Three new derivatives of (4-methoxyphenyl) ethynyl-naphthalimide were synthesized by Sonogashira coupling reaction. These compounds showed robust and strong fluorescent signals, which shift from blue to orange as the solvent polarity increases. Computational calculations revealed that in low-polarity solvents, the molecules preferred a 90° rotation between the naphthalimide and ethynyl benzene fragments. In high-polarity solvents, where the energy barrier for rotation of the alkyne bond was higher, the molecules favored the 0° conformer, leading to longer emission wavelengths. The compound with a 2-methoxyethyl group tethered to the naphthalimide nitrogen demonstrated sensitivity to water presence in the ranges of 0–30 % (v/v) in THF, 0–15 % (v/v) in DMSO, 0–30 % (v/v) in MeCN, 0–15 % (v/v) in acetone, and 0–40 % (v/v) in EtOH. The detection limits for water were determined to be 0.0523 %, 0.1365 %, 0.0337 %, 0.0570 %, and 0.1170 % (v/v) in THF, DMSO, MeCN, acetone, and EtOH, respectively. The effectiveness of this compound in quantifying ethanol content in spirit samples was successfully demonstrated.

中文翻译：

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用于检测有机溶剂中水的溶剂化显色荧光乙炔基萘酰亚胺衍生物


通过Sonogashira偶联反应合成了三种新的(4-甲氧基苯基)乙炔基萘酰亚胺衍生物。这些化合物显示出强烈的荧光信号，随着溶剂极性的增加，荧光信号从蓝色变为橙色。计算表明，在低极性溶剂中，分子倾向于在萘二甲酰亚胺和乙炔基苯片段之间旋转 90°。在高极性溶剂中，炔键旋转的能垒较高，分子倾向于 0° 构象异构体，从而产生更长的发射波长。具有与萘酰亚胺氮相连的 2-甲氧基乙基的化合物表现出对水存在的敏感性，THF 中为 0–30% (v/v)，DMSO 中为 0–15% (v/v)，DMSO 中为 0–30% (v/v) 在 MeCN 中，0–15 % (v/v) 在丙酮中，以及 0–40 % (v/v) 在 EtOH 中。在 THF、DMSO、MeCN、丙酮和 EtOH 中，水的检测限分别为 0.0523%、0.1365%、0.0337%、0.0570% 和 0.1170% (v/v)。该化合物在定量烈酒样品中乙醇含量方面的有效性已得到成功证明。