Fabrication and performances of an optical sensor system constructed by a novel Cu(I) complex embedded on silica matrix

In this paper, a novel diamine ligand of 2-(pyridin-2-yl)-5-p-tolyl-1.3.4-oxadiazole (PTO) and its corresponding Cu(I) complex of [Cu(PTO)(PPh3)2]BF4 with triphenylphosphine (PPh3) as the auxiliary ligand are synthesized. Single crystal analysis confirms its identity. Its photophysical properties, including UV–vis absorption, emission spectrum, and luminescence decay dynamics, are measured and studied. The room temperature luminescence is a yellow one with long excited state lifetime of 64.4 μs under pure nitrogen atmosphere. Combined with density functional calculation on the cation of the Cu(I) complex, the yellow emission is assigned as a phosphorescent character of metal-to-ligand-charge-transfer, whose excited state is expected to be sensitive towards molecular oxygen. [Cu(PTO)(PPh3)2]BF4 is then doped into a silica supporting matrix of MCM-41 to construct an oxygen-sensitive probe of [Cu(PTO)(PPh3)2]BF4/MCM-41, which shows a maximum sensitivity (luminescence intensity in O2 medium/intensity in N2 medium) of 5.95 towards oxygen with short response time of 10 s. This sensing system shows a good photodurability upon continuous excitation radiation.