Synthesis of luminescent lanthanide complexes within crosslinked protein crystal matrices

Abstract

Crosslinked protein crystals offer unique properties as a host matrix for hybrid materials, due to their precise periodic array of solvent channels suitable for the capture of functional guest molecules. To prepare luminescent protein crystals containing guest Eu(TTA)₃phen (TTA = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato, phen = 1,10-phenanthroline), we developed a solvent substitution scheme in which the crystals were first loaded with the hydrophobic ligands and subsequently loaded with Eu(III) in anhydrous ethanol. Notably, we also observed crystal denaturation and renaturation, concomitant with a dramatic volume expansion, in response to high DMSO concentrations. Given the possible future utility of this reversible expansion for hybrid materials preparation, we characterized the volumetric changes quantitatively.