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Saha S, Biswas PK, Schmittel M. Reversible Interconversion of a Static Metallosupramolecular Cage Assembly into a High-Speed Rotor: Stepless Adjustment of Rotational Exchange by Nucleophile Addition. Inorg Chem 2019; 58:3466-3472. [PMID: 30789716 DOI: 10.1021/acs.inorgchem.8b03567] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The self-assembled cage ROT-1 was prepared from the pyridine-terminated rotator 1, the phenanthroline-appended stator 2, DABCO, and copper(I) ions in a ratio of 1:1:1:4. This four-component assembly is held together by two pyridine→[Cu(phenAr2)]+ as well as two DABCO→zinc porphyrin interactions (phenAr2 = 2,9-diarylphenanthroline) and does not show any motion on the NMR time scale ( k < 0.1 s-1, 298 K). However, it is converted to the fast nanorotor ROT-1 xCD3CN by addition of CD3CN [ x = (v/v)% of acetonitrile in dichloromethane] due to acceleration of both pyridine→copper(I) dissociation steps. Now the rotator is able to visit all four copper(I)-loaded phenanthroline stations of the stator. Depending on the amount of CD3CN, the exchange frequency of the nanorotor varies from 0.7 s-1 (CD3CN:CD2Cl2 = 1:29) to 8000 s-1 (CD3CN:CD2Cl2 = 1:5) at 25 °C. When iodide (I-) is added to the static assembly ROT-1, the rotational speed increases even more drastically ( k = 20 000 s-1), again due to accelerating the rate-determining pyridine→copper(I) dissociation step. In both cases, a sigmoidal relationship is established between exchange frequency and the concentration of added nucleophile (CD3CN or iodide) that suggests the presence of a cooperative effect. Reversible switching between the static assembly and fast rotor was performed several times without any decomposition of the system. In contrast, addition of the common nucleophile PPh3 to ROT-1 does not increase the rotational speed, a finding that is explained on thermodynamic grounds.
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Affiliation(s)
- Suchismita Saha
- Center of Micro- and Nanochemistry and Engineering , Organische Chemie I , Adolf-Reichwein-Str. 2 , D-57068 Siegen , Germany
| | - Pronay Kumar Biswas
- Center of Micro- and Nanochemistry and Engineering , Organische Chemie I , Adolf-Reichwein-Str. 2 , D-57068 Siegen , Germany
| | - Michael Schmittel
- Center of Micro- and Nanochemistry and Engineering , Organische Chemie I , Adolf-Reichwein-Str. 2 , D-57068 Siegen , Germany
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2
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Nikitin K, O'Gara R. Mechanisms and Beyond: Elucidation of Fluxional Dynamics by Exchange NMR Spectroscopy. Chemistry 2019; 25:4551-4589. [PMID: 30421834 DOI: 10.1002/chem.201804123] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Indexed: 12/31/2022]
Abstract
Detailed mechanistic information is crucial to our understanding of reaction pathways and selectivity. Dynamic exchange NMR techniques, in particular 2D exchange spectroscopy (EXSY) and its modifications, provide indispensable intricate information on the mechanisms of organic and inorganic reactions and other phenomena, for example, the dynamics of interfacial processes. In this Review, key results from exchange NMR studies of small molecules over the last few decades are systemised and discussed. After a brief introduction to the theory, the key types of dynamic processes are identified and fundamental examples given of intra- and intermolecular reactions, which, in turn, could involve, or not, bond-making and bond-breaking events. Following that logic, internal molecular rotation, intramolecular stereomutation and molecular recognition will first be considered because they do not typically involve bond breaking. Then, rearrangements, substitution-type reactions, cyclisations, additions and other processes affecting chemical bonds will be discussed. Finally, interfacial molecular dynamics and unexpected combinations of different types of fluxional processes will also be highlighted. How exchange NMR spectroscopy helps to identify conformational changes, coordination and molecular recognition processes as well as quantify reaction energy barriers and extract detailed mechanistic information by using reaction rate theory in conjunction with computational techniques will be shown.
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Affiliation(s)
- Kirill Nikitin
- School of Chemistry, University College Dublin, Belfield, Dublin, Ireland
| | - Ryan O'Gara
- School of Chemistry, University College Dublin, Belfield, Dublin, Ireland
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3
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Heteroleptic copper phenanthroline complexes in motion: From stand-alone devices to multi-component machinery. Coord Chem Rev 2018; 376:478-505. [PMID: 32287354 PMCID: PMC7126816 DOI: 10.1016/j.ccr.2018.08.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/07/2018] [Accepted: 08/13/2018] [Indexed: 12/27/2022]
Abstract
Two and a half decades of copper phenanthroline-based switches, devices and machines have illustrated the rich dynamic nature of these metal complexes. With an emphasis on the metal-ligand dissociation as the rate-determining step the present review summarizes not only spectacular examples of machinery, but also highlights rate data collected during a variety of investigations. Copper-ligand exchange reactions are mostly triggered by redox processes, addition of metal ions or addition of ligands. While the rate data spread over >8 orders of magnitude, individual effects of solvent, steric bulk, flexibility, σ-basicity and the trajectory (intra- vs. intermolecular dissociation) have large impact. Unfortunately, in many cases the exact mechanism in the rate-determining step (nucleophile-induced vs. monomolecular metal-ligand dissociation) has not been determined, suggesting to invest further efforts in the physical (in)organic chemistry of such coordination-driven systems.
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Mohankumar M, Monti F, Holler M, Niess F, Delavaux-Nicot B, Armaroli N, Sauvage JP, Nierengarten JF. Combining topological and steric constraints for the preparation of heteroleptic copper(I) complexes. Chemistry 2014; 20:12083-90. [PMID: 25056825 DOI: 10.1002/chem.201402429] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Indexed: 11/09/2022]
Abstract
Heteroleptic copper(I) complexes have been prepared from a macrocyclic ligand incorporating a 2,9-diphenyl-1,10-phenanthroline subunit (M30) and two bis-phosphines, namely bis[(2-diphenylphosphino)phenyl] ether (POP) and 1,3-bis(diphenylphosphino)propane (dppp). In both cases, the diphenylphosphino moieties of the PP ligand are too bulky to pass through the 30-membered ring of M30 during the coordination process, hence the formation of C2v-symmetrical pseudo-rotaxanes is prevented. When POP is used, X-ray crystal structure analysis shows the formation of a highly distorted [Cu(M30)(POP)](+) complex in which the POP ligand is only partially threaded through the M30 unit. This compound is poorly stable as the Cu(I) cation is not in a favorable coordination environment due to steric constraints. By contrast, in the case of dppp, the bis-phosphine ligand undergoes both steric and topological constraints and adopts a nonchelating coordination mode to generate [Cu2(M30)2(μ-dppp)](BF4)2. This compound exhibits metal-to-ligand charge transfer (MLCT) emission characterized by a very large Stokes' shift (≈200 nm) that is not attributed to a dramatic structural distortion between the ground and the emitting states but to very weak MLCT absorption transitions at longer wavelengths. Accordingly, [Cu2(M30)2(μ-dppp)](BF4)2 shows unusually high luminescence quantum yields for Cu(I) complexes, both in solution and in the solid state (0.5 and 7 %, respectively).
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Affiliation(s)
- Meera Mohankumar
- Laboratoire de Chimie des Matériaux Moléculaires, Université de Strasbourg et CNRS (UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux, 25 rue Becquerel, 67087 Strasbourg Cedex 2 (France)
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5
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Kaeser A, Mohankumar M, Mohanraj J, Monti F, Holler M, Cid JJ, Moudam O, Nierengarten I, Karmazin-Brelot L, Duhayon C, Delavaux-Nicot B, Armaroli N, Nierengarten JF. Heteroleptic copper(I) complexes prepared from phenanthroline and bis-phosphine ligands. Inorg Chem 2013; 52:12140-51. [PMID: 24083360 DOI: 10.1021/ic4020042] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Preparation of [Cu(NN)(PP)](+) derivatives has been systematically investigated starting from two libraries of phenanthroline (NN) derivatives and bis-phosphine (PP) ligands, namely, (A) 1,10-phenanthroline (phen), neocuproine (2,9-dimethyl-1,10-phenanthroline, dmp), bathophenanthroline (4,7-diphenyl-1,10-phenanthroline, Bphen), 2,9-diphenethyl-1,10-phenanthroline (dpep), and 2,9-diphenyl-1,10-phenanthroline (dpp); (B) bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppFc), and bis[(2-diphenylphosphino)phenyl] ether (POP). Whatever the bis-phosphine ligand, stable heteroleptic [Cu(NN)(PP)](+) complexes are obtained from the 2,9-unsubstituted-1,10-phenanthroline ligands (phen and Bphen). By contrast, heteroleptic complexes obtained from dmp and dpep are stable in the solid state, but a dynamic ligand exchange reaction is systematically observed in solution, and the homoleptic/heteroleptic ratio is highly dependent on the bis-phosphine ligand. Detailed analysis revealed that the dynamic equilibrium resulting from ligand exchange reactions is mainly influenced by the relative thermodynamic stability of the different possible complexes. Finally, in the case of dpp, only homoleptic complexes were obtained whatever the bis-phosphine ligand. Obviously, steric effects resulting from the presence of the bulky phenyl rings on the dpp ligand destabilize the heteroleptic [Cu(NN)(PP)](+) complexes. In addition to the remarkable thermodynamic stability of [Cu(dpp)2]BF4, this negative steric effect drives the dynamic complexation scenario toward almost exclusive formation of homoleptic [Cu(NN)2](+) and [Cu(PP)2](+) complexes. This work provides the definitive rationalization of the stability of [Cu(NN)(PP)](+) complexes, marking the way for future developments in this field.
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Affiliation(s)
- Adrien Kaeser
- Laboratoire de Chimie des Matériaux Moléculaires, Université de Strasbourg et CNRS (UMR 7509) , 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
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Furusho Y, Goto H, Itomi K, Katagiri H, Miyagawa T, Yashima E. Synthesis and optical resolution of a Cu(I) double-stranded helicate with ketimine-bridged tris(bipyridine) ligands. Chem Commun (Camb) 2011; 47:9795-7. [PMID: 21818481 DOI: 10.1039/c1cc13333k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A tetranuclear Cu(I) double-stranded helicate was synthesized from ketimine-bridged tris(bipyridine) ligands and Cu(I) ions, and the racemate was successfully resolved by diastereomeric salt formation using an optically pure phosphate anion followed by anion exchange with NaPF(6) without racemization.
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Affiliation(s)
- Yoshio Furusho
- Yashima Super-Structured Helix Project, ERATO, Japan Science and Technology Agency (JST), Japan.
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7
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Share AI, Parimal K, Flood AH. Bilability is defined when one electron is used to switch between concerted and stepwise pathways in Cu(I)-based bistable [2/3]pseudorotaxanes. J Am Chem Soc 2010; 132:1665-75. [PMID: 20070081 DOI: 10.1021/ja908877d] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Supramolecular switches operate as simple machines by using a stimulus to turn stations off and on, generating thermodynamic differences that define bistability and enable motion. What has not been previously investigated, yet is required to gain further control over molecular movements for complex operations, is an understanding of how the same stimulus can also switch pathways off and on, thus, defining the kinetic property of bilability. To address this challenge, the mechanisms of the forward and return reactions of redox-switchable Cu(I)-based [2/3]pseudorotaxanes have been quantitatively characterized utilizing mechanistic cyclic voltammetry and employing a series of isosteric bis-bidentate ligands. First, the bistability of the switch is retained across the series of ligands: Reduction of the ligand drives the reaction forward where a [2]pseudorotaxane switches into a reduced [3]pseudorotaxane and reoxidation drives the switching cycle back to the beginning. Second, the switch is bilabile with the forward reaction following an association-activated interchange pathway (concerted), whereas the reverse reaction follows a different dissociation-based dethreading pathway (stepwise). The forward reaction is more sensitive to denticity (bidentate tetrazinyl ligand, k(2) = 12,000 M(-1) s(-1), versus the monodentate pyrazinyl ligand, k(2) = 1500 M(-1) s(-1)) than to electronics (k(2) = 12,000 M(-1) s(-1) for methyl and trifluoromethyl substituents). The rate of return with the pyrazinyl ligand is k(1) = 50 s(-1). Consequently, both the mechanism and the thermodynamics of switching are stimuli dependent; they change with the oxidation state of the ligand. These findings have implications for the future design of molecular motors, which can be built from systems displaying allosterically coupled bistability and bilability.
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Affiliation(s)
- Andrew I Share
- Department of Chemistry, University of Indiana, Bloomington, 800 E. Kirkwood Ave., Bloomington, Indiana 47405, USA
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8
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De S, Mahata K, Schmittel M. Metal-coordination-driven dynamic heteroleptic architectures. Chem Soc Rev 2010; 39:1555-75. [PMID: 20419210 DOI: 10.1039/b922293f] [Citation(s) in RCA: 341] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic heteroleptic coordination at metal centres is quite common in Nature and often related to a specific biological function, such as in zinc finger proteins and in hemoglobin for oxygen transport. To achieve the required high heteroleptic fidelity, representative biological systems avail themselves of "intramolecular" multidentate coordination using the protein backbone as a "superligand". In contrast, dynamic heteroleptic coordination at a single metal centre in solution requires to bind different freely exchanging ligands under thermodynamic control. In this tutorial review we present the emerging principles of how to assemble dissimilar ligands at dynamically exchanging metal centres, with a particular emphasis on using the precepts for the fabrication of heteroleptic supramolecular assemblies in solution.
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Affiliation(s)
- Soumen De
- Center of Micro and Nanochemistry and Engineering, Organische Chemie I, Universität Siegen, Adolf-Reichwein-Str., 2, D-57068 Siegen, Germany
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9
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Dehghanpour S, Rominger F. Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4. RUSS J COORD CHEM+ 2009. [DOI: 10.1134/s1070328409040058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Gschwind RM. Organocuprates and Diamagnetic Copper Complexes: Structures and NMR Spectroscopic Structure Elucidation in Solution. Chem Rev 2008; 108:3029-53. [DOI: 10.1021/cr800286r] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruth M. Gschwind
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany
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11
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Company A, Güell M, Popa D, Benet-Buchholz J, Parella T, Fontrodona X, Llobet A, Solà M, Ribas X, Luis JM, Costas M. Redox-Controlled Molecular Flipper Based on a Chiral Cu Complex. Inorg Chem 2006; 45:9643-5. [PMID: 17112258 DOI: 10.1021/ic0618549] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A molecular bipaddled flipper based on a tetradentate chiral Cu complex has been designed. The paddling motion of this unprecedented molecular-scale machine can be controlled by reversible oxidation of the metal center. Kinetic and computational (density functional theory) analyses provide a detailed picture of the flipper motion at the molecular scale, rationalize the switching role of the metal-ion oxidation state, and pose the basis for the fine-tuning of the dynamic motion of this new class of molecular-scale devices.
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Affiliation(s)
- Anna Company
- Departament de Química and Institut de Química Computacional, Universitat de Girona, Campus de Montilivi, E-17071 Girona, Spain
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12
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Amirnasr M, Kickelbick G, Dehghanpour S. Synthesis, Characterization, and X-Ray Crystal Structures of Bis[N-(3,3-diphenylallylidene)quinolin-8-amine-κN,κN8]copper(1+) Tetraphenylborate(1−) ([Cu(dpa-qa)2]BPh4) and Bis[N,N′-bis(3,3-diphenylallylidene)-[1,1′-biphenyl]-2,2′-diamine-κN,κN′]copper(1+) Perchlorate ([Cu(bdpa-bda)2]ClO4 ⋅ 3 H2O). Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Hebbe-Viton V, Desvergnes V, Jodry JJ, Dietrich-Buchecker C, Sauvage JP, Lacour J. Chiral spiro Cu(i) complexes. Supramolecular stereocontrol and isomerisation dynamics by the use of TRISPHAT anions. Dalton Trans 2006:2058-65. [PMID: 16625249 DOI: 10.1039/b515540a] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Association of enantiopure TRISPHAT anion (1) with chiral spiro [Cu(LL')2] complexes (LL' = 2-R-phen, 2, 6-R-bpy, 3, and 2-iminopyridine, 4) leads to an efficient NMR enantiodifferentiation. Variable temperature 1H NMR spectroscopy has been used to determine the isomerisation kinetics of these pseudo-tetrahedral complexes and to evaluate their configurational stability; the latter depending on the structure of the diimine ligands. In the case of the 2-anthracenyl-phen derivative, a decent level of supramolecular stereocontrol was noted (d.e. up to 45%); the configuration of the complex being determined by electronic circular dichroism (ECD).
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Affiliation(s)
- Virginie Hebbe-Viton
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, CH-1211, Geneva 4, Switzerland
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Hutin M, Nitschke J. Solvent-tunable inversion of chirality transfer from carbon to copper. Chem Commun (Camb) 2006:1724-6. [PMID: 16609784 DOI: 10.1039/b601012a] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A change of solvent causes an inversion of the stereochemistry at copper of the chiral Cu(I) complex described herein.
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Affiliation(s)
- Marie Hutin
- Department of Organic Chemistry, University of Geneva, 30 Quai Ernest Ansermet, 1211 Genève 4, Switzerland
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Mamula O, von Zelewsky A, Brodard P, Schläpfer CW, Bernardinelli G, Stoeckli-Evans H. Helicates of Chiragen-Type Ligands and Their Aptitude for Chiral Self-Recognition. Chemistry 2005; 11:3049-57. [PMID: 15770706 DOI: 10.1002/chem.200401109] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Two (-)-5,6-pinene-bipyridine moieties connected by a para-xylylene bridge (so-called chiragen-type ligands), (-)-L1, undergo self-assembly upon reaction with equimolar amounts of CuI to form enantiopure circular hexanuclear P-helicates. If both enantiomers of L1 are used, mixtures of P and M hexanuclear helicates are exclusively obtained through a complete chiral recognition; that is, no mixing of the (+) and (-) ligands, respectively, occurs upon complexation. This was proven by a) NMR spectroscopy where identical spectra to those for complexes with the enantiomerically pure ligands were obtained and b) circular dichroism (CD) spectroscopy. The reaction is completely changed by the use of the corresponding meso-L1. Instead of well-defined species, oligomeric mixtures are observed, a result demonstrating the crucial role played by ligand chirality in self-assembly processes. Structural variations on the chiral ligand L1, such as a meta-xylylene bridge instead of a para-xylylene one (in L4) or four pinene groups instead of two (in L5 and L6), favor nondiscrete coordination assembly.
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Affiliation(s)
- Olimpia Mamula
- Department of Chemistry, University of Fribourg, Pérolles, 1700, Fribourg, Switzerland
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