Facile rhenium-peptide conjugate synthesis using a one-pot derived Re(CO)3 reagent

An Organometallic Isostere of an Amino Acid

An organometallic complex that mimics an amino acid, also known as an amino acid isostere, can be synthesized from a functionalized bipyridine ligand and a fac-[Re(CO)₃]⁺ center. The reaction of an achiral ligand and metal results in a racemic mixture of chiral-at-metal complexes. These metal species have amine and carboxy termini, a side chain type unit that can be varied, as well as the chiral metal that is analogous to the α carbon of an amino acid. The racemic mixtures can be separated into enantiomers by chiral chromatography, and the metal complexes can be incorporated into peptides by using solid-phase peptide synthesis.

Lipophilic Re(CO)3pyca complexes for Mid-IR imaging applications

Several Re(i)pyca conjugates incorporating long aliphatic amines have been synthesized through a one-pot methodology. The compounds have been fully characterized, and seven compounds have been structurally elucidated by single crystal X-ray diffraction. The C14 variant was probed as a potential organometallic IR dye. Large unilamellar vesicles were generated with DOPC and the C14 compound and we observed incorporation of the rhenium complex as observed by FTIR microscopy.

Systematically altering the lipophilicity of rhenium(I) tricarbonyl anticancer agents to tune the rate at which they induce cell death

Rhenium-based anticancer agents have arisen as promising alternatives to conventional platinum-based drugs. Based on previous studies demonstrating how increasing lipophilicity improves drug uptake within the cell, we sought to investigate the effects of lipophilicity on the anticancer activity of a series of six rhenium(i) tricarbonyl complexes. These six rhenium(i) tricarbonyl structures, called Re-Chains, bear pyridyl imine ligands with different alkyl chains ranging in length from two to twelve carbons. The cytotoxicities of these compounds were measured in HeLa cells. At long timepoints (48 h), all compounds are equally cytotoxic. At shorter time points, however, the compounds with longer alkyl chains are significantly more active than those with smaller chains. Cellular uptake studies of these compounds show that they are taken up via both passive and active pathways. Collectively, these studies show how lipophilicity affects the rate at which these Re compounds induce their biological activities.

Using Hydrazine to Link Ferrocene with Re(CO)3: A Modular Approach

Acetyl ferrocene and diacetyl ferrocene both readily react with an excess of hydrazine to afford the corresponding hydrazone compounds. These compounds can then be linked to Re(CO)₃ via a metal-mediated Schiff base reaction, resulting in a series of ferrocene-Re(CO)₃ conjugates with different stoichiometries. Conjugates with 1:1, 1:2, and 2:1 ferrocene: Re(CO)₃ ratios can be produced via this "modular" type synthesis approach. Several examples of these conjugates were structurally characterized, and their spectroscopic, electrochemical, and spectroelectrochemical behaviors were investigated. The electronic structures of these compounds were also probed using DFT and TDDFT calculations.