Xanthene derivatives constitute an important class of oxygen-containing heterocycles with broad biological, pharmacological, and photonic relevance. In this study, the photophysical behavior of the anionic fluorescent dyes Eosin Y and Eosin E was systematically investigated across twelve solvents spanning a wide polarity range, with particular emphasis on solvent-induced modulation of their electronic transitions and spectral responses. Linear solvation energy relationship (LSER) analysis based on the Kamlet-Abboud-Taft (KAT) and Catal & aacute;n models revealed the hydrogen bond acceptor ability (beta, or SB depending on the solvatochromic model) as the predominant solvatochromic parameter governing the spectral behavior of both dyes. Excited-state dipole moments, estimated using the Bakshiev method, exhibited pronounced polarity-dependent enhancement, increasing from 1.32 to 5.37 D for Eosin Y and from 1.12 to 3.58 D for Eosin E. These trends are consistent with structural differences and molecular asymmetry introduced by the benzoate and ethyl ester substituents, which modulate electron delocalization and intramolecular proton-transfer dynamics within the xanthene framework. The substantial increase in dipole moment upon excitation provides compelling evidence for efficient charge separation and the involvement of intramolecular proton transfer processes. Combined with the Intrinsic Polarity Descriptor (IPD*), our results underscore the decisive role of solvent polarity in shaping the photophysical properties of xanthene-based dyes and enable a more reliable assessment of their performance as environment-sensitive fluorescent probes for potential applications.
The mechanisms of electric transport in dye-based liquids are not well known since most of the studies in dielectric spectroscopy are focused on permittivity and not on the relation between conductivity, impedance and dielectric loss. In this study, methylene blue (MB) in methanol (MeOH) with various weight fractions (X) is investigated systematically from 20 Hz to 2 MHz at 293.15 K to 323.15 K. The frequency-dependent behavior of the imaginary parts of AC conductivity ( sigma ac '' (omega)), impedance (Z ', Z '') and loss tangent (tan delta) was analyzed for different MB concentrations. The increasing sigma ' ac (omega) and decreasing Z ' with frequency and temperature indicate thermally activated ionic conduction, while sigma ac '' (omega), Z '' and tan delta reveal relaxation associated with interfacial polarization and ionic movement. These correlations offer a unified framework for understanding conduction, relaxation, and molecular interactions in dye solutions.
A new, sensitive and selective bulk sensor membrane has been designed for the quantification of trace amounts of aluminum [Al3+] employing a polymer inclusion membrane (PIM). This innovative membrane has been used analytical performance, including a low reported detection limit, a relatively broad calibration range, membrane regeneration, and application to several real samples. The PIM contains 35% di(2-ethylhexyl)phosphoric acid (D2EHPA) as the carrier, 50% poly(vinyl chloride) (PVC) as the base polymer, 12.5% dioctyl sebacate (DOS) as the plasticizer, and 2.5% of the colorimetric reagent for Al3+, 4-(2-amino-3-hydroxy-pyridine-4-ylazo)1,5-dimethyl-2-phenyl-1,2-dihydropyra-zol-3-one (AHDDO). In this research, Al3+ ions are absorbed into the PIM forming an Al3+-D2EHPA complex, which then interacts with AHDDO, resulting in a pink Al3+-AHDDO complex (lambda max = 589 nm). A central composite design was utilized to optimize various parameters such as the quantity of additives and AHDDO, pH levels, and response time, all of which significantly influence the sensor's performance. Under the ideal circumstances, the sensor membrane achieves a lower limit of quantification (LOQ) of 5.00 ng mL-1 and a limit of detection (LOD) of 1.50 ng mL-1 compared to other sensor reported early. The sensor membrane exhibits excellent stability and reproducibility with a relatively long lifetime, indicating its capability for accurate and reliable monitoring of Al3+ ion concentrations. The sensor was successfully regenerated by 0.10 M EDTA and 0.10 M NaF solution. The response was reproducible and reversible, with an RSD of 1.45% or more. The PIM- AHDDO sensor was successfully applied to determine Al3+ ions in real samples from pharmaceutical, biological, and environmental sources.
One of the significant technologies is spectrum sensing that is employed to resolve the limited accessibility of the spectrum resource. Spectral signal validation acts as a significant part in forecasting and characterizing the occupancy conditions of dynamic frequency platforms. To improve the spectrum usage, the technology of Cognitive Radio (CR) is suggested. This research addresses the concerns in spectrum sensing in CR by developing a heuristic-based deep learning model. At first, the signal data collected from the network is subjected to feature extraction based on the developed Ensemble Autoencoder with Multihead Coordinate Attention Fusion Network (EA-MCAFNet). The developed EA-MCAFNet model includes rigorous characteristics to operate at noisy conditions, as it combines the ability of the Autoencoder and MCAFNet. The developed EA-MCAFNet identifies both the spatio-temporal features from the signal data, and these extracted features are sent to the developed Adaptive Residual Gated Recurrent Unit (ARGRU) for spectrum state detection. Here, the layers within GRU are set for parameter tuning based on the newly implemented Movement-updated Revolution Optimization (MRO). The suggested network is effective and has high reliability to operate in low Signal-to-Noise Ratio (SNR) conditions, and successfully achieves high spectrum state detection accuracy. Experiments follow a comparative study against the well-defined methods, and the results are achieved on standard data sources to ensure the efficacy of the approach.
The determination of the absolute configuration of chiral molecules is essential because of the 3D arrangement of the atoms directly affects the chemical reactivity, biological activity, and therapeutic effects. Therefore, the absolute configuration of the major chiral components of the essential oil of Bubonium graveolens plant was determined by experimental VCD studies and DFT-calculated VCD spectra. The major components of B. graveolens plant studied were trans-chrysanthemyl acetate, delta-cadinol and delta-cadinene. The absolute configurations of trans-chrysathenyl acetate isomer were 5S,9R,10R, while the two isomers of delta-cadinol had 1R,4S,5R,10S and 1R,4R,5R,10S configurations. The absolute configurations of delta-cadinene isomers were 1R,10S and 1S,10R, respectively. Only one isomer of trans-chrysanthemyl acetate is present in this plant, while two isomers of delta-cadinol and delta-cadinene are available in B. graveolens. The predicted optical rotations of 5S,9R,10R of trans-chrysanthenyl acetate and 1S,10R of delta-cadinene were dextrorotatory, while the levorotatory signs were shown by 1R,4S,5R,10S and 1R,4R,5R,10S isomers of delta-cadinol and 1R,10S isomer of delta-cadinene, respectively. This approach has contributed to a deeper understanding of the structural, conformational and optical rotation properties of the chiral chemical species present in the B. graveolens plant. This research is highly useful in chemical asymmetric synthesis, drug development and effective fragrance preparations.
