Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction

Publication: Research - peer-reviewJournal article – Annual report year: 2011

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Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction. / Holm-Jørgensen, Jacob Rørdam; Jensen, Mikael; Bjerrum, Morten J.

In: Inorganic Chemistry, Vol. 50, No. 24, 2011, p. 12705-12713.

Publication: Research - peer-reviewJournal article – Annual report year: 2011

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Holm-Jørgensen, Jacob Rørdam; Jensen, Mikael; Bjerrum, Morten J. / Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction.

In: Inorganic Chemistry, Vol. 50, No. 24, 2011, p. 12705-12713.

Publication: Research - peer-reviewJournal article – Annual report year: 2011

Bibtex

@article{e92f454c586949e8bc5be835f8c7e153,
title = "Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction",
keywords = "Agents, Photochemistry, Hevesy Laboratory, IN-VIVO EVALUATION, Mechanism, Chemistry, Complexes, 1,4,7,10-TETRAAZABICYCLO<5.5.3>PENTADECANE, UV, RADIOPHARMACEUTICALS, Hevesy laboratoriet",
publisher = "American Chemical Society",
author = "Holm-Jørgensen, {Jacob Rørdam} and Mikael Jensen and Bjerrum, {Morten J.}",
year = "2011",
doi = "10.1021/ic201839w",
volume = "50",
number = "24",
pages = "12705--12713",
journal = "Inorganic Chemistry",
issn = "0020-1669",

}

RIS

TY - JOUR

T1 - Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction

A1 - Holm-Jørgensen,Jacob Rørdam

A1 - Jensen,Mikael

A1 - Bjerrum,Morten J.

AU - Holm-Jørgensen,Jacob Rørdam

AU - Jensen,Mikael

AU - Bjerrum,Morten J.

PB - American Chemical Society

PY - 2011

Y1 - 2011

N2 - To enable utilization of the broad potential of copper isotopes in nuclear medicine, rapid and robust chelation of the copper is required. Bowl adamanzanes (bicyclic tetraaza ligands) can form kinetically stable copper complexes, but they are usually formed at low rates unless high pH values and high temperatures are applied. We have investigated the effects of the variation in the pH, different anions, and UV irradiation on the chelation rate. UV spectra of mixtures of Cu2+ and [24.31]adz in water show the existence of a long-lived two-coordinated copper(II) intermediate (only counting coordinated amine groups) at pH above 6. These findings are supported by pH titrations of mixtures of Cu2+ and [24.31]adz in water. Irradiation of this complex in the ligand-to-metal charge-transfer (LMCT) band by a diode-array spectrophotometer leads to photodeprotonation and subsequently to formation of the four-coordinated copper(II) complex at a rate up to 7800-fold higher at 25 °C than in the dark. Anions in the solution were found to have three major effects: competitive inhibition due to CuII binding anions, inhibition of the photoinduced transchelation from UV-absorbing anions, and photoredox inhibition from acido ligands capable of acting as electron donors in LMCT reactions. Dissolved O2 was also found to result in photoredox inhibition.

AB - To enable utilization of the broad potential of copper isotopes in nuclear medicine, rapid and robust chelation of the copper is required. Bowl adamanzanes (bicyclic tetraaza ligands) can form kinetically stable copper complexes, but they are usually formed at low rates unless high pH values and high temperatures are applied. We have investigated the effects of the variation in the pH, different anions, and UV irradiation on the chelation rate. UV spectra of mixtures of Cu2+ and [24.31]adz in water show the existence of a long-lived two-coordinated copper(II) intermediate (only counting coordinated amine groups) at pH above 6. These findings are supported by pH titrations of mixtures of Cu2+ and [24.31]adz in water. Irradiation of this complex in the ligand-to-metal charge-transfer (LMCT) band by a diode-array spectrophotometer leads to photodeprotonation and subsequently to formation of the four-coordinated copper(II) complex at a rate up to 7800-fold higher at 25 °C than in the dark. Anions in the solution were found to have three major effects: competitive inhibition due to CuII binding anions, inhibition of the photoinduced transchelation from UV-absorbing anions, and photoredox inhibition from acido ligands capable of acting as electron donors in LMCT reactions. Dissolved O2 was also found to result in photoredox inhibition.

KW - Agents

KW - Photochemistry

KW - Hevesy Laboratory

KW - IN-VIVO EVALUATION

KW - Mechanism

KW - Chemistry

KW - Complexes

KW - 1,4,7,10-TETRAAZABICYCLO<5.5.3>PENTADECANE

KW - UV

KW - RADIOPHARMACEUTICALS

KW - Hevesy laboratoriet

U2 - 10.1021/ic201839w

DO - 10.1021/ic201839w

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 24

VL - 50

SP - 12705

EP - 12713

ER -