Salophen-type Schiff base ligands derived from salicylaldehyde and naphthalene aldehydes were synthesized and coordinated to Ni(II) to obtain three nickel complexes (NiL1–NiL3), which were evaluated as heterogeneous electrocatalysts for the methanol electro-oxidation reaction (MOR) in alkaline media. The ligands and complexes were fully characterized by FT-IR, 1H NMR, EPR, DART-MS, and elemental analysis, confirming tetradentate coordination through imine nitrogen and phenoxide oxygen donors. Electrochemical studies were carried out using carbon paste electrodes modified with 15 wt % of each complex. Cyclic voltammetry revealed that the electrocatalytic activity is mediated by the Ni(II)/Ni(III) redox couple, with Ni(III) oxohydroxide species acting as the active sites for methanol oxidation. Among the evaluated systems, NiL1@CPE showed superior performance at low methanol concentrations, while NiL2@CPE and NiL3@CPE exhibited higher current densities at elevated methanol concentrations. Scan-rate studies indicated that the oxidation process is diffusion-controlled, and a linear response to methanol concentration was observed over a wide concentration range. The results demonstrate that ligand structure and coordination geometry play a crucial role in modulating the electrocatalytic behavior of Ni(II) Schiff base complexes, highlighting their potential as cost-effective molecular catalysts for alkaline methanol oxidation.

The study aimed to verify the possible use of DFT calculation in the prediction of the orientation in electrophilic aromatic substitution. An activated ortho/para orienting substrate, and a deactivated meta orienting substrate, were used in DFT calculations using B3LYP, B3PW91, BPV86, CAM-B3LP, HCTH, HSEH1PBE, LSDA, MPW1PW91, PBEPBE, TPSSTPSS, and WB97XD functionals. The results showed that the reactivity of anisole can be adequately described considering charge control in reaction performed in hard conditions (nitration), while frontier orbital control can play a role in reactions performed in softer conditions (chlorination). Nitration of benzaldehyde can be rationalized through Hirshfeld charges analysis. Neither the frontier orbital nor Mulliken charges approach adequately account for behavior observed in chlorination of benzaldehyde. The effect of different basis sets was tested performing calculations with B3LYP functional and aug-cc-pVDZ, 6-311G+(d,p), aug-cc-pVQZ, DGTZVP, and LanL2DZ basis sets. For anisole, all basis sets provided a HOMO electron density distribution consistent with experimental reactivity; Hirshfeld charges analysis consistently reproduced the observed reactivity of anisole across all tested basis sets. All the basis sets were able to explain the observed reactivity of benzaldehyde in hard experimental condition, while they failed to give a correct description when a softer reagent was used.

In the present work, we describe the synthesis of a new heterocyclic derivative, 2-(naphthalen-1-yl)-2,3,5,6-tetrahydro-1H-isoquinolino[8,1,2-hij]quinazoline 1, using the reaction between the aminal 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane 2 (TATD) and 1-naphthylamine 3 as the first scaffold of a four-step linear synthetic route. In the first step, a condensation catalyzed by acetic acid in 96% ethanol was carried out, leading to the formation of the intermediate 3-(naphthalen-1-yl)-1,2,3,4-tetrahydrobenzo[h]quinazoline 4. Subsequently, this intermediate was acylated with 2-chloroacetyl chloride in the presence of triethylamine and under an inert atmosphere, obtaining the compound 2-chloro-1-(3-(naphthalen-1-yl)-3,4-dihydrobenzo[h]quinazolin-1(2H)-yl)ethan-1-one 5. In the third step, an intramolecular Friedel–Crafts cyclization was carried out using aluminum trichloride as a catalyst, yielding 2-(naphthalen-1-yl)-1,2,3,6-tetrahydro-5H-isoquinolino[8,1,2-hij]quinazolin-5-one 6. Finally, the reduction of this lactam with phosphorus pentachloride and sodium borohydride under anhydrous conditions led to the further closure of the polycyclic system, yielding the final product 1. The proposed route demonstrates the feasibility of using TATD 2 as a versatile precursor for constructing condensed heterocyclic systems of structural interest and potential relevance in advanced organic synthesis.

2-Aryl-2-(3-indolyl)acetohydroxamic acids have emerged as promising antitumor agents; however, their poor pharmacokinetic profile remains a significant drawback. To address this limitation, we have synthesized a homolog of such acids—specifically 2-aryl-2-(3-indolyl)propionic acid (IC50 > 100 mM (U87)), along with several other derivatives: ethyl ester (IC50 > 100 mM (U87)), hydroxamate (IC50 21.2 ± 1.0 mM (U87)) and hydrazide (IC50 > 100 mM (U87)). The cytotoxicity of these compounds against glioblastoma cell lines was evaluated and compared to that of the parent acetohydroxamic acid derivatives.

This study aims to investigate the relative stability of the diaminodinitroethylene isomers (cis, trans, and gem). To achieve this goal, calculations at several levels of theory were carried out. The B3LYP, PBE0, and CAM-B3LYP functionals, based on density functional theory (DFT), were used. G4 and MP2 calculations were also executed. All calculation methods predicted that the gem isomer is the most stable, while the cis isomer is the least stable. The energy order obtained for the isomers studied was rationalized by analysis of the detected intramolecular hydrogen bonding, electron delocalization, charge distribution, and changes in atomic energies in the structures studied. The origins of the superior stability of the gem isomer are demonstrated and justified.

1,3-Dipolar cycloaddition reactions of nitrile imines are a powerful tool for the construction of spirocyclic frameworks, yet controlling chemoselectivity remains challenging when dipolarophiles contain multiple reactive sites. In this study, we investigated the cycloaddition of nitrile imines with 5-arylmethylene-2-methylthiohydantoins, which possess both exocyclic C=C and endocyclic C=N bonds. Nitrile imines were generated from hydrazonoyl chlorides under basic conditions and reacted with the thiohydantoin substrates under optimized reaction conditions. The cycloaddition proceeded smoothly, affording spiro-fused thiohydantoin–pyrazoline derivatives. In all cases, the reaction occurred selectively at the exocyclic C=C bond, while the C=N bond remained unreactive even in the presence of excess dipole. This chemoselectivity is attributed to the greater steric accessibility of the exocyclic double bond. These results clarify key factors governing nitrile imine chemoselectivity and provide a reliable approach to structurally complex spirocyclic thiohydantoin derivatives.

Commercially available resorufin was shown to function as an organic photocatalyst for visible-light-induced aqueous radical polymerization under low-irradiance illumination. Polymers with narrow molecular weight distributions and high monomer conversions were successfully synthesized from acrylate and acrylamide monomers. The photopolymerization catalyzed by resorufin was consistent with a reductive quenching mechanism. Good temporal control of the reaction was achieved by toggling visible light irradiation.

In this study, the singlet oxygen photosensitization potential of three natural African plant extracts was investigated using the photooxygenation of α-terpinene (1). Utilizing visible light, the Carpolobia lutea extract achieved high conversions towards the anthelmintic ascaridole (2) of >60% after 90 min of irradiation, while the extracts of Hibiscus sabdariffa and Justicia secunda failed to induce significant photoreactivity. Quenching using 1,4-diazabicyclo[2.2.2]octane (DABCO) confirmed a singlet oxygen pathway for irradiation with the C. lutea extract. Further separation of the C. lutea extract and subsequent photooxygenation screening established several active fractions for ascaridole generation. Advanced HPLC–MS analyses of these active fractions revealed several photosensitizing constituents. These findings establish C. lutea extract as a sustainable and effective photosensitiser with comparable performance to commercial dyes.

A conjugated helical cage, comprising two 1,3,5-tris(phenylethynyl)benzene units connected by diyne linkers, was successfully synthesized. X-ray crystallography revealed helical molecular structures with large twisted angles and a 1:1 mixture of P- and M-enantiomers. Variable-temperature-NMR measurement indicated the racemization process between the enantiomers occurs rapidly on the NMR timescale. The rapid interconversion is attributed to the flexible diyne linkages, even though they were believed to be rigid.

Our previous study demonstrated that thiophene-substituted synthetic curcumin analogs possessed better antibacterial activity and stability than natural curcumin, demethoxycurcumin, or bisdemethoxycurcumin in antibacterial photodynamic therapy (aPDT). In addition, the activity of the furan-substituted analogs was weaker than that of the thiophene-substituted compounds. As oxygen, sulfur, and selenium belong to the same group in the periodic table, the antibacterial and anticancer activities of these three different elemental analogs were compared and investigated. The thiophene-substituted analog (compound 3) exhibited the most potent antibacterial activity in aPDT experiments. However, the furan-substituted analog (compound 1) exhibited the most potent anticancer activity. These results indicate that the differences in atomic radii or energy levels in these compounds produce different cell-attack results on generated free radicals. Ruthenium(II) complexes have a good reputation for use in PDT for cancer treatment. Our results show that complexation of ruthenium(II) with thiophene-substituted curcumin analogs does not enhance their antibacterial or anticancer activity.