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Article: Versatile self-complexing compounds based on covalently linked donor-acceptor cyclophanes
Title | Versatile self-complexing compounds based on covalently linked donor-acceptor cyclophanes |
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Authors | |
Keywords | Donor-acceptor systems Molecular switches Self-complexing Thermochromism Thermodynamics |
Issue Date | 2005 |
Citation | Chemistry - A European Journal, 2005, v. 11, n. 1, p. 369-385 How to Cite? |
Abstract | A range of covalently linked donor-acceptor compounds which contain 1) a hydroquinone (HQ) unit, 2) a 1,5-dioxynaphthalene (DNP) ring system, or 3) a tetrathiafulvalene (TTF) unit as the π-donor, and 4) cyclobis(paraquat-p- phenylene) (CBPQT4+) as the π-accepting tetracationic cyclophane were prepared and shown to operate as simple molecular machines. The π-donating arms can be included inside the cyclophane in an intramolecular fashion by virtue of stabilizing noncovalent bonding interactions. What amounts to self-complexing/decomplexing equilibria were shown to be highly temperature dependent when the π-donating arm contains either an HQ or DNP moiety. The thermodynamic parameters associated with the equilibria have been unraveled by using variable-temperature 1HNMR spectroscopy. The negative ΔH° and ΔS° values account for the fact that the "uncomplexed" conformation becomes the dominant species, since the entropy gain associated with the decomplexation process overcomes the enthalpy loss resulting from the breaking of the donor-acceptor interactions. The arm's in-and-out movements with respect to the linked cyclophanes can be arrested by installing a bulky substituent at the end of the arm. In the case of compounds carrying a DNP ring system in their side arm, two diastereoisomeric, self-complexing conformations are observed below 272 K in hexadeuterioacetone. By contrast, control over the TTF-containing arm's movement is more or less ineffective through the thermally sensitive equilibrium although it can be realized by chemical and electrochemical ways as a result of TTF's excellent redox properties. Such self-complexing compounds could find applications as thermo- and electroswitches. In addition, the thermochromism associated with the arm's movement could lead to some of the compounds finding uses as imaging and sensing materials. |
Persistent Identifier | http://hdl.handle.net/10722/332607 |
ISSN | 2021 Impact Factor: 5.020 2020 SCImago Journal Rankings: 1.687 |
DC Field | Value | Language |
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dc.contributor.author | Liu, Yi | - |
dc.contributor.author | Flood, Amar H. | - |
dc.contributor.author | Moskowitz, Ross M. | - |
dc.contributor.author | Stoddart, J. Fraser | - |
dc.date.accessioned | 2023-10-06T05:12:50Z | - |
dc.date.available | 2023-10-06T05:12:50Z | - |
dc.date.issued | 2005 | - |
dc.identifier.citation | Chemistry - A European Journal, 2005, v. 11, n. 1, p. 369-385 | - |
dc.identifier.issn | 0947-6539 | - |
dc.identifier.uri | http://hdl.handle.net/10722/332607 | - |
dc.description.abstract | A range of covalently linked donor-acceptor compounds which contain 1) a hydroquinone (HQ) unit, 2) a 1,5-dioxynaphthalene (DNP) ring system, or 3) a tetrathiafulvalene (TTF) unit as the π-donor, and 4) cyclobis(paraquat-p- phenylene) (CBPQT4+) as the π-accepting tetracationic cyclophane were prepared and shown to operate as simple molecular machines. The π-donating arms can be included inside the cyclophane in an intramolecular fashion by virtue of stabilizing noncovalent bonding interactions. What amounts to self-complexing/decomplexing equilibria were shown to be highly temperature dependent when the π-donating arm contains either an HQ or DNP moiety. The thermodynamic parameters associated with the equilibria have been unraveled by using variable-temperature 1HNMR spectroscopy. The negative ΔH° and ΔS° values account for the fact that the "uncomplexed" conformation becomes the dominant species, since the entropy gain associated with the decomplexation process overcomes the enthalpy loss resulting from the breaking of the donor-acceptor interactions. The arm's in-and-out movements with respect to the linked cyclophanes can be arrested by installing a bulky substituent at the end of the arm. In the case of compounds carrying a DNP ring system in their side arm, two diastereoisomeric, self-complexing conformations are observed below 272 K in hexadeuterioacetone. By contrast, control over the TTF-containing arm's movement is more or less ineffective through the thermally sensitive equilibrium although it can be realized by chemical and electrochemical ways as a result of TTF's excellent redox properties. Such self-complexing compounds could find applications as thermo- and electroswitches. In addition, the thermochromism associated with the arm's movement could lead to some of the compounds finding uses as imaging and sensing materials. | - |
dc.language | eng | - |
dc.relation.ispartof | Chemistry - A European Journal | - |
dc.subject | Donor-acceptor systems | - |
dc.subject | Molecular switches | - |
dc.subject | Self-complexing | - |
dc.subject | Thermochromism | - |
dc.subject | Thermodynamics | - |
dc.title | Versatile self-complexing compounds based on covalently linked donor-acceptor cyclophanes | - |
dc.type | Article | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1002/chem.200400614 | - |
dc.identifier.scopus | eid_2-s2.0-19944426350 | - |
dc.identifier.volume | 11 | - |
dc.identifier.issue | 1 | - |
dc.identifier.spage | 369 | - |
dc.identifier.epage | 385 | - |