Jaime Llanos

This article focuses on the synthesis and characterization of an amorphous carbon derived from spent coffee grounds converted into a porous amorphous carbon (Cp₁) by carbonization up to 900 °C and subsequently combined with aluminum via mechanochemical treatment to obtain the composite Al@Cp₁. Powder X-Ray diffraction, Raman spectroscopy, and X-Ray photoelectron spectroscopy indicate turbostratic carbon domains (ID/IG ≈ 1.04) and an Al–O/Al–OH surface layer (Al₂O₃/Al(OH)₃) with a minor metallic Al contribution. Electrochemical performance in Li half-cells was evaluated by cyclic voltammetry, galvanostatic cycling, rate capability tests, and electrochemical impedance spectroscopy. At 0.02 A g⁻¹, Al@Cp₁ delivers 212.1 mAh g⁻¹, compared with 83.0 mAh g⁻¹ for Cp₁, with an initial coulombic efficiency of ~44%. Across increasing current densities, Al@Cp₁ retains higher reversible capacities than Cp₁ and shows stable cycling over extended tests (>160 cycles). Impedance analysis indicates a reduced interfacial/charge transfer resistance after electrode conditioning, consistent with interfacial stabilization by the Al-containing surface layer. These results demonstrate a simple, scalable route to upgrade coffee waste carbon into a higher-performance lithium-ion battery anode through mechanochemical interfacial engineering.

The porous structure of metal-organic framework UiO-66 present a suitable scaffold to design drug delivery devices that improve the administration of drugs with low solubility and low absorption such the calcium-channel-blockers.

Cross-aldol condensation reaction study using a family of UiO-66 MOFs between benzaldehyde and acetone to produce benzalacetone.

MOF-808-SO₄-M (M = Zr(iv), Hf(iv)) is obtained by post-synthetic modification (PSM) of MOF-808-M. The introduction of superacidity significantly improves its catalytic activity in the acetalization of benzaldehyde.

This article discloses the synthesis of four new positional isomeric zwitterionic ligands exhibiting semi-flexible and flexible characteristics—n-pyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-PTCA), and n-methylpyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-MPTCA; where n = 3, 4)—which were derived from an aqueous solution of the corresponding sodium salts in an acidic medium (HCl). These compounds are successfully synthesized and characterized with FT-IR and multinuclear NMR spectroscopy; likewise, proper single crystals are obtained for each compound. All compounds adopt zwitterionic forms in the solid state, which are stabilized via intermolecular proton transfer processes involving HCl and solvent molecules. A single-crystal X-ray analysis revealed how positional isomerism and molecular flexibility influence the supramolecular topology. Specifically, 3-PTCA and 4-PTCA exhibit isomorphic hydrogen bond networks, while 3-MPTCA and 4-MPTCA display distinct packing motifs, attributed to the presence of a methylene spacer between the pyridinium and triazole rings. The Hirshfeld surface analysis quantitatively confirmed the dominance of O···H/H···O and N···H/H···N interactions in the solid-state architecture. These strong hydrogen-bonding networks are indicative of the potential proton-conductive behavior in the crystalline state, positioning these compounds as promising candidates for applications in proton-conducting materials. The structural insights gained underscore the pivotal role of molecular topology in tailoring crystal packing, with implications for the rational design of zwitterionic ligands in functional materials, including MOFs and coordination polymers. The calculated HOMO-LUMO energy gaps reveal a significant electronic variability among the ligands, influenced primarily by the positional isomerism and structural flexibility introduced by the methylene spacer.

The Atacama Desert's extreme UV radiation impacts photovoltaic devices, reducing silicon solar cell efficiency through overheating and photodegradation. To address this, we integrated a europium complex derived from 1-(diphenylphosphoryl)-3-isoquinolinecarboxylic acid into a polyvinyl butyral (PVB) matrix, forming a luminescent down-shifting layer (LDSL) that converts UV radiation into visible light. This LDSL improves light harvesting and mitigates UV-induced degradation. After LDSL application, photovoltaic analysis of a c-Si cell showed significant enhancements: short-circuit current density (J_sc) increased from 28.82 to 34.69 mA cm⁻², open-circuit voltage (V_oc) rose from 630.6 to 635.7 mV, and the fill factor (FF) remained stable. Incident photon-to-current efficiency (IPCE) curves indicated better performance, particularly in the UVA range, with overall cell efficiency improving from 14.10% to 16.62% at higher Eu complex concentrations. Electrochemical impedance spectroscopy (EIS) revealed that the Eu complex improved charge transfer, reducing recombination losses. This approach demonstrates significant potential for enhancing solar cell performance in high-irradiance environments like the Atacama Desert.

Two new Cu(II) (CP1) and Co(II) (CP2) coordination polymers (CPs) with the triazole ligand 5-methyl-1-(pyridin-4-yl-methyl)-1H-1,2,3-triazole-4-carboxylate (L1) have been synthesized and structurally characterized by SCXRD (Single Crystal X-Ray Difraccion), PXRD (Power X-Ray Difracction), FT-IR (Fourier Transform Infrared), TG (Theermo Gravimetric), and electrochemical techniques. Both CPs were obtained at the water/n-butanol interface by reacting nitrate salts of each metal with the NaL1 ligand. SCXRD analysis revealed that CP1 (Coordination Polymer 1) and CP2 (Coordination Polymer 2) crystallize in the monoclinic space groups C2/c (No. 15) and P2₁/n (No. 14), respectively, forming 1D zigzag chain structures, which further lead to a 2D supramolecular network through O-H⋯O and C-H⋯O hydrogen bond interactions, respectively. In CP1, the supramolecular structure is assembled by hydrogen bonds involving water molecules. In contrast, CP2 forms its supramolecular network mainly through hydrogen bonds between adjacent triazole ligand molecules. Hirshfeld surface analysis revealed that the most significant contributions to the crystal packing come from H⋯O/O⋯H, H⋯H, H⋯N/N⋯H, and H⋯C/C⋯H interactions. In addition, FT-IR provided information on the functional groups involved in the coordination, while the decomposition patterns of both CPs were evaluated by TGA. Electrochemical studies conducted in a saline environment showed that CP1 exhibits superior hydrogen evolution reaction (HER) kinetics compared to CP2, as evidenced by a higher exchange current density and a lower Tafel slope. Density functional theory calculations and experimental bandgap measurements provided a deeper understanding of the electronic properties influencing the electrochemical behavior. The results highlight the potential of CP1 as an efficient catalyst for HER under saline conditions.

MOF-808-M with M = Zr( iv ), Hf( iv ) and Ce( iv ) catalyzes the acetalization of benzaldehyde with methanol.

The context of global economic instability and armed conflicts has caused fossil fuels to reach unprecedented levels. In this sense, Concentrating Solar Power (CSP) technology has proven to be an excellent option to diversify the energy matrix dependent on fossil fuels, especially in places where there is a good quality solar resource, such as desert areas. These good qualities can be overshadowed by local phenomena such as soiling that can affect the viability of a project. In this paper, the effect of soiling on CSP mirrors installed in a cold desert climate in the Atacama Desert, Chile, is presented. During the 202 days (continuous) of outdoor exposure, atmospheric parameters such as humidity and temperature, as well as reflectance were evaluated daily. At the end of the experiment, the chemical composition of the material deposited on the mirror surface was analyzed by scanning electron microscopy (SEM) and elemental analysis (EDX). The characterization of the material detected the presence of Gypsum (soluble salt), which was shown to have the ability to cement the deposited material. The atmospheric parameters showed that the relative humidity at the site can exceed 60%, sufficient values to solubilize the Gypsum, producing the cementation process. The reflectance values showed that the effect of the cemented material, for 202 days of exposure, can reach a 47% loss of its reflective capacity. This means that the longer the exposure time, the greater the effect of the cementation and the more energy will be needed to clean the mirrors.