Thermally activated delayed fluorescent (TADF) coordination polymer with the generation of singlet oxygen

4,4'-{9,9'-Spirobi[10H-acridine]-10,100-diyl}dibenzoic acid (L, C29H26N2O4) was designed and synthesized as a new donor-acceptor motif molecule. Due to the large dihedral angle between the planes of the carboxyphenyl group and the spiroacridine moiety, L possess thermally activated delayed fluorescence (TADF). By applying L as a ligand and using Cd as a metal connector, we synthesized the coordination polymer catena-poly[hemi-mu-aqua-aqua(mu(3)-4,4'{9,9'-spirobi[10H-acridine]-10,10'-diyl} dibenzoato) cadmium(II)], [Cd(C29H24-N2O4)(H2O)(1.5)](n), (I). X-ray crystallographic analysis revealed that this coordination polymer exhibits one-dimensional chains constructed from molecular twist-ring moieties, with Cd2O11 clusters as the connection nodes. The stacking pattern of the two-dimensional network was formed by C-H center dot center dot center dot pi interactions in the solid state. Similar to L, (I) presents a sky-blue TADF emission, together with a photoluminescence quantum yield (PLQY) of 40%. It is worth noting that the photocatalytic activity toward the generation of singlet oxygen of this coordination polymer is confirmed.