134881-77-9Relevant articles and documents
From p-dimethoxybenzene to crown-benzenophanes, 4: Cation-complexing properties of Bis(p-phenylene-34-crown-10) - A structural and spectrophotometric study
Marquis, Damien,Greiving, Helmut,Desvergne, Jean-Pierre,Lahrahar, Nacer,Marsau, Pierre,Hopf, Henning,Bouas-Laurent, Henri
, p. 97 - 106 (1997)
The title compound 2, an electron-rich macrocyclic paracyclophane of the coronand type, known to form a charge-transfer complex with paraquat, was found to encapsulate strontium cations and to bind to magnesium cations. X-ray analysis revealed that 2 forms a 2:1 (metal/substrate) complex with Sr(ClO4)2, in which the two benzene rings weakly overlap, whereas in the single crystals grown from Mg(ClO4)2, the metal cation prefers to lie outside the coronand (1:1 stoichiometry). In acetonitrile solution, cations were observed to trigger an hypsochromic shift of the UV absorption spectra, proportional to their size and charge density. The stoichiometries and binding constants were also determined by UV absorption titration in acetonitrile using the LETAGROP-SPEFO program for several monovalent and divalent cations. For Na+, Ca2+, and Sr2+, 1:1 and 2:1 complexes were shown to be formed. In the free ligand, a weak interaction between the benzene rings was detected by fluorescence decay kinetic analysis, indicating the presence of two conformer populations within the nanosecond time scale. In solution, metal cations neither induce detectable excimer formation nor seem to have a strong influence on the fluorescence emission spectra, except a heavy atom quenching with Sr2+and Ba2+, in contrast to the effect observed in absorption. However, Sr2+ and Mg2+induce a clear hypsochromic shift in the single crystal fluorescence spectra. Compound 2 was prepared by a new and efficient route which is compared to the previous procedures. VCH Verlagsgesellschaft mbH, 1997.
Disabling Molecular Recognition through Reversible Mechanical Stoppering
Soto, Miguel A.,Maclachlan, Mark J.
, p. 1744 - 1748 (2019/05/10)
Mechanical stoppering of a guest molecule prevents its self-assembly with a macrocycle unit, so that both species coexist in a medium but do not recognize each other. The application of a chemical or physical stimulus reverses mechanical stoppering and su
Biscatenanes and a Bisrotaxane-Model Compounds for Polymers with Mechanically Interlocked Components
Ashton, Peter R.,Huff, Juergen,Menzer, Stephen,Parsons, Ian W.,Preece, Jon A.,et al.
, p. 31 - 44 (2007/10/03)
The self-assembly of three biscatenanes and a bisrotaxane, by two complementary strategies, is reported.A synthetic route to derivatives of bis-para-phenylenecrown-10 (BPP34C10) and 1,5-naphtho-para-phenylene-crown-10 (1/5NPP36C10) containing a fused five-membered ring with a secondary amine function is described.These intermediate N-allylimido macrocyclic polyethers undergo template-directed reactions with 1,1'-bis-4,4'-bipyridinium bis-(hexafluorophosphate) and 1,4-bis(bromo-methyl)benzene to produce catenanes containing an N-allyl functionality.The allylimido macrocyclic polyethers have also beeen reduced and deprotected to afford macrocycles possessing a free NH group, which are then linked through a 4,4'-biphenyldicarbonyl spacer to produce bis(crown ether)s, in which each crown ether moiety has two recognition sites.These ditopic BPP34C10 and 1/5NPP36C10 derivatives are capable of sustaining self-assembly reactions at both recognition sites to yield biscatenanes.The self-assembly of a complementary biscatenane, in which two tetracationic cyclophanes are linked together with a flexible hexyl chain, has also been achieved by treating 1,1'-bis-4,4'-bipyridinum bis-(hexafluorophosphate) with a compound containing two linked 1,4-bis(bromomethyl)benzene units in the presence of BPP34C10.Replacing BPP34C10 with a dumbbell-shaped compound containing a linear polyether unit intercepted by a naphthalene residue and terminated by two bulky adamantoyl groups has led to the self-assembly of a bisrotaxane.The X-ray crystal structures of one of the catenanes and its associated crown ether component are reported, together with solution state dynamic 1H NMR spectroscopic studies, showing that there is substantial degree of order characterizing the molecular structure of the catenanes. - Keywords: catenanes, polycatenanes, polyrotaxanes, rotaxanes, self-assembly.
