134881-76-8Relevant academic research and scientific papers
Disabling Molecular Recognition through Reversible Mechanical Stoppering
Soto, Miguel A.,Maclachlan, Mark J.
, p. 1744 - 1748 (2019)
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
Rigid-Strut-Containing crown ethers and [2]catenanes for incorporation into Metal-Organic frameworks
Zhao, Yan-Li,Liu, Lihua,Zhang, Wenyu,Sue, Chi-Hau,Li, Qiaowei,Miljanic, Ognjen S.,Yaghi, Omar M.,Fraser Stoddart
experimental part, p. 13356 - 13380 (2010/06/16)
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.
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.
Catenated Cyclodextrins
Armspach, Dominique,Ashton, Peter R.,Ballardini, Roberto,Balzani, Vincenzo,Godi, Anna,et al.
, p. 33 - 55 (2007/10/02)
A novel synthetic approach is described for the construction of catenanes in aqueous solution from a partially methylated cyclodextrin (CD)-namely, heptakis(2,6-di-O-methyl-β-cyclodextrin) (DM-β-CD)- and a range of substrate molecules that contain a hydrophobic central core in the form of a 4,4'-disubstituted biphenyl unit (usually bitolyl) carrying two hydrophilic polyether side chains terminated by primary amine functions.In water, the amphiphilic catenane precursors form 1:1 complexes with β-CD and DM-β-CD and 2:1 (guest:host) complexes with the larger γ-CD.Macrocyclizations of the biphenyl-containing substrates with aromatic diacid chlorides in aqueous solution and in the presence of DM-β-CD under Schotten-Baumann conditions afforded - in low yields - a range of - and catenanes.When a consitutionally asymmetrical diamine was employed as the substrate, orientational isomers of a catenane were obtained.A catenane incorporating a macrocyclic tetralactam was found to exist as a mixture of head-to-head and head-to-tail isomers, which could be separated by high pressure liquid chromatography and identified unambiguously by nuclear magnetic resonance spectroscopy.One of the catenanes afforded good single crystals from which the solid state structure was determined by X-ray crystallography.Other techniques which aided the characterization of these novel compounds included ultraviolet/visible and luminescence spectroscopy, dynamic nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry.Generally speaking, the catenated cyclodextrins are soluble in halogenated and aromatic hydrocarbons as well as in hydroxylic solvents.The existence of these new compounds gives us a unique insight into the nature of the noncovalent bonding interactions that cyclodextrins employ in binding substrate molecules. - Keywords: catenanes * cyclodextrins * macrocycles * orientational isomerism
Molecular meccano. 2. Self-assembly of [n]catenanes
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.
, p. 1271 - 1293 (2007/10/02)
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.
Molecular meccano. 1. [2]rotaxanes and a [2]catenane made to order
Anelli, Pier Lucio,Ashton, Peter R.,Ballardini, Roberto,Balzani, Vincenzo,Delgado, Milagros,Gandoffi, Maria Teresa,Goodnow, Timothy T.,Kaifer, Angel E.,Philp, Douglas,Pietraszkiewicz, Marek,Prodi, Luca,Reddington, Mark V.,Slawin, Alexandra M.Z.,Spencer, Neil,Fraser Stoddart,Vicent, Cristina,Williams, David J.
, p. 193 - 218 (2007/10/02)
A new synthetic strategy for the elaboration of supramolecular species and molecular compounds containing noncovalently interacting components is described, with the long-term objective of constructing highly ordered, wholly synthetic assemblies from readily available starting materials. These could serve as a basis for the future development of mechanoelectrical and photoelectrical communication systems and devices capable of storing and processing information. The approach was conceived against a background of a quarter of a century's experience in supramolecular, alias host-guest, chemistry. It is based on the use of irreversibly interlocked molecular systems that take the form of catenanes and rotaxanes. Such compounds are seen to be the ideal vehicles through which to transfer from supramolecular and host-guest chemistry the knowledge and experience gained from studying complexes between small chemical entities to very much larger molecular assemblies. Once we know how to interlock molecular components irreversibly and efficiently, we shall have a very much clearer idea on how to intertwine related polymer chains reversibly. A number of template-directed syntheses of [2]rotaxanes and a [2]catenane is discussed. They illustrate that there are inherently simple ways of making apparently complex unnatural products from appropriate substrates without the need for reagent control or catalysis. The noncovalent bonding interactions that are used to self-assemble the 1:1 complexes, which serve as precursors to the rotaxanes and the catenane, as well as to the [2]rotaxanes and the [2]catenane themselves, "live on" in their structures and superstructures after the self-assembly process is complete. A variety of methods, including X-ray crystallography, fast atom bombardment mass spectrometry, ultra violet-visible, luminescence, nuclear magnetic resonance, and electron spin resonance spectroscopies, and electrochemistry, demonstrate the high structural order that is incorporated into these new molecular assemblies in both the solid and solution states.
