Rhenium fac tricarbonyl bisimine complexes: biologically useful fluorochromes for cell imaging applications

Abstract

A series of lipophilic and hydrophilic fac tricarbonyl rhenium bisimine complexes have been prepared, their membrane-permeabilities explored in liposomes and their potential for application in fluorescence microscopy cell imaging demonstrated in the first application of MLCT-fluorescent rhenium complexes in cell imaging.

Time-resolved and two-photon emission imaging microscopy of live cells with inert platinum complexes

“…After incubation, the solution containing the complex was removed, and the live cells were washed with PBS and transferred on a coverslip to the microscope stage for direct imaging without being fixed. An incubation time of only 5 min was sufficient to achieve maximal emission intensity of [PtLCl] in the cells, which is strikingly shorter than that for the previously explored cationic metal complexes (11)(12)(13). The exceptionally short incubation time suggests that [PtL 1 Cl] is highly permeable across the plasma membrane of all three cell types studied and accumulates intracellularly under diffusion control.…”

“…Steady-state cell images have been obtained recently by using ruthenium(II) and rhenium(I) complexes (11)(12)(13). The temporal dimension has yet to be explored.…”

Underestimated Potential of Organometallic Rhenium Complexes as Anticancer Agents

“…Their anti-proliferative activity reached or even exceeded the one of cisplatin on various human cancer cell lines. 28,30,32,39,40,45,49,51 The cytotoxicity of the compounds generally increased with lipophilicity, 32,33,39,49,51 most probably due to an improved cellular uptake. Re(I) complexes 9 ( Figure 1A) derivatized with a fluorous pendant were the only exception to this trend.…”

“…Some cytotoxic cationic complexes such as 1a-c appear to accumulate in cells via passive diffusion. 49 Re luminescent probes used to sense Cd(II) and Zn(II) (5 on Figure 1A) are, however, taken up via an energy-dependent pathway such as endocytosis as demonstrated by temperature and ATP production inhibition uptake assays. 32 Interestingly, fluorescence microscopy cellular localization studies have never -to the best of our knowledge -identified a cytotoxic Re(I) tricarbonyl bisimine complex located inside the nucleus.…”

Enhanced Cytotoxicity through Conjugation of a “Clickable” Luminescent Re(I) Complex to a Cell-Penetrating Lipopeptide

“…37−40 [Re(CO) 3 (bipy)(py-alkyne)](BF 4 ) was synthesized following an established literature procedure employed for Re(I) factricarbonyl bipyridyl complexes with a substituted pyridine ligand. 41 In brief, the initially formed Re tricarbonyl bipyridyl chloride complex was activated via halide abstraction as the corresponding acetonitrile complex. The acetonitrile ligand was then displaced by 3-ethynylpyridine.…”