New members of the family of highly luminescent 1,3-bis(4-phenylpyridin-2-yl)-4,6-difluorobenzene platinum(ii) complexes: exploring the effect of substituents on the 4-phenylpyridine unit

The synthesis and characterization of Pt{1,3-bis(4-phenylpyridin-2-yl)-4,6-difluorobenzene}Cl and Pt{1,3-bis(4-(4-methoxy-2,6-dimethylphenyl)-pyridin-2-yl)-4,6-difluorobenzene}Cl are reported, along with their molecular structure optimized by Density Functional Theory. These new NCN-coordinated Pt(ii) complexes are both very highly luminescent in deoxygenated solution in the blue region of the spectrum: λmax = 471-480 nm and Φlum = 0.89-0.98 at room temperature. Compared to the Pt{1,3-bis(pyridin-2-yl)-4,6-difluorobenzene}Cl analogue, the complex with a simple, unsubstituted phenyl ring at position 4 of the pyridinyl rings shows an improved luminescence quantum yield. However, a further enhancement is achieved with the 2,6-dimethyl-4-methoxyphenyl substituent, the steric hindrance of which inhibits the formation of bimolecular species, allowing high quantum yields to be maintained even in concentrated solutions (2 × 10−4 M).