Journal article
Fluorination and hydrolytic stability of water-soluble platinum complexes with a borane-bridged diphosphoramidite ligand
Dalton transactions : an international journal of inorganic chemistry, Vol.51(34), pp.12895-12903
08/30/2022
DOI: 10.1039/d2dt01482c
Abstract
The high fluorophilicity of borane-containing ligands offers promise for accessing new metallodrug candidates capable of bifunctional [
18
F]-positron emission tomography (PET) imaging, but this requires water soluble and hydrolytically stable ligands that can be fluorinated under mild conditions. Toward this goal, here we report the synthesis and characterization of water-soluble Pt(
ii
) complexes containing a triaminoborane-bridged diphosphoramidite ligand called
MeO
TBDPhos that can be fluorinated using simple fluoride salts. NMR and XRD studies show that (
MeO
TBDPhos)PtCl
2
(
1
) dissolves in water with cooperative H-OH addition across the bridgehead N-B bond to form
1-H
2
O
. The B-OH bond in
1-H
2
O
undergoes rapid displacement with fluoride (<10 min) when treated with CsF in MeCN to form
1-HF
.
1-HF
can also be prepared in <10 min by addition of KF to
1
in the presence Kryptofix® 222 and (HNEt
3
)Cl in MeCN. In addition to using fluoride salts, we show how mononuclear
1
can be fluorinated with HBF
4
·Et
2
O to form dinuclear [(
MeO
TBDPhos-HF)Pt(μ-Cl)]
2
(BF
4
)
2
(
4-HF
). Comparative studies show that the B-F bond in
1-HF
undergoes hydrolysis as soon as it is dissolved in water or saline, but the B-F bond persists for hours when the pH of the solution is lowered to pH ≤ 2. In contrast to
1-HF
, the B-F bond in dinuclear
4-HF
persists for days when dissolved in water, which may be attributed to slow, sacrificial release of fluoride from the BF
4
−
anion. The results show how cooperative N-B reactivity on the ligand can be leveraged to rapidly fluorinate water-soluble
MeO
TBDPhos complexes under mild conditions and afford suggestions for how to enhance hydrolytic B-F stability, as required for use in biomedical applications.
Here we report the synthesis, characterization, and hydrolytic stability of water-soluble Pt(
ii
) complexes containing a triaminoborane-bridged diphosphoramidite ligand that can be fluorinated using simple fluoride salts.
Details
- Title: Subtitle
- Fluorination and hydrolytic stability of water-soluble platinum complexes with a borane-bridged diphosphoramidite ligand
- Creators
- Johnathan D CulpepperKyounghoon LeeWilliam PortisDale C SwensonScott R Daly
- Resource Type
- Journal article
- Publication Details
- Dalton transactions : an international journal of inorganic chemistry, Vol.51(34), pp.12895-12903
- DOI
- 10.1039/d2dt01482c
- ISSN
- 1477-9226
- eISSN
- 1477-9234
- Number of pages
- 9
- Grant note
- DOI: 10.13039/100008893, name: University of Iowa; DOI: 10.13039/100000001, name: National Science Foundation, award: CHE-1828117; DOI: 10.13039/100006770, name: American Chemical Society Petroleum Research Fund, award: 55989-DNI3
- Date published
- 08/30/2022
- Academic Unit
- Chemistry
- Record Identifier
- 9984297351702771
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