Herein, we report the synthesis and E→Z photoswitching behavior of two 4-substituted azomethine phthalimides containing anthracenyl and 4-(dimethylamino)phenyl moieties (EAMP1 and EAMP2). These compounds represent newly synthesized and unstudied photoswitches with dual fluorescence properties as E-isomers and at photostationary state (PSS) depending on the solvent polarity. Steady-state fluorescence measurements were performed in various solvents and the results show strong sensitivity on the environmental polarity. The kinetics of E→Z photoswitching to PSS was studied in AcCN by visible light activation at 410 nm (EAMP1) and long wavelength UV-light activation at 350 nm (EAMP2). The quantitative and qualitative performance of the switching behavior was evaluated by the degree of photoisomerization (R) and the rate constant (k). It was found for EAMP1 R = 6.95 %, k = 8.87 × 10⁻⁴ s⁻¹ and EAMP2 R = 88.72 %, k = 4.00 × 10⁻⁴ s⁻¹, respectively. The reason for the lower photoconversion of EAMP1 compared to the EAMP2 was analyzed through optimization of the molecular geometry of E- and Z-isomers in the ground state (S₀) and first excited state (S₁) by DFT/TD-DFT calculations with B3LYP/6-31+G(d,p) level of theory using IEFPCM in AcCN. It was found that E-isomers in the S₀ have nonplanar conformation, while the Z-isomer of EAMP1 prefers twisted conformation and the Z-isomer of EAMP2 T-shaped conformation is energetically advantageous compared to the twisted one. The reason is the weak H…..π noncovalent interaction (NCI) between 4-(dimethylamino)phenyl moiety and phthalimide ring. Moreover, the Z-isomer of EAMP2 is unusual stable up to 600 min at room temperature in dark compared to the EAMP1, which undergoes full Z→E relaxation for less than 60 min at the same conditions. The Z→E relaxation of EAMP2 is achieved for 90 min at 60 °C. The fluorescence E→Z switching behavior was studied by emission measurements in AcCN and 1,4-DOX as E-isomers and at PSS in room and liquid nitrogen (77 K) temperatures. In the polar and nonpolar solvents, red-shifted emissions with increased fluorescence quantum (Φ_fl) yields have been observed at PSS compared to the E-isomers. The molecular rotor behavior was studied in the binary mixture of glycerol:ethanol and the results show a sensitivity of the emission bands depending on the environmental viscosity. Time-resolved fluorescence decay measurements were performed in AcCN and 1,4-DOX as E-isomers and at PSS to estimate the mechanism of fundamental fluorescence bands. We found that dyes at PSS have longer lifetime (τ) compared to the E-isomers, especially in less polar 1,4-DOX.

在这里，我们报告了两个含有蒽基和4-（二甲基氨基）苯基部分（EAMP1和EAMP2）的4-取代的偶氮甲碱邻苯二甲酰亚胺的合成和E→Z光转换行为。这些化合物代表了新合成且尚未研究的光开关，具有双重荧光性质，如E-异构体，并且根据溶剂的极性处于光固定状态（PSS）。在各种溶剂中进行了稳态荧光测量，结果表明对环境极性具有很强的敏感性。E→Z的动力学在AcCN中，通过在410 nm处的可见光激活（EAMP1）和在350 nm处的长波长UV光激活（EAMP2）研究了光转换为PSS。开关行为的定量和定性性能通过光异构化程度（R）和速率常数（k）进行评估。发现分别为EAMP1 R＝ 6.95％，k＝ 8.87×10 ^-4 s ^-1和EAMP2 R＝ 88.72％，k＝ 4.00×10 ^-4 s ^-1。通过优化E-和E-的分子几何结构分析了EAMP1的光转化率低于EAMP2的原因。通过DFT / TD-DFT计算得到的Z-异构体处于基态（S ₀）和第一激发态（S ₁），其理论上的水平为B3LYP / 6-31 + G（d，p），使用AcCN中的IEFPCM。已经发现，S ₀中的E-异构体具有非平面构象，而EAMP1的Z-异构体更喜欢扭曲的构象，而EAMP2 T-形构象的Z-异构体与扭曲的相比在能量上是有利的。原因是4-（二甲基氨基）苯基部分与邻苯二甲酰亚胺环之间的H…..π非共价相互作用弱（NCI）。此外，与EAMP2的Z-异构体相比，EAMP1的Z-异构体在室温下在黑暗中长达600分钟的异常稳定。在相同条件下Z→E松弛少于60分钟。EAMP2在60°C下从Z→E弛豫90分钟。通过在AcCN和1,4-DOX中作为E异构体以及在PSS中在室温和液氮（77 K）温度下进行发射测量，研究了荧光的E→Z转换行为。在极性和非极性溶剂中，与E相比，在PSS处观察到红移发射具有增加的荧光量子（_Φfl）产量。-异构体。在甘油：乙醇的二元混合物中研究了分子转子的行为，结果表明发射带的灵敏度取决于环境粘度。在AcCN和1,4-DOX中以E异构体和PSS进行时间分辨的荧光衰减测量，以估算基本荧光带的机理。我们发现，与E异构体相比，PSS上的染料具有更长的寿命（τ），尤其是在极性较小的1,4-DOX中。