Tuning the antioxidant property of potential calixdrug calix[4]tyrosol: role of aza and thia linkages

Structural Chemistry - Calix[4]arenes are the most renowned and widely studied calix[n]arenes, which are established to have quite a few biological (e.g., antibacterial, antifungal, antioxidant,...     

Comprehensive Review on Application of FTIR Spectroscopy Coupled with Chemometrics for Authentication Analysis of Fats and Oils in the Food Products

Currently, the authentication analysis of edible fats and oils is an emerging issue not only by producers but also by food industries, regulators, and consumers. The adulteration of high quality and expensive edible fats and oils as well as food products containing fats and oils with lower ones are typically motivated by economic reasons. Some analytical methods have been used for authentication analysis of food products, but some of them are complex in sampling preparation and involving sophisticated instruments. Therefore, simple and reliable methods are proposed and developed for these authentication purposes. This review highlighted the comprehensive reports on the application of infrared spectroscopy combined with chemometrics for authentication of fats and oils. New findings of this review included (1) FTIR spectroscopy combined with chemometrics, which has been used to authenticate fats and oils; (2) due to as fingerprint analytical tools, FTIR spectra have emerged as the most reported analytical techniques applied for authentication analysis of fats and oils; (3) the use of chemometrics as analytical data treatment is a must to extract the information from FTIR spectra to be understandable data. Next, the combination of FTIR spectroscopy with chemometrics must be proposed, developed, and standardized for authentication and assuring the quality of fats and oils.     

KF-alumina-mediated Bargellini reaction

KF-alumina was found to be an efficient base for the synthesis of sterically hindered α-substituted carboxylic acids. A series of Bargellini reactions were performed by using various substituted anilines, phenols, and thiophenols as nucleophiles with ketones in the presence of chloroform and KF-alumina as a base. All the compounds were fully characterized.     

l-Proline as an efficicent catalyst for the multi-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in water

An efficient four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles involving ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes using l-proline (10 mol %) in water under mild reaction condition in excellent yields is established. A comparative study of l-proline with γ-alumina, basic alumina, and KF-alumina was also carried out. The generality and functional tolerance of this convergent and environmentally benign method is demonstrated.     

Ion association and hydration in aqueous solutions of copper(II) sulfate from 5 to 65 degrees C by dielectric spectroscopy

Aqueous solutions of copper(II) sulfate have been studied by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 less, similar nu/GHz < or = 89), concentrations (0.02 < or = m/mol kg(-1) less, similar 1.4), and temperatures (5 < or = t/ degrees C < or = 65). The spectra show clear evidence for the simultaneous existence of double-solvent-separated, solvent-shared, and contact ion pairs at all temperatures, with increasing formation especially of contact ion pairs with increasing temperature. The overall ion association constant corresponding to the equilibrium: Cu2+(aq) + SO4(2-)(aq) right harpoon over left harpoon CuSO4(0)(aq) was found to be in excellent agreement with literature data over the investigated temperature range. However, the precision of the spectra and other difficulties did not allow a thermodynamic analysis of the formation of the individual ion-pair types. Effective hydration numbers derived from the DRS spectra were high but consistent with simulation and diffraction data from the literature. They indicate that both ions influence solvent water molecules beyond the first hydration sphere. The implications of the present findings for previous observations on copper sulfate solutions are briefly discussed.     

A Tetranuclear Propane-1,3-Dithiolate Complex, [Fe2(CO)5{Ph2P(CH2)3}{(µ-SCH2)2CH2}]2, with a Bridging 1,6-Bis(diphenylphosphino)hexane Ligand

The 2:1 molar reaction of [Fe₂(CO)₆{(µ-SCH₂)₂CH₂}] (1) and a bidentate diphosphine ligand, 1,6-bis(diphenylphosphino)hexane (dpph), in the presence of Me₃NO resulted in the isolation of [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(µ-SCH₂)₂CH₂}]₂ (2) as red crystals in 71?% yield. The dpph ligand in compound 2, coordinates two Fe₂S₂ subunits as bridging mode and hence makes a linkage between two [Fe₂(CO)₅{(µ-SCH₂)₂CH₂}] fragments. Each Fe₂S₂ butterfly of the complex consists of two fused Fe(S-C-C-C-S) six-membered rings, one of which attains a chair conformation, and the other is necessarily in a boat conformation. Compound 2 has unequivocally been characterized by elemental analysis, IR, ¹H NMR and ³¹P NMR spectroscopy together with single crystal X-ray diffraction studies. Crystals of 2 are triclinic, space group P-1, a = 9.918(4) Å, b = 10.347(3) Å, c = 14.581(5) Å, α?=?72.239(12)º, β?=?80.342(12)º, γ?=?68.550(14)º and Z = 1.

Graphic Abstract

A novel tetranuclear propane-1,3-dithiolate complex, [Fe₂(CO)₅{Ph₂P(CH₂)₃}{(μ-SCH₂)₂CH₂}]₂ (2), bearing a bridging bis(diphenylphosphino)hexane (dpph) ligand, was synthesized from the Me₃NO aided room temperature displacement of carbonyls from [Fe₂(CO)₆{(μ-SCH₂)₂CH₂}] (1), and structurally characterized.

     

Nickel(II) chloride hexahydrate catalyzed reaction of aromatic aldehydes with 2-mercaptoethanol: formation of supramolecular helical assemblage of the product

Various aromatic aldehydes on reaction with 2-mercaptoethanol provided an unanticipated product, bis(2-hydroxyethyl)dithioacetals (3) as the major product along with the expected product 1,3-oxathiolanes (4) in the presence of 0.05 equiv amount of nickel(II) chloride hexahydrate (NiCl₂·6H₂O) under solvent-free conditions. Products 3c and 3e exhibit an interesting hydrogen-bonded infinite supra-molecular helical structure.     

Cellular integration and vascularisation promoted by a resorbable, particulate-leached, cross-linked poly(ε-caprolactone) scaffold

Flexible, strong scaffolds were created by crosslinking PCL with 1,6‐hexamethylenediisocyanate, using paraffin beads as a porogen. Particulate leaching generated homogeneous scaffolds with interconnected spherical pores of 5–200 µm. Subcutaneous implantation in rats for 3 months resulted in minimal scaffold resorption and a non‐inflammatory regenerative host response, with complete infiltration by alternatively‐activated CD68⁺ macrophages. In addition, scaffolds were populated extensively along microfractures by a stromal matrix, which was highly vascularised and contained a subset of stromal cells that expressed the anti‐inflammatory CD163 antigen. Such microfractures may be an important physical feature for directing stromal integration and vascularisation events.

     

Reaction of selenium dioxide with aromatic ketones in the presence of boron triflouride etherate: a protocol for the synthesis of triarylethanones

An efficient regioselective protocol for the C-C bond formation by the unexpected α,α-diarylation of aromatic ketones with unactivated arenes in the presence of selenium dioxide and boron trifluoride etherate has been developed. The generality and functional tolerance of this protocol is demonstrated by the synthesis of a series of triarylethanones.