The Role of Low-Energy Electron Interactions in cis-Pt(CO)2Br2 Fragmentation.

Maicol Cipriani,Filipe Ferreira Da Silva,Hang Lu,Styrmir Svavarsson,Oddur Ingólfsson,Lisa Mcelwee-White

doi:10.3390/ijms22168984

Abstract

Platinum coordination complexes have found wide applications as chemotherapeutic anticancer drugs in synchronous combination with radiation (chemoradiation) as well as precursors in focused electron beam induced deposition (FEBID) for nano-scale fabrication. In both applications, low-energy electrons (LEE) play an important role with regard to the fragmentation pathways. In the former case, the high-energy radiation applied creates an abundance of reactive photo- and secondary electrons that determine the reaction paths of the respective radiation sensitizers. In the latter case, low-energy secondary electrons determine the deposition chemistry. In this contribution, we present a combined experimental and theoretical study on the role of LEE interactions in the fragmentation of the Pt(II) coordination compound cis-PtBr2(CO)2. We discuss our results in conjunction with the widely used cancer therapeutic Pt(II) coordination compound cis-Pt(NH3)2Cl2 (cisplatin) and the carbonyl analog Pt(CO)2Cl2, and we show that efficient CO loss through dissociative electron attachment dominates the reactivity of these carbonyl complexes with low-energy electrons, while halogen loss through DEA dominates the reactivity of cis-Pt(NH3)2Cl2.

Highlights

Platinum coordination complexes, such as cisplatin [Pt(NH3)2Cl2], have been widely used as chemotherapeutic anticancer drugs since the 1970s [1,2]
In a 2008 study by Zheng et al [7], the authors showed that when cisplatin is covalently bonded to DNA, SSB and DSB induced by low-energy electrons (LEE) are substantially enhanced
This enhancement has been attributed to bond cleavage triggered by the formation of transient negative ions (TNI) through electron capture, i.e., dissociative electron attachment (DEA)

Summary

Introduction

Platinum coordination complexes, such as cisplatin [Pt(NH3)2Cl2], have been widely used as chemotherapeutic anticancer drugs since the 1970s [1,2]. Dissociative electron attachment studies on cisplatin have been performed by Kopyra et al [20], determining the fragmentation pathways under interaction with low-energy electrons. It was shown that electrons close to 0 eV can fragment this molecule by cleavage of the Pt−Cl bonds, leading to the loss of one or even both Cl atoms with considerable intensity.

Results

Conclusion