Search results for "BLE"
showing 10 items of 23353 documents
Photocatalytic Giese Addition of 1,4-Dihydroquinoxalin-2-ones to Electron-Poor Alkenes Using Visible Light.
2020
The visible-light photoredox-catalyzed coupling of 1,4-dihydroquinoxalin-2-ones and Michael acceptors was achieved using Ru(bpy)3Cl2 as the photocatalyst and (PhO)2PO2H as an additive. The optimized reaction conditions provide a good yield for the radical conjugate addition products (44 examples) with a wide range of structurally different Michael acceptors. A gram scale reaction using sunlight irradiation is also described. Furthermore, several transformations were carried out with the Giese addition products.
Towards the synthesis of substituted porphyrins by a pyridyl group bearing a reactive functionality
2010
Pyridyl-substituted porphyrins bearing a reactive functionality were prepared via Suzuki cross-coupling reactions and resulted in very good yields. These compounds are precursors of new porphyrin architectures able to coordinate two metals: one in the porphyrin core and the second around the pyridyl moiety. During the coupling reactions, a higher reactivity of a chloro picolyl group was evidenced compared to a bromo function on the same reacting molecule.
Protonation of Tyrosine Kinase Inhibitor Lapatinib: A Theoretical and Experimental Study
2019
The protonation process of tyrosine kinase inhibitor lapatinib was studied by means of 1HNMR and UV/Vis spectroscopy joint with the theoretical calculations at DFT and semi-empirical levels. DFT/M06-2X geometries were used to describe and compare the different cationic forms of lapatinib, while ZINDO/S-CI method performed on those geometries allowed for the interpretation of experimental UV/Vis spectra of lapatinib at various pH. We found that at low pH two different dicationic forms (N2N1 and N1N3) of lapatinib were present in ethanol and DMSO-d6 solutions. The first protonation, however, occurred on the aliphatic N1 in DMSO-d6, while in ethanol solutions most probably the quinazoline nitr…
Self-assembled Pt2L2 boxes strongly bind G-quadruplex DNA and influence gene expression in cancer cells
2017
Supramolecular Pt(ii) quadrangular boxes bind native and G-quadruplex DNA motifs in a size-dependent fashion. Three Pt molecular squares of distinct size show biological activity against cancer cells and heavily influence the expression of genes known to form G-quadruplexes in their promoter regions. The smallest Pt-box displays less activity but more selectivity for a quadruplex formed in the c-Kit gene.
Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity
2020
Abstract Reaction of [MoO2Cl2(dmso)2] with the tetradentate O2N2 donor ligand papy [H2papy = N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] leads to formation of the dioxomolybdenum(VI) complex [MoO2(papy)] (1) as a mixture of cis and trans isomers. Recrystallization from methanol furnishes solid cis-1, whereas the use of a dichloromethane-hexane mixture allows for the isolation of the trans-1 isomer. Both isomers have been structurally characterized by X-ray crystallography and the energy difference between the isomeric pair has been investigated by electronic structure calculations. Optimization of two configurational isomers in the gas phase predicts the trans isomer to lie 2.5 kcal/mol lower…
Vinyl sulfone building blocks in covalently reversible reactions with thiols
2015
In the present study we use quantum-chemical calculations to investigate how the reactivity of vinyl sulfone-based compounds can be modified from an irreversible to a reversible reaction with thiols. Based on the predictions from theory, an array of nine different vinyl sulfones with systematically varying substitution pattern was synthesized and their crystal structures were determined. Subsequent Hirshfeld surface analyses employing the principle of electrostatic complementarity aid the understanding of the crystal packing of the synthesized compounds. Reactivity studies against the nucleophile 2-phenylethanethiol mirror the properties predicted by the quantum-chemical computations in sol…
Variable Cooperative Interactions in the Pressure and Thermally Induced Multistep Spin Transition in a Two-Dimensional Iron(II) Coordination Polymer
2020
Two types of experiments conducted to investigate the effect of pressure on the spin crossover (SCO) properties of the 2D Fe(II) coordination polymer formulated {Fe[bipy(ttr)2]}n are reported, namely, (1) magnetic measurements performed at variable temperature and at fixed pressure and (2) visible spectroscopy at variable pressure and fixed temperature. The magnetic experiments carried out under a hydrostatic pressure constraint of 0.04, 0.08, and 0.8 GPa reveal a two-step spin transition behavior. The characteristic critical temperatures of the spin transition are shifted upward in temperature as pressure increases. The slope of the straight-line of the Tc vs P plot, dTc/dP, is 775 K/GPa a…
Water-Soluble Squaramide Dihydrates: N-Methylation Modulates the Occurrence of One- and Two-Dimensional Water Clusters through Hydrogen Bonding and D…
2018
Water confined in molecular size domains is distinct to bulk water. The altered interactions between adjacent water molecules, and between water molecules and molecular wall components of the confinement system, determine aspects of important phenomena in material science, biology, and nanotechnology. The structural determination of confined water, however, has proven to be challenging. Here, we describe the crystal structures of three related squaramides 1–3 whose molecular structures are modulated by the gradual incorporation of N-methyl groups to the squaramide moiety. The three squaramides differ in their hydrogen bonding capabilities due to the different degree of N-methylation of each…
Reversible O–H bond activation by an intramolecular frustrated Lewis pair
2019
The interactions of the O-H bonds in alcohols, water and phenol with dimethylxanthene-derived frustrated Lewis pairs (FLPs) have been probed. Within the constraints of this backbone framework, the preference for adduct formation or O-H bond cleavage to give the corresponding zwitterion is largely determined by pKa considerations. In the case of the PPh2/B(C6F5)2 system and p-tBuC6H4OH, an equilibrium is established between the two isomeric forms which allows the thermodynamic parameters associated with zwitterion formation via O-H bond cleavage to be probed.
Hybrid GMP–polyamine hydrogels as new biocompatible materials for drug encapsulation
2020
Here we present the preparation and characterization of new biocompatible materials for drug encapsulation. These new gels are based on positively charged [1+1] 1H-pyrazole-based azamacrocycles which minimise the electrostatic repulsions between the negatively charged GMP molecules. Rheological measurements confirm the electroneutral hydrogel structure as the most stable for all the GMP-polyamine systems. Nuclear magnetic resonance (NMR) was employed to investigate the kinetics of the hydrogel formation and cryo-scanning electron microscopy (cryo-SEM) was used to obtain information about the hydrogel morphology, which exhibited a non-homogeneous structure with a high degree of cross-linking…