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Title: Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent

Abstract

It has been more than a decade since the first reports of [Gd(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] as a potential new class of magnetic resonance imaging contrast agent (MRI-CA). The defining feature of these 1-methyl-3-hydroxypyridin-2-one (Me-3,2-HOPO) based compounds has been the use of a hexadentate ligand design, and hence an increase in the number of metal bound water molecules, without sacrificing complex stability compared to the typically octadentate contrast agents used commercially. Since that time, significant advances in the properties of these chelates have been steadily reported, including improvements in relaxivity, incorporation into macromolecular architectures and, recently, the first direct verification of solution structure using the discovery of Eu(III) centered luminescence with the isomeric 1-hydroxypyridin-2-one (1,2-HOPO) chelate as a sensitizing chromophore. Nonetheless, it has remained frustrating that direct measurements of the inner sphere hydration state, q, using luminescence techniques with the parent Me-3,2-HOPO compounds have remained elusive, even when direct laser excitation of weakly absorbing f-f transitions were employed (eg. for Eu(III) complexes). This failing can likely be traced to the presence of a low lying LMCT state which efficiently quenches metal based emission. Instead, estimates of the q and hence solution structure have relied on the fitting of relaxivity data tomore » the Solomon-Bloembergen-Morgan equations or, where sufficiently soluble in aqueous solution, studies on the temperature dependence of the paramagnetic contribution to the water {sup 17}O NMR transverse relaxation rate. Recently, Beeby et al reported on a qualitative equation to determine inner sphere hydration based on the change in lifetimes for Yb(III) in going from H{sub 2}O to D{sub 2}O solution, and we reasoned that the lower energy accepting state of Yb(III) may lie below the LMCT state which quenches Eu(III) emission, and hence may facilitate sensitized emission from Yb(III). This hypothesis was borne out experimentally, and herein we describe for the first time sensitized luminescence in the Near Infra-Red (NIR) region from a [Yb(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] complex, and hence the direct measurement of q for the archetypical member of this family of compounds.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Chemical Sciences Division
OSTI Identifier:
961831
Report Number(s):
LBNL-1261E
Journal ID: 0020-1669; TRN: US200919%%293
DOE Contract Number:  
DE-AC02-05CH11231; HL69832
Resource Type:
Journal Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Name: Inorganic Chemistry
Country of Publication:
United States
Language:
English
Subject:
37; AQUEOUS SOLUTIONS; CHELATES; DESIGN; EXCITATION; HYDRATION; HYPOTHESIS; LASERS; LUMINESCENCE; MAGNETIC RESONANCE; RELAXATION; STABILITY; TEMPERATURE DEPENDENCE; VERIFICATION; WATER

Citation Formats

Moore, Evan G, Seitz, Michael, and Raymond, Kenneth N. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent. United States: N. p., 2008. Web. doi:10.1021/ic801060x.
Moore, Evan G, Seitz, Michael, & Raymond, Kenneth N. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent. United States. https://doi.org/10.1021/ic801060x
Moore, Evan G, Seitz, Michael, and Raymond, Kenneth N. 2008. "Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent". United States. https://doi.org/10.1021/ic801060x. https://www.osti.gov/servlets/purl/961831.
@article{osti_961831,
title = {Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent},
author = {Moore, Evan G and Seitz, Michael and Raymond, Kenneth N},
abstractNote = {It has been more than a decade since the first reports of [Gd(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] as a potential new class of magnetic resonance imaging contrast agent (MRI-CA). The defining feature of these 1-methyl-3-hydroxypyridin-2-one (Me-3,2-HOPO) based compounds has been the use of a hexadentate ligand design, and hence an increase in the number of metal bound water molecules, without sacrificing complex stability compared to the typically octadentate contrast agents used commercially. Since that time, significant advances in the properties of these chelates have been steadily reported, including improvements in relaxivity, incorporation into macromolecular architectures and, recently, the first direct verification of solution structure using the discovery of Eu(III) centered luminescence with the isomeric 1-hydroxypyridin-2-one (1,2-HOPO) chelate as a sensitizing chromophore. Nonetheless, it has remained frustrating that direct measurements of the inner sphere hydration state, q, using luminescence techniques with the parent Me-3,2-HOPO compounds have remained elusive, even when direct laser excitation of weakly absorbing f-f transitions were employed (eg. for Eu(III) complexes). This failing can likely be traced to the presence of a low lying LMCT state which efficiently quenches metal based emission. Instead, estimates of the q and hence solution structure have relied on the fitting of relaxivity data to the Solomon-Bloembergen-Morgan equations or, where sufficiently soluble in aqueous solution, studies on the temperature dependence of the paramagnetic contribution to the water {sup 17}O NMR transverse relaxation rate. Recently, Beeby et al reported on a qualitative equation to determine inner sphere hydration based on the change in lifetimes for Yb(III) in going from H{sub 2}O to D{sub 2}O solution, and we reasoned that the lower energy accepting state of Yb(III) may lie below the LMCT state which quenches Eu(III) emission, and hence may facilitate sensitized emission from Yb(III). This hypothesis was borne out experimentally, and herein we describe for the first time sensitized luminescence in the Near Infra-Red (NIR) region from a [Yb(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] complex, and hence the direct measurement of q for the archetypical member of this family of compounds.},
doi = {10.1021/ic801060x},
url = {https://www.osti.gov/biblio/961831}, journal = {Inorganic Chemistry},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 09 00:00:00 EDT 2008},
month = {Mon Jun 09 00:00:00 EDT 2008}
}