Search results for " Composite"
showing 10 items of 1884 documents
Self-assembly of M4L4tetrahedral cages incorporating pendant PS and PSe functionalised ligands
2019
Herein, the synthesis of metal–organic tetrahedral cages featuring flexible thio- and selenophosphate-based ligands is described. The cages were prepared by sub-component self-assembly of AP(OC6H4NH2-4)3 (A = S, Se) or SP(SC6H4NH2-4)3, 2-pyridinecarboxaldehyde, and either Fe[BF4]2 or Co[BF4]2. Preliminary host–guest studies into the ability of the pendant PS and PSe groups to interact with suitable substrates will be discussed.
Probing the guest-binding preference of three structurally similar and conformationally adaptive macrocycles.
2019
A hybrid macrocycle was synthesized by combining the repeat units in oxatub[4]arene and zorb[4]arene, and its recognition behavior and conformational analysis were studied. Three structurally similar and conformationally adaptive macrocycles show different guest-binding selectivities and preferences even in a complex mixture containing three macrocycles and three guests.
A cyanide and hydroxo-bridged nanocage: a new generation of coordination clusters.
2013
International audience; Combining serendipitously-formed hydroxo-clusters, [CoII3(OH)(piv)4(L)]+ (where L = MeCN or Hpiv), with assembling cyanide building block, [FeIII(Tp)(CN)3]−, has led to an unprecedented architecture where polymetallic cobalt clusters and blocked tris-cyanide iron complexes define the apexes of a unique magnetic cubic nanocage.
Higher MLCT lifetime of carbene iron(ii) complexes by chelate ring expansion
2021
Combining strong σ-donating N-heterocyclic carbene ligands and π-accepting pyridine ligands with a high octahedricity in rigid iron(ii) complexes increases the 3MLCT lifetime from 0.15 ps in the prototypical [Fe(tpy)2]2+ complex to 9.2 ps in [Fe(dpmi)2]2+12+. The tripodal CNN ligand dpmi (di(pyridine-2-yl)(3-methylimidazol-2-yl)methane) forms six-membered chelate rings with the iron(ii) centre leading to close to 90° bite angles and enhanced iron-ligand orbital overlap.
Macrocyclic complexes based on [N⋯I⋯N]+ halogen bonds
2021
New 1–2 nm macrocyclic iodine(I) complexes prepared VIA a simple ligand exchange reaction manifest rigid 0.5–1 nm cavities that bind the hexafluorophosphate anion in the gas phase. The size of the cavities and the electrostatic interactions with the iodine(I) cations influence the anion binding properties of these macrocyclic complexes.
Electrochemical meso-functionalization of magnesium(II) porphine
2010
International audience; Regioselective meso-functionalization of the totally unsubstituted magnesium(II) porphine was performed by controlled potential electrolysis with pyridine and triphenylphosphine as nucleophiles leading to the original pyridinium and phosphonium substituted derivatives, respectively. The crystallographic structure of the latter is described as the only meso-phosphonium porphyrin reported to date.
Enantioselective synthesis of chiral oxazolines from unactivated ketones and isocyanoacetate esters by synergistic silver/organocatalysis
2018
[EN] A multicatalytic approach that combines a bifunctional Brønsted base¿squaramide organocatalyst and Ag+ as Lewis acid has been applied in the reaction of unactivated ketones with tert-butyl isocyanoacetate to give chiral oxazolines bearing a quaternary stereocenter. The formal [3+2] cycloaddition provided high yields of the corresponding cis-oxazolines with good diastereoselectivity and excellent enantioselectivity, being applied to aryl¿alkyl and alkyl¿alkyl ketones.
Formation and trapping of the thermodynamically unfavoured inverted-hemicucurbit[6]uril
2019
Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and cis-N,N'-cyclohexa-1,2-diylurea formation of inverted-cis-cyclohexanohemicucurbit[6]uril (i-cis-cycHC[6]) can be induced at the expense of thermodynamically favoured cis-cyclohexanohemicucurbit[6]uril (cis-cycHC[6]). The formation of i-cis-cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-a…
Helical supramolecular polymerization of C3-symmetric amides and retroamides: on the origin of cooperativity and handedness.
2016
The cooperative supramolecular polymerization of 1 and 2 yields P- or M-type helical aggregates depending on the absolute configuration (S or R) of the stereogenic centres attached to the side chains. The connectivity of the amide group does not affect the handedness of the helical aggregates, but determines a larger cooperativity for retroamides 1.
Improvement of osteogenic differentiation of human mesenchymal stem cells on composite poly l-lactic acid/nano-hydroxyapatite scaffolds for bone defe…
2020
Tissue engineering offers new approaches to repair bone defects, which cannot be repaired physiologically, developing scaffolds that mimic bone tissue architecture. Furthermore, biomechanical stimulation induced by bioreactor, provides biomechanical cues that regulate a wide range of cellular events especially required for cellular differentiation and function. The improvement of human mesenchymal stem cells (hMSCs) colonization in poly-L-lactic-acid (PLLA)/nano- hydroxyapatite (nHA) composite scaffold was evaluated in terms of cell proliferation (dsDNA content), bone differen- tiation (gene expression and protein synthesis) and ultrastructural analysis by comparing static (s3D) and dynamic…