Photochromic Coordination Compound: Oxygen-Assisted Photoinduced Color Change for Triplet Oxygen Detection

Detection of oxygen though color change is highly desirable for rapid qualitative analysis like the case of pH test papers. This work demonstrates O-3(2)-assisted photoinduced color change of a new photochromic coordination compound [Zn(4-aminopyridine)(2)Cl-2] (ZnaPyCl), which represents the first photochromic compound with a selective O-3(2) detection ability. The compound underwent photoinduced intraligand charge separation and formed a stable diradical-like triplet species in the solid state or in frozen solution, accompanied by conversion of triplet oxygen to singlet oxygen.