Alan Raul Cabrera

Four at one blow: organophotoredox-catalyzed multicomponent reaction, achieving overall the 1,2-aminoalkylation of activated alkenes.

Background and Purpose: The rise of multidrug‐resistant (MDR) bacteria poses a significant threat to global health. MDR Klebsiella pneumoniae is of particular concern because of its increasing antibiotic resistance. With limited therapeutic options, antimicrobial photodynamic therapy (aPDT), which employs light‐activated photosensitizers to produce reactive oxygen species (ROS), represents a promising alternative. Experimental Approach: We assessed the antimicrobial activity of two ruthenium‐based photosensitisers, PSRu‐379 and PSRu‐381, against both susceptible and MDR K. pneumoniae strains and explored their mode of action. Bacterial survival was measured after activation with 61.2 J·cm ⁻² of blue light. ROS production was analysed using fluorescent probes; transcriptional responses were examined by RT‐qPCR and RNA sequencing; cytotoxicity was tested in human cell lines; and interactions with cefotaxime were evaluated using fractional inhibitory concentration (FIC) analysis. Key Results: The minimum effective concentration was 4 μg·ml ⁻¹ for the susceptible strain and 8 μg·ml ⁻¹ for MDR strains. ROS analysis indicated predominant singlet oxygen generation, with minimal contribution from hydrogen peroxide, supporting a predominantly Type II photodynamic mechanism. Transcriptomic analysis revealed upregulation of sulphur metabolism and oxidative stress response pathways, along with downregulation of aminoacid biosynthesis, capsule formation and metal ion transport. The photosensitisers exhibited synergistic interactions with cefotaxime, reducing MIC values and yielding an FIC index of 0.08. Low cytotoxicity was observed in human cell lines under the tested conditions. Conclusions and Implications: Ruthenium‐based photosensitisers appear to act predominantly through singlet oxygen‐mediated oxidative stress, enhancing cefotaxime efficacy while exhibiting low cytotoxicity, and therefore represent promising adjunct therapies against MDR K. pneumoniae .

Three new heteroleptic copper(I) complexes of the form [Cu(N,N)(XantPhos)]PF₆ were synthesized and characterized, where N,N refers to phenyl-substituted imidazo[4,5-f][1,10]phenanthroline. All complexes were obtained as yellow powders in yields ranging 82–95% and were fully characterized by NMR spectroscopy, FT-IR, and mass spectrometry. The complexes were also redox-optically characterized. Their absorption profiles display a lower-energy metal-to-ligand charge-transfer (MLCT) band at approximately 412 nm. In solution, weak dual emission is observed, combining ligand-centered and MLCT contributions, with oxygen-dependent quenching supporting the presence of triplet character in the latter. Temperature- and solvent-dependent studies reveal thermally coupled emissive states, in which a relaxed ³MLCT state dominates at low temperatures. In the solid state, intense orange-to-red emission arises from restricted molecular motion and stabilized ³MLCT states, with C3 showing the highest efficiency. Additionally, aggregation-induced emission (AIE) is observed in solvent mixtures. These results suggest that remote substitution can influence the excited-state dynamics and aggregation-driven emission in Cu(I) complexes.

In this study, we report the synthesis and characterization of three Cu(I) complexes bearing functionalized dipyridylamine ligands and DPEphos. Structural analysis confirms a distorted tetrahedral coordination environment around the metal center. Photophysical studies in DMSO show similar absorption profiles (λ_abs ≈ 341–343 nm) with ligand-centered and MLCT transitions, while emission spans the visible region (λ_emi = 410–483 nm) and is strongly influenced by ligand substitution, with the CF₃ derivative displaying a marked red shift. Emission is insensitive to oxygen and exhibits short lifetimes (τ ≈ 14.9–15.3 ns), suggesting short-lived ¹MLCT excited states. Biological evaluation in A375 melanoma cells reveals that all complexes exhibit low-micromolar cytotoxicity under dark conditions (IC₅₀ = 3.33–4.92 μM). Notably, only the CF₃-substituted complex shows a significant light-induced enhancement of activity upon irradiation at 390 nm (IC₅₀ = 1.18 μM), indicating photoactivation.

We report the electroluminescent properties of a well-known Cu(I) complex based on P∧P-type ligands—specifically bis[2-(diphenylphosphino)phenyl] ether (DPEphos)—and N∧N-type ligands, namely, 2,9-dimethyl-1,10-phenanthroline (dmphen), [Cu(dmphen)(DPEphos)]BF4 (Cu1), as the emissive layer, transitioning from a light-emitting electrochemical cell (LEEC) to an organic light-emitting diode (OLED) configuration. No electroluminescence was observed in simple LEEC-type devices. However, the progressive introduction of injection and transport layers, and using 1,3-bis(carbazol-9-yl)benzene (mCP) as a host matrix, enabled efficient emission centered at 530 nm. We achieved effective charge balance and confinement of the recombination zone within the host through systematic optimization of host and transport layer thicknesses. We further investigated the effect of Cu1 doping concentration in mCP (0%–30%) on the device performance and emission color. While 10% doping yielded the highest luminance and efficiency, the emission color was also modulated—from green with bluish hues at low doping to yellowish green at higher levels—demonstrating a straightforward strategy for color tuning using a single Cu(I) complex. Although Cu1 is not the most efficient emitter available, its well-characterized nature and response to device architecture make it an ideal model for understanding structure–function relationships. This study offers valuable insights into layer engineering and compositional tuning, which can facilitate the development of more efficient and color-tunable devices with next-generation Cu(I)-based emitters.

In this work, a new asymmetric amidine–imine ligand, using 1,8-diaminonaphthalene as a rigid platform, was synthesized and characterized, and its ability to form complexes with aluminum(III) was investigated. Several aluminum complexes were synthesized and characterized in solution and in the solid state. The synthesis of a dihalogenated aluminum(III) complex (AlI₂L) using a reducing agent revealed an atypical pathway, which was investigated using Density Functional Theory (DFT). The dimethylated aluminum complex AlMe₂L and the dihalogenated aluminum complex AlI₂L were evaluated as catalysts for the transformation of CO₂ and epoxides into cyclic carbonates in the presence of Bu₄NI as a co-catalyst or in a single-component system, respectively. AlMe₂L/Bu₄NI appeared to be the most efficient system under 1 bar of CO₂ at 90 °C.

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.

We report a Cu(I)-photocatalyzed three-component coupling process to achieve the regioselective, vicinal 1,2-aminosulfonylations of alkenes. The critical aspect of this methodology is found in the utilization of in situ generated photoactive Cu(I)-amine substrate com-plexes, which facilitate the formal oxidation of Cu(I) to Cu(III) in a stepwise manner. In this way, the conceivable two-component chlorosulfonylation of alkenes is effectively suppressed, allowing the combination of styrenes, sulfonyl chlorides, and amines. Further-more, this protocol can be used to facilitate late-stage functionalization, thereby enabling the diversification of biomolecules

In this work we have successfully synthesized five new heteroleptic copper(I) complexes (C1–5), bearing N,N ligands derived from dipyridylamine and S-BINAP as the P,P auxiliary ligand. All complexes were structurally characterized using NMR, FT-IR, and elemental analysis. Furthermore, the molecular structures of C1, C4, and C5 were determined via X-ray diffraction analysis. The photophysical properties of all complexes were assessed using UV-Vis spectroscopy and spectrofluorometric measurements in dichloromethane solution the solid state. All complexes displayed absorption bands at lower energies, attributed to spin-allowed MLCT transitions. In degassed dichloromethane solution at room temperature, all complexes exhibited broad luminescence in the visible spectrum, mainly assigned to MLCT/LLCT phosphorescence, with excited state lifetimes in the μs time regime. Besides, all complexes were assessed as photoredox catalysts in chlorosulfonylation and bromonitromethylation reactions of styrene, showing remarkable performances, thus highlighting the privileged role of the dpa ligand for the design of Earth-abundant metal photocatalysts.