A series of vibratile π-extended dihydrophenazines ( BPs) and a tetrahydrodiphenazine ( TP) were synthesized via direct C–N coupling reactions. Structural alterations of the fused acene wings lead to diverse intermolecular packing arrangements as well as tunable photophysical properties. These compounds exhibit intriguing features, including large Stokes shift, multiple emissions, and environmental effects. Notably, a dramatic hypsochromic shift in emission is observed when the acene wing is linearly extended from benzene to naphthalene and anthracene. This unusual π-conjugation length-dependent emission is explained by the close correlation between the calculated fluorescence-emitting energy and the π-conjugation length of the acene subunit. In addition, the TP bearing two flexible units exhibits dynamic photophysical properties resembling those of BPs. Our results reveal a balanced control over π-conjugation and luminescence in vibratile π-systems, thereby providing new insight into the molecular design of organic near-infrared fluorophores with large Stokes shifts and dynamic emissions.

一系列振动的 π 扩展二氢吩嗪 ( BPs) 和四氢二吩嗪 ( TP) 是通过直接的 C-N 偶联反应合成的。融合并苯翼的结构改变导致了不同的分子间堆积排列以及可调的光物理特性。这些化合物表现出有趣的特征，包括大斯托克斯位移、多重排放和环境影响。值得注意的是，当并苯翼从苯线性延伸到萘和蒽时，观察到发射的显着减色偏移。这种不寻常的 π 共轭长度依赖性发射是通过计算出的荧光发射能量与并苯亚基的 π 共轭长度之间的密切相关性来解释的。除此之外 TP 承载两个柔性单元的动态光物理特性类似于 BPs。我们的结果揭示了对振动 π 系统中 π 共轭和发光的平衡控制，从而为具有大斯托克斯位移和动态发射的有机近红外荧光团的分子设计提供了新的见解。