12 research outputs found
A designed and potentially decadentate ligand for use in lanthanide(III) catalysed biomass transformations: targeting diastereoselective trans-4,5-diaminocyclopentenone derivatives
The goal of this study was to design a ligand system which can accommodate single lanthanide(III)-ions and investigate the properties of the resulting complexes. The complexes of all the accesible lanthanides and yttrium with the new ligand LH6 = N,NâČ-dimethyl-N,NâČ-ethylene-bis(5-bromo-3-(1H-benzimidazol-2-yl)hydrazineylidene)-2-hydroxybenzylamine) were obtained in high yield at room temperature under aerobic reaction conditions. The corresponding compounds were characterised using X-ray diffraction, FT-IR, elemental analysis and the optical properties of all complexes were investigated using UV-vis and fluorescence spectroscopy. The air stable complexes efficiently transform biomass furfural to trans-4,5-cyclopentenones in high yield
A multifunctional use of bis(methylene)bis(5-bromo-2-hydroxyl salicyloylhydrazone): From metal sensing to ambient catalysis of A3 coupling reactions
The potential use of bis(methylene)bis(5-bromo-2-hydroxylsalicyloylhydrazone) as a multifunctional fluorescence sensor for Cu(2+), Ni(2+), Co(2+) and Fe(2+) ions was investigated. The optical behaviour shows an increase in an absorption band at 408 nm which can be ascribed to the dâd transition (UV-vis) of the metal ions and a concomitant decrease in fluorescence intensity at 507 nm. The crystallographic analysis shows the binding site of the sensor to two Cu(2+) ions and confirms the stoichiometry of 1â:â2 (ligand to metal) which is in good agreement with a Job plot analysis. Furthermore the Cu(2+)-complex catalyses A3 coupling reactions at 1 mol% catalytic loading; chiral propargylamine derivatives were obtained in high yield after 24 h reaction time under ambient conditions
Tetranuclear Cu(II)-chiral complexes: synthesis, characterization and biological activity
Tetranuclear chiral Cu(ii)-Schiff-base complexes S-1 and R-1, were synthesised using enantiomerically pure (S)-(H(2)vanPheol) and (R)-(H(2)vanPheol) ligands respectively in the ratio of 1â:â1 of Cu(NO(3))(2) to (S/R)-(H(2)vanPheol) in MeOH at room temperature. A pair of polynuclear chiral Cu(ii)-cluster complexes were characterized using single-crystal X-ray diffraction, elemental analysis, infrared and CD spectroscopy. The results revealed the importance of these chiral ligands encouraging the arrangement of copper metal in non-centrosymmetric polar packing. The potential of the novel [Cu(4)(S/R-vanPheol)(2)(S/R-HvanPheol)(2)(CH(3)OH)(2)](NO(3))(2) complexes as biologically active compounds was assessed in particular regarding their anti-proliferative and anti-microbial properties
Polarity sensitive bioorthogonally applicable far-red emitting labels for postsynthetic nucleic acid labeling by copper-catalyzed and copper-free cycloaddition
Two
series of new, water-soluble, membrane-permeable, far-red/NIR
emitting benzothiazolium-based fluorescent labels with large Stokesâ
shifts were synthesized that can be conjugated to alkyne-modified
biomolecules through their azide moiety via azideâalkyne cycloaddition.
We have used these azide bearing labels to make fluorescent DNA constructs
using copper-catalyzed âclickâ reaction. All dyes showed
good or remarkable fluorescence intensity enhancement upon conjugation
to DNA. We also investigated the possibility to incorporate the benzocyclooctyne
motif through rigid (ethnynyl) or flexible (ethyl) linkers into the
DNA, thus enabling copper-free labeling schemes. We observed that
there is a marked difference between the two linkers applied in terms
of optical properties of the labeled oligonucleotides. We have also
tested the in vivo labeling potential of these newly synthesized dyes
on HeLa cells previously transfected with cyclooctynylated DNA. Confocal
fluorescent images showed that the dyes are all able to cross the
membrane and suitable for background-fluorescence free fluorescent
tagging of nucleic acids. Moreover, we have observed different accumulation
of the two dye series in the endosomal particles, or in the nuclei,
respectively
Synthesis of <i>gem</i>-Difluoromethylenated Bicyclo[<i>m.n.</i>0]alkan-1-ols and Their Ring-Expansion to <i>gem</i>-Difluoromethylenated Macrocyclic Lactones
Fluoride-catalyzed stereoselective nucleophilic addition of PhSCF<sub>2</sub>SiMe<sub>3</sub> (<b>1</b>) to α-carboethoxycycloalkanones <b>2</b> followed by intramolecular radical cyclization of the resulting <i>cis</i>-<b>3</b> adduct afforded the corresponding <i>gem</i>-difluoromethylenated bicyclic compounds <b>4</b>, which underwent ring-expansion followed by the BaeyerâVilliger-type oxidation of the resulting macrocyclic ketone intermediates to give <i>gem</i>-difluoromethylenated macrocyclic lactones <b>5</b>