Oxygen gas sensing by luminescence quenching in crystals of Cu(xantphos)(phen)+ complexes

We have shown that crystals of the highly emissive copper(I) compounds [Cu(POP)(dmp)]tfpb, [Cu(xantphos)(dmp)]tfpb, [Cu(xantphos)(dipp)]tfpb, and [Cu(xantphos)(dipp)]pftpb, (where POP = bis[2-(diphenylphosphino)phenyl]ether; xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; dmp = 2,9-dimethyl-1,10-phenanthroline; dipp = 2,9-diisopropyl-1,10-phenanthroline (dipp); tfpb− = tetrakis(bis-3,5-trifluoromethylphenylborate); and pftpb = tetrakis(pentfluorophenyl)borate) are oxygen gas sensors. The sensing ability correlates with the amount of void space calculated from the crystal structures. The compounds exhibit linear Stern−Volmer plots with reproducible KSV constants from sample to sample; these results reinforce the observations that the sensing materials are crystalline and the sensing sites are homogeneous within the crystals. The long lifetime (∼30 μs), high emission quantum yield (ϕ = 0.66), appreciable KSV value (5.65), and very rapid response time (51 ms for the 95% return constant) for [Cu(x...