Phosphorescent self-healing composites containing Re(I) complexes: preparation and properties

To obtain self-healing phosphorescent composites, four Re(I) complexes, Re-Ura-a (a = 1-4) with uracil group were synthesized. The ultraviolet-visible (UV-Vis) absorption spectra of Re-Ura-a (a = 1-4) are mainly comprised of the pi ->pi* transitions (200-400 nm) and the metal-to-ligand charge transfer transitions (400-450 nm). The photoluminescence (PL) spectra of Re-Ura-a (a = 1-4) peaking at 576-584 nm possess the biexponential excited-state decay lifetimes (tau) of 0.19-0.43 mu s. The PL spectra of Re-Ura-a@PAA (a = 1-4, PAA = polyacrylic acid) gel blocks redshift to ca. 600 nm with tau values of ca. 0.33 mu s. The Re-Ura-1(0.6 wt%)@PAA gel blocks could bear maximum stress of 0.191 MPa and maximum strain of 525%, and they could be ca. 40% self-healed in 5 min after being severed. Finally, the energies of the H-bonds between the carboxylic group of PAA and different parts of Re-Ura-1 were theoretically simulated to investigate the intermolecular interactions between Re-Ura-1 and PAA.