On the weak O-H···halogen hydrogen bond: a rotational study of CH3CHClF···H2O

We measured the molecular beam Fourier transform microwave spectra of six isotopologues of the 1?:?1 adduct of CH(3)CHClF with water. Water prefers to form an O-H···F rather than an O-H···Cl hydrogen bond. This is just the contrary of what was observed in the chlorofluoromethane-water adduct, where an O-H···Cl link was formed (W. Caminati, S. Melandri, A. Maris and P. Ottaviani, Angew. Chem., Int. Ed., 2006, 45, 2438). The water molecule is linked with an O-H···F bridge to the fluorine atom, with r(F···H(w)) = 2.14 ?, and with two C-H···O contacts to the alkyl hydrogens with r(C(1)-H(1)···O(w)) = 2.75 ? and r(C(2)-H(2)···O(w)) = 2.84 ?, respectively. Besides the rotational constants, the quadrupole coupling constants of the chlorine atom have been determined. In addition, information on the internal dynamics has been obtained.     

Transfer Hydrogenation of Ketones Catalyzed by Surface‐Active Ruthenium and Rhodium Complexes in Water

An improved, high‐yield, one‐pot synthetic procedure for water‐soluble ligands functionalized with trialkyl ammonium side groups H₂N(CH₂)₂NHSO₂‐p‐C₆H₄CH₂[NMe₂(C_nH_2n+1)]⁺ ( [HL ⁿ ]⁺ ; n=8, 16) was developed. The corresponding new surface‐active complexes [(p‐cymene)RuCl( L ⁿ )] and [Cp*RhCl( L ⁿ )] (Cp*=η⁵‐C₅Me₅) were prepared and characterized. For n=16 micelles are formed in water at concentrations as low as 0.6 mM , as demonstrated by surface‐tension measurements. The complexes were used for catalytic transfer hydrogenation of ketones with formate in water. Highly active catalyst systems were obtained in the case of complexes bearing C₁₆ tails due to their ability to be adsorbed at the water/substrate interface. The scope of these catalyst systems in aqueous solutions was extended from partially water soluble aryl alkyl ketones (acetophenone, butyrophenone) to hydrophobic dialkyl ketones (2‐dodecanone).     

Soy addition improves the texture of microwavable par-baked pocket-type flat doughs

Microwavable baked goods are used frequently by the food industry to enrobe meat, vegetable, and sweet items for convenient meal delivery but suffer from poor texture upon microwave re-heating. Par-baking the dough prior to the reheating stage provides an opportunity to supply fresh baked goods with a simple baking stage at retail locations. Nonetheless, reheating conditions significantly affect texture of reheated par-baked products, resulting in shrinkage, porosity reduction, and crust softening. Appropriate formula modifications have been shown to reduce microwave-induced toughness of reheated bread by virtue of water-binding agents and lipids. The objective of this study was, therefore, to assess the effect of soy addition on the water state of microwavable par-baked doughs. Four dough formulations were developed by substituting wheat flour with increasing amounts of a soy blend. Addition of soy at 20 and 26% levels improved textural properties of microwaved products, resulting in a softer and less chewy texture. Thermogravimetric analysis (TG) showed increased water binding in soy formulations 20 and 26% with a broadening of the main peak (attributed to water loss) that shifted from 40 to 80 °C. Differential scanning calorimetry (DSC) depicted a transition in the −25/−10 °C range, attributed to soy lipids melting, which broadened at high soy addition. This change in water dynamics was confirmed by proton nuclear magnetic resonance (¹H NMR) relaxation tests, T ₁ and T ₂, having lower values in soy products, and therefore, depicting a more solid-like matrix. Soy addition above 20% significantly improved the texture of microwave reheated par-baked flat doughs.     

A macrocyclic ligand as receptor and Zn(II)-complex receptor for anions in water: binding properties and crystal structures

Binding properties of 24,29-dimethyl-6,7,15,16-tetraoxotetracyclo[19.5.5.0(5,8).0(14,17)]-1,4,9,13,18,21,24,29-octaazaenatriaconta-Δ(5,8),Δ(14,17)-diene ligand L towards Zn(II) and anions, such as the halide series and inorganic oxoanions (phosphate (Pi), sulfate, pyrophosphate (PPi), and others), were investigated in aqueous solution; in addition, the Zn(II)/L system was tested as a metal-ion-based receptor for the halide series. Ligand L is a cryptand receptor incorporating two squaramide functions in an over-structured chain that connects two opposite nitrogen atoms of the Me(2)[12]aneN(4) polyaza macrocyclic base. It binds Zn(II) to form mononuclear species in which the metal ion, coordinated by the Me(2)[12]aneN(4) moiety, lodges inside the three-dimensional cavity. Zn(II)-containing species are able to bind chloride and fluoride at the physiologically important pH value of 7.4; the anion is coordinated to the metal center but the squaramide units play the key role in stabilizing the anion through a hydrogen-bonding network; two crystal structures reported here clearly show this aspect. Free L is able to bind fluoride, chloride, bromide, sulfate, Pi, and PPi in aqueous solution. The halides are bound at acidic pH, whereas the oxoanions are bound in a wide range of pH values ranging from acidic to basic. The cryptand cavity, abundant in hydrogen-bonding sites at all pH values, allows excellent selectivity towards Pi to be achieved mainly at physiological pH 7.4. By joining amine and squaramide moieties and using this preorganized topology, it was possible, with preservation of the solubility of the receptor, to achieve a very wide pH range in which oxoanions can be bound. The good selectivity towards Pi allows its discrimination in a manner not easily obtainable with nonmetallic systems in aqueous environment.     

Diastereoselective synthesis of α-amino-β-hydroxyacids

threo-α-Dibenzylamino-?-hydroxyesters (2) have been synthesised with high diastereoselectivity through the NaBH₄ reduction of α-dibenzylamino-β-oxoesters (4) and then tranformed into threo-α-amino-β-hydroxyacids.     

Mass fragmentation pattern of N- and O-substituted 2-morpholinols

The mass spectra of a series of N- and O-substituted 2-morpholinols were considered and the complex fragmentation pattern explained on the basis of evidences reported in the literature and of experimental data (high resolution, metastable ions). The primary fragmentations are given by inductive cleavage due to the heteroatoms, while ring contractions, through retro Diels-Alder reactions, form most of the secondary pattern with different ions related to N- and O-substituents. Moreover, hemiacetals in the tautomeric hydroxyaldehyde form undergo an α-cleavage.     

Mediterranean diet in a Sicilian student population. Second part: breakfast and its nutritional profile

Abstract

Breakfast habits affect the nutritional status and health of people, in particular children and adolescents. This is the second part a previous study about the adherence to the Mediterranean diet in a Sicilian (Italy) student population. The investigation analysed both normal weight and overweight subjects in order to understand how eating habits, number of meals and daily calorie intakes could affect their body mass indexes (BMI). The aim of this second part was to analyse the breakfast nutritional profiles of this student population. The results highlighted that breakfast was regularly consumed by a percentage ranging from a maximum of 84% (in normal subjects) to a minimum value of 57.4% (in overweight/obese students). Milk, yoghurt, sugar, bread/rusk and tea contributed as main foods to the breakfast composition. The results highlighted that subjects who consumed breakfast showed lower BMI values with significant differences between normal and overweight/obese students.