Gloria Cristina Valencia Uribe

The development of efficient photocatalytic materials for waterborne pathogen inactivation and self-cleaning surfaces in biomedical applications remains a critical challenge due to the rising prevalence of antimicrobial-resistant bacteria. This study systematically investigates the structural, optical, and photocatalytic disinfection properties of graphitic carbon nitride (g-C₃N₄) synthesized at variable temperatures (450–600 °C) and doped with transition metals (Mn, Co, Cu). Through FTIR and UV/Vis spectroscopy, we demonstrate that synthesis temperatures between 450 and 550 °C yield a well-ordered polymeric network with enhanced π-conjugation and charge separation, while 600 °C induces structural degradation. Metal doping with Mn and Co significantly enhances photocatalytic disinfection, achieving complete E. coli inactivation (6-log reduction) within 6 h via optimized reactive oxygen species (ROS) generation. The best material (g-C₃N₄ synthesized at 500 °C and doped with Mn) was integrated into sodium alginate hydrogel surfaces, demonstrating reusable self-cleaning functionality with sustained bactericidal activity (5.9-log CFU/mL reduction after five cycles). This work provides a roadmap for tailoring metal-doped g-C₃N₄ composites for practical antimicrobial applications, emphasizing the interplay between synthesis parameters, ROS dynamics, and real-world performance.

Los contaminantes emergentes constituyen un grupo de sustancias cuya regulación está siendo abordada, debido al incremento de su presencia en cuerpos de agua asociado principalmente a las acciones antropogénicas. Estos compuestos caracterizados como disruptores endocrinos a bajas concentraciones causan daños irreversibles en los ecosistemas y están siendo objeto de estudio especialmente en las últimas dos décadas. Para mitigar su impacto y presencia en los ecosistemas, se han estudiado alternativas para lograr su remoción, basadas en procesos de adsorción, electrocoagulación, filtración por membrana y procesos de oxidación avanzada (AOP). Específicamente el contaminante emergente 4-nonilfenol (4-NF), compuesto perteneciente a la familia de los alquilfenoles, es utilizado como principio activo de tensoactivos no iónicos para uso en detergentes, dispersantes, emulsionantes y solubilizantes, estando presente entre otros, en formulaciones producto de aseo, de plaguicidas y de pinturas, siendo su principal vía de acceso al ambiente a través de aguas residuales. Esta revisión bibliográfica reúne información acerca de algunas propiedades fisicoquímicas del 4-NF, toxicidad, métodos de cuantificación y remoción

Five monomeric complexes of Co(II), Cu(II), Ni(II), Zn(II) and Ag(I) with 6-methoxyquinoline (6-MeOQ) as ligand have been prepared, and their crystal structures have been determined by single X-ray diffractions. The Cu(II), Ni(II) and Zn(II) complexes are formulated as M(6-MeOQ)₂Cl₂, completing MN₂Cl₂ coordination spheres. On the other hand, Co(II) and Ag(I) compounds are ionic with formulae [Ag(6-MeOQ)₂]⁺ NO₃ ⁻ and H(6-MeOQ)⁺[Co(6-MeOQ)Cl₃]⁻ (where H(6-MeOQ)⁺ is the protonated ligand). Hirshfeld surface analysis was employed to study the intermolecular interactions in the crystal lattices and from these studies it was found that π-stacking contacts play an important role. Besides, the complexes have been characterized by FTIR, UV-visible and emission spectroscopies. The singlet oxygen production and fluorescence quantum yields were measured for all the complexes employing steady-state methodologies. Finally, the antibacterial activity of the complexes was screened against both Gram-positive and Gram-negative bacteria.

The already reported monomeric complex Co(SDZ)₂bpy (1) and the new ternary complex Co(SDZ)₂(6MQ)₂ (2) (SDZ = sulfadiazine, bpy = 2,2′‐bipyridine, and 6MQ = 6‐methoxyquinoline) have been synthesized in order to study their magnetic properties. X‐ray diffraction studies indicate that in both compounds the SDZ acts as a bidentate ligand coordinating through the sulfonamide and the pyrimidine N atoms giving rise to a CoN₆ coordination sphere. The complexes have been characterized based on elemental analyses, FTIR, UV/Vis spectroscopy, and thermogravimetric analysis (TGA, only for 2). Compounds 1 and 2 have been characterized magnetically, and they show slow relaxation of the magnetization below 9 and 6 K, respectively.