Issue 65, 2020

Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

Abstract

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-a]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 ε = 3320 M−1 cm−1 and ϕF = 0.01 to ε = 20 593 M−1 cm−1 and ϕF = 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-Cl2Ph), 4d (Ph) and 4e (4-MeOPh), allow good solid-state emission intensities (QYSS = 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.

Graphical abstract: Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

Supplementary files

Article information

Article type
Paper
Submitted
08 9 2020
Accepted
16 10 2020
First published
29 10 2020
This article is Open Access
Creative Commons BY license

RSC Adv., 2020,10, 39542-39552

Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

A. Tigreros, Sandra-L. Aranzazu, Nestor-F. Bravo, J. Zapata-Rivera and J. Portilla, RSC Adv., 2020, 10, 39542 DOI: 10.1039/D0RA07716J

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