Tigreros Alexis, Aranzazu Sandra-L, Bravo Nestor-F, Zapata-Rivera Jhon, Portilla Jaime
Bioorganic Compounds Research Group, Department of Chemistry, Universidad de los Andes Carrera 1 No. 18A-10 Bogotá 111711 Colombia
Molecular Electronic Structure Group, Department of Chemistry, Universidad de los Andes Carrera 1 No. 18A-10 Bogotá 111711 Colombia.
RSC Adv. 2020 Oct 29;10(65):39542-39552. doi: 10.1039/d0ra07716j. eCollection 2020 Oct 27.
Fluorescent molecules are crucial tools for studying the dynamics of intracellular processes, chemosensors, and the progress of organic materials. In this study, a family of pyrazolo[1,5-]pyrimidines (PPs) 4a-g has been identified as strategic compounds for optical applications due to several key characteristics such as their simpler and greener synthetic methodology (RME: 40-53%) as compared to those of BODIPYS (RME: 1.31-17.9%), and their tunable photophysical properties (going from = 3320 M cm and = 0.01 to = 20 593 M cm and = 0.97), in which electron-donating groups (EDGs) at position 7 on the fused ring improve both the absorption and emission behaviors. The PPs bearing simple aryl groups such as 4a (4-Py), 4b (2,4-ClPh), 4d (Ph) and 4e (4-MeOPh), allow good solid-state emission intensities (QY = 0.18 to 0.63) in these compounds and thus, solid-state emitters can be designed by proper structural selection. The properties and stability found in 4a-g are comparable to commercial probes such as coumarin-153, prodan and rhodamine 6G. Ultimately, the electronic structure analysis based on DFT and TD-DFT calculations revealed that EDGs at position 7 on the fused ring favor large absorption/emission intensities as a result of the ICT to/from this ring; however, these intensities remain low with electron-withdrawing groups (EWGs), which is in line with the experimental data and allows us to understand the optical properties of this fluorophore family.
荧光分子是研究细胞内过程动力学、化学传感器和有机材料进展的关键工具。在本研究中，吡唑并[1,5 - ]嘧啶（PPs）家族4a - g已被确定为光学应用的关键化合物，这归因于其几个关键特性，例如与BODIPYs（产率：1.31 - 17.9%）相比，其合成方法更简单、更绿色（产率：40 - 53%），以及其可调节的光物理性质（从ε = 3320 M cm⁻¹和Φ = 0.01到ε = 20593 M cm⁻¹和Φ = 0.97），其中稠环上7位的供电子基团（EDGs）改善了吸收和发射行为。带有简单芳基如4a（4 - Py）、4b（2,4 - ClPh）、4d（Ph）和4e（4 - MeOPh）的PPs在这些化合物中具有良好的固态发射强度（量子产率 = 0.18至0.63），因此，可以通过适当的结构选择设计固态发射体。在4a - g中发现的性质和稳定性与香豆素 - 153、prodan和罗丹明6G等商业探针相当。最终，基于DFT和TD - DFT计算的电子结构分析表明，稠环上7位的EDGs由于向该环的电子转移/从该环的电子转移而有利于产生大的吸收/发射强度；然而，对于吸电子基团（EWGs），这些强度仍然较低，这与实验数据一致，并使我们能够理解该荧光团家族的光学性质。
