Influence of Peripheral Substitution on the Magnetic Behavior of Single‐Ion Magnets Based on Homo‐ and Heteroleptic TbIII Bis(phthalocyaninate)

A series of homoleptic ([Tb^III(Pc)₂]) and heteroleptic ([Tb^III(Pc)(Pc′)]) Tb^III bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert‐butyl or tert‐butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron‐donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N? Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand‐field effect. In particular, heteroleptic [Tb^III(Pc)(Pc′)] complex 4 , which contains one octa(tert‐butylphenoxy)‐substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single‐molecule magnet reported to date.     

Effect of CO2 Preservation Treatments on the Sensory Quality of Pomegranate Juice

Due to the interest in identifying cost-effective techniques that can guarantee the microbiological, nutritional, and sensorial aspects of food products, this study investigates the effect of CO₂ preservation treatment on the sensory quality of pomegranate juice at t₀ and after a conservation period of four weeks at 4 °C (t₂₈). The same initial batch of freshly squeezed non-treated (NT) juice was subjected to non-thermal preservation treatments with supercritical carbon dioxide (CO₂), and with a combination of supercritical carbon dioxide and ultrasound (CO₂-US). As control samples, two other juices were produced from the same NT batch: A juice stabilized with high pressure treatment (HPP) and a juice pasteurized at high temperature (HT), which represent an already established non-thermal preservation technique and the conventional thermal treatment. Projective mapping and check-all-that-apply methodologies were performed to determine the sensory qualitative differences between the juices. The volatile profile of the juices was characterized by gas chromatography-mass spectrometry. The results showed that juices treated with supercritical CO₂ could be differentiated from NT, mainly by the perceived odor and volatile compound concentration, with a depletion of alcohols, esters, ketones, and terpenes and an increase in aldehydes. For example, in relation to the NT juice, limonene decreased by 95% and 90%, 1-hexanol decreased by 9% and 17%, and camphene decreased by 94% and 85% in the CO₂ and CO₂-US treated juices, respectively. Regarding perceived flavor, the CO₂-treated juice was not clearly differentiated from NT. Changes in the volatile profile induced by storage at 4 °C led to perceivable differences in the odor quality of all juices, especially the juice treated with CO₂-US, which underwent a significant depletion of all major volatile compounds during storage. The results suggest that the supercritical CO₂ process conditions need to be optimized to minimize impacts on sensory quality and the volatile profile.     

A new disposable electrochemical sensor on medical adhesive tape

Journal of Solid State Electrochemistry - In this work, the use of medical adhesive tape—as a substrate to develop novel sensor architecture for the detection of hemoglobin (HB) has been...     

Synthesis,characterization, crystal structure and toxicity evaluation of Co (II), Cu (II), Mn (II), Ni (II), Pd (II) and Pt (II) complexes with Schiff base derived from 2-chloro-5-(trifluoromethyl)aniline

A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)imino)methyl) phenol ( HL ¹ ) and its complexes [Co(L¹)₂(H₂O)₂] ( 1 ), [Cu(L¹)₂] ( 2 ), [Mn(L¹)₂(H₂O)₂] ( 3 ), [Ni(L¹)₂(H₂O)₂] ( 4 ), [Pd₂(L¹)₂(OAc)₂·1.16H₂O] ( 5 ), [Pt(L¹)₂] ( 6 ) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, ¹H-NMR, ¹³C-NMR, UV–Vis, mass spectroscopies and X-ray powder diffraction (XRD). The molecular structures of ligand HL ¹ and two complexes ( 2 and 5 ) were confirmed by X-ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square-planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R-3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells.     

Mechanochemical synthesis,characterization and thermal study of new cocrystals of ciprofloxacin with pyrazinoic acid and p-aminobenzoic acid

Journal of Thermal Analysis and Calorimetry - Novel cocrystals of ciprofloxacin with pyrazinoic acid and p-aminobenzoic acid in the 1:1 stoichiometric ratio were obtained by the mechanochemical...     

Octanuclear Ni4Ln4 Coordination Aggregates from Schiff Base Anion Supports and Connecting of Two Ni2Ln2 Cubes: Syntheses,Structures, and Magnetic Properties

A family of 3d–4f aggregates have been reported through guiding the dual coordination modes of ligand anion (HL^?) and in situ generated ancillary bridge driven self‐assembly coordination responses toward two different types of metal ions. Reactions of lanthanide(III) nitrate (Ln=Gd, Tb, Dy, Ho and Yb), nickel(II) acetate and phenol‐based ditopic ligand anion of 2‐[{(2‐hydroxypropyl)imino}methyl]‐6‐methoxyphenol (H₂L) in MeCN‐MeOH (3 : 1) mixture and LiOH provided five new octanuclear Ni‐4f coordination aggregates from two Ni₂Ln₂ cubanes. Single‐crystal X‐ray diffraction analysis reveals that all the members of the family are isostructural, with the central core formed from the coupling of two distorted [Ni₂Ln₂O₄] heterometallic cubanes [Ni₂Ln₂(HL)₂(μ₃‐OH)₂(OH)(OAc)₄]⁺ (Ln=Gd ( 1 ), Tb ( 2 ), Dy ( 3 ), Ho ( 4 ) and Yb ( 5 )). Higher coordination demand of 4f ions induced the coupling of the two cubes by (OH)(OAc)₂ bridges. Variable temperature magnetic study reveals weak coupling between the Ni²⁺ and Ln³⁺ ions. For the Tb ( 2 ) and Dy ( 3 ) analogs, the compounds are SMMs without an applied dc field, whereas the Gd ( 1 ) analogue is not an SMM. The observation revealed thus that the anisotropy of the Ln³⁺ ions is central to display the SMM behavior within this structurally intriguing family of compounds.     

Unexpected Imidazoquinoxalinone Annulation Products in the Photoinitiated Reaction of Substituted‐3‐Methyl‐Quinoxalin‐2‐Ones with N‐Phenylglycine

Photoinduced electron transfer between N ‐phenylglycine (NPG) and electronically excited triplets of 7‐substituted‐3‐methyl‐quinoxalin‐2‐ones in acetonitrile generate the respective ion radical pair, where by decarboxylation the phenyl‐amino‐alkyl radical, PhNHCH₂?, is generated. This radical reacts with the 3‐methyl‐quinoxalin‐2‐ones ground states, leading to the product 2. Other, unexpected, 7‐substituted‐1,2,3,3a‐tetrahydro‐3a‐methyl‐2‐phenylimidazo[1,5‐a]quinoxalin‐4(5H)‐ones, annulation products, 3a–f, were generated; likely by the addition of two PhNHCH₂? radicals, to positions 3 and 4 of the quinoxalin‐2‐ones. The reaction mechanism includes a photoinduced one electron transfer initiation step, propagation steps involving radical intermediates and NPG with radical chain termination steps that lead to the respective products 2a–f and 3a–f and NPG by‐products. The proposed mechanism accounts for the strong dependency found for the initial photoconsumption quantum yields on the electron‐withdrawing power of the substituent. Therefore, photolysis of common reactants widely used such as NPG and substituted quinoxalin‐2‐ones may provide a simple synthetic way to the unusual, unreported tetrahydro‐imidazoquinoxalinones 3a–f.     

Ethyl 2,2-bis(4-methylphenylsulfonamido)acetate to aromatic α-amino acids: stable substrates for catalytic arylation reactions

This paper reports the development of a novel methodology for the catalytic synthesis of aromatic α-amino acids, which involves the addition of aryl-organoboron reagents to α,α-ditosylamino esters derived from ethyl glyoxylate, using transition metal catalysts, like Rh and Pd. A library of α-amino esters (12 with Pd and 8 with Rh), was synthesized with moderate to excellent yields. A highest enantioselectivity of 30% ee was obtained using Hayashi's ligand. This method was applied to the synthesis of phenylglycine.     

99mTc-labeled bombesin analog for breast cancer identification

Bombesin is a tetradecapeptide that binds specifically to gastrin releasing peptide receptors in humans. Several forms of cancer, including lung, prostate, breast, and colon express receptors for bombesin-like peptides. Radiolabeled bombesin analogs with a high affinity for these receptors might therefore be used for scintigraphic imaging of these tumor types. A truncated bombesin derivative (HYNIC-βAla-Bombesin_(7–14)) was radiolabeled with technetium-99m using EDDA and tricine as coligands. In vitro stability was evaluated in presence of plasma and excess of cysteine. The receptor-binding affinity assays was evaluated in MDA-MB-231 cancer cell line. In addition, in vivo biodistribution was performed in nude mice bearing breast tumor. In vitro assay showed a good affinity for the MDA-MB-231 cell line, showing 20.0 % of internalization at 4 h post-administration. ^99mTc-HYNIC-βAla-Bombesin_(7–14) biodistribution revealed a rapid clearance and a significant renal excretion. In addition, tumor uptake was higher than non-excretory organs, such as the spleen, the liver, and muscles. Tumor-to-muscle and tumor-to-blood ratios for ^99mTc-HYNIC-βAla-Bombesin_(7–14) showed high values at 4 h post-injection (5.34 and 4.55, respectively). Furthermore, blocked studies using cold bombesin peptide were performed, which demonstrated an important decrease in tumor uptake, indicating a tumor specificity for ^99mTc-HYNIC-βAla-Bombesin_(7–14). The ^99mTc-HYNIC-βAla-Bombesin_(7–14) displayed suitable radiochemical characteristics, and adequate affinity to breast tumor cells (MDA-MB-231). Therefore, this analog can be considered as a candidate for the identification of bombesin-positive tumors.     

Synthesis of a co-cross-linked nanocomposite hydrogels from poly(methyl vinyl ether-co-maleic acid)-polyethylene glycol and nanofibrillated cellulose

This study demonstrates the preparation of a renewable and biocompatible co-cross-linked nanocomposite hydrogel from poly(methyl vinyl ether-co-maleic acid), poly(ethylene glycol) and nanofibrillated cellulose (NFC). The cross-linking reaction was favored by the formation of ester linkages as evidenced by Fourier transform infrared spectroscopy. The increase in gel fraction content of the treated NFC varied from 22 to 85 % which exhibited an increase in degree of chemical cross-linking to form a rigid network with the addition of varying amount of NFC (20–60 %). This increase in gel rigidity influenced gel swelling, showing relatively reduced water uptake ability above 40 % NFC. Rheological measurements indicated the formation of gels with superior mechanical properties.