Isocyanide Ligands Promote Ligand-to-Metal Charge Transfer Excited States in a Rhenium(II) Complex.

A metal-to-ligand charge transfer with mixed intraligand character is observed for the rhenium hexakisarylisocyanide complex [Re(CNAr)]PF (CNAr = 2,6-dimethylphenylisocyanide, λ = 300 nm). Upon oxidation to [Re(CNAr)](PF), the dominant low energy optical transition is a ligand-to-metal charge transfer (LMCT) mixed with intraligand transitions (λ = 650 nm). TD-DFT was used to identify the participating ligand-based orbitals in the LMCT transition, revealing that the majority of the donor orbital is based on the aryl ring (85%) as opposed to the CN bond (14%).

The ligand-to-metal charge transfer excited state of [Re(dmpe)].

The ligand-to-metal charge transfer (LMCT) transitions of [Re(dmpe)] (dmpe = bis-1,2-(dimethylphosphino)ethane) were interrogated using UV/Vis absorbance spectroscopy, photoluminescence spectroscopy, and time-dependent density functional theory. The solvent dependence of the lowest energy charge transfer transition was quantified; no solvatochromism was observed. TD-DFT calculations reveal the dominant LMCT transition is highly symmetric and delocalized involving all phopshine ligand donors in the charge transfer, providing an understanding for the absence of solvatochromism of [Re(dmpe)].

A study of 2-component i, i + 3 peptide stapling using thioethers.

Peptides are promising scaffolds for use as therapeutics, targeting interactions previously considered to be "undruggable" by small molecules. While short peptides are generally unstructured in solution and rapidly degraded by proteases in the cell cytosol, peptide stapling offers an effective method to both stabilize peptides in a helical structure and increase resistance to proteolytic degradation. Most studies of peptide stapling have focused on residues with i, i + 4 and i, i + 7 spacing, while stapling of residues with i, i + 3 spacing has been understudied.