This paper presents the synthesis of eight new pyrazole azo dyes using ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate as the diazotization component and various active methylene derivatives as coupling components. These new azo dyes were characterized by spectroscopic (FT-IR, UV-VIS), and spectrometric (¹H NMR, ¹³C NMR, MS) analyses. The dye structures were modeled by the MMFF94s force field and quantum chemical density functional theory (DFT) calculations using the B3LYP functional and the 6-311G(d,p) basis set, in the gas phase. Weak electrostatic hydrogen bonds for the azo and hydrazo dye tautomers were found in the ground state. The CIS, TD (using the B3LYP and M06-2X functionals), and ZINDO methods were used to estimate the dye UV-VIS spectra in ethanol, which were compared with the experimental ones. The anti-configuration arrangement of the π-bonds and the presence of the prevalent hydrazo dye tautomer were supported by the computed ¹H NMR and ¹³C NMR spectra. A good accordance between the experimental and predicted absorption maxima and chemical shifts was observed. Color investigations using the CIEL*a*b* space were conducted for all dyes in powder and for their mixtures in water-based acrylic resins. The results confirm the newly synthesized dyes’ color properties and that they might be used for light color paints in the varnishes industry.

The optimization of the photoactive electrode based on TiO₂ with a complex architecture for UV dyes along with water-based electrolyte has successfully allowed us (i) to obtain a photovoltaic efficiency of the dye-sensitized solar cell with 1.45 times higher than the best efficiency reported for synthetic dye and 3 times for curcumin dye so far; (ii) transparency on the entire Photosynthetic Active Radiation domain; (iii) preserving high efficiency for lighting 1 sun (summer) and shading, especially for 60 mW/cm², which represents the maximum illumination in the rest of the seasons. Our water-based dye-sensitized solar cells loaded with synthetic and natural UV dyes have revealed that the implementation of a dye-sensitized solar cell in autonomous greenhouses is a viable and inexpensive concept.

The use of vegetable oils and their derivatives for polymer synthesis has been a major focus in recent years due to their universal availability, low production costs and biodegradability. In this study, the enzymatic synthesis of oligoesters of ricinoleic acid obtained from castor oil combined with three aromatic natural derivatives (cinnamyl alcohol, sinapic acid, and caffeic acid) was investigated. The formation of the reaction products was demonstrated by FT-IR, MALDI-TOF MS and NMR spectroscopy and for the oligo (ricinoleyl)-caffeate the thermal properties and biodegradability in sweet water were analyzed and a rheological characterization was performed. The successful enzymatic synthesis of oligoesters from ricinoleic acid and aromatic monomers using lipases not only highlights the potential of biocatalysis in green chemistry but also contributes to the development of sustainable and biodegradable methods for synthesizing products with potential applications as cosmetic ingredients.

In this paper, a comparative study of the physico-chemical properties and composition of walnuts and peanuts oils obtained by cold pressing or Soxhlet extraction in hexane was performed. The physical properties (color, density, refractive index, acidity, saponification, iodine and peroxide values, rheological behavior), the distribution of the major fatty acids in oils (through gas-chromatographic analysis) and the metal content were determined.

The rheological behavior of some mayonnaise varieties prepared from liquid egg yolks, fresh or frozen, whose oily phase is made up of mixtures of sesame oil and rapeseed oil was studied in the current paper. The study examined the influence of the freezing time of the egg yolk, of the ratio between the two types of oil, as well as of the storage time, on the rheological parameters (apparent viscosity, consistency coefficient, flow behavior index). It has been shown that all types of mayonnaise present non-Newtonian behavior (pseudoplastic), because the values of the flow behavior index established from the specific mathematical models (Ostwald de Waele and Herschel-Bulkley) are sub-unit, and the apparent viscosity decreases with the increase of the shear rate. Mayonnaises prepared from frozen egg yolks and those with an oily phase in which sesame oil is predominant, have a higher consistency. The oxidation stability was evaluated by determining the acid values, which increase slightly with the freezing time of the egg yolk and with the amount of sesame oil in the oily phase. From the color tests carried out in the CIELAB color space, the characteristic parameters L*, a* and b* were determined and the lightness of the mayonnaise was assessed.

The natural selectivity of titanium dioxide (TiO₂) using the anthocyanins extracted from frozen blueberry fruit has been investigated for the improvement of the natural dye-sensitized solar cell. The main drawback of the dye-sensitized solar cell-based natural dyes is the low efficiency caused by the weak binding between natural dye molecules with TiO₂ film. High-efficiency dye-sensitized solar cells use the synthetic organic dyes, which are most frequently anchored on metal oxide photoanode through the carboxylic group. Herein, the addition of carboxyl group by the acidification of crude blueberry extract with acetic acid was provided. The carboxyl group is proposed to improve the anchorage of the anthocyanin dye molecules onto the surface of TiO₂. Optical analysis and atomic force microscopy show the increase of the visible absorbance and the uniform anchoring of the natural dye molecules over the whole TiO₂ film causing a higher dye loading. Dye-sensitized solar cells were fabricated using natural dye obtained by the acidification with hydrochloric acid and acetic acid. Beneficial effect of the carboxylic groups in the anchorage of the natural dye molecules onto the surface of TiO₂ was confirmed. The best photovoltaic efficiency of 0.722% under 1 sun was achieved by the dye acidification with acetic acid.