- From p-dimethoxybenzene to crown-benzenophanes, 4: Cation-complexing properties of Bis(p-phenylene-34-crown-10) - A structural and spectrophotometric study
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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.
- Marquis, Damien,Greiving, Helmut,Desvergne, Jean-Pierre,Lahrahar, Nacer,Marsau, Pierre,Hopf, Henning,Bouas-Laurent, Henri
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- Disabling Molecular Recognition through Reversible Mechanical Stoppering
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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
- Soto, Miguel A.,Maclachlan, Mark J.
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p. 1744 - 1748
(2019/05/10)
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- Rigid-Strut-Containing crown ethers and [2]catenanes for incorporation into Metal-Organic frameworks
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To introduce crown ethers into the struts of metal - organic frameworks (MOFs), general approaches have been developed for the syntheses of dicarboxylic acid dibenzo[30]crown-10 (DB30C10DA), dicarboxylic acid di-2,3-naphtho[30] crown-10 (DN30C10DA), dicarboxylic acid bisparaphenylene[34]crown-10 (BPP34C10DA), and dicarboxylic acid 1, 5-naphthoparaphenylene[36]crown-10 (NPP36C10DA). These novel crown ethers not only retain the characteristics of their parent crown ethers since they can 1) bind cationic guests and 2) serve as templates for making mechanically interlocked molecules (MIMs), such as catenanes and rotaxanes, but they also present coordination sites to connect with secondary building units (SBUs) in MOFs. The binding behavior of BPP34C10DA with 1,1′-dimethy 1-4, 4′-bipyridinium bis(hexafluorophosphate) (DMBP·2PF6) has been investigated by means of UV/ Vis, fluorescence, and NMR spectroscopic techniques. The crystal superstructure of the complex DMBP·2PF6C BPP34C10DA was determined by X-ray crystallography. The NPP36C10DA-based [2]catenane (H 2NPP36C10DC·CAT4PFfi) and the BPP34C10DA-based [2]catenane (H2BPP34C10DC-CAT-4PF6) were prepared in DMF at room temperature by the template-directed clipping reactions of the planarly chiral NPP36C10DA and BPP34C10DA with 1, 1′-[1,4-phenylenebis(methylene)]di4, 4′-bipyridin-l-ium bis(hexafluorophosphate) and 1,4-bis(bromomethyl) benzene, respectively. The crystal structure of the dimethyl ester (BPP34C10DE-CAT·4PF6) of the [2]catenane H 2BPP34C10DC-CAT·4PF6 was investigated by X-ray crystallography, which revealed racemic R and S isomers with planar chirality present in the crystal in a 1:1 ratio. These crown ether based struts serve as excellent organic ligands to bind with transition metal ions in the construction of MOFs: the crown ethers BPP34C10DA and NPP36C10DA in the presence of Zn(NO3)2·4H2O afforded the MOF-1001 and MOF-1002 frameworks, respectively. The crystal structures of MOF-1001 and MOF-1002 are both cubic and display Fm3m symmetry. The unit cell parameter of the metal - organic frameworks is α= 52.9345 A. Since such MOFs, containing electron-donating crown ethers are capable of docking incoming electronaccepting substrates in a stereoelectronically controlled fashion, the present work opens a new access to the preparation and application of MOFs.
- Zhao, Yan-Li,Liu, Lihua,Zhang, Wenyu,Sue, Chi-Hau,Li, Qiaowei,Miljanic, Ognjen S.,Yaghi, Omar M.,Fraser Stoddart
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experimental part
p. 13356 - 13380
(2010/06/16)
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- Biscatenanes and a Bisrotaxane-Model Compounds for Polymers with Mechanically Interlocked Components
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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.
- Ashton, Peter R.,Huff, Juergen,Menzer, Stephen,Parsons, Ian W.,Preece, Jon A.,et al.
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- Molecular meccano. 3. Constitutional and translational isomerism in [2]catenanes and [n]pseudorotaxanes
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The mutual molecular recognition expressed between two classes of compounds has led to the self-assembly of a range of [2]catenanes, composed of cyclic polyethers intercepted by π-electron donors, and a range of [n]-pseudorotaxanes, composed of similar ac
- Amabilino, David B.,Anelli, Pier-Lucio,Ashton, Peter R.,Brown, George R.,Córdova, Emilio,Godínez, Luis A.,Hayes, Wayne,Kaifer, Angel E.,Philp, Douglas,Slawin, Alexandra M. Z.,Spencer, Neil,Stoddart, J. Fraser,Tolley, Malcolm S.,Williams, David J.
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p. 11142 - 11170
(2007/10/03)
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- Molecular meccano. 2. Self-assembly of [n]catenanes
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The mutual molecular recognition between different structural components in large rings has led to the template-directed synthesis of a wide range of catenanes composed of from two to five interlocked rings. The molecular self-assembly processes rely upon the recognition between (i) π-electron rich and π-electron deficient aromatic units and (ii) hydrogen bond donors and acceptors, in the different components. In order to increase our knowledge of the factors involved in such molecular self-assembly processes, a homologous series of [2]catenanes has been constructed using macrocyclic polyethers of the bis(p-phenylene)-(3n+4)-crown-n (n = 9-14) type as templates for the formation of the tetracationic cyclophane, cyclobis(paraquat-p-phenylene). Increasing the size of the tetracationic cyclophane to cyclobis(paraquat-4,4′-bitolyl) allows the simultaneous entrapment of two hydroquinone ring-containing macrocyclic polyethers affording a series of [3]catenanes, and one [4]catenane incorporating a cyclic dimer of the expanded cyclophane and three bis(p-phenylene)-34-crown-10 components. By analogy, increasing the number of hydroquinone rings in the macrocyclic polyether permits the self-assembly of more than one tetracationic cyclophane around the templates present in the macrocyclic polyether. In this context, the template-directed synthesis of two [3]catenanes, incorporating two cyclobis(paraquat-p-phenylene) components and either (i) tris(p-phenylene)-51-crown-15 or (ii) tetrakis(p-phenylene)-68-crown-20, has been achieved and is reported. A combination of these two approaches has led to the successful self-assembly, in two steps, of a linear [4]catenane, together with a small amount of a [5]catenane. The creation of these intricate molecular compounds lends support to the contention that self-assembly is a viable paradigm for the construction of nanometer-scale molecular architectures incorporating a selection of simple components.
- Amabilino, David B.,Ashton, Peter R.,Brown, Christopher L.,Córdova, Emilio,Godínez, Luis A.,Goodnow, Timothy T.,Kaifer, Angel E.,Newton, Simon P.,Pietraszkiewicz, Marek,Philp, Douglas,Raymo, Fran?isco M.,Reder, Anatoli S.,Rutland, Marcus T.,Slawin, Alexandra M. Z.,Spencer, Neil,Stoddart, J. Fraser,Williams, David J.
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p. 1271 - 1293
(2007/10/02)
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- The Template-directed Synthesis of Porphyrin-stoppered Rotaxanes
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Two rotaxanes, composed of (i) a polyether chain intercepted by (a) one centrally-located and (b) two symmetrically-located ?-electron-rich hydroquinol rings and terminated by free-base and metallated (Zn) tetraarylporphyrin groups respectively and (II
- Ashton, Peter R.,Johnston, Martin R.,Stoddart, J. Fraser,Tolley, Malcom S.,Wheeler, John W.
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p. 1128 - 1131
(2007/10/02)
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