Syntheses, structures and hydrolytic properties of copper(II) complexes of asymmetrically N-functionalised 1,4,7-triazacyclononane ligands

Matthew James Belousoff, Andrew Raymond Battle, Bimbil Graham, Leone Spiccia

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Abstract

A series of new asymmetrically N-substituted derivatives of the 1,4,7-triazacyclononane (tacn) macrocycle have been prepared from the common precursor 1,4,7-triazatricyclo[5.2. 1.0(4,10)]decane: 1-ethyl-4-isopropyl-1,4,7-triazacyclononane (L1), 1-isopropyl-4-propyl-1,4,7-triazacyclononane (L2),]1-(3-aminopropyl)-4-benzyl-7-isopropyl-1,4,7-triazacyclononane (L3), 1-benzyl-4-isopropyl-1,4,7-triazacyclononane (L4) and 1,4-bis(3-aminopropyl)-7-isopropyl-1,4,7-triazacyclononane (L5). The corresponding monomeric copper(11) complexes were synthesised and were found to be of composition: [Cu(L1)Cl-2] . 1/2H(2)O (0), [Cu(L4)Cl-2] . 4H(2)O (C2), [Cu(L3)(MeCN)I(ClO4)(2) (C3), [Cu(L5)](ClO4)2 . MeCN . NaClO4 (C4) and [Cu(L2)Cl-2] . 1/2H(2)O (C5). The X-ray crystal structures of each complex revealed a distorted square-pyramidal copper(II) geometry, with the nitrogen donors on the ligands occupying 3 (C1 and C2), 4 (0) or 5 (C4) coordination sites on the Cu(II) centre. The metal complexes were tested for the ability to hydrolytically cleave phosphate esters at near physiological conditions, using the model phosphodiester, bis(p-nitrophenyl)phosphate (BNPP). The observed rate constants for BNPP cleavage followed the order k(C1), P: k(C2) > k(C5) > k(C3) > k(C4), confirming that tacn-type Cu(II) complexes efficiently accelerate phosphate ester hydrolysis by being able to bind phosphate esters and also form the nucleophile necessary to carry out intramolecular cleavage. Complexes C1 and C2, featuring asymmetrically disubstituted ligands, exhibited rate constants of the same order of magnitude as those reported for the Cu(11) complexes of symmetrically tri-N-alkylated tacn ligands (k similar to 1.5 x 10(-5) s(-1)). (c) 2006 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)344 - 355
Number of pages12
JournalPolyhedron
Volume26
Issue number2
Publication statusPublished - 2007

Cite this

@article{8f8f25d00be34c10848febd6e41e3f21,
title = "Syntheses, structures and hydrolytic properties of copper(II) complexes of asymmetrically N-functionalised 1,4,7-triazacyclononane ligands",
abstract = "A series of new asymmetrically N-substituted derivatives of the 1,4,7-triazacyclononane (tacn) macrocycle have been prepared from the common precursor 1,4,7-triazatricyclo[5.2. 1.0(4,10)]decane: 1-ethyl-4-isopropyl-1,4,7-triazacyclononane (L1), 1-isopropyl-4-propyl-1,4,7-triazacyclononane (L2),]1-(3-aminopropyl)-4-benzyl-7-isopropyl-1,4,7-triazacyclononane (L3), 1-benzyl-4-isopropyl-1,4,7-triazacyclononane (L4) and 1,4-bis(3-aminopropyl)-7-isopropyl-1,4,7-triazacyclononane (L5). The corresponding monomeric copper(11) complexes were synthesised and were found to be of composition: [Cu(L1)Cl-2] . 1/2H(2)O (0), [Cu(L4)Cl-2] . 4H(2)O (C2), [Cu(L3)(MeCN)I(ClO4)(2) (C3), [Cu(L5)](ClO4)2 . MeCN . NaClO4 (C4) and [Cu(L2)Cl-2] . 1/2H(2)O (C5). The X-ray crystal structures of each complex revealed a distorted square-pyramidal copper(II) geometry, with the nitrogen donors on the ligands occupying 3 (C1 and C2), 4 (0) or 5 (C4) coordination sites on the Cu(II) centre. The metal complexes were tested for the ability to hydrolytically cleave phosphate esters at near physiological conditions, using the model phosphodiester, bis(p-nitrophenyl)phosphate (BNPP). The observed rate constants for BNPP cleavage followed the order k(C1), P: k(C2) > k(C5) > k(C3) > k(C4), confirming that tacn-type Cu(II) complexes efficiently accelerate phosphate ester hydrolysis by being able to bind phosphate esters and also form the nucleophile necessary to carry out intramolecular cleavage. Complexes C1 and C2, featuring asymmetrically disubstituted ligands, exhibited rate constants of the same order of magnitude as those reported for the Cu(11) complexes of symmetrically tri-N-alkylated tacn ligands (k similar to 1.5 x 10(-5) s(-1)). (c) 2006 Elsevier Ltd. All rights reserved.",
author = "Belousoff, {Matthew James} and Battle, {Andrew Raymond} and Bimbil Graham and Leone Spiccia",
year = "2007",
language = "English",
volume = "26",
pages = "344 -- 355",
journal = "Polyhedron",
issn = "0277-5387",
publisher = "Elsevier",
number = "2",

}

Syntheses, structures and hydrolytic properties of copper(II) complexes of asymmetrically N-functionalised 1,4,7-triazacyclononane ligands. / Belousoff, Matthew James; Battle, Andrew Raymond; Graham, Bimbil; Spiccia, Leone.

In: Polyhedron, Vol. 26, No. 2, 2007, p. 344 - 355.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Syntheses, structures and hydrolytic properties of copper(II) complexes of asymmetrically N-functionalised 1,4,7-triazacyclononane ligands

AU - Belousoff, Matthew James

AU - Battle, Andrew Raymond

AU - Graham, Bimbil

AU - Spiccia, Leone

PY - 2007

Y1 - 2007

N2 - A series of new asymmetrically N-substituted derivatives of the 1,4,7-triazacyclononane (tacn) macrocycle have been prepared from the common precursor 1,4,7-triazatricyclo[5.2. 1.0(4,10)]decane: 1-ethyl-4-isopropyl-1,4,7-triazacyclononane (L1), 1-isopropyl-4-propyl-1,4,7-triazacyclononane (L2),]1-(3-aminopropyl)-4-benzyl-7-isopropyl-1,4,7-triazacyclononane (L3), 1-benzyl-4-isopropyl-1,4,7-triazacyclononane (L4) and 1,4-bis(3-aminopropyl)-7-isopropyl-1,4,7-triazacyclononane (L5). The corresponding monomeric copper(11) complexes were synthesised and were found to be of composition: [Cu(L1)Cl-2] . 1/2H(2)O (0), [Cu(L4)Cl-2] . 4H(2)O (C2), [Cu(L3)(MeCN)I(ClO4)(2) (C3), [Cu(L5)](ClO4)2 . MeCN . NaClO4 (C4) and [Cu(L2)Cl-2] . 1/2H(2)O (C5). The X-ray crystal structures of each complex revealed a distorted square-pyramidal copper(II) geometry, with the nitrogen donors on the ligands occupying 3 (C1 and C2), 4 (0) or 5 (C4) coordination sites on the Cu(II) centre. The metal complexes were tested for the ability to hydrolytically cleave phosphate esters at near physiological conditions, using the model phosphodiester, bis(p-nitrophenyl)phosphate (BNPP). The observed rate constants for BNPP cleavage followed the order k(C1), P: k(C2) > k(C5) > k(C3) > k(C4), confirming that tacn-type Cu(II) complexes efficiently accelerate phosphate ester hydrolysis by being able to bind phosphate esters and also form the nucleophile necessary to carry out intramolecular cleavage. Complexes C1 and C2, featuring asymmetrically disubstituted ligands, exhibited rate constants of the same order of magnitude as those reported for the Cu(11) complexes of symmetrically tri-N-alkylated tacn ligands (k similar to 1.5 x 10(-5) s(-1)). (c) 2006 Elsevier Ltd. All rights reserved.

AB - A series of new asymmetrically N-substituted derivatives of the 1,4,7-triazacyclononane (tacn) macrocycle have been prepared from the common precursor 1,4,7-triazatricyclo[5.2. 1.0(4,10)]decane: 1-ethyl-4-isopropyl-1,4,7-triazacyclononane (L1), 1-isopropyl-4-propyl-1,4,7-triazacyclononane (L2),]1-(3-aminopropyl)-4-benzyl-7-isopropyl-1,4,7-triazacyclononane (L3), 1-benzyl-4-isopropyl-1,4,7-triazacyclononane (L4) and 1,4-bis(3-aminopropyl)-7-isopropyl-1,4,7-triazacyclononane (L5). The corresponding monomeric copper(11) complexes were synthesised and were found to be of composition: [Cu(L1)Cl-2] . 1/2H(2)O (0), [Cu(L4)Cl-2] . 4H(2)O (C2), [Cu(L3)(MeCN)I(ClO4)(2) (C3), [Cu(L5)](ClO4)2 . MeCN . NaClO4 (C4) and [Cu(L2)Cl-2] . 1/2H(2)O (C5). The X-ray crystal structures of each complex revealed a distorted square-pyramidal copper(II) geometry, with the nitrogen donors on the ligands occupying 3 (C1 and C2), 4 (0) or 5 (C4) coordination sites on the Cu(II) centre. The metal complexes were tested for the ability to hydrolytically cleave phosphate esters at near physiological conditions, using the model phosphodiester, bis(p-nitrophenyl)phosphate (BNPP). The observed rate constants for BNPP cleavage followed the order k(C1), P: k(C2) > k(C5) > k(C3) > k(C4), confirming that tacn-type Cu(II) complexes efficiently accelerate phosphate ester hydrolysis by being able to bind phosphate esters and also form the nucleophile necessary to carry out intramolecular cleavage. Complexes C1 and C2, featuring asymmetrically disubstituted ligands, exhibited rate constants of the same order of magnitude as those reported for the Cu(11) complexes of symmetrically tri-N-alkylated tacn ligands (k similar to 1.5 x 10(-5) s(-1)). (c) 2006 Elsevier Ltd. All rights reserved.

UR - http://<Go to ISI>://000243850500016

M3 - Article

VL - 26

SP - 344

EP - 355

JO - Polyhedron

JF - Polyhedron

SN - 0277-5387

IS - 2

ER -