Abstract. Every kind of honey is a very precious natural product which is made by Mellifera bees species. The chemical composition of honey depends on its origin or mode of production. Honey consists essentially of different sugars, predominantly fructose and glucose. There are also nonsugar ingredients like proteins and amino acids, as well as some kind of enzymes, such as: invertase, amylase, glucose oxidase, catalase and phosphatase. The fact that honey is one of the oldest medicine known worldwide is remarkable. Scientists all over the world have been trying to improve analytical methods as well as to implement new ones in order to reaffirm the high quality of honey the benefits of which may be distracted or disturbed. There are many methods and popular analytical techniques, including as follows: mass spectroscopy and molecular spectroscopy (especially FTIR spectroscopy). The infrared spectroscopy technique is one of the most common analytical methods which are used to analyse honey nowadays. The main aim of the task was to use ATR-FTIR infrared spectroscopy to compare selected honey samples as well as typical sequences coming out from certain functional groups in the analysed samples.

A fluorescence quenching-based mechanism for the determination of hypochlorite was proposed based on spectroscopic and chromatographic studies on the hypochlorite-sensing potency of three structurally similar and highly fluorescent coumarins. The mode of action was found to rely upon a chlorination of the coumarin-based probes resulting from their reaction with sodium hypochlorite. Importantly, the formation of chlorinated derivatives was accompanied by a linear decrease in the fluorescence intensities of the probes tested. The results obtained suggest the applicability of a coumarin-dependent hypochlorite recognition mechanism for the detection of, as well as for quantitative determination of, hypochlorite species in vitro.

The article presents the results of spectroscopic studies focused on a selected compound from the 1,3,4-thiadiazole group—2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thia-diazole (FABT)—in a micellar system formed by Triton X-100, a non-ionic detergent. Fluorescence measurements revealed the phenomenon of dual fluorescence whose emergence is related to the particular molecular organisation of the compound, which depends both on the concentration of the detergent and, most of all, the concentration of the compound itself. Dual fluorescence of FABT in a micellar system was observed for the compound dissolved in a methanol aqueous system, i.e., an environment wherein the dual fluorescence of the compound had never been reported before. Based on the interpretation of UV-Vis electronic absorption, resonance light scattering (RLS), emission and excitation fluorescence spectra, as well as measurements of dynamic light scattering (DLS) and Principal Component Analysis (PCA), we were able to relate the occurrence of this effect to the process of molecular aggregation taking place between FABT molecules in the micellar system in question. Results of fluorescence spectra measurements and time-correlated single photon counting (TCSPC) indicate that dual fluorescence occurs at detergent concentrations necessary to form micellar systems, which in turn facilitate the process of aggregation of FABT molecules. The correlation between the observed fluorescence effects and the previous measurements performed for analogues from this group suggests the possibility of charge transfer (CT) within the range of detergent concentrations wherein the aforementioned fluorescence effects are observed. It ought to be emphasised that this type of fluorescence effects are relatively easy to induce, which predisposes this groups of fluorophores as ideal fluorescence probes in the context of biological samples.

Oils often have similar properties and can be difficult to identify based on color, smell or taste alone. The present paper suggests the use of Fourier-transform infrared spectroscopy (FTIR) in combination with chemometric methods to explore similarities and differentiate between samples of Moldavian dragonhead oil subjected to different storage conditions. Dragonhead is a plant characterized by very good honey output and ease of cultivation. Principal component analysis (PCA) was applied to a standard, full range of FTIR spectra. Additionally, hierarchical cluster analysis (HCA) was employed to explore the organization of the samples in groups relative to their “proximity” (similarity), by way of Euclidean distance measurement. PC1 and PC2 accounted respectively for 85.4% and 10.1% of the total data variance. PC1 and PC2 were strongly, negatively correlated within the entire spectral range; the only exception was the region corresponding to νs(-C-Hvst, -CH2) vibrations (aliphatic groups in triglycerides), where PC2 was positively correlated. The use of FTIR spectral analysis revealed noticeable differences in the intensity of bands characteristic of the ageing processes (markers of oxidative processes, etc.) taking place in oleaginous samples and related to the processes of fatty acids oxidation.

In our previous work, we discussed the emergence of the dual fluorescence phenomenon in selected compounds from the group of 1,3,4-thiadiazoles. The results obtained in a number of experimental studies, supported by [TD]DFT calculations, clearly indicated that the phenomenon of dual fluorescence stemmed from an overlap of several factors, including the correct conformation of the analyzed molecule and, very significantly in this context, aggregation effects. Where those two conditions were met, we could observe the phenomenon of intermolecular charge transfer (CT) and the emergence of electronic states responsible for long wave emissions. However, in light of the new studies presented in this paper, we were able, for the first time, to provide a specific theory for the effect of dual fluorescence observed in the analyzed group of 1,3,4-thiadiazoles. We present the results of spectroscopic measurements conducted for two selected analogues from the 1,3,4-thiadiazole group, both in polar and non-polar solvents, which clearly evidence (as we have already suspected in the past, albeit have not shown in publications to date) the possibility of processes related to emission from the tautomer formed in the process of excited state intramolecular proton transfer, which is responsible for the long-wavelength emissions observed in the selected analogues. The presented results obtained with the use of UV-Vis, fluorescence (stationary and time-resolved), FTIR, and Raman spectroscopy, as well as from calculations of dipole moment changes between the ground and excited state with the use of two derivatives with different structures of the resorcylic system, corroborated our standing hypothesis. At the same time, they excluded the presence of ground state keto forms of the analyzed analogues unless necessitated by the structure of the molecule itself. In this case, aggregation factors enhance the observed effects related to the dual fluorescence of the analyzed compounds (by way of AIE—aggregated induced emissions).