Photoinduced Reactions of cis,trans,cis- [PtIV(N 3)2(OH)2(NH3)2] with 1-methylimidazole

Hazel I.A. Phillips; Luca Ronconi; Peter J. Sadler

doi:10.1002/chem.200802206

Photoinduced Reactions of cis,trans,cis- [Pt^IV(N ₃)₂(OH)₂(NH₃)₂] with 1-methylimidazole

Hazel I.A. Phillips
, Luca Ronconi
, Peter J. Sadler

Research output: Contribution to a Journal (Peer & Non Peer) › Article › peer-review

54 Citations (Scopus)

Abstract

The photodecomposition of cis,trans,cis-[Pt^IV(N ₃)₂(OH)₂(NH₃)₂] in phosphate buffered saline (PBS), as well as in the presence of 1-methylimidazole (1-Melm), induced by UVA light (centred at λ = 365 nm) has been studied by multinuclear NMR spectroscopy. We show that photoreduction, photoisomerisation and trans-labilisation pathways are involved. The photodecomposition pathway in PBS, which involves azide release, as detected by ¹⁴N NMR spectroscopy, appears to differ from that in acidic aqueous conditions, under which N₂ is a product. A number of trans-{N-Pt ^II-NH₃} species were also observed as photoproducts, as well as the release of free ammonia with a corresponding increase in pH. Oxygen was also detected as a product in solution. In the presence of 1-methylimidazole, surprisingly the major photoproduct was the tetra-substituted Pt^II complex [Pt^II(1-MeIm-N³) ₄]²⁺ (structure confirmed by crystallography), even at a Pt/1-Melm molar ratio of 1:1, together with cis- and trans-[Pt ^II-(NH₃)₂(1-MeIm-N³) ₂]²⁺ as minor products. In these photoinduced 1-MeIm reactions, free ammonia, azide and oxygen were also detected. The results from this study illustrate that photoinduced reactions of platinum complexes can lead to novel reaction pathways, and therefore to new cytotoxic mechanisms in cancer cells.

Original language	English
Pages (from-to)	1588-1596
Number of pages	9
Journal	Chemistry - A European Journal
Volume	15
Issue number	7
DOIs	https://doi.org/10.1002/chem.200802206
Publication status	Published - 2 Feb 2009
Externally published	Yes

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SDG 3 Good Health and Well-being

Keywords

Azides
Bioinorganic chemistry
Drug discovery
NMR spectroscopy
Photochemistry
Platinum

Access to Document

10.1002/chem.200802206

Cite this

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title = "Photoinduced Reactions of cis,trans,cis- [PtIV(N 3)2(OH)2(NH3)2] with 1-methylimidazole",

abstract = "The photodecomposition of cis,trans,cis-[PtIV(N 3)2(OH)2(NH3)2] in phosphate buffered saline (PBS), as well as in the presence of 1-methylimidazole (1-Melm), induced by UVA light (centred at λ = 365 nm) has been studied by multinuclear NMR spectroscopy. We show that photoreduction, photoisomerisation and trans-labilisation pathways are involved. The photodecomposition pathway in PBS, which involves azide release, as detected by 14N NMR spectroscopy, appears to differ from that in acidic aqueous conditions, under which N2 is a product. A number of trans-\{N-Pt II-NH3\} species were also observed as photoproducts, as well as the release of free ammonia with a corresponding increase in pH. Oxygen was also detected as a product in solution. In the presence of 1-methylimidazole, surprisingly the major photoproduct was the tetra-substituted PtII complex [PtII(1-MeIm-N3) 4]2+ (structure confirmed by crystallography), even at a Pt/1-Melm molar ratio of 1:1, together with cis- and trans-[Pt II-(NH3)2(1-MeIm-N3) 2]2+ as minor products. In these photoinduced 1-MeIm reactions, free ammonia, azide and oxygen were also detected. The results from this study illustrate that photoinduced reactions of platinum complexes can lead to novel reaction pathways, and therefore to new cytotoxic mechanisms in cancer cells.",

keywords = "Azides, Bioinorganic chemistry, Drug discovery, NMR spectroscopy, Photochemistry, Platinum",

author = "Phillips, \{Hazel I.A.\} and Luca Ronconi and Sadler, \{Peter J.\}",

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doi = "10.1002/chem.200802206",

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T1 - Photoinduced Reactions of cis,trans,cis- [PtIV(N 3)2(OH)2(NH3)2] with 1-methylimidazole

AU - Phillips, Hazel I.A.

AU - Ronconi, Luca

AU - Sadler, Peter J.

PY - 2009/2/2

Y1 - 2009/2/2

N2 - The photodecomposition of cis,trans,cis-[PtIV(N 3)2(OH)2(NH3)2] in phosphate buffered saline (PBS), as well as in the presence of 1-methylimidazole (1-Melm), induced by UVA light (centred at λ = 365 nm) has been studied by multinuclear NMR spectroscopy. We show that photoreduction, photoisomerisation and trans-labilisation pathways are involved. The photodecomposition pathway in PBS, which involves azide release, as detected by 14N NMR spectroscopy, appears to differ from that in acidic aqueous conditions, under which N2 is a product. A number of trans-{N-Pt II-NH3} species were also observed as photoproducts, as well as the release of free ammonia with a corresponding increase in pH. Oxygen was also detected as a product in solution. In the presence of 1-methylimidazole, surprisingly the major photoproduct was the tetra-substituted PtII complex [PtII(1-MeIm-N3) 4]2+ (structure confirmed by crystallography), even at a Pt/1-Melm molar ratio of 1:1, together with cis- and trans-[Pt II-(NH3)2(1-MeIm-N3) 2]2+ as minor products. In these photoinduced 1-MeIm reactions, free ammonia, azide and oxygen were also detected. The results from this study illustrate that photoinduced reactions of platinum complexes can lead to novel reaction pathways, and therefore to new cytotoxic mechanisms in cancer cells.

AB - The photodecomposition of cis,trans,cis-[PtIV(N 3)2(OH)2(NH3)2] in phosphate buffered saline (PBS), as well as in the presence of 1-methylimidazole (1-Melm), induced by UVA light (centred at λ = 365 nm) has been studied by multinuclear NMR spectroscopy. We show that photoreduction, photoisomerisation and trans-labilisation pathways are involved. The photodecomposition pathway in PBS, which involves azide release, as detected by 14N NMR spectroscopy, appears to differ from that in acidic aqueous conditions, under which N2 is a product. A number of trans-{N-Pt II-NH3} species were also observed as photoproducts, as well as the release of free ammonia with a corresponding increase in pH. Oxygen was also detected as a product in solution. In the presence of 1-methylimidazole, surprisingly the major photoproduct was the tetra-substituted PtII complex [PtII(1-MeIm-N3) 4]2+ (structure confirmed by crystallography), even at a Pt/1-Melm molar ratio of 1:1, together with cis- and trans-[Pt II-(NH3)2(1-MeIm-N3) 2]2+ as minor products. In these photoinduced 1-MeIm reactions, free ammonia, azide and oxygen were also detected. The results from this study illustrate that photoinduced reactions of platinum complexes can lead to novel reaction pathways, and therefore to new cytotoxic mechanisms in cancer cells.

KW - Azides

KW - Bioinorganic chemistry

KW - Drug discovery

KW - NMR spectroscopy

KW - Photochemistry

KW - Platinum

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