Hybrid phosphines with anionic hard donor functions can be used to create an adaptable ligand environment for soft late transition metals. Herein, we show that the change of coordination of a Show more
Hybrid phosphines with anionic hard donor functions can be used to create an adaptable ligand environment for soft late transition metals. Herein, we show that the change of coordination of a diphosphine–phosphinic acid (P3OOH) in response to acid–base interactions or hydrogen bonding results in structural transformations of a disilver complex [Ag2(P3OO)2] (1) to give solvated and protonated derivatives [Ag2(P3OOH)2]2+ (2) and [Ag3(P3OO)3H]+ (3), accompanied by the alteration of the quantum yield of the solid-state photoluminescence from 0.06 up to 0.69. The related diphosphine–phosphide oxide complexes [M2(P3O)2] (M = Ag, Au) are oxidized to phosphinate compounds 2 and non-luminescent [Au2(P3OO)2H]+ (5) in the presence of triflic acid. Alternatively, [Au2(P3O)2] readily accommodates an additional gold(I) ion to yield a trinuclear cluster [Au3(P3O)2]+ (6), which is brightly sky-blue phosphorescent in the crystalline state (Φem = 0.76). The phosphide oxide group −PO in 6 is stable towards oxidation under acidic conditions in solution but undergoes protonation that results in two orders of magnitude (>170-fold) increase of the emission intensity. Complex 6 acts as a guest in the crystalline matrix of 5 due to their structural similarity and affords solid solutions with bright luminescence at a doping content of 1–2%.
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DNA crosslinking agents such as cisplatin and related platinum(II) analogs are effective drugs to treat solid tumors. However, these therapeutics can cause high toxicity in the body, and tumors can de Show more
DNA crosslinking agents such as cisplatin and related platinum(II) analogs are effective drugs to treat solid tumors. However, these therapeutics can cause high toxicity in the body, and tumors can develop resistance to them. To develop less toxic and more effective DNA crosslinkers, medicinal chemists have focused on tuning the ligands in square planar platinum(II) complexes to modulate their bioavailability, targeted cell penetration, and DNA binding rates. Unfortunately, linking in vitro DNA binding capacity of DNA crosslinkers with their in vivo efficacy has proven challenging. Here we report an electrochemical biosensor strategy that allows the study of platinum(II)-DNA binding in real time. Our biosensors contain a purine-rich deoxynucleotide sequence, T6 (AG)10 , modified with a 5' hexylthiol linker for easy self-assembly onto gold electrodes. The 3' terminus is functionalized with the redox reporter methylene blue. Electron transfer from methylene blue to the sensor is a function of platinum(II) compound concentration and reaction time. Using these biosensors, we resolve DNA binding mechanisms including monovalent and bivalent binding, as well as base stacking. Our approach can measure DNA binding kinetics in buffers and in 50 % serum, offering a single-step, real-time approach to screen therapeutic compounds during drug development. Show less