Xie and Bobliotti describe the synthesis and applications of carbohydrate-derived macrocyclic compounds. Topics addressed include natural carbohydrate-containing macrocycles, macrocycles containing ...ester, amide, amine, ether, or acetal linkages, and macrocycles containing triazole linkages.
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The shape of the spectral features in arrival time distributions (ATDs) recorded by ion mobility spectrometry (IMS) can often be interpreted in terms of the coexistence of different isomeric species. ...Interconversion between such species is also acknowledged to influence the shape of the ATD, even if no general quantitative description of this effect is available. We present an analytical model that allows simulating ATDs resulting from interconverting species. This model is used to reproduce experimental data obtained on a bistable system and to interpret discrepancies between measurements on different types of instruments. We show that the proposed model can be further exploited to extract kinetic and thermodynamic data from tandem-IMS measurements.
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Carbohydrate‐based 23‐ to 28‐membered BODIPY‐containing macrocycles have been efficiently synthesised from alkyne‐functionalised BODIPY acid, C‐glucosyl azido amine, and amino acids by employing ...CuAAC for the macrocyclisation step. BF(OMe) and B(OMe)2 derivatives have also been obtained by treating macrocycle 1 with BCl3 in CH2Cl2 followed by treatment with MeOH. These compounds exhibited similar excellent photophysical properties to those of BODIPY. Investigation of potential receptor properties of the 23‐ and 27‐membered macrocycles 1 and 2 showed that these compounds are sensitive to both anions (F– and CN–) and cations (Cu2+ and Fe3+) in MeCN.
Carbohydrate‐based 23‐ to 28‐membered BODIPY‐containing macrocycles with excellent photophysical and selective ion recognition properties can be efficiently synthesised from alkyne‐functionalised BODIPY acid, C‐glucosyl azido amine, and amino acids.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A series of arene ruthenium complexes containing o-sulfonamide azobenzene ligands were synthesized and found to exhibit uncommon coordination pattern with an exocyclic NN bond. Upon irradiation, ...these complexes cleanly undergo E → Z photoisomerization followed by thermal Z → E isomerization (upon resting in the dark) whose rate is dependent on the solvent, the nature of the arene group, the sulfonamide moiety, and azobenzene substitution, as revealed by structure–property studies.
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Chemical cross-linking of proteins permits the stabilization of noncovalent complexes through introduction of covalent bonds. A crucial challenge is to find the fastest and most efficient ...cross-linkers in order to minimize reaction times and to handle delicate complexes. New cross-linkers were synthesized by introducing N-hydroxyphthalimide, hydroxybenzotriazole, and 1-hydroxy-7-azabenzotriazole as leaving groups instead of the commonly used N-hydroxysuccimidyl moiety. With the use of matrix-assisted laser desorption ionization (MALDI) mass spectrometry, these new cross-linkers were then compared with the commercially available disuccinimidyl suberate (DSS) for covalent stabilization of the gluthatione-S-transferase (GST) dimer and of an antibody−antigen complex. They showed a better efficiency, generated about 30% more cross-linked complex, and reacted about 10 times faster than DSS. The reaction with the GST dimer was utilized to get information about their reaction efficiency and kinetics. Their ability to stabilize only specific protein complexes was verified by incubating them with a mixture of the proteins GST and ubiquitin. Finally, the cross-linkers were incubated with synthetic peptides to study the selectivity of the binding with various amino acid side chains. Not only lysine but also tyrosine was found to react with the newly synthesized cross-linker containing 1-hydroxy-7-azabenzotriazole as the reactive group.
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Abstract
Photo‐release of triphenylphosphine from a sulfonamide azobenzene ruthenium–arene complex was exploited to activate Pd
II
Cl
2
into Pd
0
catalyst, for the photo‐initiation of Sonogashira ...cross‐coupling. The transformation was initiated on demand – by using simple white LED strip lights – with a high temporal response and the ability to control reaction rate by changing the irradiation time. Various substrates were successfully applied to this photo‐initiated cross‐coupling, thus illustrating the wide functional‐group tolerance of our photo‐caged catalyst activator, without any need for sophisticated photochemistry apparatus.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A specific light trigger for activating endothelial Nitric Oxide-Synthase (eNOS) in real time would be of unique value to decipher cellular events associated with eNOS activation or to generate on ...demand cytotoxic levels of NO at specific sites for cancer research. We previously developed novel tools called nanotriggers (NT), which recognized constitutive NO-synthase, eNOS or neuronal NOS (nNOS), mainly via their 2' phosphate group which is also present in NADPH in its binding site. Laser excitation of NT1 bound to eNOS triggered recombinant NOS activity and released NO. We recently generated new NTs carrying a 2' or 3' carboxylate group or two 2' and 3' carboxylate moieties replacing the 2' phosphate group of NADPH. Among these new NT, only the 3' carboxylate derivative released NO from endothelial cells upon laser activation. Here, Molecular Dynamics (MD) simulations showed that the 3' carboxylate NT formed a folded structure with a hydrophobic hub, inducing a good stacking on FAD that likely drove efficient activation of nNOS. This NT also carried an additional small charged group which increased binding to e/nNOS; fluorescence measurements determined a 20-fold improved affinity upon binding to nNOS as compared to NT1 affinity. To gain in specificity for eNOS, we augmented a previous NT with a "hook" targeting variable residues in the NADPH site of eNOS. We discuss the potential of exploiting the chemical diversity within the NADPH site of eNOS for reversal of endothelial dysfunction in cells and for controlled generation of cytotoxic NO-derived species in cancer tissues.
In this work, we report on the development of a newly synthesized photoactive reversible azobenzene derived surfactant polymer, which enables active and fast control of the merging of microdroplets ...in microfluidic chambers, driven by a pulsed UV laser optical stimulus and the well known
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photo-isomerisation of azobenzene groups. We show for the first time that merging of microdroplets can be achieved optically based on a photo-isomerization process with a high spatio-temporal resolution. Our results show that the physical process lying behind the merging of microdroplets is not driven by a change in surface activity of the droplet stabilizing surfactant under UV illumination (as originally expected), and they suggest an original mechanism for the merging of droplets based on the well-known opto-mechanical motion of azobenzene molecules triggered by light irradiation.
Photo‐release of triphenylphosphine from a sulfonamide azobenzene ruthenium–arene complex was exploited to activate PdIICl2 into Pd0 catalyst, for the photo‐initiation of Sonogashira cross‐coupling. ...The transformation was initiated on demand – by using simple white LED strip lights – with a high temporal response and the ability to control reaction rate by changing the irradiation time. Various substrates were successfully applied to this photo‐initiated cross‐coupling, thus illustrating the wide functional‐group tolerance of our photo‐caged catalyst activator, without any need for sophisticated photochemistry apparatus.
Tuning by timing: The photo‐initiation of Sonogashira cross‐coupling was achieved using a simple white LED combined with a triphenylphosphine ruthenium–arene complex bearing an azobenzene ligand. The strategy developed in this work involves the photo‐controlled release of metal catalyst activator (PPh3) through Z‐to‐E azobenzene isomerization, thus generating competent Pd0 active species, and allows fine tuning of reaction kinetics according to irradiation time.
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A series of sulfonamide azobenzenes bearing alkyl substituents of increasing steric bulk at the position ortho to the N=N bond and their corresponding chloro(hexamethylbenzene)ruthenium(II) complexes ...were synthesized. The latter bearing mono‐substituted ligands exhibited an exocyclic azo bond under the E configuration, and underwent reversible E → Z photoisomerization upon irradiation with visible light, followed by thermal Z → E back isomerization upon resting in the dark at 20 °C. In contrast, the corresponding 2,6‐dimethyl substituted azobenzene complex, while also exhibiting an exocyclic azo bond, was isolated as the Z‐ isomer and underwent uncommon solvent dependent irreversible photodissociation of azobenzene ligand upon visible light irradiation. Valuable insights into the photophysical and structural properties of these complexes were gained by combination of computational and X‐ray diffraction studies.
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