Cyclometalated luminescent platinum(II) complexes of dissymmetrical 2,2':4',2''-terpyridine and its self-assembled dimer presenting Pt-Ag dative bonds.

A series of cyclometalated (N^C^N) Pt(II)-platinum complexes featuring a terpyridine ligand with a non-coordinating nitrogen atom and a Pt-C bond was synthesized. In the presence of Ag, the bis(isonitrile)Pt(II) complex formed a remarkable self-assembled helicoidal dimer stabilized by coordination of Ag(I) and metallophilic Pt-Ag interactions. Its assembly was observed in the solid state and maintained in solution.

Allergen-specific immunotherapy and COVID-19: What happened?

Background: The COVID-19 infection played a key role in the discontinuation of patient treatment, such as allergen-specific immunotherapy, in chronic diseases.

Objectives: We conducted a retrospective observational study at Verona University Hospital, Verona, Italy, to assess the level of adherence to sublingual immunotherapy (SLIT) in patients affected by allergic rhinitis and mild asthma.

Materials And Methods: We compared and analysed data related to first prescription and collection of 5-grass-pollen 300-index of reactivity (IR) SLIT and tablet lyophilisate, containing 75,000 standardized quality tablet units (SQ-T) allergen extract of grass-pollen from L, for the five-year period 2017-2021.

Proton-detected fast-magic-angle spinning NMR of paramagnetic inorganic solids.

Fast (60 kHz) magic angle spinning solid-state NMR allows very sensitive proton detection in highly paramagnetic organometallic powders. We showcase this technique with the complete assignment of H and C resonances in a high-spin Fe(ii) polymerisation catalyst with less than 2 mg of sample at natural abundance.

Development of a Borane-(Meth)acrylate Photo-Click Reaction.

In the development of 3D printing fuels, there is a need for new photoinitiating systems working under mild conditions and/or leading to polymers with new and/or enhanced properties. In this context, we introduce herein N-heterocyclic carbene-borane complexes as reagents for a new type of photo-click reaction, the borane-(meth)acrylate click reaction. Remarkably, the higher bond number of boranes relative to thiols induced an increase of the network density associated with faster polymerization kinetics.

Picometer Resolution Structure of the Coordination Sphere in the Metal-Binding Site in a Metalloprotein by NMR.

Most of our understanding of chemistry derives from atomic-level structures obtained with single-crystal X-ray diffraction. Metal centers in X-ray structures of small organometallic or coordination complexes are often extremely well-defined, with errors in the positions on the order of 10-10 Å. Determining the metal coordination geometry to high accuracy is essential for understanding metal center reactivity, as even small structural changes can dramatically alter the metal activity.

Paramagnetic Cobalt(II) Complexes with Cyclam Derivatives: Toward F MRI Contrast Agents.

In order to develop novel, more efficient, and/or selective contrast agents for magnetic resonance imaging (MRI), different are explored as alternatives to water-relaxation enhancement. In this work, cobalt(II/III) complexes of bis(-trifluoroethyl)cyclam derivatives with two acetate or two phosphonate pendant arms, H and H, were prepared and investigated. X-ray diffraction structures confirmed octahedral coordination with a very stable - cyclam conformation and with fluorine atoms located about 5.

Dual switchable molecular tweezers incorporating anisotropic Mn-salphen complexes.

An alternative strategy for the synthesis of terpyridine based switchable molecular tweezers has been developed to incorporate anisotropic Mn(iii)-salphen complexes. The free ligand was synthesized using a building block strategy based on Sonogashira coupling reactions and was then selectively metalated with manganese in a last step. The conformation of the tweezers was switched from an open 'W' shaped form to a closed 'U' form by Zn(ii) coordination to the terpyridine unit bringing the two Mn-salphen moieties in close spatial proximity as confirmed by X-ray crystallography.

Pseudocontact shifts and paramagnetic susceptibility in semiempirical and quantum chemistry theories.

Pseudocontact shifts are traditionally described as a function of the anisotropy of the paramagnetic susceptibility tensor, according to the semiempirical theory mainly developed by Kurland and McGarvey [J. Magn. Reson.

Synthesis and Guest Recognition of Switchable Pt-Salphen Based Molecular Tweezers.

Molecular tweezers are artificial receptors that have an open cavity generated by two recognition units pre-organized by a spacer. Switchable molecular tweezers, using a stimuli-responsive spacer, are particularly appealing as prototypes of the molecular machines that combine mechanical motion and allosteric recognition properties. In this present study, the synthesis of switchable molecular tweezers composed of a central terpyridine unit substituted in 4,4″ positions by two Pt(II)-salphen complexes is reported.

Six States Switching of Redox-Active Molecular Tweezers by Three Orthogonal Stimuli.

A six level molecular switch based on terpyridine(Ni-salphen) tweezers and addressable by three orthogonal stimuli (metal coordination, redox reaction, and guest binding) is reported. By a metal coordination stimulus, the tweezers can be mechanically switched from an open "W"-shaped conformation to a closed "U"-shaped form. Theses two states can each be reversibly oxidized by the redox stimulus and bind to a pyrazine guest resulting in four additional states.

A Straightforward Access to Stable, 16 Valence-electron Phosphine-Stabilized Fe Olefin Complexes and their Reactivity.

The use of the dialkene divinyltetramethyldisiloxane (dvtms) allows easy access to the reactive 16 valence-electron complexes [Fe(L-L)(dvtms)], (L-L) = dppe (1,2-bis(diphenylphosphino)ethane), (), dppp (1,2-bis(diisopropylphosphino)propane), (), pyNMeP(Pr) (N-(diisopropylphosphino)-N-methylpyridin-2-amine), (), dipe (1,2-bis(diisopropylphosphino)ethane), (), and [Fe(L)(dvtms)], L = PMe, (), by a mild reductive route using AlEt(OEt) as reducing agent. In contrast, by the same methodology, the 18 valence-electron complexes [Fe(L-L)(ethylene)], (L-L) = dppm (1,2-bis(diphenylphosphino)methane), , (L-L) = dppa (1,2-bis(diphenylphosphino)amine) or (L-L)=dppe, , were obtained, which do not contain dvtms. In addition, a combined DFT and solid-state paramagnetic NMR methodology is introduced for the structure determination of .

Pseudo-Contact NMR Shifts over the Paramagnetic Metalloprotein CoMMP-12 from First Principles.

Long-range pseudo-contact NMR shifts (PCSs) provide important restraints for the structure refinement of proteins when a paramagnetic metal center is present, either naturally or introduced artificially. Here we show that ab initio quantum-chemical methods and a modern version of the Kurland-McGarvey approach for paramagnetic NMR (pNMR) shifts in the presence of zero-field splitting (ZFS) together provide accurate predictions of all PCSs in a metalloprotein (high-spin cobalt-substituted MMP-12 as a test case). Computations of 314 C PCSs using g- and ZFS tensors based on multi-reference methods provide a reliable bridge between EPR-parameter- and susceptibility-based pNMR formalisms.

Building Virtual Watersheds: A Global Opportunity to Strengthen Resource Management and Conservation.

Modern land-use planning and conservation strategies at landscape to country scales worldwide require complete and accurate digital representations of river networks, encompassing all channels including the smallest headwaters. The digital river networks, integrated with widely available digital elevation models, also need to have analytical capabilities to support resource management and conservation, including attributing river segments with key stream and watershed data, characterizing topography to identify landforms, discretizing land uses at scales necessary to identify human-environment interactions, and connecting channels downstream and upstream, and to terrestrial environments. We investigate the completeness and analytical capabilities of national to regional scale digital river networks that are available in five countries: Canada, China, Russia, Spain, and United States using actual resource management and conservation projects involving 12 university, agency, and NGO organizations.

Vibrational Properties of the Phosphate Group Investigated by Molecular Dynamics and Density Functional Theory.

The phosphate group (PO2(-)) is an important building block occurring in many components of living matter including nucleic acids. It provides distinct features in vibrational spectra and is useful as a local probe of NA conformation and interactions with the environment. For this purpose, it is desirable to explore in detail various factors influencing spectral shapes of characteristic phosphate vibrations.

Efficacy and acceptability of antidepressants on the continuum of depressive experiences in patients with cancer: Systematic review and meta-analysis.

Background: Patients with cancer are particularly vulnerable to depressive experiences, ranging from severe emotional reactions to proper depressive syndromes, including major depression. These experiences may deeply affect the course and outcome of the disease. The aim of this study was to assess the efficacy acceptability of antidepressants on the continuum of depressive experiences in patients suffering from cancer.

Determination of size of molecular clusters of ethanol by means of NMR diffusometry and hydrodynamic calculations.

The microscopic structure of ethanol in the liquid state is characterized as a dynamic equilibrium of hydrogen-bonded clusters of different sizes and topologies. We have developed a novel method for determination of the average size of the clusters that combines the measurement of diffusion coefficient by means of NMR diffusometry technique and hydrodynamic simulations. The approach includes the use of HydroNMR [J.

Influence of the O-phosphorylation of serine, threonine and tyrosine in proteins on the amidic ¹⁵N chemical shielding anisotropy tensors.

Density functional theory was employed to study the influence of O-phosphorylation of serine, threonine, and tyrosine on the amidic (15)N chemical shielding anisotropy (CSA) tensor in the context of the complex chemical environments of protein structures. Our results indicate that the amidic (15)N CSA tensor has sensitive responses to the introduction of the phosphate group and the phosphorylation-promoted rearrangement of solvent molecules and hydrogen bonding networks in the vicinity of the phosphorylated site. Yet, the calculated (15)N CSA tensors in phosphorylated model peptides were in range of values experimentally observed for non-phosphorylated proteins.

Detection of mercury-TpT dinucleotide binding by Raman spectra: a computational study.

The Hg(2+) ion stabilizes the thymine-thymine mismatched base pair and provides new ways of creating various DNA structures. Recently, such T-Hg-T binding was detected by the Raman spectroscopy. In this work, detailed differences in vibrational frequencies and Raman intensity patterns in the free TpT dinucleotide and its metal-mediated complex (TpT·Hg)(2) are interpreted on the basis of quantum chemical modeling.

Raman spectroscopic detection of the T-Hg II-T base pair and the ionic characteristics of mercury.

Developing applications for metal-mediated base pairs (metallo-base-pair) has recently become a high-priority area in nucleic acid research, and physicochemical analyses are important for designing and fine-tuning molecular devices using metallo-base-pairs. In this study, we characterized the Hg(II)-mediated T-T (T-Hg(II)-T) base pair by Raman spectroscopy, which revealed the unique physical and chemical properties of Hg(II). A characteristic Raman marker band at 1586 cm(-1) was observed and assigned to the C4=O4 stretching mode.

Correlating the 31P NMR chemical shielding tensor and the 2J(P,C) spin-spin coupling constants with torsion angles ζ and α in the backbone of nucleic acids.

Determination of nucleic acid (NA) structure with NMR spectroscopy is limited by the lack of restraints on conformation of NA phosphate. In this work, the (31)P chemical shielding tensor, the Γ(P,C5'H5'1) and Γ(P,C5'H5'2) cross-correlated relaxation rates, and the (2)J(P,C3'), (2)J(P,C5'), and (3)J(P,C4') coupling constants were calculated in dependence on NA backbone torsion angles ζ and α. While the orientation of the (31)P chemical shielding tensor was almost independent of the NA phosphate conformation, the principal tensor components varied by up to ~40 ppm.

Calculating the response of NMR shielding tensor σ(31P) and 2J(31P,13C) coupling constants in nucleic acid phosphate to coordination of the Mg2+ cation.

Dependence of NMR (31)P shielding tensor and (2)J(P,C) coupling constants on solvation of nucleic acid phosphate by Mg(2+) and water was studied using methods of bioinformatic structural analyses of crystallographic data and DFT B3LYP calculations of NMR parameters. The effect of solvent dynamics on NMR parameters was calculated using molecular dynamic. The NMR calculations for representative solvation patterns determined in crystals of B-DNA and A-RNA molecules pointed out the crucial importance of local Mg(2+) coordination geometry, including hydration by explicit water molecules and necessity of dynamical averaging over the solvent reorientation.

On the role of mercury in the non-covalent stabilisation of consecutive U-Hg(II)-U metal-mediated nucleic acid base pairs: metallophilic attraction enters the world of nucleic acids.

Metal atoms with a closed-shell electronic structure and positive charge as for example the Au(I), Pt(II), Ag(I), Tl(I) or Hg(II) atoms do not in some compounds repel each other due to the so-called metallophilic attraction (P. Pyykkö, Chem. Rev.

Theoretical modeling of magnesium ion imprints in the Raman scattering of water.

Hydration envelopes of metallic ions significantly influence their chemical properties and biological functioning. Previous computational studies, nuclear magnetic resonance (NMR), and vibrational spectra indicated a strong affinity of the Mg(2+) cation to water. We find it interesting that, although monatomic ions do not vibrate themselves, they cause notable changes in the water Raman signal.

Theoretical study of the effective Chemical Shielding Anisotropy (CSA) in peptide backbone, rating the impact of CSAs on the cross-correlated relaxations in L-alanyl-L-alanine.

The dependence of the effective chemical shielding anisotropy (effective CSA, Deltasigma(eff)) on the phi and psi peptide backbone torsion angles was calculated in the l-alanyl-l-alanine (LALA) peptide using the DFT method. The effects of backbone conformation, molecular charge including the cation, zwitterion, and anion forms of the LALA peptide, and the scaling taking into account the length of the dipolar vector were calculated for the effective CSAs in order to assess their structural behaviors and to predict their magnitudes which can be probed for the beta-sheet and alpha-helix backbone conformations via measurement of the cross-correlated relaxation rates (CCR rates). Twenty different CSA-DD cross-correlation mechanisms involving the amide nitrogen and carbonyl carbon chemical shielding tensors and the C(alpha)H(alpha) (alpha-carbon group), NH(N) (amide group), C(alpha)H(N), NH(alpha), C'H(alpha), and C'H(N) (alpha = alpha1, alpha2) dipolar vectors were investigated.