Imidazo[1,5-a]pyridine is a stable scaffold, widely used for the development of emissive compounds in many application fields (e.g., optoelectronics, coordination chemistry, sensors, chemical biology). Their compact shape along with remarkable photophysical properties make them suitable candidates as cell membrane probes. The study of the membrane dynamics, hydration, and fluidity is of importance to monitor the cellular health and to explore crucial biochemical pathways. In this context, five imidazo[1,5-a]pyridine-based fluorophores were synthesized according to a one-pot cyclization between an aromatic ketone and benzaldehyde in the presence of ammonium acetate and acetic acid. The photophysical features of prepared compounds were investigated in several organic solvents and probes 2–4 exhibited the greatest solvatochromic behavior, resulting in a higher suitability as membrane probes. Their interaction with liposomes as artificial membrane model was tested showing a successful intercalation of the probes in the lipid bilayer. Kinetic experiments were carried out and the lipidic phase influence on the photophysical features was evaluated through temperature-dependent experiments. The results herein reported encourage further investigations on the use of imidazo[1,5-a]pyridine scaffold as fluorescent membrane probes.

中文翻译：

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咪唑并[1,5-a]吡啶基荧光探针：脂质体模型的光物理研究

咪唑并[1,5- a ]吡啶是一种稳定的支架，在许多应用领域（如光电子学、配位化学、传感器、化学生物学）中广泛用于发射化合物的开发。它们紧凑的形状以及卓越的光物理特性使其成为细胞膜探针的合适候选者。膜动力学、水合作用和流动性的研究对于监测细胞健康和探索关键的生化途径具有重要意义。在此背景下，五咪唑[1,5- a]吡啶基荧光团是根据在乙酸铵和乙酸存在下芳族酮和苯甲醛之间的一锅环化合成的。在几种有机溶剂中研究了制备化合物的光物理特性，探针2-4表现出最大的溶剂致变色行为，因此更适合作为膜探针。测试了它们与作为人工膜模型的脂质体的相互作用，显示探针成功插入脂质双层。进行了动力学实验，并通过温度依赖性实验评估了脂质相对光物理特征的影响。本文报告的结果鼓励进一步研究咪唑[1,5- a]吡啶支架作为荧光膜探针。