We report herein the first application of a silica gel bound enantiopure crown ether as a catalyst in a continuous-flow enantioselective Strecker reaction. The model transformation-among benzaldehyde, aniline, and KCN-was conducted in a packed-bed reactor containing functionalized silica gel covalently modified with an enantiopure acridino-crown ether. The transient phase preceding steady-state conditions was systematically examined under isothermal conditions using dichloromethane and ethanol as solvents. By collecting and analyzing time-resolved fractions, we studied how solvent polarity affects both conversion and enantioselectivity throughout the startup period. Surprisingly, ethanol provided superior conversion and enantioselectivity, despite expectations suggesting less polar environments. These findings are supported by mechanistic considerations involving ion pairing and solvation effects within the confined environment of the immobilized catalyst. This study highlights the dynamic nature of asymmetric induction under flow conditions and offers early insights into a previously unexplored class of catalytic systems.

Although sulfonated acridines and acridones are valuable scaffolds in diagnostics and materials science, to our best knowledge, there is no comprehensive study that addresses how the degree of sulfonation depends on reaction parameters. To fill this gap, we investigated the sulfonation behavior of unsubstituted acridine and acridone under classical conditions, using sulfuric acid, oleum, and chlorosulfonic acid. A factorial experimental design was applied to systematically evaluate the influence of temperature and reagent excess on the extent of sulfonation, while keeping the reaction time constant. Products were analyzed by HPLC–MS/MS to determine the degree of sulfonation and its distribution. Regioselectivity and product isolation were not addressed in this study. Our results provide a foundational dataset for controlling sulfonation level for these heterocycles and can help future synthetic applications where defined sulfonation patterns are desired.

Microtiter-plate-based systems are unified platforms of high-throughput experimentation (HTE). These polymeric devices are used worldwide on a daily basis-mainly in the pharmaceutical industry-for parallel syntheses, reaction optimization, various preclinical studies and high-throughput screening methods. Accordingly, laboratory automation today aims to handle these commercially available multiwell plates, making developments focused on their modifications a priority area of modern applied research. We performed the covalent functionalization of the porous PVDF-membrane of microtiter filter plates as the essence of conventional and common sandwich plate systems by introducing a generalizable method. After surface-activation of the indifferent membrane polymer, customizable functionalization becomes feasible by covalently attached monofunctional molecular linkers. The study was designed with future adaptability, and thus, industrially widespread atmospheric plasma and two different chemical treatments were investigated and compared in terms of practical implementation, polarization effects, extent of labeling, effects on morphology and porosity as well as on permeability. For critical comparison, contact angle measurements, surface ATR-FTIR, 1H-NMR, 19F-NMR, UV-Vis spectroscopy, scanning electron microscopy and permeability tests were used.

An additive package with large natural material content was prepared and its stabilization efficiency was compared to that of an industrial stabilizer combination. A new phosphine-type secondary antioxidant was synthesized to increase the bio-based content of the package. The stabilization effect of the packages was studied in multiple extrusion experiments followed by the measurement of chemical structure, rheology, residual stability, and color. The interaction of the components was studied by thermogravimetry and FTIR spectroscopy. The comparison of the additive packages showed that the bio-based package offers many advantages compared to the currently used industrial package; better stabilization efficiency is achieved at smaller additive content. The natural antioxidant used, quercetin, interacts with the secondary stabilizers. Quercetin initiates the decomposition of a phosphonite stabilizer containing P(III)O bonds, but it increases the inherent stability of the newly synthesized phosphine antioxidant. The interactions result in changes in the reactions of the vinyl groups of the polymer. Besides long chain branching, other competitive reactions take place, which consume vinyl groups but do not increase viscosity. The new stabilizer package offers excellent melt stability and exceptional residual stability for the Phillips polyethylene used in this study. The main drawback of the package is the limited solubility of quercetin and the strong color of the processed material.

Bipyridine ethers are commonly occurring structural motifs in supramolecular chemistry. The herein reported efforts aim to extend the synthetic platform of bipyridino-precursors with new bifunctional intermediates and to improve some previously reported synthetic strategies for structural analogues, like bipyridine-diols as common macrocycle precursors. In addition, their optimized and highly efficient oxidation to the corresponding dialdehydes is reported to obtain further reactive intermediates with wide modifiability. Furthermore, methylations of pyridine-carbaldehydes were carried out alongside different synthetic strategies to introduce chirality centers. Synthetic difficulties and some unsuccessful approaches are also reported to help in focusing future efforts.

Small‐molecule amines, typically studied in their more stable and water‐soluble protonated forms, are of central importance in drug discovery. Their structural diversification often relies on N ‐alkylation, yielding mixtures of analogs with varying degrees of substitution‐posing a key challenge for purification. While advanced chromatographic techniques exist, no high‐throughput, broadly applicable alternative has emerged that aligns with the capabilities of automated synthesis. Here, a reusable microplate‐based assay enabling ultra‐high‐throughput, parallel separation of protonated amines‐including alkyl‐, aryl‐, and aralkylamines‐at submicromolar levels is reported. The method exploits a covalently immobilized tris(pyridino)‐crown ether selector, which forms reversible host–guest complexes by H ‐bonds, which differ with the degree of N ‐substitution. This supramolecular recognition strategy eliminates the need for compound‐specific method development, derivatization, or preparative‐scale quantities. In addition, the present article introduces a generally applicable surface‐functionalization protocol for customizing standard commercial microplates into molecular recognition platforms. The present approach resolves key limitations of current separation technologies‐such as high energy use, low integration with liquid‐handling systems, inevitable sample dilution, and time‐intensive workflows‐offering a transformative tool for rapid and efficient purification directly compatible with modern synthesis pipelines.

9-Substituted-4,5-bifunctionalized acridines are common subunits of numerous drugs and fluorescent dyes, thus studies were carried out on a series of their potential precursors from the aspect of preparation, reactivity, chemical stability and potential applications. The syntheses of the new 9-fluoro-, 9-triflate and 9-lithiated derivatives of 4,5-dimethoxyacridine were reported. All the new intermediates supplemented with the recently synthetized 9-haloacridine analogues were compared and their applicability was discussed. The reactivity of the studied acridino-precursors was tested by using them as starting materials in Suzuki-Miyaura and Kharasch type cross-couplings as well as in Li-organic reactions.

Because of environmental impact, there is a great need for chemosensors, especially for toxic heavy metals such as lead. The conventional instrumental analytical techniques rarely provide an available real-time sensing platform, thus the development of highly selective and stable synthetic chemosensor molecules is of great importance. Acridono-18-crown-6 ethers have such properties, and much research has proven their outstanding applicability in various supramolecular devices. In this present work, we aimed to enable their covalent immobilization capability by synthesizing functionalized derivatives while preserving the favored molecular recognition ability. Several new macrocycle analogues were synthesized, while synthetization difficulties and design aspects were also dealt with. The selectivity of the macrocycle analogues was studied using UV–Vis spectroscopy and compared with that of the parent compounds. The ultimate crown ether derivative showed high Pb2+-selectivity, reversibility (decomplexation by extraction with water) and stability.

Zn2+ has a crucial role both in biology and the environment, while Pb2+ presents serious hazards in the same areas due to its toxicity, and the need for their analysis often exceeds available instrumental capacity. We report, herein, a new high-throughput optochemical screening method for Zn2+ and Pb2+ in various solutions. Moreover, we also introduced a new and generalizable three-step-microplate-modification technique, including plasma treating, linker-docking and photocatalytic copolymerization. The surface of a commercially available 96-well-cycloolefin-microplate was treated with atmospheric plasma, and then, the bottoms of the wells were covered by covalently attaching a methacrylate-containing linker-monolayer. Finally, the preactivated microplate wells were covalently functionalized by immobilizing bis(acridino)-crown ether-type sensor molecules, via photocatalytic copolymerization, to a polymethacrylate backbone. This sensing tool can be used in all microplate readers, is compatible with liquid handling platforms and provides an unprecedently fast monitoring (>1000 samples/hour, extrapolated from the time required for 96 measurements) of dissolved Zn2+ and Pb2+ among recent alternatives above the detection limits of 8.0 × 10−9 and 3.0 × 10−8 mol/L, respectively, while requiring a sample volume of only 20 µL.

Oligoamines in cellular metabolism carry extremely diverse biological functions (i.e., regulating Ca2+-influx, neuronal nitric oxide synthase, membrane potential, Na+, K+-ATPase activity in synaptosomes, etc.). Furthermore, they also act as longevity agents and have a determinative role in autophagy, cell growth, proliferation, and death, while oligoamines dysregulation is a key in a variety of cancers. However, many of their mechanisms of actions have just begun to be understood. In addition to the numerous biosensing methods, only a very few simple small molecule-based tests are available for their selective but reversible tracking or fluorescent labeling. Motivated by this, we present herein a new fluorescent bis(acridino)-crown ether as a sensor molecule for biogenic oligoamines. The sensor molecule can selectively distinguish oligoamines from aliphatic mono- and diamino-analogues, while showing a reversible 1:2 (host:guest) complexation with a stepwise binding process accompanied by a turn-on fluorescence response. Both computational simulations on molecular docking and regression methods on titration experiments were carried out to reveal the oligoamine-recognition properties of the sensor molecule. The new fluorescent chemosensor molecule has a high potential for molecular-level functional studies on the oligoamine systems in cell processes (cellular uptake, transport, progression in cancers, etc.).

Although atmospheric plasma treatment is an industrially widespread, scalable, and environmentally friendly method, it has been generally used for surface modification, decontamination, or sterilization. In this paper, a novel, sustainable, green, and ultrafast oxidation method is described for aldehydes on a preparative thin-layer chromatographic plate as a solid support. The plasma treatment has proven to be suitable for producing the corresponding carboxylic acids by using only air as a reactant source under mild reaction conditions, while the isolation of the products is also directly integrated into the oxidation process. Extensibility to other reaction types is not explored yet, but we are sure that this novel synthesis conception carries a lot of possibilities.

This study aims to introduce a fluorescence-based chemosensing method for Zn2+ in aqueous suspensions and untreated surface waters, conditions which generally hinder the application of conventional optochemical sensing platforms. A macrocyclic fluoroionophore was covalently bonded to a silica-coated magnetic nanoparticle and applied according to a predetermined protocol for analyzing trace amounts of Zn2+ under rarely investigated conditions. Utilizing the reversible complexation of the immobilized fluoroionophore, rapid regeneration was carried out via simple acidification after the magnetic-assisted solid-phase extraction of the particles. Forming inclusion complexes with Zn2+ with the receptor units of the particles leads to a significant enhancement in fluorescence intensity at 370 nm, above the detection limit of 5 ppb, with a dynamic linear range of quantification of 15–3000 ppb in a pH range of 5.5–7.5. Practical applicability was confirmed by analyzing untreated river water and an aqueous suspension of pumpkin seed flour as real and relevant heterogeneous multicomponent samples of predetermined sample composition and natural Zn2+ content. Our practical approach aims to broaden the applicability range of optochemical sensing platforms for Zn2+.

We present here a critical overview on the effects of the second heterocyclic subunit in a bisacridino-crown ether by the discussion of its role in modulating optochemical behavior and preference in molecular recognition. The preparation of a new bisacridono-crown ether is presented including synthetic difficulties, and its fluorescence properties and selectivity in formation of inclusion complexes with various cations are evaluated in the light of reported analogues.

We present here a critical overview on the effects of the second heterocyclic subunit in a bisacridino-crown ether by the discussion of its role in modulating optochemical behavior and preference in molecular recognition. The preparation of a new bisacridono-crown ether is presented including synthetic difficulties, and its fluorescence properties and selectivity in formation of inclusion complexes with various cations are evaluated in the light of reported analogues.

Palladium-catalyzed hydroaminocarbonylation reactions of olefins using aliphatic amines were performed under carbon monoxide atmosphere. Despite the strong basicity of the applied nucleophiles, the targeted amides were successfully synthesized in the absence of acidic additives. Styrene, oct-1-ene and isoprene were transformed to the corresponding amide isomers in moderate to good isolated yields under optimized reaction conditions. Various aliphatic amines were used as N-nucleophiles. The effect of chiral diphosphines on product distribution, that is, on chemo-, regio- and enantioselectivities was also studied. Plausible explanation was given for the additive-free hydroaminocarbonylation reaction.

Dry-column vacuum chromatographic technique is introduced for remediation of wastewater for the first time. A previously prepared chemically modified silica gel containing covalently immobilized Hg2+-selective acridino-crown ether selector molecules was used as an adsorbent. Removal of Hg2+ from highly contaminated river water was carried out to study practical applicability. Adsorption capacity, preconcentration factor, pH-sensitivity and selectivity in separation were determined. The adsorbent proved to be outstanding in selectivity, only Ag+ and Cu2+ interfered among 29 cations, was inert toward organic contaminants, exhibited regenerability and pH-independency between 3.0 ≤ pH ≤ 7.0. The proposed method showed a moderate efficiency in both adsorption (32 mg Hg2+ / 1 g adsorbent) and preconcentration (preconcentration factor of 100). A maximum 10 L of wastewater / 1 g adsorbent ratio is recommended as an upper limit for applicability. The described method showed a unique robustness and simplicity compared to conventional ion-chromatographic methods and an improved selectivity over physical interaction- or simple functional group-based adsorptions.

The reported optical resolution method was designed to support high-throughput enantioseparation of molecular building blocks obtained by automated small-scale synthetic methods. Lipophilic esters of common resolving agents were prepared and used as liquid membranes on the indifferent polymer surface of a microtiter assay. Chiral model compounds were enriched in one of the enantiomers starting from the aqueous solutions of their racemic mixture. Enantiodiscrimination was provided by forming diastereomeric coordination complexes of lipophilic enantiopure esters with the enantiomers of the chiral building blocks inside the liquid membranes. This enantiomeric recognition resulted in a greater distribution ratio of the preferred isomer in the membrane phase, thus the process enables a simultaneous enantioenrichment of the solutions outside the membrane. This paper reports a novel microplate-integrated stereoselective membrane enrichment technique satisfying the need for automatable enantioseparation on a subpreparative scale.

A new phosphine-type potential secondary stabilizer was synthesized successfully with large natural raw material content. The stabilizer is a waxy white powder with a relatively low melting temperature. Both the thermal and the storage stability of the stabilizer are sufficient for practical use. The new stabilizer was introduced into a Phillips-type high-density polyethylene, and its stabilizing efficiency was determined by multiple extrusions. Commercial phosphite and phosphonite stabilizers were used as references. The additive packages contained a primary antioxidant and a phosphorus compound, both added at 1000 ppm. The chemical structure of the polymer, viscosity, color, and residual stability were determined after each extrusion. The comparison of the stabilizing efficiency of the three secondary antioxidants showed that the phosphine stabilizer is at least as efficient as the phosphorous secondary stabilizers available in the market. The new stabilizer proved to be the most efficient in melt stabilization and in preventing discoloration; the residual stability of the polymer was similar in the presence of all three secondary antioxidants. This feasibility study proved that the new compound could be used as a potential stabilizer in practice.