In this report a short and efficient synthesis of the dibenz[b,f]oxepin framework through intramolecular S_NAr and McMurry reactions is described. The diaryl ethers required for the McMurry reaction have been obtained in good yields under microwave-assisted conditions of the reaction of salicylaldehydes with fluorobenzaldehydes without catalysts. Application of an intramolecular McMurry reaction to the synthesized diarylethers using TiCl₄/Zn in THF gave the target dibenzo[b,f]oxepin system in 53%–55% yields.

One of the most urgent threats to public health worldwide is the ongoing rise of multidrug-resistant (MDR) bacterial strains. Among the most critical pathogens are MDR-Klebsiella pneumoniae strains. The lack of new antibiotics has led to an increased need for non-antibiotic antimicrobial therapies. Photodynamic therapy (PDT) has become increasingly significant in treating MDR bacteria. PDT uses photosensitizer compounds (PS) that generate reactive oxygen species (ROS) when activated by light. These ROS produce localized oxidative stress, damaging the bacterial envelope. A downside of PDT is the limited bioavailability of PSs in vivo, which can be enhanced by conjugating them with carriers like nanoparticles (NPs). Zinc nanoparticles possess antibacterial properties, decreasing the adherence and viability of microorganisms on surfaces. The additive or synergistic effect of the combined NP-PS could improve phototherapeutic action. Therefore, this study evaluated the effectiveness of the copper(I)-based PS CuC1 compound in combination with Zinc Oxide NP, ZnONP, to inhibit the growth of both MDR and sensitive K. pneumoniae strains. The reduction in bacterial viability after exposure to a PS/NP mixture activated by 61.2 J/cm² of blue light photodynamic treatment was assessed. The optimal PS/NP ratio was determined at 2 µg/mL of CuC1 combined with 64 µg/mL of ZnONP as the minimum effective concentration (MEC). The bacterial gene response aligned with a mechanism of photooxidative stress induced by the treatment, which damages the bacterial cell envelope. Additionally, we found that the PS/NP mixture is not harmful to mammalian cells, such as Hep-G2 and HEK-293. In conclusion, the CuC1/ZnONP combination could effectively aid in enhancing the antimicrobial treatment of infections caused by MDR bacteria.

A series of four novel heteroleptic Cu(I) complexes, bearing bis(1H-indazol-1-yl)methane analogues as N,N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N,N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH₂Cl₂ at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1H-indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.