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

Abstract

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 π→π* 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 (τ) of 0.19–0.43 μs. The PL spectra of Re-Ura-a@PAA (a = 1–4, PAA = polyacrylic acid) gel blocks redshift to ca. 600 nm with τ values of ca. 0.33 μs. 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.