Structure and conductivity of AOT solutions in n-hexadecane-chloroform mixtures

The structure and conductivity of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) solutions (2.5 × 10⁻⁴–2.5 × 10⁻¹ M) in n-hexadecane-chloroform mixture at the chloroform concentration from 50 to 100 vol% were studied. The diffusion ordered spectroscopy NMR study revealed that in the indicated range, the observed hydrodynamic diameter of micelles depends only on the AOT concentration and does not depend on the chloroform content. Molar fractions of free AOT molecules and those aggregated into micelles were calculated using the Lindman's law: at concentrations above 2.5 × 10⁻¹ М, the solutions contain mostly the micelles, whereas at concentrations below 2.5 × 10⁻⁴ M, the solutions contain AOT molecules. The transition region contains both the AOT molecules and the micelles. Conductivity measurements were used to determine free charge carriers in the bulk of solutions and their contributions to conductivity.     

Reply to the Comment on “Realization of Lewis Basic Sodium Anion in the NaBH3− Cluster”

We reply to the comment by S. Pan and G. Frenking who challenged our interpretation of the Na^?:→BH₃ dative bond in the recently synthesized NaBH₃^? cluster. Our conclusion remains the same as that in our original paper ( https://doi.org/10.1002/anie.201907089 and https://doi.org/10.1002/ange.201907089 ). This conclusion is additionally supported by the energetic pathways and NBO charges calculated at UCCSD and CASMP2(4,4) levels of theory. We also discussed the suitability of the Laplacian of electron density (QTAIM) and Adaptive Natural Density Partitioning (AdNDP) method for bond type assignment. It seems that AdNDP yields more sensible results. This discussion reveals that the complex realm of bonding is full of semantic inconsistencies, and we invite experimentalists and theoreticians to elaborate this topic and find solutions incorporating different views on the dative bond.     

Nanosecond Calibration of a Piezo Transducer by Comparing Thermoacoustic and Vaporization Pressure Signals at Pulsed Laser Irradiation of a Metal Target

Physics of Wave Phenomena - A possibility of calibrating a piezo transducer by comparing thermoacoustic and vaporization pressure signals generated in a metal (liquid mercury) irradiated with...     

Chemical Exchange Saturation Transfer (CEST) Agents: Quantum Chemistry and MRI

Diamagnetic chemical exchange saturation transfer (CEST) contrast agents offer an alternative to Gd³⁺‐based contrast agents for MRI. They are characterized by containing protons that can rapidly exchange with water and it is advantageous to have these protons resonate in a spectral window that is far removed from water. Herein, we report the first results of DFT calculations of the ¹H nuclear magnetic shieldings in 41 CEST agents, finding that the experimental shifts can be well predicted (R²=0.882). We tested a subset of compounds with the best MRI properties for toxicity and for activity as uncouplers, then obtained mice kidney CEST MRI images for three of the most promising leads finding 16 (2,4‐dihydroxybenzoic acid) to be one of the most promising CEST MRI contrast agents to date. Overall, the results are of interest since they show that ¹H NMR shifts for CEST agents—charged species—can be well predicted, and that several leads have low toxicity and yield good in vivo MR images.     

Novel approach to 6-alkenyl-substituted pyridoxine derivatives based on the Heck reaction

A new synthetic approach to 6-alkenyl-substituted pyridoxine derivatives was developed based on the Heck reaction. The reaction, which was catalyzed using a mixture of Pd(OAc)₂, (o-Tol)₃P and Bu₃N as a base, led to seven new 6-alkenyl pyridoxine derivatives. When acrylic acid was used the products of decarboxylation and dimerization were formed.     

Homologous series of novel adamantane–colchicine conjugates: synthesis and cytotoxic effect on human cancer cells

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