Sol-gel microextraction phases for sample preconcentration in chromatographic analysis

Sol-gel technology provides a simple and reliable method for solid-phase microextraction (SPME) fiber preparation through in situ creation of surface-bonded organic-inorganic hybrid coatings characterized by enhanced thermal stability and solvent-resistance properties that are important for the coupling of SPME with GC and HPLC, respectively. The sol-gel coating technology has led to the development of an extensive array of sol-gel sorbent coatings for SPME. In this article, sol-gel microextraction coatings are reviewed, with particular attention on their synthesis, characterization, and applications in conjunction with GC and HPLC analyses. In addition, the development of sol-gel-coated stir bars, their inherent advantages, and applications are discussed. Next, the development and applications of sol-gel capillary microextraction (CME) in hyphenation with GC and HPLC is extensively reviewed. The newly emerging germania- and titania-based sol-gel microextraction phases look promising, especially in terms of pH and hot solvent stability. Finally, sol-gel monolithic beds for CME are reviewed. Such monolithic beds are in a position to greatly improve the extracting capabilities and enhanced sensitivity in CME.     

Design of novel substituted phthalocyanines; synthesis and fluorescence,DFT, photovoltaic properties

The 4-(2-[3,4-dimethoxyphenoxy] phenoxy) phthalonitrile was synthesized as the starting material of new syntheses. Zinc, copper, and cobalt phthalocyanines were achieved by reaction of starting compound with Zn(CH3COO)2, CuCl2, and CoCl2 metal salts. Basic spectroscopic methods such as nuclear magnetic resonance electronic absorption, mass and infrared spectrometry were used in the structural characterization of the compounds. Absorption, excitation, and emission measurements of the fluorescence zinc phthalocyanine compound were also investigated in THF. Then, structural, energy, and electronic properties for synthesized metallophthalocyanines were determined by quantum chemical calculations, including the DFT method. The bandgap of HOMO and LUMO was determined to be chemically active. Global reactivity (I, A, η, s, μ, χ, ω) and nonlinear properties were studied. In addition, molecular electrostatic potential (MEP) maps were drawn to identify potential reactive regions of metallophthalocyanine (M-Pc) compounds. Photovoltaic performances of phthalocyanine compounds for dye sensitive solar cells were investigated. The solar conversion efficiency of DSSC based on copper, zinc, and cobalt phthalocyanine compounds was 1.69%, 1.35%, and 1.54%, respectively. The compounds have good solubility and show nonlinear optical properties. Zinc phthalocyanine gave fluorescence emission.     

Microbial Natural Products with Antiviral Activities,Including Anti-SARS-CoV-2: A Review

The SARS-CoV-2 virus, which caused the COVID-19 infection, was discovered two and a half years ago. It caused a global pandemic, resulting in millions of deaths and substantial damage to the worldwide economy. Currently, only a few vaccines and antiviral drugs are available to combat SARS-CoV-2. However, there has been an increase in virus-related research, including exploring new drugs and their repurposing. Since discovering penicillin, natural products, particularly those derived from microbes, have been viewed as an abundant source of lead compounds for drug discovery. These compounds treat bacterial, fungal, parasitic, and viral infections. This review incorporates evidence from the available research publications on isolated and identified natural products derived from microbes with anti-hepatitis, anti-herpes simplex, anti-HIV, anti-influenza, anti-respiratory syncytial virus, and anti-SARS-CoV-2 properties. About 131 compounds with in vitro antiviral activity and 1 compound with both in vitro and in vivo activity have been isolated from microorganisms, and the mechanism of action for some of these compounds has been described. Recent reports have shown that natural products produced by the microbes, such as aurasperone A, neochinulin A and B, and aspulvinone D, M, and R, have potent in vitro anti-SARS-CoV-2 activity, targeting the main protease (M^pro). In the near and distant future, these molecules could be used to develop antiviral drugs for treating infections and preventing the spread of disease.     

1,3,4-Oxadiazole-containing hybrids as potential anticancer agents: Recent developments,mechanism of action and structure-activity relationships

Chemotherapy is an important therapeutic approach for the treatment of cancer. Currently, many anticancer drugs are available in the market that plays an important role in cancer treatment, but concerns such as, drug resistance and side effects create an urgent need for the development of new anti-tumor drugs with high potency and less side effects. Heterocycles are of great interest due to their fascinating anticancer activity. Among them, 1,3,4-oxadiazoles showed attracting anti-tumor activity and its derivatives are under clinical trials for the treatment of cancer. Hybridization of 1,3,4-oxadiazole moiety with other heterocyclic pharmacophoresis a promising approach to overcome various disadvantages of current anticancer drugs such as drug resistance, toxicity, and other side effects. Thus, 1,3,4-oxadiazole-heterocycle hybrids occupy a significant position in the discovery of anti-tumor drugs. Among the reported oxadiazole-based hybrids reviewed here, compounds 45i, 59j, and 62x showed the highest anticancer activity with IC₅₀ values in the nanomolar range. This review summarizes the recent developments in the anticancer potential, structure–activity relationships, and mechanisms of actions of 1,3,4-oxadiazole-heterocycle hybrids.     

Synthesis and preliminary cytotoxic activity of dimethoxy-acridines and dimethoxynitroacridines

The preparation of a series of dimethoxy and dimethoxynitroacridines and their activity in oxic and hypoxic cells is reported. Anthranilic acids 1,4,14 were prepared according to the Ullmann condensation. 9-chloroacridines were obtained from anthranilic acids by refluxing in phosphorus oxychloride. The synthesis of two new acridine dimers 9,10 is described. Nitration of 9-chloro-2,4-dimethoxyacridine 15 gave 3-nitro isomer 19 . By phenol-mediated coupling reaction from all the 9-chloroacridines, the respective 9-(alkylamino)acridines were obtained. By nitration of 17 a new 2,4-dimethoxy-3,7-dinitroacridine 21 was prepared     

Salting-Out of <Emphasis Type="Italic">n</Emphasis>-Propyl Alcohol with Potassium Nitrate from Aqueous Solutions

The solubility of components and critical phenomena in the ternary system constituted by potassium nitrate, water, and n-propyl alcohol were studied by the visual polythermal method in the temperature range 25–80°C. The temperature of formaiton of the critical node of the monotectic equilibrium (critical solution-solid phase) and the solution compositions corresponding to the critical solution points at different temperatures were determined. The isothermal solubility diagrams of the system were constructed and the distribution coefficients of n-propyl alcohol at different temperatures were calculated. A comparative analysis of the salting-out effect exerted by potassium nitrate on aqueous solutions of n-propyl alcohol and isopropyl alcohol was done.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 398–402.Original Russian Text Copyright © 2005 by Sinegubova, Cherkasov, Il’in.     

Effect of Sodium Dodecylbenzenesulfonate on the Association Behavior of Promethazine Hydrochloride in Aqueous/Electrolyte Solutions at Different Temperatures

The interaction between the amphiphilic phenothiazine drug promethazine hydrochloride (PMT) and an anionic surfactant sodium dodecylbenzenesulfonate has been investigated using the conductometric technique in the absence and presence of an inorganic salt (50 mmol·kg^?1 NaCl) at five different compositions and temperatures. PMT is employed for the cure of allergic symptoms. Different physicochemical parameters such as critical micellar concentration (cmc), thermodynamic, and micellar composition are evaluated and discussed in detail using regular solution theory (RST). The addition of salt decreased the surface charge of micelles, lowering the cmc values of the amphiphile. The interaction parameter (β) is negative at all temperatures and compositions indicating attractive interactions. Due to the presence of NaCl in mixed systems the attractive interaction (β) was further increased (β values more negative). The negative values of Gibbs energy (\( \Delta G^{0}_{\text{m}} \)) of mixing revealed the stability of the solution. Owing to the presence of NaCl, the \( \Delta G^{0}_{\text{m}} \) values are found to be more negative suggesting that the driving force for interaction was significantly increased and micellization more thermodynamically favorable.     

Conformational isomerism of the seven-membered heterocycle in a single crystal of [η<Superscript>2</Superscript>-Ph<Subscript>2</Subscript>P(O)(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>C(O)NМе<Subscript>2</Subscript>]TiF<Subscript>4</Subscript> adduct

The crystal structure of TiF₄[(Ph₂P(O)CH₂CH₂C(O)NMe₂)] chelate (I) was studied by X-ray crystallography, which revealed four crystallographically independent complex molecules of similar structure (1–4). It was found that the molecules are only slightly different in the bond lengths between the coordinated atoms and the central titanium ion and considerably different in the geometry of the seven-membered TiOPCCCO chelate ring. The geometry of the chelate rings was found to be almost identical in each pair of complexes 1, 2 (A) and 3, 4 (B), and a conclusion was drawn on the presence of two conformational isomers (A and B) of the chelate complex. Quantum chemical calculations of the relative thermodynamic stability of molecules 1–4 were performed, and their geometry optimization led to one theoretical structure. The comparison of the chelate ring geometry in the theoretical structure and in conformers A and B revealed that the conformation of the theoretical chelate ring coincides with that of conformer A.