Indirect Anti-Markovnikov Hydrofunctionalization of Terminal Alkenes via an Alkenyl Thianthrenium Intermediate.

The anti-Markovnikov hydrofunctionalization of terminal, unactivated olefins is an evergreen synthetic challenge in organic chemistry. Several direct and indirect anti-Markovnikov methods have been developed, ranging from the classical hydroboration/oxidation protocol to state-of-the-art photoredox catalytic, transition metal complex-catalyzed and enzymatic procedures. Despite the ever-expanding suite of synthetic capabilities, these methods still have limited generality in their substrate scope, especially with nucleophiles.

Finding the best column for polar basic analytes across reversed-phase and hydrophilic interaction liquid chromatography.

Background: The chromatographic measurement of polar molecules is often surprisingly complicated. On the one hand, the standard experiments use C18 columns, which is usually unsuitable. On the other hand, these types of molecules can behave vastly differently despite their similarities.

Studies on a Urea-Complexed Iron(III) Dichromate, a Precursor of Chromium-Rich Nanospinel Catalysts Prepared for the Reductive Transformation of Carbon Dioxide.

Energy-saving and cost-efficient reaction routes to prepare highly active catalysts for CO hydrogenation or solid oxide fuel cells (SOFCs) are enormously important. In this paper, we report a detailed study of a dichromate salt of [Fe(urea)], a member of the [(urea)] complex family ( = Fe, Al, Mn, Cr, V, or Ti) with oxidizing anions, which is a promising precursor of a Cr-rich mixed chromium iron oxide catalyst prepared at a low temperature in the solid phase. The single-crystal X-ray structure, various (infrared, ultraviolet-visible, and Raman) spectroscopic studies, and thermal analysis (differential scanning calorimetry and thermogravimetric analysis/mass spectrometry) of [hexakis(urea-)iron(III)] dichromate {[Fe(urea-O)](CrO)} and its decomposition products confirmed the presence of a quasi-intramolecular redox reaction between the urea ligands and dichromate anions.

Carborane-Decorated Siloles with Highly Efficient Solid-State Emissions - What Drives the Photophysical Properties?

New hybrids were synthesised by linking carboranes and siloles, both of which are known as aggregation-induced emission active units. Although most of the newly synthesised systems do not display notable quantum yield either in solution or in the aggregated state, they emit strongly in the solid-state, and a quantum yield of up to 100 % can be achieved. The tailorable quantum yield can be attributed to the packing of the molecules in the crystal lattice ruled by the carborane and phenyl moieties according to the SC-XRD data.

Nonionic Amphiphilic Copolymers of Poly(poly(ethylene Glycol) Methacrylate) Brushes with Methyl Methacrylate Prepared by Atom Transfer Radical Polymerization as Dry Solid Polymer Electrolytes for Next Generation Li-ion Battery Applications.

Amphiphilic copolymers of comb-like poly(poly(ethylene glycol) methacrylate) (PPEGMA) with methyl methacrylate (MMA) synthesized by one-pot atom transfer radical polymerization were mixed with lithium bis (trifluoromethanesulfonyl) imide salt to formulate dry solid polymer electrolytes (DSPE) for semisolid-state Li-ion battery applications. The PEO-type side chain length (EO monomer's number) in the PEGMA macromonomer units was varied, and its influence on the mechanical and electrochemical characteristics was investigated. It was found that the copolymers, due to the presence of PMMA segments, possess viscoelastic behavior and less change in mechanical properties than a PEO homopolymer with 100 kDa molecular weight in the investigated temperature range.

Solution equilibrium and redox properties of metal complexes with 2-formylpyridine guanylhydrazone derivatives: Effect of morpholine and piperazine substitutions.

Schiff bases derived from aminoguanidine are extensively investigated for their structural versatility. The tridentate 2-formylpyridine guanylhydrazones act as analogues of 2-formyl or 2-acetylpyridine thiosemicarbazones, where the thioamide unit is replaced by the guanidyl group. Six derivatives of 2-formylpyridine guanylhydrazone were synthesized and their proton dissociation and complex formation processes with Cu(II), Fe(II) and Fe(III) ions were studied using pH-potentiometry, UV-visible, NMR and electron paramagnetic resonance spectroscopic methods.

Organometallic Half-Sandwich Complexes of 8-Hydroxyquinoline-Derived Mannich Bases with Enhanced Solubility: Targeting Multidrug Resistant Cancer.

Drug resistance is a major obstacle in cancer treatment. Herein, four novel organometallic complexes, with the general formula [Ru(η--cymene)(HL)Cl]Cl and [Rh(η-CMe)(HL)Cl]Cl, were developed to target multidrug-resistant (MDR) cancer cells, where HL denotes 8-hydroxyquinoline-derived Mannich bases (HQCl-pyr and HQCl-pip). The aim of the complexation was to obtain compounds with improved drug-like properties.

Seeing and Cleaving: Turn-Off Fluorophore Uncaging and Its Application in Hydrogel Photopatterning and Traceable Neurotransmitter Photocages.

The advancements in targeted drug release and experimental neuroscience have amplified the scientific interest in photolabile protecting groups (PPGs) and photouncaging. The growing need for the detection of uncaging events has led to the development of reporters with fluorescence turn-on upon uncaging. In contrast, fluorescent tags with turn-off properties have been drastically underexplored, although there are applications where they would be sought after.

Reversible covalent c-Jun N-terminal kinase inhibitors targeting a specific cysteine by precision-guided Michael-acceptor warheads.

There has been a surge of interest in covalent inhibitors for protein kinases in recent years. Despite success in oncology, the off-target reactivity of these molecules is still hampering the use of covalent warhead-based strategies. Herein, we disclose the development of precision-guided warheads to mitigate the off-target challenge.

Targeting a key protein-protein interaction surface on mitogen-activated protein kinases by a precision-guided warhead scaffold.

For mitogen-activated protein kinases (MAPKs) a shallow surface-distinct from the substrate binding pocket-called the D(ocking)-groove governs partner protein binding. Screening of broad range of Michael acceptor compounds identified a double-activated, sterically crowded cyclohexenone moiety as a promising scaffold. We show that compounds bearing this structurally complex chiral warhead are able to target the conserved MAPK D-groove cysteine via reversible covalent modification and interfere with the protein-protein interactions of MAPKs.

An Unprecedented Tridentate-Bridging Coordination Mode of Permanganate Ions: The Synthesis of an Anionic Coordination Polymer-[Co(NH)][(K(κ-Cl)(μ-(κ-O,O',O″-MnO))]-Containing Potassium Central Ion and Chlorido and Permanganato Ligands.

A unique compound (compound ) with structural features including an unprecedented tridentate-bridging coordination mode of permanganate ions and an eight-coordinated (rhombohedral) κ-chlorido and tridentate permanganato ligand in a potassium complex containing coordination polymer (Co(NH)][(K(κ-Cl)(μ-(κ-O,O',O″-MnO))) with isolated regular octahedral hexamminecobalt(III) cation was synthesized with a yield of >90%. The structure was found to be stabilized by mono and bifurcated N-H∙∙∙Cl and N-H∙∙∙O (bridging and non-bridging) hydrogen bonds. Detailed spectroscopic (IR, far-IR, and Raman) studies and correlation analysis were performed to assign all vibrational modes.

New Members of the Centrapalus Coumarin and Pauciflorin Series from .

Monoterpene and 5-methylcoumarin- or 5-methylchromone-coupled meroterpenoids occurring mainly in the Asteraceae species proved to have high potency against protozoans, worms, and various tumor cells, which make them interesting targets for searching for new bioactive compounds. The African plant was applied in traditional medicine for healing chest pain and stomach aches. Three new meroterpenoids named centrapalus coumarin N (), pauciflorins P (), and Q (), and the already known cyclohoehnelia coumarin (), were isolated from the chloroform extract of , together with centrapalus coumarin O (), which was obtained for the first time from a natural source.

Strain-Release-Driven Modular Synthesis of Oxetane-Based Amide Bioisosteres: Concise, Robust and Scalable Approach.

Amide bioisoterism is a widely used strategy in drug development to fine-tune physicochemical, pharmacokinetic, and metabolic properties, eliminate toxicity and gain intellectual property rights in uncharted chemical space. Of these, oxetane-amines offer particularly exciting possibilities as bioisosteres, although they are less frequently investigated than warranted due to the lack of simple and widely applicable synthetic methods. Herein, we report a two-step, practical, modular, robust, and scalable method for the construction of oxetane-containing amide bioisosteres that relies on the readily available oxetan-3-one.

Diagnosis of Melanoma with Cu-Labeled PET Tracer.

Until the recent years, substances containing radioactive Cu were strongly considered as potential positron-emitting radiopharmaceuticals for use in positron emission tomography (PET) applications; however, due to their suitably long half-life, and generator-independent and cost-effective production, they seem to be economically viable for human imaging. Since malignant melanoma (MM) is a major public health problem, its early diagnosis is a crucial contributor to long-term survival, which can be achieved using radiolabeled α-melanocyte-stimulating hormone analog NAPamide derivatives. Here, we report on the physicochemical features of a new CB-15aneN-based Cu(II) complex ([Cu(KFTGdiac)]) and the and characterization of its NAPamide conjugate.

Complex formation of ML324, the histone demethylase inhibitor, with essential metal ions: Relationship between solution chemistry and anticancer activity.

N-(3-(dimethylamino)propyl-4-(8-hydroxyquinolin-6-yl)benzamide (ML324, HL) is a potent inhibitor of the iron-containing histone demethylase KDM4, a recognized potential target of cancer therapeutics. Herein, we report the proton dissociation and complex formation processes of ML324 with essential metal ions such as Fe(II), Fe(III), Cu(II) and Zn(II) using UV-visible, fluorescence, electron paramagnetic resonance and H NMR spectroscopic methods. The electrochemical behaviour of the copper and iron complexes was characterized by cyclic voltammetry and spectroelectrochemistry.

A Comparative Study on the Complexation of the Anticancer Iron Chelator VLX600 with Essential Metal Ions.

As cancer cells exhibit an increased uptake of iron, targeting the interaction with iron has become a straightforward strategy in the fight against cancer. This work comprehensively characterizes the chemical properties of 6-methyl-3-{(2)-2-[1-(2-pyridinyl)ethylidene]hydrazino}-5-[1,2,4]triazino[5,6-]indole (VLX600), a clinically investigated iron chelator, in solution. Its protonation processes, lipophilicity, and membrane permeability as well as its complexation with essential metal ions were investigated using UV-visible, electron paramagnetic resonance, and NMR spectroscopic and computational methods.

Dynamic Structures of Bioactive Proteins as Determined by Nuclear Magnetic Resonance.

According to "Panta rhei", a phrase by the ancient Greeks, you cannot enter the same river two times [...

Application of Normal-Phase Silica Column in Hydrophilic Interaction Liquid Chromatography Mode for Simultaneous Determination of Underivatized Amino Acids from Human Serum Samples via Liquid Chromatography-Tandem Mass Spectrometry.

In neonatal screening, amino acids have a significant diagnostic role. Determination of their values may identify abnormal conditions. Early diagnosis and continuous monitoring of amino acid disorders results in a better disease outcome.

What is isostructurality? Questions on the definition.

Investigation of isostructurality leads to a deeper understanding of close-packing principles and contributes to the ability of crystal engineering. A given packing motif may tolerate small molecular changes within a limit. Slight alterations of a crystal packing arrangement are carried out in order to fine-tune the structural and macroscopic properties, keeping the balance of the spatial requirements and electrostatic effects of the altered molecules in the crystals, preserving their isostructurality.

Salicylideneaniline/Dithienylethene Hybrid Molecular Switches: Design, Synthesis, and Photochromism.

A hybrid molecular switch comprising salicylideneaniline (SA) and dithienylethene (DTE) moieties around a single benzene ring is reported. Due to an interplay between solvent-assisted enol-keto tautomerization in the former moiety and photochromic electrocyclization in the latter, this dithienylbenzene derivative was found to be photoresponsive at room temperature with a thermally stable closed form. The main photoproduct featuring ring-closed DTE and keto-enamine SA structures could be isolated and converted back to the starting material by irradiation with visible light.

Iron(II) Complexes of P -Chain Ligands: Structural Diversity.

Iron(II) complexes containing ligands with a R P-P-PR unit were synthesized by metathesis reactions. With R=tBu, a mixture of two isomers is formed; in one of them, the terminal phosphorus binds to the Fe center (ylidic structure), while in the other one, the central P atom is linked to Fe. Starting from differently functionalized parent triphosphanes and corresponding functionalized Fe complexes, the ratio of isomers does not change.

Cu(II) and Zn(II) Complexes of New 8-Hydroxyquinoline Schiff Bases: Investigating Their Structure, Solution Speciation, and Anticancer Potential.

We report the synthesis and characterization of three novel Schiff bases (-) derived from the condensation of 2-carbaldehyde-8-hydroxyquinoline with amines containing morpholine or piperidine moieties. These were reacted with CuCl and ZnCl yielding six new coordination compounds, with the general formula ML, where M = Cu(II) or Zn(II) and L = -, which were all characterized by analytical, spectroscopic (Fourier transform infrared (FTIR), UV-visible absorption, nuclear magnetic resonance (NMR), or electron paramagnetic resonance (EPR)), and mass spectrometric techniques, as well as by single-crystal X-ray diffraction. In the solid state, two Cu(II) complexes, with and , are obtained as dinuclear compounds, with relatively short Cu-Cu distances (3.

Effect of time-invariant pressure gradients on peak formation and efficiency in ultrahigh-pressure liquid chromatography.

In chromatography, pressure can affect the retention factors of compounds significantly. In liquid chromatography, this effect is primarily related to the change in the molecular volume of solute during adsorption that is remarkably high for large biomolecules such as peptides and proteins. As a result, the migration velocities of chromatographic bands vary spatially through the column affecting the degree of band broadening.

Syntheses of 2- and 3-Substituted Morpholine Congeners via Ring Opening of 2-Tosyl-1,2-Oxazetidine.

Diastereoselective and diastereoconvergent syntheses of 2- and 3-substituted morpholine congeners are reported. Starting from tosyl-oxazatedine and α-formyl carboxylates , base catalysis is utilized to yield morpholine hemiaminals. Their further synthetic elaborations allowed the concise constructions of conformationally rigid morpholines.