Synthesis of New Glucosylated Porphyrins Bearing an α‐d‐Linkage

This paper presents the synthesis of two new glucosyl tritolylporphyrins in which the carbohydrate moiety is connected through a carboxymethyl glycosidic α‐D‐linkage. These compounds have been obtained by reaction between porphyrins bearing an amino function with a lactone prepared from the available disaccharide isomaltulose. The photocytotoxicity of these compounds against K562 human chronic myelogenous leukemia cells has been evaluated in comparison to Photofrin II.     

Acid–Base‐Controlled Stereoselective Metalation of Overhanging Carboxylic Acid Porphyrins: Consequences for the Formation of Heterobimetallic Complexes

Overhanging carboxylic acid porphyrins have revealed promising ditopic ligands offering a new entry in the field of supramolecular coordination chemistry of porphyrinoids. Notably, the adjunction of a so‐called hanging‐atop (HAT) Pb^II cation to regular Pb^II porphyrin complexes allowed a stereoselective incorporation of the N‐core bound cation, and an allosterically controlled Newton’s cradle‐like motion of the two Pb^II ions also emerged from such bimetallic complexes. In this contribution, we have extended this work to other ligands and metal ions, aiming at understanding the parameters that control the HAT Pb^II coordination. The nature of the N‐core bound metal ion (Zn^II, Cd^II), the influence of the deprotonation state of the overhanging COOH group and the presence of a neutral ligand on the opposite side (exogenous or intramolecular), have been examined through ¹H NMR spectroscopic experiments with the help of radiocrystallographic structures and DFT calculations. Single and bis‐strap ligands have been considered. They all incorporate a COOH group hung over the N‐core on one side. For the bis‐strap ligands, either an ester or an amide group has been introduced on the other side. In the presence of a base, the mononuclear Zn^II or Cd^II complexes incorporate the carbonyl of the overhanging carboxylate as apical ligand, decreasing its availability for the binding of a HAT Pb^II. An allosteric effector (e.g., 4‐dimethylaminopyridine (DMAP), in the case of a single‐strap ligand) or an intramolecular ligand (e.g., an amide group), strong enough to compete with the carbonyl of the hung COO^?, is required to switch the N‐core bound cation to the opposite side with concomitant release of the COO^?, thereby allowing HAT Pb^II complexation. In the absence of a base, Zn^II or Cd^II binds preferentially the carbonyl of the intramolecular ester or amide groups in apical position rather than that of the COOH. This better preorganization, with the overhanging COOH fully available, is responsible for a stronger binding of the HAT Pb^II. Thus, either allosteric or acid–base control is achieved through stereoselective metalation of Zn^II or Cd^II. In the latter case, according to the deprotonation state of the COOH group, the best electron‐donating ligand is located on one or the other side of the porphyrin (COO^?>CONHR>COOR>COOH): the lower affinity of COOH for Zn^II and Cd^II, the higher for a HAT Pb^II. These insights provide new opportunities for the elaboration of innovative bimetallic molecular switches.     

Polymerization of Ethylene by Silica‐Supported Dinuclear CrIII Sites through an Initiation Step Involving C?H Bond Activation

The insertion of an olefin into a preformed metal–carbon bond is a common mechanism for transition‐metal‐catalyzed olefin polymerization. However, in one important industrial catalyst, the Phillips catalyst, a metal–carbon bond is not present in the precatalyst. The Phillips catalyst, CrO₃ dispersed on silica, polymerizes ethylene without an activator. Despite 60 years of intensive research, the active sites and the way the first Cr C bond is formed remain unknown. We synthesized well‐defined dinuclear Cr^II and Cr^III sites on silica. Whereas the Cr^II material was a poor polymerization catalyst, the Cr^III material was active. Poisoning studies showed that about 65 % of the Cr^III sites were active, a far higher proportion than typically observed for the Phillips catalyst. Examination of the spent catalyst and isotope labeling experiments showed the formation of a Si–(μ‐OH)–Cr^III species, consistent with an initiation mechanism involving the heterolytic activation of ethylene at Cr^III O bonds.     

Ru(II)-Catalyzed Hydroarylation of in situ Generated 3,3,3-Trifluoro-1-propyne by C−H Bond Activation: A Facile and Practical Access to β-Trifluoromethylstyrenes

In this study, a practical and straightforward synthesis of β-(E)-trifluoromethylstyrenes by ruthenium-catalyzed C−H bond activation was developed. The readily available and inexpensive 2-bromo-3,3,3-trifluoropropene (BTP), a non-ozone depleting reagent, was used as a reservoir of 3,3,3-trifluoropropyne. With this approach, the monofunctionalization of a panel of heteroarenes was possible in a safe and scalable manner (23 examples, up to 87 % yield). Mechanistic investigations and density functional theory (DFT) calculations were also conducted to get a better understanding of the mechanism of this transformation. These studies suggested that 1) a cyclometallated ruthenium complex enabled the transformation, 2) this complex exhibited high efficiency in this transformation compared to the commercially available [RuCl₂(p-cymene)]₂ and 3) the mechanism proceeded through a bis-cyclometallated ruthenium intermediate for the carboruthenation step.     

Ion chromatograph with three-dimensional printed absorbance detector for indirect ultraviolet absorbance detection of phosphate in effluent and natural waters

An ion chromatography system employing a low-cost three-dimensional printed absorbance detector for indirect ultraviolet detection towards portable phosphate analysis of environmental and industrial waters has been developed. The optical detection cell was fabricated using stereolithography three-dimensional printing of nanocomposite material. Chromatographic analysis and detection of phosphate were carried out using a CS5A 4 × 250 mm analytical column with indirect ultraviolet detection using a 255 nm light-emitting diode. Isocratic elution using a 0.6 mM potassium phthalate eluent combined with 1.44 mM sodium bicarbonate was employed at a flow rate of 0.75 mL/min. A linear calibration range of 0.5 to 30 mg/L PO₄³⁻ applicable to environmental and wastewater analysis was achieved. For retention time and peak area repeatability, relative standard deviation values were 0.68 and 4.09%, respectively. Environmental and wastewater samples were analyzed with the optimized ion chromatography platform and the results were compared to values obtained by an accredited ion chromatograph. For the analysis of environmental samples, relative errors of <14 % were achieved. Recovery analysis was also carried out on both freshwater and wastewater samples and recovery results were within the acceptable range for water analysis using standard ion chromatography methods.     

Solubility and Stability of Some Pharmaceuticals in Natural Deep Eutectic Solvents-Based Formulations

Some medicines are poorly soluble in water. For tube feeding and parenteral administration, liquid formulations are required. The discovery of natural deep eutectic solvents (NADES) opened the way to potential applications for liquid drug formulations. NADES consists of a mixture of two or more simple natural products such as sugars, amino acids, organic acids, choline/betaine, and poly-alcohols in certain molar ratios. A series of NADES with a water content of 0–30% (w/w) was screened for the ability to solubilize (in a stable way) some poorly water-soluble pharmaceuticals at a concentration of 5 mg/mL. The results showed that NADES selectively dissolved the tested drugs. Some mixtures of choline-based NADES, acid-neutral or sugars-based NADES could dissolve chloral hydrate (dissociated in water), ranitidine·HCl (polymorphism), and methylphenidate (water insoluble), at a concentration of up to 250 mg/mL, the highest concentration tested. Whereas a mixture of lactic-acid–propyleneglycol could dissolve spironolacton and trimethoprim at a concentration up to 50 and 100 mg/mL, respectively. The results showed that NADES are promising solvents for formulation of poorly water-soluble medicines for the development of parenteral and tube feeding administration of non-water-soluble medicines. The chemical stability and bioavailability of these drug in NADES needs further studies.     

Synthesis and Antiviral Evaluation of (1,4-Disubstituted-1,2,3-Triazol)-(E)-2-Methyl-but-2-Enyl Nucleoside Phosphonate Prodrugs

A series of hitherto unknown (1,4-disubstituted-1,2,3-triazol)-(E)-2-methyl-but-2-enyl nucleosides phosphonate prodrugs bearing 4-substituted-1,2,3-triazoles were prepared in a straight approach through an olefin acyclic cross metathesis as the key synthetic step. All novel compounds were evaluated for their antiviral activities against HBV, HIV and SARS-CoV-2. Among these molecules, only compound 15j, a hexadecyloxypropyl (HDP)/(isopropyloxycarbonyl-oxymethyl)-ester (POC) prodrug, showed activity against HBV in Huh7 cell cultures with 62% inhibition at 10 μM, without significant cytotoxicity (IC₅₀ = 66.4 μM in HepG2 cells, IC₅₀ = 43.1 μM in HepG2 cells) at 10 μM.     

Simulations of ferrite-dielectric-wire composite negative index materials

We perform extensive finite difference time domain simulations of ferrite based negative index of refraction composites. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both negative and positive index of refraction transmission peaks in the vicinity of the ferrite resonance. Notwithstanding the extreme anisotropy in the index of refraction of the composite, negative refraction is seen at the composite air interface allowing the construction of a focusing concave lens with a magnetically tunable focal length.