Phenazinium- and Malachite Green-Based Pd(II) Cages: Chiroptical Discrimination of Nucleoside Triphosphates

Abstract

Organic chromophores have been successfully implemented into supramolecular systems to bestow them with distinct photophysical properties for various applications, ranging from solar energy conversion, photochemical reactions or as receptors for guest molecules with optical readout. We had previously introduced first members of the large family of coal-tar dyes (methylene blue, crystal violet and rhodamine) as integral components of coordination cages. Here, we add two new chromophores, malachite green (MGP) and a purple phenazinium dye (PHP), serving as backbones of bis-monodentate banana-shaped ligands with pyridine donors. We show the formation of corresponding green and purple coloured Pd₂L₄ coordination cages and investigate their interaction with chiral guest molecules via UV-Vis and CD spectroscopy. The PHP cage can be used to recognize nucleoside triphosphates, based on chirality transfer from the guests to the structurally flexible helicate. In combination with the already known methylene blue cage MBP we could further differentiate between all four canonical NTPs through characteristic changes in the observed CD signatures.