regarding their anti-proliferative and anti-microbial properties., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

We describe the synthesis, characterisation and magnetic studies of four tetranuclear, isostructural "butterfly" heterometallic complexes: [MIII2LnIII2(μ 3 -OH) 2 ( p -Me-PhCO 2 ) 6 (L) 2 ] (H 2 L = 2,2'-((pyridin-2-ylmethyl)azanediyl)bis(ethan-1-ol), M = Cr, Ln = Dy ( 1 ), Y ( 2 ), M = Mn, Ln = Dy ( 3 ), Y ( 4 )), which extend our previous study on the analogous 5 {Fe 2 Dy 2 }, 6 {Fe 2 Y 2 } and 7 {Al 2 Dy 2 } compounds. We also present data on the yttrium diluted 7 {Al 2 Dy 2 }: 8 {Al 2 Dy 0.18 Y 1.82 }. Compounds dc and ac magnetic susceptibility data reveal single-molecule magnet (SMM) behaviour for complex 3 {Mn 2 Dy 2 }, in the absence of an external magnetic field, with an anisotropy barrier U eff of 19.2 K, while complex 1 {Cr 2 Dy 2 }, shows no ac signals even under applied dc field, indicating absence of SMM behaviour. The diluted sample 8 {Al 2 Dy 0.18 Y 1.82 } shows field induced SMM behaviour with an anisotropy barrier U eff of 69.3 K. Furthermore, the theoretical magnetic properties of [MIII2LnIII2(μ 3 -OH) 2 ( p -Me-PhCO 2 ) 6 (L) 2 ] (M = Cr, 1 or Mn, 3 ) and their isostructural complexes: [MIII2DyIII2(μ 3 -OH) 2 ( p -Me-PhCO 2 ) 6 (L) 2 ] (M = Fe, 5 or Al, 7 ) are discussed and compared. To understand the experimental observations for this family, DFT and ab initio CASSCF + RASSI-SO calculations were performed. The experimental and theoretical calculations suggest that altering the 3d III ions can affect the single-ion properties and the nature and the magnitude of the 3d III -3d III , 3d III -Dy III and Dy III -Dy III magnetic coupling, thus quenching the quantum tunneling of magnetisation (QTM) significantly, thereby improving the SMM properties within this motif. This is the first systematic study looking at variation and therefore role of trivalent transition metal ions, as well as the diamgnetic Al III ion, on slow relaxation of magnetisation within a series of isostructural 3d-4f butterfly compounds.

In the search for new single molecule magnets (SMM), i.e., molecular systems that can retain their magnetization without the need to apply an external magnetic field, a successful strategy is to associate 3 d and 4 f ions to form molecular coordination clusters. In order to efficiently design such systems, it is necessary to chemically project both the magnetic building blocks and the resultant interaction before the synthesis. Lanthanide ions can provide the required easy axis magnetic anisotropy that hampers magnetization reversal. In the rare examples of 3 d/ 4 f SMMs containing Cr III ions, the latter turn out to act as quasi-isotropic anchors which can also interact via 3 d -4 f coupling to neighbouring Ln centres. This has been demonstrated in cases where the intramolecular exchange interactions mediated by Cr III ions effectively reduce the efficiency of tunnelling without applied magnetic field. However, describing such high nuclearity systems remains challenging, from both experimental and theoretical perspectives, because the overall behaviour of the molecular cluster is heavily affected by the orientation of the individual anisotropy axes. These are in general non-collinear to each other. In this article, we combine single crystal SQUID and torque magnetometry studies of the octanuclear [Cr 4 Dy 4 (μ 3 -OH) 4 (μ-N 3 ) 4 (mdea) 4 (piv) 8 ]·3CH 2 Cl 2 single molecule magnet (piv=pivalate and mdea= N -methyldiethanol amine). These experiments allowed us to probe the magnetic anisotropy of this complex which displays slow magnetization dynamics due to the peculiar arrangement of the easy-axis anisotropy on the Dy sites. New ab initio calculations considering the entire cluster are in agreement with our experimental results.

The reaction of N -(2-pyridylmethyl)iminodiethanol (H 2 L, pmide), FeCl 2 ·4H 2 O or AlCl 3 ·6H 2 O with ErCl 3 ·6H 2 O and p -Me-PhCO 2 H in the ratio of 2:1:1:4 in the presence of Et 3 N in MeOH and MeCN yielded compounds [Fe 2 Er 2 (μ 3 -OH) 2 (pmide) 2 ( p -Me-PhCO 2 ) 6 ]·2MeCN ( 1 ) and [Al 2 Er 2 (μ 3 -OH) 2 (pmide) 2 ( p -Me-PhCO 2 ) 6 ]·2MeCN ( 2 ). These two complexes are isostructural, possessing a planar butterfly motif with the Er III ions in the wingtip positions. Both compounds show single molecule magnet (SMM) behavior. For the [Al 2 Er 2 ] compound, the slow relaxation of the magnetization under zero applied direct current (dc) field does not show maxima, but the relaxation processes could be analyzed using an applied dc field of 1000 Oe. In-depth alternating current measurements under different dc fields on the [Fe 2 Er 2 ] compound reveals that the Fe-Fe and Fe-Er interactions speed up the relaxation and decrease the energy barrier height of the SMM in comparison with the [Al 2 Er 2 ] case., Competing Interests: The authors declare no competing financial interest.

The reaction of [ α -P₂W 15 O 56 ] 12- with Mn II and Dy III in an aqueous basic solution led to the isolation of an all inorganic heterometallic aggregate Na 10 (OH₂) 42 [{Dy(H₂O)₆}₂Mn₄P₄W 30 O 112 (H₂O)₂]·17H₂O ( Dy₂Mn₄-P₂W 15 ). Single-crystal X-ray diffraction revealed that Dy₂Mn₄-P₂W 15 crystallizes in the triclinic system with space group P 1 ¯ , and consists of a tetranuclear manganese(II)-substituted sandwich-type phosphotungstate [Mn₄(H₂O)₂(P₂W 15 O 56 )₂] 16- ( Mn₄-P₂W 15 ), Na, and Dy III cations. Compound Dy₂Mn₄-P₂W 15 exhibits a 1D ladder-like chain structure based on sandwich-type segments and dysprosium cations as linkers, which are further connected into a three-dimensional open framework by sodium cations. The title compound was structurally and compositionally characterized in solid state by single-crystal XRD, powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TGA), and elemental analyses. Further, the absorption and emission electronic spectra in aqueous solutions of Dy₂Mn₄-P₂W 15 and Mn₄-P₂W 15 were studied. Also, magnetic properties were studied and compared with the magnetic behavior of [Mn₄(H₂O)₂(P₂W 15 O 56 )₂] 16- ., Competing Interests: The authors declare no conflicts of interest.

Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and robust FLFL-dipeptide construct to which a meso-tetraphenylporphyrin has been appended and which self-assembles to fibrils, platelets or nanospheres depending on the solvent composition. The fibrils, functioning as quenched antennas, give intense excitonic couplets in the electronic circular dichroism spectra which are mirror imaged if the unnatural FDFD-analogue is used. By slightly increasing the solvent polarity, these light-harvesting fibres disassemble to spherical structures with silent electronic circular dichroism spectra but which fluoresce. Upon further dilution with the nonpolar solvent, the intense Cotton effects are recovered, thus proving a reversible switching. A single crystal X-ray structure shows a head-to-head arrangement of porphyrins that explains both their excitonic coupling and quenched fluorescence.

In-depth investigations of the low energy electronic structures of mononuclear lanthanide complexes, including single molecule magnets, are challenging at the best of times. For magnetically coupled polynuclear systems, the task seems well nigh impossible. However, without detailed understanding of the electronic structure, there is no hope of understanding their static and dynamic magnetic properties in detail. We have been interested in assessing which techniques are most appropriate for studying lanthanide single-molecule magnets. Here we present a wide ranging theoretical and experimental study of the archetypal polynuclear lanthanide single-molecule magnet Dy 3 and derive the simplest model to describe the results from each experimental method, including high-frequency electron paramagnetic resonance and far-infrared spectroscopies and cantilever torque magnetometry. We conclude that a combination of these methods together with ab initio calculations is required to arrive at a full understanding of the properties of this complex, and potentially of other magnetically coupled lanthanide complexes.

Laser writing is used to structure surfaces in many different ways in materials and life sciences. However, combinatorial patterning applications are still limited. Here we present a method for cost-efficient combinatorial synthesis of very-high-density peptide arrays with natural and synthetic monomers. A laser automatically transfers nanometre-thin solid material spots from different donor slides to an acceptor. Each donor bears a thin polymer film, embedding one type of monomer. Coupling occurs in a separate heating step, where the matrix becomes viscous and building blocks diffuse and couple to the acceptor surface. Furthermore, we can consecutively deposit two material layers of activation reagents and amino acids. Subsequent heat-induced mixing facilitates an in situ activation and coupling of the monomers. This allows us to incorporate building blocks with click chemistry compatibility or a large variety of commercially available non-activated, for example, posttranslationally modified building blocks into the array's peptides with >17,000 spots per cm(2).

To intimately combine a chelating ligand function with the numerous properties of a viologen-like redox-active centre would offer a rare possibility to design controllable multi-redox states, whose properties arise from strongly correlated phenomena between the organic ligand as well as with any metalloid coordinated centres. Such a concept previously proved to be feasible, however is not widely applicable owing to challenges in terms of synthesis, isolation, and aerial sensitivity of both the ligand and its metal complexes. Here we report the first stable example of such a redox-active molecule, N , N '-dimethyl-3,3'-biquinoxalinium 2+/ ˙ +/0 "methylbiquinoxen, MBqn 2+/ ˙ +/0 ", which shows a rich redox chemistry and chelates a metal ion in the case of the metal complex [CdCl 2 (MBqn 0 )]. This goes beyond what is possible to achieve using viologens, which are limited by not providing chelation as well as having no accessible biradicaloid state, corresponding to the neutral direduced MBqn 0 open-shell behaviour we observe here.

Magnetic Resonance Imaging is a powerful tool for the investigation of a biofilms' physical structure determining mass transport behavior which is of major importance in biofilm research. The entire biofilm is imaged in situ non-invasively and non-destructively on a meso-scale. In this study, different contrast agents were applied to study the biofilm's properties with the focus on mass transport, which is achieved by varying the contrast agents with respect to their NMR and interaction properties. The spatio-temporal tracking of these cluster, molecular and particulate contrast agents in biofilms was achieved by T1-, T2-weighted and proton density images during short (20h) and long (14 d) term exposures. The best biofilm surface visualization was observed when applying a new high spin coordination cluster (Fe10Gd10) showing a high affinity to the biofilm's surface and a fast immobilization within minutes. Contrarily, the small molecular contrast agents show no immobilization and fully penetrated into the biofilm. A concentration equilibrium was observed which was confirmed in back diffusion experiments. Interactions between larger nanoparticulate contrast agents and the biofilm required hours to achieve immobilization. Thus, the penetration depth into the biofilm is predominantly size-dependent. Here, it is shown that biofilm surface interactions can be observed in situ and spatio-temporarily resolved. The reported methodology demonstrates a new means to explore mass transfer of various substances in biofilms., Statement of Significance: In biofilm research, the investigation of the biofilms' physical structure is of high relevance for the understanding of mass transport processes. However, commonly used imaging techniques for biofilm imaging such as CLSM or electron microscopy rarely visualize the real biofilm due to their invasiveness and destructiveness. Magnetic Resonance Imaging (MRI) represents the ideal tool to image the biofilm in situ, non-invasively and non-destructively with a spatial resolution of several 10μm. To gain specific structural and functional information, a variety of MRI contrast agents (molecular and particulate) was applied with different properties for the first time. Results elucidate the interactions between the biofilms' surface and the contrast agents and open a new field for biotechnological applications by functional contrast enhancement., (Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Heparan sulfate (HS) polysaccharides are ubiquitous components of the cell surface and extracellular matrix of all multicellular animals, whereas heparin is present within mast cells and can be viewed as a more sulfated, tissue-specific, HS variant. HS and heparin regulate biological processes through interactions with a large repertoire of proteins. Owing to these interactions and diverse effects observed during in vitro, ex vivo and in vivo experiments, manifold biological/pharmacological activities have been attributed to them. The properties that have been thought to bestow protein binding and biological activity upon HS and heparin vary from high levels of sequence specificity to a dependence on charge. In contrast to these opposing opinions, we will argue that the evidence supports both a level of redundancy and a degree of selectivity in the structure-activity relationship. The relationship between this apparent redundancy, the multi-dentate nature of heparin and HS polysaccharide chains, their involvement in protein networks and the multiple binding sites on proteins, each possessing different properties, will also be considered. Finally, the role of cations in modulating HS/heparin activity will be reviewed and some of the implications for structure-activity relationships and regulation will be discussed., (© 2015 The Author(s).)

Single-molecule magnets are compounds that exhibit magnetic bistability purely of molecular origin. The control of anisotropy and suppression of quantum tunneling to obtain a comprehensive picture of the relaxation pathway manifold, is of utmost importance with the ultimate goal of slowing the relaxation dynamics within single-molecule magnets to facilitate their potential applications. Combined ab initio calculations and detailed magnetization dynamics studies reveal the unprecedented relaxation mediated via the second excited state within a new DyNCN system comprising a valence-localized carbon coordinated to a single dysprosium(III) ion. The essentially C2v symmetry of the Dy(III) ion results in a new relaxation mechanism, hitherto unknown for mononuclear Dy(III) complexes, opening new perspectives for means of enhancing the anisotropy contribution to the spin-relaxation barrier.

By using Mössbauer spectroscopy in combination with susceptibility measurements it was possible to identify the supertransferred hyperfine field through the oxygen bridges between Dy(III) and Fe(III) in a {Fe4Dy2} coordination cluster. The presence of the dysprosium ions provides enough magnetic anisotropy to "block" the hyperfine field that is experienced by the iron nuclei. This has resulted in magnetic spectra with internal hyperfine fields of the iron nuclei of about 23 T. The set of data permitted us to conclude that the direction of the anisotropy in lanthanide nanosize molecular clusters is associated with the single ion and crystal field contributions and (57)Fe Mössbauer spectroscopy may be informative with regard to the the anisotropy not only of the studied isotope, but also of elements interacting with this isotope.

Systematical studies of the electrochemical performance of CF x -derived carbon-FeF2 nanocomposites for reversible lithium storage are presented. The conversion cathode materials were synthesized by a simple one-pot synthesis, which enables a reactive intercalation of nanoscale Fe particles in a CF x matrix, and the reaction of these components to an electrically conductive C-FeF2 compound. The pretreatment and the structure of the utilized CF x precursors play a crucial role in the synthesis and influence the electrochemical behavior of the conversion cathode material. The particle size of the CF x precursor particles was varied by ball milling as well as by choosing different C/F ratios. The investigations led to optimized C-FeF2 conversion cathode materials that showed specific capacities of 436 mAh/g at 40 °C after 25 cycles. The composites were characterized by Raman spectroscopy, X-Ray diffraction measurements, electron energy loss spectroscopy and TEM measurements. The electrochemical performances of the materials were tested by galvanostatic measurements.

Array methodologies have become powerful tools for interrogation of glycan-protein interactions but have critically lacked the ability to generate cell response data. Here, we report the development of a slide-based array method exemplified by measurement of activation of fibroblast growth factor signaling by heparin saccharides. Heparan sulfate-deficient Swiss 3T3 cells were overlaid onto an aminosilane-coated slide surface onto which heparin saccharides had been spotted and immobilized. The cells were transiently stimulated with FGF2 and immunofluorescence measured to assess downstream ERK1/2 phosphorylation. Activation of this signaling pathway response was restricted to cells exposed to heparin saccharides competent to activate FGF2 signaling. Differential activation of the overlaid cells by different-sized heparin saccharides was demonstrated by quantitative measurement of fluorescence intensity. This "glycobioarray" platform has significant potential as a generic tool for functional glycomics screening., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Parkinson's disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified Cu(II)(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that Cu(II)(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.

With the discovery of the phenomenon of single-molecule magnetism, coordination chemists have turned their attention to synthesizing cluster aggregates of paramagnetic ions. This has led to a plethora of coordination clusters with various topologies and diverse magnetic properties. In this paper, we present ways of describing and understanding such compounds as well as outlining a new approach, which we have recently developed, to describing cluster topology. Our approach is based upon and pays tribute to the huge contribution made to coordination chemistry through the development of the Schläfli symbols for describing architectures. To illustrate the developments that are taking place in modern coordination chemistry, we start with some basic definitions of relevance to what follows. Then we describe approaches to discovering new magnetically interesting 3d/4f clusters, assigning their topological descriptions. Finally, we show how the concepts behind the construction of metal-organic frameworks can be extended to using clusters as nodes in the frameworks to give super metal-organic frameworks.

The reaction of CoCl(2).6H(2)O with m-BDTH(2) (1,3-benzeneditetrazol-5-yl) leads to [Co(C(8)H(6)N(8))(2)(H(2)O)(2)(CH(3)CN)(2)]Cl(2) (1). Both tetrazolic groups remain protonated existing in a 1H tautomeric form. A trifurcated chlorine atom and stacking interactions assemble compound 1 into a three-dimensional network.

Glycomics is a developing field that provides structural information on complex populations of glycans isolated from tissues, cells and organs. Strategies employing matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) are central to glycomic analysis. Current MALDI-based glycomic strategies are capable of efficiently analyzing glycoprotein and glycosphingolipid glycomes but little attention has been paid to devising glycomic methodologies suited to the analysis of glycosaminoglycan (GAG) polysaccharides which pose special problems for MALDI analysis because of their high level of sulfation and large size. In this paper, we describe MALDI strategies that have been optimized for the analysis of highly sulfated GAG-derived oligosaccharides. A crystalline matrix norharmane, as well as an ionic liquid 1-methylimidazolium alpha-cyano-4-hydroxycinnamate (ImCHCA), have been used for the analysis of heparin di-, tetra-, hexa- and decasaccharides carrying from 2 to 13 sulfate groups. Information about the maximum number of sulfate groups is obtained using the ionic liquid whereas MALDI-TOF/TOF MS/MS experiments using norharmane allowed the determination of the nature of the glycosidic backbone, and more precise information about the presence and the position in the sequence of N-acetylated residues.

Slit is a large secreted protein that provides important guidance cues in the developing nervous system and in other organs. Signaling by Slit requires two receptors, Robo transmembrane proteins and heparan sulfate (HS) proteoglycans. How HS controls Slit-Robo signaling is unclear. Here we show that the second leucine-rich repeat domain (D2) of Slit, which mediates binding to Robo receptors, also contains a functionally important binding site for heparin, a highly sulfated variant of HS. Heparin markedly enhances the affinity of the Slit-Robo interaction in a solid-phase binding assay. Analytical gel filtration chromatography demonstrates that Slit D2 associates with a soluble Robo fragment and a heparin-derived oligosaccharide to form a ternary complex. Retinal growth cone collapse triggered by Slit D2 requires cell surface HS or exogenously added heparin. Mutation of conserved basic residues in the C-terminal cap region of Slit D2 reduces heparin binding and abolishes biological activity. We conclude that heparin/HS is an integral component of the minimal Slit-Robo signaling complex and serves to stabilize the relatively weak Slit-Robo interaction.

Using numerical optimization algorithm, non-periodic Mo/Si, Mo/Be, and Ni/C broad angular multilayer analyzers have been designed. At the wavelength of 13 nm and the angular range of 45~49 degrees , the Mo/Si and Mo/Be multilayer can provide the plateau s-reflectivity of 65% and 45%, respectively. At 5.7 nm, the s-reflectivity of Ni/C multilayer is 16% in the 44~46 degrees range. The non-periodic Mo/Si broad angular multilayer was also fabricated using DC magnetron sputtering, and characterized using the soft X-ray polarimeter at BESSY. The s-reflectivity is higher than 45.6% over the angular range of 45~49 degrees at 13 nm, where, the degree of polarization is more than 99.98%.

The structures and electrochemistry of N-benzylated meso-tetrakis (3,5-di-tert-butyl-4-oxo-cyclohexa-2,5-dienylidene) porphyrinogens have been investigated. Structural determinations reveal the isomeric identity of the products obtained from the N-alkylation of the parent meso-tetra (oxo-cyclohexadienylidene) porphyrinogen. The compounds are subject to increased macrocyclic deformations upon increasing N-substitution culminating in the tetra-N-benzyl derivative, which has a buckling superimposed on the already highly puckered macrocycle. The electrochemical analyses emphasize the electron deficiency of the N-benzylated meso-tetra(oxo-cyclohexadienylidene) porphyrinogens and indicate that they can be considered as quinones conjugated via the unsaturated tetrapyrrolic macrocycle. The N-benzylated compounds studied form stable and well-defined pi-cation radical and pi-anion radical species because of their highly conjugated nature. Ab initio molecular orbital calculations at the B3LYP/3-21G() level confirmed the high degree of conjugation between tetrapyrrole and meso substituents and also gave good agreement between calculated and experimentally determined HOMO-LUMO band gap energies.