Photoinduced DNA Interstrand Cross-Linking by 1,1′-Biphenyl Analogues: Substituents and Leaving Groups Combine to Determine the Efficiency of Cross-Linker

Two series of 1,1′-biphenyl analogues with various leaving groups (L=OAc, OCH₃, OCHCH=CH₂, OCH₂Ph, SPh, SePh, and Ph₃P⁺) were synthesized. Their reactivity towards DNA and the reaction mechanism were investigated by determining DNA interstrand cross-link (ICL) efficiency, radical and carbocation formation, and the cross-linking reaction sites. All compounds induced DNA ICL formation upon 350 nm irradiation via a carbocation that was generated from oxidation of the corresponding free radicals. The ICL efficiency and the reaction rate strongly depended on the combined effect of the leaving group and the substituent. Among all compounds tested, the high ICL efficiency (30–43 %) and fast reaction rate were observed with compounds carrying a nitrophenyl group and acetate ( 2 a ), ether ( 2 b and 2 c) , or triphenylphosphonium salt ( 2 g ) as leaving groups. Most compounds with a 4-methoxybenzene group showed similar DNA ICL efficiency (≈30 %) with a slow DNA cross-linking reaction rate. Both cation trapping and free radical trapping adducts were detected in the photo activation process of these compounds, which provided direct evidence for the proposed mechanism. Heat stability study in combination with sequence study suggested that these photo-generated benzyl cations alkylate DNA at dG, dA, and dC sites.     

含二齿膦配体的二羰基铁化合物的制备及光诱导释放一氧化碳性能

一氧化碳释放剂(CORM)为CO在人体的精准输送提供了便利。为提高CORM的稳定性,以[Fe(CO)₄I₂]为前驱体,通过与二齿膦配体dppe、dppp、PNP(dppe=1,2-双(二苯基膦酰)乙烷,dppp=1,3-双(二苯基膦酰)丙烷,PNP=N-环己基-N-(二苯基膦酰)-1,1-二苯基膦胺(Ph₂PN(cyclohexyl)PPh₂)的配位取代反应制得了二齿膦二羰基铁化合物1~3,并利用FT-IR、UV-Vis、NMR、元素分析、单晶X射线衍射(化合物2、3)进行表征。通过红外光谱法研究了化合物1~3的降解释放CO性能,以评估其作为CORM的潜能。在二甲亚砜溶剂中、黑暗条件下这些化合物表现出良好稳定性;但在可见光(红光、绿光、蓝光)照射下,均可降解释放CO,其降解速率与光源的能量和化合物的结构有关。此外,在蓝光和绿光照射下,发现化合物1和2可从顺式构型向反式构型发生转化,而红光下因能量不足未见构型转化。