Search results for "010402 general chemistry"

Monte Carlo Simulations of Au38(SCH3)24 Nanocluster Using Distance-Based Machine Learning Methods

2020

We present an implementation of distance-based machine learning (ML) methods to create a realistic atomistic interaction potential to be used in Monte Carlo simulations of thermal dynamics of thiol...

Luminescent TOP Nanosensors for Simultaneously Measuring Temperature, Oxygen, and pH at a Single Excitation Wavelength

2019

Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near-infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pH-sensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands, allowing for r…

Sensitive Assays by Nucleophile-Induced Rearrangement of Photoactivated Diarylethenes.

2018

Upon light-induced isomerization, diarylethenes (DAEs) equipped with reactive aldehyde moieties rearrange selectively in the presence of amines, accompanied by decoloration. In a comprehensive study, the probe structure was optimized with regard to its inherent reactivity in the nucleophile-triggered rearrangement reaction. Detailed structure−reactivity relationships could be derived, in particular with regard to the type of integrated (het)aryl moieties as well as the location of the formyl residue, and the probes’ intrinsic reactivity with primary and secondary amines was optimized. Utilizing an ancillary base, the initially formed rearrangement product can engage in a subsequent catalyti…

A solvent-directed stereoselective and electrocatalytic synthesis of diisoeugenol.

2018

A stereoselective and electrocatalytic coupling reaction of isoeugenol has been reported for the first time in a 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)/boron-doped diamond (BDD) electrode system. This particular C-C bond formation and diastereoselectivity is driven by a solvate interaction between the radical species and another isoeugenol molecule. Due to an electrocatalytic cycle, only understoichiometric amounts of charge are necessary. Since electric current is directly employed as the oxidant, the reaction is metal and reagent-free. In addition, the electrolysis can be conducted in a very simple undivided beaker-type cell under constant current conditions. Therefore, the protocol is …

Determination of the chemical warfare agents Sarin, Soman and Tabun in natural waters employing fluorescent hybrid silica materials

2017

[EN] A novel mesoporous silica material containing boron-dipyrromethene (BODIPY) moieties (I) is employed for the detection of nerve agent simulants (NASs) and the organophosphate nerve or chemical warfare agents (CWAs) Sarin (GB), Soman (GD), and Tabun (GA) in aqueous environments. The reactive BODIPY dye with an optimum positioned hydroxyl group undergoes acylation reactions with phosph(on)ate substrates, yielding a bicyclic ring. Due to aggregation of the dyes in water, the sensitivity of the free dye in solution is very low. Only after immobilization of the BODIPY moieties into the silica substrates is aggregation inhibited and a sensitive determination of the NASs diethyl cyanophosphon…

Catalytic epoxidation using dioxidomolybdenum(VI) complexes with tridentate aminoalcohol phenol ligands

2019

Reaction of the tridentate aminoalcohol phenol ligands 2,4-di-tert-butyl-6-(((2 hydroxyethyl)(methyl)amino)methyl)phenol (H2L1) and 2,4-di-tert-butyl-6-(((1-hydroxybutan-2-yl)amino)methyl)phenol (H2L2) with [MoO2(acac)2] in methanol solutions resulted in the formation of [MoO2(L1)(MeOH)] (1) and [MoO2(L2)(MeOH)] (3), respectively. In contrast, the analogous reactions in acetonitrile afforded the dinuclear complexes [Mo2O2(μ-O)2(L1)2] (2) and [Mo2O2(μ-O)2(L2)2] (4). The corresponding reactions with the potentially tetradentate ligand 3-((3,5-di-tert-butyl-2-hydroxybenzyl)(methyl)amino)propane-1,2-diol (H3L3) led to the formation of the mononuclear complex [MoO2(L3)(MeOH)] (5) in methanol whi…

Iminium Catalysis (n → π*)

2016

The Taming of Redox‐Labile Phosphidotitanocene Cations

2019

International audience; Tame d0 phosphidotitanocene cations stabilized with a pendant tertiary phosphane arm are reported. These compounds were obtained by one-electron oxidation of d1 precursors with [Cp2Fe][BPh4]. The electronic structure of these compounds was studied experimentally (EPR, UV/Vis, and NMR spectroscopy, X-ray diffraction analysis) and through DFT calculations. The theoretical analysis of the bonding situation by using the electron localization function (ELF) shows the presence of π-interactions between the phosphido ligand and Ti in the d0 complexes, whereas dπ–pπ repulsion prevents such interactions in the d1 complexes. In addition, CH–π interactions were observed in seve…

Oxidovanadium(V) amine bisphenolates as epoxidation, sulfoxidation and catechol oxidation catalysts

2017

Air-stable oxidovanadium(V) complexes with tetradentate amine bisphenolate ligands were made by the reaction of VOSO4·xH2O and ligand precursors in MeOH solutions. Isolated compounds were studied as catechol oxidase models as well as catalysts for epoxidation and sulfoxidation reactions. All compounds can catalyse such oxidation reactions without notable structure-activity correlations. The 51V NMR studies indicate that the complexes turn to the number of different species during the catalytic experiments. peerReviewed

Enantioselective synthesis of 4H-pyranonaphthoquinones via sequential squaramide and silver catalysis

2015

Chemical communications 52(8), 1669-1672(2016). doi:10.1039/C5CC09592A