This work reports on two thiourea-based receptors with pyridine and amine units including 1-naphthyl (MT1N) and 4-nytrophenyl (MT4N) as signaling units. For both compounds, their affinity and signaling ability toward various anions of different geometry and basicity in DMSO were studied using UV-vis, fluorescence, and ¹H NMR techniques. Anion recognition studies revealed that both MT1N and MT4N have, in general, high affinities toward basic anions. In this regard, a higher acidity of the MT4N receptor was demonstrated. Furthermore, MT4N has a higher affinity for fluoride (log K₁ = 5.98) than for the other anions and can effectively detect it through colorimetric changes that can be monitored by the UV-vis technique. The interaction between receptors and anions mainly involves the hydrogens of the amino and thiourea groups of the former. Complementary single-crystal X-ray diffraction studies and molecular modeling at the DFT level were also performed.

Two bis-urea type receptors were synthesized containing a polyether bridge and two 4-nitrophenyl groups as chromogenic units, R1 and R2. Molecular recognition studies of receptors towards different tetraalkylammonium and alkali metal salts were carried out in DMSO by UV-Vis and ¹H-NMR spectroscopy. The receptors were found to have high affinity for diverse anions and ion-pairs, showing the highest affinities towards the tetramethylammonium and sodium salts. The cation binding ability of the receptors was evidenced by means ¹H NMR, mass spectrometric ESI⁺ studies and the crystal structures of some precursors. Additionally, the molecular modelling at the DFT level of the tetramethylammonium acetate complexes illustrates the potential ion-pair binding ability of the receptors: the anion is recognized through strong hydrogen bonds from the NH─ groups from the two urea sites, while the cation is bound by a combination of cation─π, C-H···O and C-H···π interactions.

A series of N,N′-disubstituted tetrandrine derivatives, comprising both newly synthesized and previously reported compounds, were investigated as a strategy to enhance antibacterial activity. Four derivatives (DIT, DAT, DNT, and DBT) had been previously reported by our group, whereas three new analogues (DQT, DAcT, and DeBT) were synthesized and fully characterized. Antibacterial effects were evaluated by the broth microdilution method against Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa. In contrast to natural tetrandrine, quaternized derivatives exhibited markedly enhanced antibacterial potency, particularly against S. aureus, highlighting DAcT (minimum inhibitory concentration (MIC) = 0.04 μg/mL), DQT (MIC = 0.11 μg/mL), and DNT (MIC = 0.14 μg/mL), with activities comparing favorably to those of reference antibiotics such as ampicillin, chloramphenicol, and ciprofloxacin. Antioxidant activity was also assessed using ABTS•+ and DPPH• assays, with the highest response observed in the ABTS•+ assay for DeBT (63.72% inhibition, IC50 = 21.53 μg/mL), followed by DNT (40.97% inhibition). Cytotoxicity studies of the newly synthesized derivatives against ARPE-19, MCF-7, HeLa, and A549 cell lines revealed low toxicity (IC50 > 50 μg/mL), consistent with previously reported analogues, suggesting a favorable selectivity profile. DNA-binding studies by fluorescence spectroscopy indicated efficient interaction with double-stranded DNA. In addition, molecular modeling and docking studies against relevant bacterial targets provided mechanistic insight and showed good agreement with the experimental antibacterial results. Overall, the combined in vitro and in silico findings identify N,N′-disubstituted tetrandrine derivatives as promising scaffolds for the development of new antibacterial agents.

Understanding the intrinsic Li–H₂ interaction, decoupled from substrate effects, is essential to rationalize the performance of lithium-decorated hydrogen storage materials. To address the current lack of a clean theoretical baseline, we characterized the sequential H₂ adsorption on the gas-phase Li₆ superatomic cluster using high-level density functional theory (DFT), complemented by Energy Decomposition Analysis (EDA), QTAIM, and NICS(0) calculations. Li₆ acts as a structurally rigid platform (RMSD < 0.032 Å) where ligand-induced polarization progressively strengthens its σ-aromaticity (NICS(0) from −2.917 to −13.98 ppm) and increases the HOMO–LUMO gap up to 5.05 eV. EDA identifies the binding as field-activated physisorption, electrostatically dominated (65–67%) and mechanistically distinct from Kubas coordination, as confirmed by QTAIM closed-shell interaction parameters. Negative cooperativity governs an effective loading capacity of n = 2 molecules under cryogenic conditions (T_eq = 143.76 and 114.64 K), while an entropic bottleneck renders higher loading non-spontaneous at all temperatures. These results establish Li₆(H₂)_n as a foundational gas-phase reference, providing a systematic, contamination-free descriptor set for the intrinsic Li–H₂ interaction. This framework is essential for isolating the electronic role of the lithium superatom and unambiguously identifying substrate-induced modulations in supported hydrogen storage materials.

A library of twelve heteroditopic bis-urea and bis-thiourea receptors supported on Merrifield and Wang resins was prepared by solid-phase synthesis. The receptors incorporate dual hydrogen-bond-donor units for anion binding and a polyether spacer that simultaneously functions as a cation-binding site, enabling ion-pair recognition at the solid–liquid interface. Molecular recognition studies were performed using several inorganic and tetraalkylammonium salts, and fluorescence changes were monitored by microplate measurements in DMSO and DMSO/H₂O (95:5, v/v). Univariate and factorial statistical analyses revealed statistically significant fluorescence changes and identified the structural variables governing guest recognition in each medium. Under the conditions examined, several systems exhibited reproducible ion-pair-induced fluorescence responses, highlighting the influence of receptor type and spacer architecture. These findings provide a basis for the rational optimization of supported receptors for sensing and extraction applications.