EPR characterization of Mn(ii) complexes for distance determination with pulsed dipolar spectroscopy.

The four Mn(ii) complexes Mn-DOTA, Mn-TAHA, Mn-PyMTA, and Mn-NO3Py were characterized by electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), and relaxation measurements, to predict their relative performance in the EPR pulse dipolar spectroscopy (PDS) experiments. High spin density localization on the metal ions was proven by ENDOR on H, D, N, and Mn nuclei. The transverse relaxation of the Mn(ii) complexes appears to be slow enough for PDS-based spin-spin distance determination.

Rapid acquisition of mean Raman spectra of eukaryotic cells for a robust single cell classification.

Raman spectroscopy has previously been used to identify eukaryotic and prokaryotic cells. While prokaryotic cells are small in size and can be assessed by a single Raman spectrum, the larger size of eukaryotic cells and their complex organization requires the acquisition of multiple Raman spectra to properly characterize them. A Raman spectrum from a diffraction-limited spot at an arbitrary location within a cell results in spectral variations that affect classification approaches.

Bis(mesitoyl)phosphinic acid: photo-triggered release of metaphosphorous acid in solution.

Bis(mesitoyl)phosphinic acid and its sodium salt display a unique photo-induced reactivity: both derivatives stepwise release two mesitoyl radicals and, remarkably, metaphosphorous acid (previously postulated as transient species in the gas phase), providing a new phosphorus-based reagent.

Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device.

Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(μ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports.

Efficient determination of accurate atomic polarizabilities for polarizeable embedding calculations.

We evaluate embedding potentials, obtained via various methods, used for polarizable embedding computations of excitation energies of para-nitroaniline in water and organic solvents as well as of the green fluorescent protein. We found that isotropic polarizabilities derived from DFTD3 dispersion coefficients correlate well with those obtained via the LoProp method. We show that these polarizabilities in conjunction with appropriately derived point charges are in good agreement with calculations employing static multipole moments up to quadrupoles and anisotropic polarizabilities for both computed systems.

Cellular uptake of PLA nanoparticles studied by light and electron microscopy: synthesis, characterization and biocompatibility studies using an iridium(III) complex as correlative label.

We present the synthesis of polylactide by ring-opening polymerization using a luminescent iridium(III) complex acting as initiator. The polymer was formulated into nanoparticles, which were taken up by HEK-293 cells. We could show that the particles provided an appropriate contrast in both superresolution fluorescence and electron microscopy, and, moreover, are non-toxic, in contrast to the free iridium complex.

All-in-one: a versatile gas sensor based on fiber enhanced Raman spectroscopy for monitoring postharvest fruit conservation and ripening.

In today's fruit conservation rooms the ripening of harvested fruit is delayed by precise management of the interior oxygen (O2) and carbon dioxide (CO2) levels. Ethylene (C2H4), a natural plant hormone, is commonly used to trigger fruit ripening shortly before entering the market. Monitoring of these critical process gases, also of the increasingly favored cooling agent ammonia (NH3), is a crucial task in modern postharvest fruit management.

Resonant X-ray emission spectroscopy of platinum(II) anticancer complexes.

Platinum-based drugs are commonly used in cancer treatment. The biological activity of a metallodrug is obviously closely related to its chemical and stereochemical characteristics. An overlooked aspect is the effect of the ligand to the electronic structure of the metal atom (coordinated atom).

Quantitative Activity Measurements of Brown Adipose Tissue at 7 T Magnetic Resonance Imaging After Application of Triglyceride-Rich Lipoprotein 59Fe-Superparamagnetic Iron Oxide Nanoparticle: Intravenous Versus Intraperitoneal Approach.

Objectives: The aim of this study was to determine metabolic activity of brown adipose tissue (BAT) with in vivo magnetic resonance imaging (MRI) after intravenous (IV) and intraperitoneal (IP) injection of radioactively labeled superparamagnetic iron oxide nanoparticles (SPIOs) embedded into a lipoprotein layer.

Materials And Methods: Fe-labeled SPIOs were either polymer-coated or embedded into the lipid core of triglyceride-rich lipoproteins (TRL-Fe-SPIOs). First biodistribution and blood half time analysis in thermoneutral mice after IP injection of either TRL-Fe-SPIOs or polymer-coated Fe-SPIOs (n = 3) were performed.

Reformulation of the D3(Becke-Johnson) Dispersion Correction without Resorting to Higher than C₆ Dispersion Coefficients.

A reformulated version of Grimme's most recent DFT dispersion correction with Becke-Johnson damping (DFT-D3(BJ)) is presented, which only depends on C6 dispersion coefficients. The role of the higher order correction terms in the DFT-D3(BJ) model is critically investigated, and a sigmoidal interpolation function for adjusting to different density functional approximations (DFA) is employed alternatively, while keeping finite damping of Becke and Johnson. For the proposed C6-only dispersion correction scheme, only one parameter needs to be fitted per DFA (instead of three for DFT-D3(BJ)).

Developments in spontaneous and coherent Raman scattering microscopic imaging for biomedical applications.

First, the potential role of Raman-based techniques in biomedicine is introduced. Second, an overview about the instrumentation for spontaneous and coherent Raman scattering microscopic imaging is given with a focus of recent developments. Third, imaging strategies are summarized including sequential registration with laser scanning microscopes, line imaging and global or wide-field imaging.

Energy transfer and formation of long-lived (3)MLCT states in multimetallic complexes with extended highly conjugated bis-terpyridyl ligands.

Multimetallic complexes with extended and highly conjugated bis-2,2':6',2''-terpyridyl bridging ligands, which present building blocks for coordination polymers, are investigated with respect to their ability to act as light-harvesting antennae. The investigated species combine Ru(II)- with Os(II)- and Fe(II)-terpyridyl chromophores, the latter acting as energy sinks. Due to the extended conjugated system the ligands are able to prolong the lifetime of the (3)MLCT states compared to unsubstituted terpyridyl species by delocalization and energetic stabilization of the (3)MLCT states.

High-resolution X-ray absorption spectroscopy of iron carbonyl complexes.

We apply high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) to study iron carbonyl complexes. Mono-, bi-, and tri-nuclear carbonyl complexes and pure carbonyl complexes as well as carbonyl complexes containing hydrocarbon ligands are considered. The HERFD-XANES spectra reveal multiple pre-edge peaks with individual signatures for each complex, which could not be detected previously with conventional XANES spectroscopy.

Tailored surface-enhanced Raman nanopillar arrays fabricated by laser-assisted replication for biomolecular detection using organic semiconductor lasers.

Organic semiconductor distributed feedback (DFB) lasers are of interest as external or chip-integrated excitation sources in the visible spectral range for miniaturized Raman-on-chip biomolecular detection systems. However, the inherently limited excitation power of such lasers as well as oftentimes low analyte concentrations requires efficient Raman detection schemes. We present an approach using surface-enhanced Raman scattering (SERS) substrates, which has the potential to significantly improve the sensitivity of on-chip Raman detection systems.

Cytoadhesion of Plasmodium falciparum-infected erythrocytes to chondroitin-4-sulfate is cooperative and shear enhanced.

Infections with the human malaria parasite Plasmodium falciparum during pregnancy can lead to severe complications for both mother and child, resulting from the cytoadhesion of parasitized erythrocytes in the intervillous space of the placenta. Cytoadherence is conferred by the specific interaction of the parasite-encoded adhesin VAR2CSA with chondroitin-4-sulfate (CSA) present on placental proteoglycans. CSA presented elsewhere in the microvasculature does not afford VAR2CSA-mediated cytoadhesion of parasitized erythrocytes.

Plasmons in molecules: microscopic characterization based on orbital transitions and momentum conservation.

In solid state physics, electronic excitations are often classified as plasmons or single-particle excitations. The former class of states refers to collective oscillations of the electron density. The random-phase approximation allows for a quantum-theoretical treatment and a characterization on a microscopic level as a coherent superposition of a large number of particle-hole transitions with the same momentum transfer.

Emergent long-range couplings in arrays of fluid cells.

We present a system exhibiting extraordinarily long-range cooperative effects, on a length scale far exceeding the bulk correlation length. We give a theoretical explanation of these phenomena based on the mesoscopic picture of phase coexistence in finite systems, which is confirmed by Monte Carlo simulation studies. Our work demonstrates that such action at a distance can occur in classical systems involving simple or complex fluids, such as colloid-polymer mixtures or ferromagnets.

Efficient calculation of anharmonic vibrational spectra of large molecules with localized modes.

The analysis and interpretation of the vibrational spectra of complex (bio)molecular systems, such as polypeptides and proteins, requires support from quantum-chemical calculations. Such calculations are currently restricted to the harmonic approximation. Here, we show how one of the main bottlenecks in such calculations, the evaluation of the potential energy surface, can be overcome by using localized modes instead of the commonly employed normal modes.

Why selenocysteine replaces cysteine in thioredoxin reductase: a radical hypothesis.

Thioredoxin reductases, important biological redox mediators for two-electron transfers, contain either 2 cysteines or a cysteine (Cys) and a selenocysteine (Sec) at the active site. The incorporation of Sec is metabolically costly, and therefore surprising. We provide here a rationale: in the case of an accidental one-electron transfer to a S-S or a S-Se bond during catalysis, a thiyl or a selanyl radical, respectively would be formed.

An isomeric reaction benchmark set to test if the performance of state-of-the-art density functionals can be regarded as independent of the external potential.

Some representative density functionals are assessed for isomerization reactions in which heteroatoms are systematically substituted with heavier members of the same element group. By this, it is investigated if the functional performance depends on the elements involved, i.e.

Critical Casimir forces along the isofields.

Using quasiexact numerical density-matrix renormalization-group techniques we calculate the critical Casimir force for a two-dimensional (2D) Ising strip with equal strong surface fields, along the thermodynamic paths corresponding to the fixed nonzero bulk field h≠0. Using the Derjaguin approximation we also determine the critical Casimir force and its potential for two disks. We find that varying the temperature along the isofields lying between the bulk coexistence and the capillary condensation critical point leads to a dramatic increase of the critical Casimir interactions with a qualitatively different functional dependence on the temperature than along h=0.

Synthesis of polyhydroxylated quinolizidines and azaspiro[4.5]decanes from D-xylose.

The synthesis of novel polyhydroxylated quinolizidines and azaspiro[4.5]decanes is reported. A key step of this transformation involved an addition of allylmagnesium bromide to an ω-bromonitrile derived from D-xylose followed by an intramolecular displacement of a bromide.

Adhesion maturation of neutrophils on nanoscopically presented platelet glycoprotein Ibα.

Neutrophilic granulocytes play a fundamental role in cardiovascular disease. They interact with platelet aggregates via the integrin Mac-1 and the platelet receptor glycoprotein Ibα (GPIbα). In vivo, GPIbα presentation is highly variable under different physiological and pathophysiological conditions.

Quantum-Chemical Electron Densities of Proteins and of Selected Protein Sites from Subsystem Density Functional Theory.

The ability to calculate accurate electron densities of full proteins or of selected sites in proteins is a prerequisite for a fully quantum-mechanical calculation of protein-protein and protein-ligand interaction energies. Quantum-chemical subsystem methods capable of treating proteins and other biomolecular systems provide a route to calculate the electron densities of proteins efficiently and further make it possible to focus on specific parts. Here, we evaluate and extend the 3-partition frozen-density embedding (3-FDE) scheme [Jacob, C.

The chemical sensitivity of X-ray spectroscopy: high energy resolution XANES versus X-ray emission spectroscopy of substituted ferrocenes.

X-ray spectroscopy at the metal K-edge is an important tool for understanding catalytic processes and provides insight into the geometric and electronic structures of transition metal complexes. In particular, X-ray emission-based methods such as high-energy resolution fluorescence detection (HERFD), X-ray absorption near-edge spectroscopy (XANES) and valence-to-core X-ray emission spectroscopy (V2C-XES) hold the promise of providing increased chemical sensitivity compared to conventional X-ray absorption spectroscopy. Here, we explore the ability of HERFD-XANES and V2C-XES spectroscopy to distinguish substitutions beyond the directly coordinated atoms for the example of ferrocene and selected ferrocene derivatives.