Figure 6 - uploaded by Mario N Berberan Santos
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Portrait of Sir George Gabriel Stokes (permission obtained from AIP Emilio Segre Visual Archives, E. Scott Barr Collection).
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Fluorescence and phosphorescence are two forms of photoluminescence used in modern research and in practical applications. The early observations of these phenomena, before the emergence of quantum theory, highlight the investigation into the mechanism of light emission. In contrast to incandescence, photoluminescence does not require high temperat...
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... INVENTION OF THE TERM FLUORESCENCE 4,6,8 A major event in the history of photoluminescence was the publication by Sir George Gabriel Stokes (Figure 6), physicist and professor of mathematics at Cambridge, of his famous paper entitled "On the Refrangibility of Light" in 1852. 4 In it, and in detailed experimental studies on several samples, both organic (including quinine) and inorganic (including a fluorite crystal similar to that shown in Figure 4, reported to be from Alston Moor, England c ), he clearly identified a common phenomenon he called dispersive reflection: the wavelengths of the dispersed light are always longer than the wavelength of the original light. ...
Citations
... Photoluminescence (fluorescence and/or phosphorescence) is the re-emission of absorbed photons from matter, usually at a higher wavelength than the absorption wavelength [1]. It occurs in many animals (e.g., fish [2][3][4], amphibians [5][6][7], reptiles [8][9][10] birds [11][12][13]), including mammals [14][15][16]. ...
Bright photoluminescence in the fur of mammals has recently raised considerable scientific interest. The fur of many mammal species, including Australian northern long-nosed (Perameles pallescens) and northern brown (Isoodon macrourus) bandicoots, photoluminesces strongly, displaying pink, yellow, blue and/or white colours. We used reversed-phase high-performance liquid chromatography and electrospray ionisation mass spectrometry to investigate the luminophores contributing to this photoluminescence. At least two classes of luminophore were observed in bandicoot fur extracts, and four of the orange-pink photoluminescent molecules had molecular masses consistent with protoporphyrin, coproporphyrin, uroporphyrin and heptacarboxylporphyrin isomers. Fur extracts of three other species of marsupial, a placental and a monotreme also contained a luminophore consistent with the molecular mass of protoporphyrin, whether or not pink photoluminescence was evident in the pelage as a whole. This study is the first chemical analysis of luminophores contributing to photoluminescence in the fur of Australasian mammals since two tryptophan metabolites were identified more than 50 years ago.
... Among the various techniques used to analyze wine, fluorescence spectroscopy is one of less frequently employed. The term "fluorescence" has been introduced to describe the unusual properties of the mineral fluorite, also called fluorspar (calcium fluoride) [9]. Fluorescence denotes a phenomenon occurring in some molecules (fluorophores), consisting of an immediate (in the nanosecond range) emission of light by a substance irradiated with a light of a shorter wavelength or UV radiation. ...
... All PCs are mutually orthogonal, and each successive PC contains less of the total variability of the initial dataset. This procedure reduces the dimensionality of the data, which enables the effective visualization, classification, and regression of multivariate data [9]. The PCA components do not necessarily have a clear physical meaning, but they can be efficiently used to understand and classify the wine data. ...
Rapid and cost-effective measurements of the autofluorescence of wine can provide valuable information on the brand, origin, age, and composition of wine and may be helpful for the authentication of wine and detection of forgery. The list of fluorescent components of wines includes flavonoids, phenolic acids, stilbenes, some vitamins, aromatic amino acids, NADH, and Maillard reaction products. Distinguishing between various fluorophores is not simple, and chemometrics are usually employed to analyze the fluorescence spectra of wines. Front-face fluorescence is especially useful in the analysis of wine, obviating the need for sample dilution. Front-face measurements are possible using most plate readers, so they are commonly available. Additionally, the use of fluorescent probes allows for the detection and quantification of specific wine components, such as resveratrol, oxygen, total iron, copper, hydrogen sulfite, and haze-forming proteins. Fluorescence measurements can thus be useful for at least a preliminary rapid evaluation of wine properties.
... Fluorescence is established by, G.G. Stokes, in the 19th century (Valeur & Berberan-Santos, 2011). In the field of molecular spectroscopy, the word "fluorescence" is frequently used to describe the spin-permitted radiative transitions between the first excited singlet state and the ground state in which the excited orbital electron is paired with the second electron in the ground state orbital (of opposite spin). ...
... The phenomenon of photoluminescence results from light photon absorption (Shinde et al., 2012). There are two pathways of photoluminescence: fluorescence and phosphorescence based on the type of excited state and lifetime (Valeur & Berberan-Santos, 2011). ...
... From the early observations by the Aztecs, who noted a type of wood with medicinal properties that imparted vibrant colors to water, to the first decades of the 20th century-with a pivotal moment in the 1850s through the work of George Gabriel Stokes who described the emission of light by quinine sulfate solutions upon illumination with the "invisible part of sunlight" (Stokes 1852)-fluorescence has attracted the attention of writers, poets and scientists, mainly in the field of physics and, to a lesser and descriptive degree, biology (Valeur and Berberan-Santos 2011;Jameson 2014). ...
Fluorescence is one of the most widely used techniques in biological sciences. Its exceptional sensitivity and versatility make it a tool of first choice for quantitative studies in biophysics. The concept of phasors, originally introduced by Charles Steinmetz in the late 19th century for analyzing alternating current circuits, has since found applications across diverse disciplines, including fluorescence spectroscopy. The main idea behind fluorescence phasors was posited by Gregorio Weber in 1981. By analyzing the complementary nature of pulse and phase fluorometry data, he shows that two magnitudes -denoted as G and S- derived from the frequency-domain fluorescence measurements correspond to the real and imaginary part of the Fourier transform of the fluorescence intensity in the time domain. This review provides a historical perspective on how the concept of phasors originates and how it integrates into fluorescence spectroscopy. We discuss their fundamental algebraic properties, which enable intuitive model-free analysis of fluorescence data despite the complexity of the underlying phenomena. Some applications in biophysics illustrate the power of this approach in studying diverse phenomena, including protein folding, protein interactions, phase transitions in lipid mixtures and formation of high-order structures in nucleic acids.
... In fact, this protocol is a result of systematic experiments performed by several groups of students for their senior capstone project, where a total of 13 students distributed in five groups (2 or 3 students each) took part in the experiments. Fluorescence spectroscopy is a widely used analytical technique that has many practical applications due to its high analytical sensitivity [20,21]. For example, a spectrofluorometer is typically used for inorganic chemistry applications such as for the determination of chromium and manganese in steel or aluminum in alloys [22]. ...
... It is also commonly applied in the identification and quantification of organic compounds such as polycyclic aromatic hydrocarbons [23]. In principle, fluorescence is the emission of a molecule from its singlet excited electronic state to its ground state upon the absorption of UV or visible radiation [20,22]. Because of the direct relationship between the intensity of fluorescence and the concentration of an analyte in dilute solutions, fluorescence spectroscopy has been used to quantify quinine in tonic water samples. ...
Quinine is known for treating malaria, muscle cramps, and, more recently, has been used as an additive in tonic water due to its bitter taste. However, it was shown that excessive consumption of quinine can have severe side effects on health. In this work, we utilized fluorescence spectroscopy to measure the concentration of quinine in commercial tonic water samples. An external standard method was used to calculate the concentrations of quinine in two commercially available tonic water brands, namely Canada Dry and Schweppes, and compare them to the maximum allowable concentration of quinine in beverages. Upon analysis of the data collected by five different groups, the levels of quinine were found to be above the average concentration in most commercial tonic water samples, but below the maximum permitted concentration. Moreover, the five replicate sets of data demonstrated high reproducibility of the method employed in this study. The simple yet instructive protocol that we developed can be adapted to determine the concentration of other fluorescent compounds in foods and beverages. Further, the presented method and detailed protocol can be easily adopted for undergraduate labs and in chemical education.
... The word "fluorescence" was first coined in 1852 when George Gabriel Stokes published a paper on the change in the refrangibility of light, demonstrating how quinine reacts with ultraviolet light to produce a blue color [1]. It is typically short-lived (a few nanoseconds) and does not involve intersystem crossing, which is observed when an excited molecule or atom relaxes to a lower energy state by emitting a photon without reversing its spin multiplicity [2]. Fluorescence emission is intimately linked to the processes of excitation and emission: a photon of a particular wavelength is absorbed by a molecule, ...
Fluorescence is a remarkable property exhibited by many chemical compounds and biomolecules. Fluorescence has revolutionized analytical and biomedical sciences due to its wide-ranging applications in analytical and diagnostic tools of biological and environmental importance. Fluorescent molecules are frequently employed in drug delivery, optical sensing, cellular imaging, and biomarker discovery. Cancer is a global challenge and fluorescence agents can function as diagnostic as well as monitoring tools, both during early tumor progression and treatment monitoring. Many fluorescent compounds can be found in their natural form, but recent developments in synthetic chemistry and molecular biology have allowed us to synthesize and tune fluorescent molecules that would not otherwise exist in nature. Naturally derived fluorescent compounds are generally more biocompatible and environmentally friendly. They can also be modified in cost-effective and target-specific ways with the help of synthetic tools. Understanding their unique chemical structures and photophysical properties is key to harnessing their full potential in biomedical and analytical research. As drug discovery efforts require the rigorous characterization of pharmacokinetics and pharmacodynamics, fluorescence-based detection accelerates the understanding of drug interactions via in vitro and in vivo assays. Herein, we provide a review of natural products and synthetic analogs that exhibit fluorescence properties and can be used as probes, detailing their photophysical properties. We have also provided some insights into the relationships between chemical structures and fluorescent properties. Finally, we have discussed the applications of fluorescent compounds in biomedical science, mainly in the study of tumor and cancer cells and analytical research, highlighting their pivotal role in advancing drug delivery, biomarkers, cell imaging, biosensing technologies, and as targeting ligands in the diagnosis of tumors.
... The melting point of the compounds was determined using digital melting point equipment. 1 H and 13 C NMR spectra were obtained using an FT-NMR spectrometer System-400 MHz, with TMS as the internal standard and CDCl 3 as the solvent. HRMS spectra were acquired using the HRMS-ESI + ve Table 4. Electrochemical properties of 5a-j. . ...
We present here a series of 4,6-diarylpyrimidin-2-amine derivatives (5a-j) with tunable optical properties both in the solid and solution states. Our plug-and-play fluorophore design demonstrates that the aryl groups at the 4th and 6th positions of the 2-aminopyrimidine core enable distinct optical characteristics for each derivative. The fluorophore design concept was validated using theoretical and spectroscopic methods. The designed compounds were synthesised in moderate to good yields, and their structures were confirmed via IR, NMR, HRMS, and single-crystal XRD analyses. Optical studies revealed that varying the aryl substituents significantly impacts absorption, emission, and bandgap values in both phases. The absolute quantum yields (ϕF) of the synthesised derivatives ranged from 8.11 to 71.00% in DMF and 5.86–29.43% in thin films, with fluorescence lifetimes (τ) between 0.8 and 1.5 ns in DMF and 0.63–3.16 ns in films, respectively. CIE (Commission Internationale de l’Éclairage) diagrams indicate blue-green emission for 5a-j in the visible spectrum. The electrochemical analysis confirmed that the HOMO/LUMO (Highest Occupied Molecular Orbital/Lowest Unoccupied Molecular Orbital) energy levels can be modulated by altering the substituent rings. These results highlight the dual-state emission properties of 2-aminopyrimidine fluorophores, demonstrating their potential for a wide range of optoelectronic and advanced applications.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-024-81723-1.
... The word "fluorescence" was first coined in 1852 when George Gabriel Stokes published a paper on the change in the refrangibility of light, demonstrating how quinine reacts with ultraviolet light to produce a blue color [1]. It is typically short-lived (a few nanoseconds) and does not involve intersystem crossing, which is observed when an excited molecule or atom relaxes to a lower energy state by emitting a photon without reversing its spin multiplicity [2]. Fluorescence emission is intimately linked to the processes of excitation and emission: a photon of a particular wavelength is absorbed by a molecule, which, in turn, excites the molecule to a higher energy state. ...
Fluorescence is a remarkable property exhibited by many chemical compounds and biomolecules. Fluorescence has revolutionized analytical and biomedical sciences due to its wide-ranging applications in analytical and diagnostic tools of biological and environmental importance. Fluorescent molecules are frequently employed in drug delivery, optical sensing, cellular imaging and biomarker discovery. Cancer is a global challenge and fluorescence agents can function as diagnostic as well as monitoring tools both during early tumor progression and treatment monitoring. Many fluorescent compounds can be found in their natural form but recent developments in synthetic chemistry and molecular biology have allowed us to synthesize and tune fluorescents molecules which otherwise wouldn’t exist in the nature. Naturally derived fluorescent compounds are generally more biocompatible and environmentally friendly. They can also be modified in cost-effective and target-specific ways with the help of synthetic tools. Understanding their unique chemical structures and photophysical properties is key to harnessing their full potential in biomedical and analytical research. As drug discovery efforts require rigorous characterization of pharmacokinetics and pharmacodynamics, fluorescence-based detection accelerates the understanding of drug interactions via in vitro and in vivo assays. Herein, we provide a review of natural products and synthetic analogs that exhibit fluorescence properties and can be used as probes, detailing their photophysical properties. We have also provided some insights into the relationships between chemical structures and fluorescent properties. Finally, we have discussed the applications of fluorescent compounds in biomedical science; mainly in the study of tumor and cancer cells and analytical research, highlighting their pivotal role in advancing drug delivery, biomarkers, cell imaging, biosensing technologies, and as targeting ligands in the diagnosis of tumors.
... In 1852, Sir George Gabriel Stokes used a prism to disperse sunlight into its constituent wavelengths and demonstrate that a quinine solution emitted a blue glow only when irradiated by the invisible ultraviolet rays (<400 nm) (Stokes, 1852). Stokes observed that the emitted light was always of a longer wavelength than the incident light, a phenomenon he termed 'fluorescence' and mistakenly attributed to light scattering (Valeur and Berberan-Santos, 2011). ...
Ever since Robert Hooke's 17th century discovery of the cell using a humble compound microscope, light–matter interactions have continuously redefined our understanding of cell biology. Fluorescence microscopy has been particularly transformative and remains an indispensable tool for many cell biologists. The subcellular localization of biomolecules is now routinely visualized simply by manipulating the wavelength of light. Fluorescence polarization microscopy (FPM) extends these capabilities by exploiting another optical property – polarization – allowing researchers to measure not only the location of molecules, but also their organization or alignment within larger cellular structures. With only minor modifications to an existing fluorescence microscope, FPM can reveal the nanoscale architecture, orientational dynamics, conformational changes and interactions of fluorescently labeled molecules in their native cellular environments. Importantly, FPM excels at imaging systems that are challenging to study through traditional structural approaches, such as membranes, membrane proteins, cytoskeletal networks and large macromolecular complexes. In this Review, we discuss key discoveries enabled by FPM, compare and contrast the most common optical setups for FPM, and provide a theoretical and practical framework for researchers to apply this technique to their own research questions.
