Herein, we demonstrate the progressive excited-state structural evolution of a flexible polycyclic π-skeleton by introducing a “rigid-flexible coupling” macrocyclization strategy to impose an ever-escalating constraint. Here, a series of compounds DPAC-RFn (n = 3, 5, 8, 9, 10, 11, 12, 15, 17) were prepared by cyclizing the molecule N,N′-diphenyl-dihydrodibenzo[a,c]-phenazine (DPAC) with a “rigid-flexible coupled” chain composed of a rigid phenyl ring and flexible alkyl chains of varying lengths. Although the absorption remains unchanged (around 350 nm), their emissions exhibit significant chain-length dependence. Nanosecond time-resolved measurements and theoretical calculation confirm the excited-state structural evolution of DPAC-RFn from bend–planar–twist conformers, correlating with successive emission distributions in the blue-green region (n = 3, 5, 8, 9, 470–500 nm), yellow-green region (n = 10, 11, 520–530 nm), and orange-red region (n = 12, 15, 17, 590–620 nm). This study explicitly reveals the excited-state structural diversity of flexible polycyclic π-skeleton derivatives and achieves a large-scale coverage in the emission colors, thereby implying the potential prospects for fundamental studies and practical applications.

中文翻译：

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通过“刚柔耦合”大环化逐步控制N,N'-二苯基二氢二苯并[a,c]吩嗪的激发态结构演化


在这里，我们通过引入“刚性-柔性耦合”大环化策略来施加不断升级的约束，展示了柔性多环π-骨架的渐进激发态结构演化。这里，通过环化分子 N,N'-二苯基-二氢二苯并[a,c]- 制备了一系列化合物 DPAC-RFn (n = 3, 5, 8, 9, 10, 11, 12, 15, 17)。吩嗪（DPAC）具有由刚性苯环和不同长度的柔性烷基链组成的“刚性-柔性耦合”链。尽管吸收保持不变（约 350 nm），但它们的发射表现出显着的链长依赖性。纳秒时间分辨测量和理论计算证实了 DPAC-RFn 从弯曲-平面-扭曲构象异构体的激发态结构演化，与蓝绿色区域的连续发射分布相关 (n = 3, 5, 8, 9, 470 –500 nm）、黄绿色区域（n = 10、11、520–530 nm）和橙红色区域（n = 12、15、17、590–620 nm）。该研究明确揭示了柔性多环π骨架衍生物的激发态结构多样性，并实现了发射颜色的大规模覆盖，从而暗示了基础研究和实际应用的潜在前景。