Pyridine-Based Small-Molecule Fluorescent Probes as Optical Sensors for Benzene and Gasoline Adulteration

Abstract

Here we present simple fluorophores based on the pyridine core, obtained with straightforward synthetic methodologies. These compounds present in solution absorption maxima in the UV region and fluorescence emission of between 300 and 450 nm, depending on the solvent and chemical structure of the fluorophore. The nature of the solvent was shown to play a fundamental role in their excite-state deactivation, which allowed successful exploration of these compounds as optical sensors for benzene and fuel adulteration in gasoline. In ethanolic solution, upon the addition of benzene, in general the fluorophores presented fluorescence quenching, where a linear correlation between the emission intensity and the amount of benzene (quencher) was observed. In addition, the application of an optical sensor for the detection of fuel adulteration in commercial standard and premium gasoline was successfully presented and discussed. Theoretical calculations were also applied to better understand the solvent–fluorophore interactions.

Synthesis and Photophysical Evaluation of Dialkynyl‐N‐(het)arylpyrroles: Promising Key Compounds in Fluorescence Chemistry

“…As an illustration, we have recently reported the synthesis of fluorophores derived from the alkynylpyridine core, showcasing their application as optical sensors for detecting benzene and gasoline adulteration (Figure 1, compound I) [8] . In this study, the nature of the solvent was shown to play a fundamental role in their excited‐state deactivation.…”

“…[12] As an illustration, we have recently reported the synthesis of fluorophores derived from the alkynylpyridine core, showcasing their application as optical sensors for detecting benzene and gasoline adulteration (Figure 1, compound I). [8] In this study, the nature of the solvent was shown to play a fundamental role in their excited-state deactivation. Additionally, Rosadoni and colleagues documented the synthesis of alkynylimidazoles and their utilization as fluorescent dyes in thin-film luminescent solar concentrators (Figure 1, compound II).…”

“…[6] Despite the extensive knowledge of various fluorophores, [7] over the past decade, chemists have shown interest in developing novel fluorescent compounds derived from small nitrogenous organic molecules. [8][9][10] Since the presence of heteroaromatic rings frequently imparts interesting properties to the overall system, including elevated polarizability, intense charge transfer upon electronic excitation, chemical inertness, and thermal stability, these rings also serve as donor or acceptor moieties due to the presence of one or more heteroatoms. [11] Moreover, the triple carbon-carbon bond can function as an efficient π-spacer unit, extending the conjugation by minimizing steric hindrance between the two (hetero)aromatic rings.…”

“…Furthermore, these versatile materials are fundamental in a multitude of applications, widely used in organic light emitting diode (OLED) devices, [4] extending to nonlinear optics [5] and sensor technologies [6] . Despite the extensive knowledge of various fluorophores, [7] over the past decade, chemists have shown interest in developing novel fluorescent compounds derived from small nitrogenous organic molecules [8–10] . Since the presence of heteroaromatic rings frequently imparts interesting properties to the overall system, including elevated polarizability, intense charge transfer upon electronic excitation, chemical inertness, and thermal stability, these rings also serve as donor or acceptor moieties due to the presence of one or more heteroatoms [11] .…”

Fluorescent Probes for Detection of Environmental Contaminants (NACs & VOCs): Probe Design from a Supramolecular Perspective

“…[53][54][55] Furthermore, most of the aromatic VOCs, i. e., benzene, toluene, and xylene derivatives, are electron-rich systems and can interact effectively with the electron-deficient fluorescent chemosensors through intermolecular π-π stacking and hydrophobic interactions. [56][57][58] The nature of the electron transfer process predominantly depends upon the band energies of both the fluorophore and sensing analytes which has been discussed in detail afterward. However, their specific recognition is often difficult in some cases, due to the similarity in their interaction patterns.…”