Synthesis and X‐ray Crystallography of Two Lead(II) Decahydro‐closo‐Decaborate Hydrates

The reaction of Pb[CO₃] with an aqueous solution of (H₃O)₂[B₁₀H₁₀] in an equimolar ratio leads to two lead(II) decahydro‐closo‐decaborate hydrates both as triclinic, pale yellow single crystals. The water‐rich compound with the formula [Pb(H₂O)₃]₂Pb[B₁₀H₁₀]₃ · 5.5H₂O crystallizes in the space group P1 (a = 711.72(4), b = 1243.14(8), c = 2064.83(12) pm, α = 81.806(3), β = 83.795(3), γ = 80.909(3)°) with Z = 2. The compound with the lower water content, [Pb(H₂O)₃]Pb[B₁₀H₁₀]₂ · 1.5H₂O, also crystallizes in P1 (a = 718.46(4), b = 1288.75(8), c = 1279.91(8) pm, α = 70.145(3), β = 75.976(3), γ = 80.324(3)°) with Z = 2. Both structures can be described as layered arrangements and contain one Pb²⁺ cation each, which is only coordinated by the hydridic hydrogen atoms of the hydroborate anions. All the others are primarily surrounded by three water molecules in a non‐planar fashion and additional hydrogen atoms of [B₁₀H₁₀]^2– anions. The non‐lead‐bonded crystal water molecules in both structures are all connected via hydrogen bonds to the water molecules, which coordinate the Pb²⁺ cations, as well as via non‐classical hydrogen bonds to the cluster anions and reside between the layers. The [B₁₀H₁₀]^2– anions show only slight distortions from their ideal shape as bicapped square antiprisms.     

The Synthesis and STM/AFM Imaging of ‘Olympicene’ Benzo[cd]pyrenes

H‐Benzo[cd]pyrene (‘Olympicene′) is a polyaromatic hydrocarbon and non‐Kekulé fragment of graphene. A new synthetic method has been developed for the formation of 6H‐benzo[cd]pyrene and related ketones including the first time isolation of the unstable alcohol 6H‐benzo[cd]pyren‐6‐ol. Molecular imaging of the reaction products with scanning tunnelling microscopy (STM) and non‐contact atomic force microscopy (NC‐AFM) characterised the 6H‐benzo[cd]pyrene as well as the previously intangible and significantly less stable 5H‐benzo[cd]pyrene, the fully conjugated benzo[cd]pyrenyl radical and the ketones as oxidation products.     

Spatially Resolved Quantification of Gadolinium(III)‐Based Magnetic Resonance Agents in Tissue by MALDI Imaging Mass Spectrometry after In Vivo MRI

Gadolinium(III)‐based contrast agents improve the sensitivity and specificity of magnetic resonance imaging (MRI), especially when targeted contrast agents are applied. Because of nonlinear correlation between the contrast agent concentration in tissue and the MRI signal obtained in vivo, quantification of certain biological or pathophysiological processes by MRI remains a challenge. Up to now, no technology has been able to provide a spatially resolved quantification of MRI agents directly within the tissue, which would allow a more precise verification of in vivo imaging results. MALDI imaging mass spectrometry for spatially resolved in situ quantification of gadolinium(III) agents, in correlation to in vivo MRI, were evaluated. Enhanced kinetics of Gadofluorine M were determined dynamically over time in a mouse model of myocardial infarction. MALDI imaging was able to corroborate the in vivo imaging MRI signals and enabled in situ quantification of the gadolinium probe with high spatial resolution.     

Imidazolin‐2‐ylidenaminophosphines as Highly Electron‐Rich Ligands for Transition‐Metal Catalysts

A variety of chemical transformations benefit from the use of strong electron‐donating ancillary ligands, such as alkylphosphines or N‐heterocyclic carbenes when electron‐rich metal centers are required. Herein, we describe a facile and highly modular access to monodentate and bidentate imidazolin‐2‐ylidenamino‐substituted phosphines. Evaluation of the phosphine’s electronic properties substantiate that the formal replacement of alkyl or aryl groups by imidazolin‐2‐ylidenamino groups dramatically enhance their donor ability beyond that of alkylphosphines and even N‐heterocyclic carbenes. The new phosphines have been coordinated onto palladium(II) centers, and the beneficial effect of the novel substitution patterns has been explored by using the corresponding complexes in the palladium‐catalyzed Suzuki–Miyaura cross‐coupling reaction of non‐activated aryl chloride substrates.     

Experimental and Theoretical Investigations of the Existence of CuII,CuIII, and CuIV in Copper Corrolato Complexes

The most common oxidation states of copper in stable complexes are +I and +II. Cu^III complexes are often considered as intermediates in biological and homogeneous catalysis. More recently, Cu^IV species have been postulated as possible intermediates in oxidation catalysis. Despite the importance of these higher oxidation states of copper, spectroscopic data for these oxidation states remain scarce, with such information on Cu^IV complexes being non‐existent. We herein present the synthesis and characterization of three copper corrolato complexes. A combination of electrochemistry, UV/Vis/NIR/EPR spectroelectrochemistry, XANES measurements, and DFT calculations points to existence of three distinct redox states in these molecules for which the oxidation states +II, +III, and +IV can be invoked for the copper centers. The present results thus represent the first spectroscopic and theoretical investigation of a Cu^IV species, and describe a redox series where Cu^II, Cu^III, and Cu^IV are discussed within the same molecular platform.     

Reactivity and Passivation of Fe Nanoclusters on h-BN/Rh(111)

The reactivity of iron nanocluster arrays on h-BN/Rh(111) was studied using in situ high-resolution X-ray photoelectron spectroscopy. The morphology and reactivity of the iron nanoclusters (Fe-NCs) were investigated by CO adsorption. On-top and hollow/edge sites were determined to be the available adsorption sites on the as-prepared Fe-NCs and CO dissociation was observed at 300 K. C- and O-precovered Fe-NCs showed no catalytic activity towards CO dissociation because the hollow/edge sites were blocked by the C and O atoms. Therefore, these adsorption sites were identified to be the most active sites of the Fe-NCs.     

Examining Trichloroisocyanuric Acid and Oxalyl Chloride in Complementary Approaches to Fluorination of Group 15 Heteroatoms

A mild, oxidative fluorination approach to a variety of fluorinated phosphorus compounds using trichloroisocyanuric acid (TCICA) and KF was developed as a complement to a recent study on deoxygenative fluorination using oxalyl chloride. Herein, the syntheses of several fluorinated organophosphorus compounds are reported, and both TCICA/KF and oxalyl chloride/KF conditions are compared and contrasted throughout. Initial investigations of the method on other group 15 heteroatoms (i. e., As, Sb, and Bi) are also reported, with varied success. This work notably extends the known TCICA/KF reactivity series to another group of elements beyond previously studied chalcogens (S, Se, and Te) and halogens (iodine) and expands the utility of the previously reported oxalyl chloride/KF method.     

Cytoplasmic delivery of quantum dots via microelectrophoresis technique

Nanoparticles with specific properties and functions have been developed for various biomedical research applications, such as in vivo and in vitro sensors, imaging agents and delivery vehicles of therapeutics. The development of an effective delivery method of nanoparticles into the intracellular environment is challenging and success in this endeavor would be beneficial to many biological studies. Here, the well-established microelectrophoresis technique was applied for the first time to deliver nanoparticles into living cells. An optimal protocol was explored to prepare semiconductive quantum dots suspensions having high monodispersity with average hydrodynamic diameter of 13.2–35.0 nm. Micropipettes were fabricated to have inner tip diameters of approximately 200 nm that are larger than quantum dots for ejection but less than 500 nm to minimize damage to the cell membrane. We demonstrated the successful delivery of quantum dots via small electrical currents (–0.2 nA) through micropipettes into the cytoplasm of living human embryonic kidney cells (roughly 20–30 μm in length) using microelectrophoresis technique. This method is promising as a simple and general strategy for delivering a variety of nanoparticles into the cellular environment.     

Analytical characterization of natural waxes employing pyrolysis–gas chromatography–mass spectrometry

Three natural waxes (bleached beeswax, lanolin, yellow carnauba wax) were investigated by means of pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). Pyrograms were obtained showing very characteristic signal patterns. Mass spectrometric detection enabled the structural identification of the pyrolytically formed fragments. For a more detailed investigation of the thermal degradation behaviour of waxy materials, relevant model compounds were selected. Hexadecylpalmitate, cholesterylstearate, heptadecanoic acid and 1-hexacosanol were examined under identical Py–GC–MS conditions. From the resulting product distribution general statements were able to be derived according to the thermal degradation pathways of typical wax constituents. The findings obtained from the model compounds were then applied to the interpretation of the real wax pyrograms. As a result, conclusions according to their origin from corresponding wax constituents were drawn for the majority of pyrolysis products. Thus, the extended potential of the method for the compositional analysis of natural waxes is demonstrated.