Room-Temperature Phosphorescence of Cocrystals of Aromatic Bisimides and Triplet Sensitizer Pt(acac)2

Additional data to report https://doi.org/10.1002/adfm.202412843: Four sterically shielded aromatic bisimides are synthesized and their ability to form cocrystals with the triplet sensitizer platinum(II) acetylacetonate (Pt(acac)2) is investigated. Single crystals of the individual electron-deficient bisimides are studied first, two showing bright blue fluorescence with quantum yields up to 28%, while the other two barely emit at all. After successful cocrystallization of all four aromatic bisimides with the electron-rich Pt(II) complex, two different stoichiometries, either 1:1 or 1:2, are found in the crystalline solid state, whose absorbance and photoluminescence exhibit distinct bathochromic shifts. While two naphthalene bisimides show strong and long-lived room-temperature phosphorescence (RTP) with quantum yield up to over 50%, the other two aromatic bisimides show only minor photoluminescence at RT, but a bright low-temperature phosphorescence (LTP) at 80 K. Theoretical calculations reveal the importance of changing the magnetic quantum number m of the involved d-orbitals at the platinum center as well as the alignment of the Pt(II) center above an aromatic C-C bond for an efficient intersystem crossing in these systems.补充数据详见：https://doi.org/10.1002/adfm.202412843：本研究合成了四种空间位阻屏蔽型芳香双酰亚胺，并探究了其与三重态敏化剂乙酰丙酮合铂(II)（platinum(II) acetylacetonate，Pt(acac)₂）形成共晶体的能力。研究首先针对单组分缺电子双酰亚胺的单晶展开，其中两种展现出明亮的蓝色荧光，量子产率最高可达28%，剩余两种则几乎无荧光发射。在四种芳香双酰亚胺均与富电子Pt(II)配合物成功实现共结晶后，晶体固态中发现了两种不同的化学计量比（1:1或1:2），其吸收光谱与光致发光光谱均呈现出显著的红移。其中两种萘双酰亚胺展现出强且长寿命的室温磷光（room-temperature phosphorescence，RTP），量子产率超过50%；剩余两种芳香双酰亚胺在室温下仅表现出微弱的光致发光，但在80 K时呈现出明亮的低温磷光（low-temperature phosphorescence，LTP）。理论计算结果表明，对于该体系中的高效系间窜越而言，铂中心所涉及的d轨道磁量子数m的改变，以及Pt(II)中心位于芳香族C-C键上方的空间排布，均发挥着关键作用。