Structures and Photoluminescence Properties of Bis(aromatic amino)-Based Isomers with Biphenyl as Bridge

Herein, two series of isomers are developed based on biphenyl (BP) and two typical donor groups diphenylamine (DPA) and 9,9-dimethyl-9,10-dihydroacridine (DMAc) to figure out the isomerization effect on structures and photophysical properties. The computational simulations and photophysical analyses indicate that the substitution positions influence not only the molecular conformations but also the frontier molecular orbital distributions, which further influence the photoluminescence properties. We find that twisted structure is beneficial for the separation of the frontier molecular orbitals, while more planar structure contributes to higher luminescent intensity for both fluorescence and phosphorescence. Meanwhile, room temperature phosphorescence (RTP) is caught when these isomers are doped in 4,4 '-dibromo-1,1 '-biphenyl (DBBP). The p-DDPA/DBBP complex shows the highest intensity of phosphorescence and the longest lifetime (81.71 ms). The photoluminescence quantum yield of the p-DDPA/DBBP complex is as high as 54 % with RTP quantum efficiency approximately 12 %, which is 28 % for pure p-DDPA without afterglow.

Automated summary

Two series of isomers based on biphenyl and two typical donor groups diphenylamine and 9,9-dimethyl-9,10-dihydroacridine are developed to investigate the effect of isomerization on structures and photophysical properties. Computational simulations and photophysical analyses demonstrate that the substitution positions not only influence molecular conformations, but also frontier molecular orbital distributions, which further impact the photoluminescence properties. The study reveals that twisted structures facilitate the separation of frontier molecular orbitals, while more planar structures contribute to higher luminescent intensity. Additionally, room temperature phosphorescence (RTP) is observed when these isomers are doped in 4,4'-dibromo-1,1'-biphenyl, with the p-DDPA/DBBP complex exhibiting the highest intensity of phosphorescence and the longest lifetime.