62107-77-1Relevant academic research and scientific papers
Synthesis and structures of transition metal pacman complexes of heteroditopic Schiff-base pyrrole macrocycles
Leeland, James W.,Finn, Colin,Escuyer, Bérengère,Kawaguchi, Hiroyuki,Nichol, Gary S.,Slawin, Alexandra M.Z.,Love, Jason B.
, p. 13815 - 13831 (2013/01/15)
A series of polydentate dual-compartment, Schiff-base pyrrole macrocycles has been prepared through the straightforward Lewis acid catalysed [1 + 1] condensation reactions between ONO or O5-linked aryldiamines and dipyrromethane dialdehydes. These macrocycles display hydrogen-bond acceptor and donor properties and provide distinct N4 and O5/ONO donor sets for metallation reactions, so forming alkali, alkaline earth, and transition metal complexes that were characterised spectroscopically and crystallographically. While the conformationally flexible O5 donor set allows the formation of helical potassium salt structures, the transition metal complexes of all variants of these macrocycles invariably adopt wedged, Pacman-shaped structures in which the metal is bound in the pyrrole-imine N 4 donor set, so leaving the ONO/O5 donor set pendant and apical. In some cases (V, Cr, and Co), this proximate combination of Lewis acid binding site and hydrogen bond acceptor facilitates the coordination of water within the molecular cleft; alternatively, direct interaction between the pendant arm and the metal is seen (e.g. Ti). Higher order [2 + 2] macrocycles were also prepared as minor, inseparable by-products of cyclisation, and Fe 2, Mn2, and Co2 complexes of these larger macrocycles were found to adopt binuclear helical structures by X-ray crystallography.
The stability of imine-containing dynamic [2]rotaxanes to hydrolysist
Leung, Ken Cham-Fai,Wong, Wing-Yan,Arico, Fabio,Haussmann, Philip C.,Fraser Stoddart
scheme or table, p. 83 - 89 (2010/04/06)
Large amounts (> 100 mol equivalents) of water are required to effect by hydrolysis the partial disassembly of the rings from the dumbbell components of two dynamic [2]rotaxanes. The two dynamic [2]rotaxanes are comprised of [24]crown-8 rings-each of which incorporate two imine bonds-encircling a dumbbell component composed of a dibenzylammonium ion in which each of the two benzyl substituents carries two methoxyl groups attached to their 3- and 5-positions. A mechanism for the partial disassembly of the two dynamic [2]rotaxanes, involving the cleavage of the kinetically labile imine bonds by water molecules, is proposed. The most important experimental observation to be noted is the fact that the hydrolysis of the macrocyclic diimines, associated with the templating -CH2NH2+CH 2-centres in the middle of their dumbbells, turns out to be an uphill task to perform in the face of the molecular recognition provided by strong [N+-H ... O] hydrogen bonds and weaker, yet not insignificant, [C-H ... O] interactions. The dynamic nature of the imine bond formation and hydrolysis is such that the acyclic components produced during hydrolysis of the imine bonds can be enticed to cyclise once again around the -CH 2NH2+CH2-template, affording the [2]rotaxanes. The reluctance of imine bonds, present in substantial numbers in larger molecular and extended structures, is significant when it comes to exercising dynamic chemistry in compounds where multiple imine bonds are present. The Royal Society of Chemistry 2010.
Preparation and Characterization of New Amino-Substituted Crowns and Podands
Kilic, Zeynel,Weber, Edwin,Guenduez, Necla,Kilic, Emine,Nazir, Hasan,et al.
, p. 547 - 552 (2007/10/02)
A number of macrocyclic (1b-3b) and linear oligoether compounds (4b-8b) with 2,2'-methylenebis(4-aminophenol) or 2-aminophenol characteristic building blocks have been synthesized by reduction of the corresponding nitro derivatives with Pd-C/hydrazine hydrate.The pKa' values of the new compounds have been determined by potentiometric titration.These and the observed spectroscopic data are discussed and compared with related compounds.A crystalline 1:1 complex of the diamino crown 3b with NaSCN has also been prepared and characterized. Keywords: Amino Crowns, Amino Podands, Synthesis, Spectroscopic Studies
SYNTHESIS OF NOVEL CROWN DERIVATIVES INCORPORATING A DIAMINOPHOSPHINE GROUP IN A POLYETHER MACROCYCLE
Dutasta, Jean Pierre,Simon, Pascal
, p. 3577 - 3580 (2007/10/02)
The efficient synthesis of 17- to 21-membered ring phosphorus compounds is described.The derivatives incorporate a diaminophosphine group in a polyether macrocycle.
Ligand Structure and Complexation, LI. - Multidentate Neutral Ligands with Variable Cavities and Pseudo Cavities
Sieger, Heinz,Voegtle, Fritz
, p. 425 - 440 (2007/10/02)
New cyclic and non-cyclic neutral ligand systems have been synthesized.They contain repeating oligoethylene glycol ethers and carboxamide functions, which allow attractive interactions between single chain segments and with terminal groups.Crystalline com
