The adsorption of paracetamol and non-steroidal anti-inflammatory drugs (ibuprofen and naproxen) on ordered mesoporous carbons (OMC) and, for comparison, on commercial activated carbon, were investigated in this work. OMC adsorbents were obtained by the soft-templating method and were characterized by low-temperature nitrogen adsorption and scanning electron microscopy (SEM). The effects of contact time and initial concentration of organic adsorbates on the adsorption were studied. The contact time to reach equilibrium for maximum adsorption was 360 min for all the studied adsorbates. The adsorption mechanism was found to fit pseudo-second-order and intra particle-diffusion models. Freundlich, Langmuir and Langmuir-Freundlich isotherm models were used to analyze equilibrium adsorption data. Based on the obtained experimental data, the adsorption isotherm in the applied concentration range for all the studied adsorbates was well represented by the Freundlich-Langmuir model. The adsorption ability of ordered mesoporous carbon materials was much higher for paracetamol and naproxen in comparison to commercial activated carbon. The removal efficiency for ibuprofen was significantly lower than for other studied pharmaceuticals and comparable for all adsorbents. Theoretical calculations made it possible to obtain optimized chemical structures of (S)-naproxen, ibuprofen, and paracetamol molecules. Knowledge of charge distributions of these adsorbate molecules can be helpful to explain why paracetamol and naproxen can react more strongly with the surface of adsorbents with a large numbers of acidic groups compared to ibuprofen facilitating more efficient adsorption of these pharmaceuticals on ordered mesoporous carbons.

The photophysical and sensory properties of the donor–acceptor pyrazoloquinoline derivative (PQPc) were investigated using absorption, steady-state, and time-resolved fluorescence measurements. The compound synthesized from commercial, readily available substrates exhibited absorptions in the UV–Vis range, with a maximum of the longwave band around 390 nm. The maximum fluorescence was around 460–480 nm, depending on the solvent. The quantum yield was between 12.87% (for n-hexane) and 0.75% (for acetonitrile) and decreased with increasing solvent polarity. The PET mechanism was implicated as the cause of fluorescence quenching. Divalent ions such as Zn²⁺, Pb²⁺, Cd²⁺, Ca²⁺, Mg²⁺, Co²⁺, Ni²⁺, and Cu²⁺ were introduced to study the fluorescent response of PQPc. A 13-times increase in fluorescence quantum yield was observed after the addition of Zn²⁺ ions. Detailed research was carried out for the PQPc-Zn²⁺ system in order to check the possibility of analytical applications of PQPc as a fluorescent sensor. A detection limit of Zn²⁺ was set at the value level 1.93 × 10⁻⁷ M. PQPc-Zn²⁺ complexes had a stoichiometry of 1:1 with a binding constant of 859 M⁻¹. Biological studies showed that the sensor was localized in cells near the membrane and cytoplasm and may be used to detect zinc ions in eukaryotic cells.

The adsorption of ketoprofen, naproxen, and diclofenac (non-steroidal anti-inflammatory drugs, NSAIDs) on halloysite/carbon nanocomposites and non-modified halloysite were investigated in this work. Halloysite/carbon nanocomposites were obtained through liquid phase impregnation and carbonization using halloysite as the template and saccharose as the carbon precursor. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FT-IR), and low-temperature nitrogen adsorption method were employed to study the morphological and structural changes of the halloysite/carbon nanocomposites. The effects of contact time, initial concentration of adsorbates, pH of solution, and mass of adsorbent on the adsorption were studied. Adsorption mechanism was found to fit pseudo-second-order and intra-particle diffusion models. The obtained experimental adsorption data were well represented by the Langmuir multi-center adsorption model. Adsorption ability of halloysite/carbon nanocomposites was much higher for all the studied NSAIDs in comparison to non-modified halloysite. Optimized chemical structures of ketoprofen, naproxen, and diclofenac obtained by Density Functional Theory (DFT) calculation showed that charge distributions of these adsorbate molecules and their ions can be helpful to explain the details of adsorption mechanism of NSAIDs on halloysite/carbon nanocomposites.

2-(2-Fluoro-4-biphenyl) propionic acid (flurbiprofen), from the phenylalkanoic acid family of nonsteroidal anti-inflammatory drugs (NSAID’s), is currently on the pharmaceutical market as a racemate. This racemic compound was tested for its propensity to undergo the self-disproportionation of enantiomers (SDE) phenomenon by various forms of chromatography (SDEvC), such as routine gravity-driven column chromatography, medium-pressure liquid chromatography (MPLC), preparative thin-layer chromatography (PTLC), and size-exclusion chromatography (SEC), as well as by sublimation (SDEvS). Furthermore, examination by nuclear magnetic resonance (NMR) in various solvents found that flurbiprofen exhibited the phenomenon of self-induced diastereomeric anisochronism (SIDA). By measurement of the diffusion coefficient (D), the longitudinal relaxation time (T₁), and the transverse relaxation time (T₂) using NMR, as well as by electrospray ionization-mass spectrometry (ESI-MS) examinations, the preferred intermolecular association was found to be solvent dependent, e.g., heterochiral association was preferred in toluene, while homochiral association was preferred in more polar solvents. This study also attempted, unsuccessfully, to correlate the NMR measurements of flurbiprofen with chromatographic outcomes for the rationalization and prediction of chromatographic results based on NMR measurements. Because the intermolecular hydrogen bonding of the acid groups in flurbiprofen overwhelmingly predominates over other intermolecular interactions, flurbiprofen seemed to represent a good test case for this idea. The behavior of scalemic samples of flurbiprofen is important, as, although it is currently dispensed as a racemate, clinical applications of the R enantiomer have been investigated. SDEvC and SDEvS both have ramifications for the preparation, handling, and storage of enantioenriched flurbiprofen, and this concern applies to other chiral drugs as well.