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 Sept. 2020
Accepted
16 Okt. 2020
First published
29 Okt. 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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