Polynuclear lanthanide complexes of a series of bridging ligands containing two tridentate N,N′,O-donor units

Structures and luminescence properties

T.K. Ronson, H. Adams, L.P. Harding, S.J.A. Pope, D. Sykes, S. Faulkner, M.D. Ward

Research output: Contribution to journalArticle

Abstract

A set of three potentially bridging ligands containing two tridentate chelating N,N′,O-donor (pyrazole–pyridine–amide) donors separated by an o, m, or p-phenylene spacer has been prepared and their coordination chemistry with lanthanide(III) ions investigated. Ligand L1 (p-phenylene spacer) forms complexes with a 2 : 3 M : L ratio according to the proportions used in the reaction mixture; the Ln2(L1)3 complexes contain two 9-coordinate Ln(III) centres with all three bridging ligands spanning both metal ions, and have a cylindrical (non-helical) ‘mesocate’ architecture. The 1 : 1 complexes display a range of structural types depending on the conditions used, including a cyclic Ln4(L1)4 tetranuclear helicate, a Ln2(L1)2 dinuclear mesocate, and an infinite one-dimensional coordination polymer in which metal ions and bridging ligands alternate along the sequence. ESMS studies indicate that the 1 : 1 complexes form a mixture of oligonuclear species {Ln(L1)}n in solution (n up to 5) which are likely to be cyclic helicates. In contrast, ligands L2 and L3 (with o- and m-phenylene spacers, respectively) generally form dinuclear Ln2L2 Ln(III) complexes in which the two ligands may be arranged in a helical or non-helical architecture about the two metal ions. These complexes also contain an additional exogenous bidentate bridging ligand, either acetate or formate, which has arisen from hydrolysis of solvent molecules promoted by the Lewis-acidity of the Ln(III) ions. Luminescence studies on some of the Nd(III) complexes showed that excitation into ligand-centred π–π* transitions result in the characteristic near-infrared luminescence from Nd(III) at 1060 nm.
Original languageEnglish
Pages (from-to)1006-1022
Number of pages17
JournalDalton Transactions
Issue number10
DOIs
Publication statusPublished - Feb 2007

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Lanthanoid Series Elements
Luminescence
Ligands
Metal ions
formic acid
Ions
Electron transitions
Chelation
Acidity
Hydrolysis
Polymers
Acetates
Infrared radiation
Molecules

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title = "Polynuclear lanthanide complexes of a series of bridging ligands containing two tridentate N,N′,O-donor units: Structures and luminescence properties",
abstract = "A set of three potentially bridging ligands containing two tridentate chelating N,N′,O-donor (pyrazole–pyridine–amide) donors separated by an o, m, or p-phenylene spacer has been prepared and their coordination chemistry with lanthanide(III) ions investigated. Ligand L1 (p-phenylene spacer) forms complexes with a 2 : 3 M : L ratio according to the proportions used in the reaction mixture; the Ln2(L1)3 complexes contain two 9-coordinate Ln(III) centres with all three bridging ligands spanning both metal ions, and have a cylindrical (non-helical) ‘mesocate’ architecture. The 1 : 1 complexes display a range of structural types depending on the conditions used, including a cyclic Ln4(L1)4 tetranuclear helicate, a Ln2(L1)2 dinuclear mesocate, and an infinite one-dimensional coordination polymer in which metal ions and bridging ligands alternate along the sequence. ESMS studies indicate that the 1 : 1 complexes form a mixture of oligonuclear species {Ln(L1)}n in solution (n up to 5) which are likely to be cyclic helicates. In contrast, ligands L2 and L3 (with o- and m-phenylene spacers, respectively) generally form dinuclear Ln2L2 Ln(III) complexes in which the two ligands may be arranged in a helical or non-helical architecture about the two metal ions. These complexes also contain an additional exogenous bidentate bridging ligand, either acetate or formate, which has arisen from hydrolysis of solvent molecules promoted by the Lewis-acidity of the Ln(III) ions. Luminescence studies on some of the Nd(III) complexes showed that excitation into ligand-centred π–π* transitions result in the characteristic near-infrared luminescence from Nd(III) at 1060 nm.",
author = "T.K. Ronson and H. Adams and L.P. Harding and S.J.A. Pope and D. Sykes and S. Faulkner and M.D. Ward",
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Polynuclear lanthanide complexes of a series of bridging ligands containing two tridentate N,N′,O-donor units : Structures and luminescence properties. / Ronson, T.K.; Adams, H.; Harding, L.P.; Pope, S.J.A.; Sykes, D.; Faulkner, S.; Ward, M.D.

In: Dalton Transactions, No. 10, 02.2007, p. 1006-1022.

Research output: Contribution to journalArticle

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T2 - Structures and luminescence properties

AU - Ronson, T.K.

AU - Adams, H.

AU - Harding, L.P.

AU - Pope, S.J.A.

AU - Sykes, D.

AU - Faulkner, S.

AU - Ward, M.D.

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PY - 2007/2

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AB - A set of three potentially bridging ligands containing two tridentate chelating N,N′,O-donor (pyrazole–pyridine–amide) donors separated by an o, m, or p-phenylene spacer has been prepared and their coordination chemistry with lanthanide(III) ions investigated. Ligand L1 (p-phenylene spacer) forms complexes with a 2 : 3 M : L ratio according to the proportions used in the reaction mixture; the Ln2(L1)3 complexes contain two 9-coordinate Ln(III) centres with all three bridging ligands spanning both metal ions, and have a cylindrical (non-helical) ‘mesocate’ architecture. The 1 : 1 complexes display a range of structural types depending on the conditions used, including a cyclic Ln4(L1)4 tetranuclear helicate, a Ln2(L1)2 dinuclear mesocate, and an infinite one-dimensional coordination polymer in which metal ions and bridging ligands alternate along the sequence. ESMS studies indicate that the 1 : 1 complexes form a mixture of oligonuclear species {Ln(L1)}n in solution (n up to 5) which are likely to be cyclic helicates. In contrast, ligands L2 and L3 (with o- and m-phenylene spacers, respectively) generally form dinuclear Ln2L2 Ln(III) complexes in which the two ligands may be arranged in a helical or non-helical architecture about the two metal ions. These complexes also contain an additional exogenous bidentate bridging ligand, either acetate or formate, which has arisen from hydrolysis of solvent molecules promoted by the Lewis-acidity of the Ln(III) ions. Luminescence studies on some of the Nd(III) complexes showed that excitation into ligand-centred π–π* transitions result in the characteristic near-infrared luminescence from Nd(III) at 1060 nm.

U2 - 10.1039/b618258e

DO - 10.1039/b618258e

M3 - Article

SP - 1006

EP - 1022

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

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ER -