Synergistic Action of Crystallophore and Imaging‐Crystallophore Enhances the Production and Imaging of Protein Crystals

Abstract The synthesis and photophysical characterization of a new family of terbium(III) complexes called Imaging ‐crystallophore, substituted by π‐conjugated antennas, is reported. Previous crystallophore variants (such as Tb‐Xo4) have shown very interesting nucleating properties to obtain high‐quality protein crystals. In addition, the Imaging ‐crystallophore emits in the green and accumulates in the protein crystals, enabling very easy crystal detection using fluorescence microscopy under one‐photon but also under two‐photon excitations. X‐ray diffraction crystallography and molecular dynamics simulations demonstrate that the binding site of the Imaging ‐crystallophore in hen‐egg white lysozyme (HEWL) is similar to that of the Tb‐Xo4 but present additional hydrophobic interactions with the conjugated antennas. However, its nucleating properties are not as effective as those of Tb‐Xo4. Finally, we emphasize the synergy between the two generations of crystallophore by preparing and analyzing the properties of the mix (10/0.2) corresponding to a mixture of Tb‐Xo4 and Imaging ‐crystallophore. By combining the best of nucleating and imaging properties, we can easily obtain and detect high‐quality protein crystals