Behera Kanhu Charan, Ravikanth Mangalampalli
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Phys Chem Chem Phys. 2023 Dec 6;25(47):32584-32593. doi: 10.1039/d3cp04234k.
In search of white light emitting fluorophores, a hydrazine bridged Schiff base compound, bis(3-pyrrolyl BODIPY), was synthesized by condensing readily available α-formyl 3-pyrrolyl BODIPY with hydrazine hydrate in CHOH under reflux for 5 h followed by recrystallization. Bis(3-pyrrolyl BODIPY) was thoroughly characterized by HR-MS, 1D and 2D NMR, and X-ray crystallography. The X-ray structure revealed that the 3-pyrrolyl BODIPY units in the dyad were arranged to each other with respect to the hydrazine moiety. Bis(3-pyrrolyl BODIPY) showed absorption bands in the region of 390-705 nm and exhibited multiple fluorescence bands in the region of 395-720 nm at different excitation wavelengths. The protonated derivative of bis(3-pyrrolyl BODIPY) generated by the addition of TFA to its CHCl solution showed significant changes in the optical properties and generated white fluorescence under UV light with specific emission bands observed in blue, green, and red regions, indicating that bis(3-pyrrolyl)BODIPY is a single white light emitting halochromic fluorophore under acidic conditions. DFT and TD-DFT studies justify the structural and electronic properties of the protonated derivative of bis(3-pyrrolyl BODIPY) exhibiting white light emission.
为了寻找白色发光荧光团，通过将易于获得的α-甲酰基-3-吡咯基BODIPY与水合肼在甲醇中回流5小时进行缩合，然后重结晶，合成了一种肼桥联席夫碱化合物双（3-吡咯基BODIPY）。通过高分辨质谱（HR-MS）、一维和二维核磁共振（NMR）以及X射线晶体学对双（3-吡咯基BODIPY）进行了全面表征。X射线结构表明，二元体系中的3-吡咯基BODIPY单元相对于肼部分相互排列。双（3-吡咯基BODIPY）在390 - 705 nm区域显示吸收带，并在不同激发波长下于395 - 720 nm区域呈现多个荧光带。向其氯仿溶液中加入三氟乙酸（TFA）生成的双（3-吡咯基BODIPY）质子化衍生物在光学性质上有显著变化，在紫外光下产生白色荧光，在蓝色、绿色和红色区域观察到特定发射带，表明双（3-吡咯基）BODIPY在酸性条件下是一种单一的白色发光酸碱变色荧光团。密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）研究证实了双（3-吡咯基BODIPY）质子化衍生物呈现白色发光的结构和电子性质。
