Triacylglycerol Composition and Chemical-Physical Properties of Cocoa Butter and Its Derivatives: NMR, DSC, X-ray, Rheological Investigation.

In recent years, the food industry has become increasingly involved in researching vegetable fats and oils with appropriate mechanical properties (ease of transport, processing, and storage) and a specific lipidic composition to ensure healthy products for consumers. The chemical-physical behavior of these matrices depends on their composition in terms of single fatty acids (FA). However, as we demonstrate in this work, these properties, as well as the absorption, digestion and uptake in humans of specific FAs, are also largely determined by their regiosomerism within the TriAcylGlycerols (TAG) moieties (sn-1,2,3 positions). The goal of this work is to study for the first time vegetable fats obtained directly from a sample of natural cocoa butter (CB) through a process that manipulates the distribution of FAs but not their nature. Even if the initial percentage of each FA in the mixture remains the same, CB derivatives seem to show improved chemical-physical features. In order to understand which factors account for their physical and chemical characteristics, and to check whether or not the obtained new matrices could be considered as valid alternatives to other vegetable fats (e.g., palm oil (PO)), we carried out an experimental investigation at both the macroscopic and molecular level including: (i) Differential Scanning Calorimetry (DSC) analyses to examine thermal features; (ii) rheological testing to explore mechanical properties; (iii) powder X-ray diffraction (PXRD) to evaluate the solid-state phases of the obtained fats; and (iv) 1H and 13C Nuclear Magnetic Resonance (NMR, 1D and 2D) spectroscopy to rapidly analyze fatty acid composition including regioisomeric distribution on the glycerol backbone. These last results open up the possibility of using NMR spectroscopy as an alternative to the chromatographic techniques routinely employed for the investigation of similar matrices.

Water-Assisted Concerted Proton-Electron Transfer at Co(II)-Aquo Sites in Polyoxotungstates With Photogenerated RuIII (bpy)33+ Oxidant.

The cobalt substituted polyoxotungstate [Co6 (H2 O)2 (α-B-PW9 O34 )2 (PW6 O26 )]17- (Co6) displays fast electron transfer (ET) kinetics to photogenerated RuIII (bpy)33+ , 4 to 5 orders of magnitude faster than the corresponding ET observed for cobalt oxide nanoparticles. Mechanistic evidence has been acquired indicating that: (i) the one-electron oxidation of Co6 involves Co(II) aquo or Co(II) hydroxo groups (abbreviated as Co6(II)-OH2 and Co6(II)-OH, respectively, whose speciation in aqueous solution is associated to a pKa of 7.6), and generates a Co(III)-OH moiety (Co6(III)-OH), as proven by transient absorption spectroscopy; (ii) at pH>pKa , the Co6(II)-OH→RuIII (bpy)33+ ET occurs via bimolecular kinetics, with a rate constant k close to the diffusion limit and dependent on the ionic strength of the medium, consistent with reaction between charged species; (iii) at pH

Ferro- and Antiferromagnetic Interactions in Oxalato-Centered Inverse Hexanuclear and Chain Copper(II) Complexes with Pyrazole Derivatives.

Two novel copper(II) complexes of formulas {[Cu(4-Hmpz)4][Cu(4-Hmpz)2(µ3-ox-κ2O1,O2:κO2':κO1')(ClO4)2]}n (1) and {[Cu(3,4,5-Htmpz)4]2[Cu(3,4,5-Htmpz)2(µ3-ox-κ2O1,O2:κO2':κO1')(H2O)(ClO4)]2[Cu2(3,4,5-Htmpz)4(µ-ox-κ2O1,O2:κ2O2',O1')]}(ClO4)4·6H2O (2) have been obtained by using 4-methyl-1H-pyrazole (4-Hmpz) and 3,4,5-trimethyl-1H-pyrazole (3,4,5-Htmpz) as terminal ligands and oxalate (ox) as the polyatomic inverse coordination center. The crystal structure of 1 consists of perchlorate counteranions and cationic copper(II) chains with alternating bis(pyrazole)(µ3-κ2O1,O2:κO2':κO1'-oxalato)copper(II) and tetrakis(pyrazole)copper(II) fragments. The crystal structure of 2 is made up of perchlorate counteranions and cationic centrosymmetric hexanuclear complexes where an inner tetrakis(pyrazole)(µ-κ2O1,O2:κ2O2',O1'-oxalato)dicopper(II) entity and two outer mononuclear tetrakis(pyrazole)copper(II) units are linked through two mononuclear aquabis(pyrazole)(µ3-κ2O1,O2:κO2':κO1'-oxalato)copper(II) units. The magnetic properties of 1 and 2 were investigated in the temperature range 2.0-300 K. Very weak intrachain antiferromagnetic interactions between the copper(II) ions through the µ3-ox-κ2O1,O2:κO2':κO1' center occur in 1 [J = -0.42(1) cm-1, the spin Hamiltonian being defined as H = -J∑S1,i · S2,i+1], whereas very weak intramolecular ferromagnetic [J = +0.28(2) cm-1] and strong antiferromagnetic [J' = -348(2) cm-1] couplings coexist in 2 which are mediated by the µ3-ox-κ2O1,O2:κO2':κO1' and µ-ox-κ2O1,O2:κ2O2',O1' centers, respectively. The variation in the nature and magnitude of the magnetic coupling for this pair of oxalato-centered inverse copper(II) complexes is discussed in the light of their different structural features, and a comparison with related oxalato-centered inverse copper(II)-pyrazole systems from the literature is carried out.

Divergent Syntheses of ( Z)-3-Alkylideneisobenzofuran-1(3 H)-ones and 1 H-Isochromen-1-ones by Copper-Catalyzed Cycloisomerization of 2-Alkynylbenzoic Acids in Ionic Liquids.

The cycloisomerization of readily available 2-alkynylbenzoic acids 1 in ionic liquids (ILs) as recyclable reaction media has been studied under the catalytic action of CuCl2. With substrates bearing an aryl group on the triple bond, a mixture of ( Z)-3-alkylideneisobenzofuran-1(3 H)-ones (from 5- exo- dig cyclization) and 1 H-isochromen-1-ones (from 6- endo- dig cyclization) was observed in 1-ethyl-3-methylimidazolium ethyl sulfate (EmimEtSO4), while the reaction turned out to be selective toward the formation of the isobenzofuranone only using N-ethyl- N-methylmorpholinium dicyanamide [Mor1,2N(CN)2] as the solvent. The 5-membered product was also obtained selectively when the substrate bearing a terminal triple bond was employed, either in EmimEtSO4 or Mor1,2N(CN)2. On the other hand, 2-alkynylbenzoic acids bearing an alkyl or an alkenyl group on the triple bond selectively led, in EmimEtSO4, to 1 H-isochromen-1-ones, while the formation of a regioisomeric mixture was observed in Mor1,2N(CN)2. In any case, the solvent/catalyst system could be easily recycled after extraction of the product from the reaction mixture with diethyl ether. DFT calculations have been carried out to clarify the reaction outcome depending on reaction conditions, and the structures of two representative products, which are ( Z)-3-benzylideneisobenzofuran-1(3 H)-one and ( Z)-3-(4-methylphenylmethylidene)isobenzofuran-1(3 H)-one, have been confirmed by X-ray diffraction analysis.

Microfluidic light-driven synthesis of tetracyclic molecular architectures.

Herein we report an effective synthetic method for the direct assembly of highly functionalized tetracyclic pharmacophoric cores. Coumarins and chromones undergo diastereoselective [4 + 2] cycloaddition reactions with light-generated photoenol intermediates. The reactions occur by aid of a microfluidic photoreactor (MFP) in high yield (up to >98%) and virtually complete diastereocontrol (>20:1 dr). The method is easily scaled-up to a parallel setup, furnishing 948 mg of product over a 14 h reaction time. Finally, a series of manipulations of the tetracyclic scaffold obtained gave access to valuable precursors of biologically active molecules.

Cytosine Nucleobase Ligand: A Suitable Choice for Modulating Magnetic Anisotropy in Tetrahedrally Coordinated Mononuclear CoII Compounds.

A family of tetrahedral mononuclear CoII complexes with the cytosine nucleobase ligand is used as the playground for an in-depth study of the effects that the nature of the ligand, as well as their noninnocent distortions on the Co(II) environment, may have on the slow magnetic relaxation effects. Hence, those compounds with greater distortion from the ideal tetrahedral geometry showed a larger-magnitude axial magnetic anisotropy (D) together with a high rhombicity factor (E/D), and thus, slow magnetic relaxation effects also appear. In turn, the more symmetric compound possesses a much smaller value of the D parameter and, consequently, lacks single-ion magnet behavior.

Divergent syntheses of iodinated isobenzofuranones and isochromenones by iodolactonization of 2-alkynylbenzoic acids in ionic liquids.

The regiochemical outcome of the iodolactonization of 2-alkynylbenzoic acids, carried out at 100 °C in ionic liquids (ILs) as unconventional solvents and with molecular iodine as the iodine source, in the absence of external bases, was found to be strongly dependent on the nature of the IL medium. In particular, while the use of N-ethyl-N-methylmorpholinium dicyanamide (Mor1,2N(CN)2) promoted the stereoselective formation of (E)-3-(iodomethylene)isobenzofuran-1(3H)-ones, through an anti-5-exo-dig cyclization route, the use of 1-ethyl-3-methylimidazolium ethyl sulfate (EmimEtSO4) tended to favor the 6-endo-dig cyclization mode, with preferential or selective formation of 4-iodo-1H-isochromen-1-ones. In any case, the IL solvent could be easily recycled after extraction of the product from the reaction mixture with diethyl ether. DFT calculations have been carried out to clarify the role of the IL's nature in favoring either the anti-5-exo-dig cyclization route or the 6-endo-dig mode. In the case of iodocyclization of 2-ethynylbenzoic acid, only the 5-exo-dig mode was observed in both EmimEtSO4 and Mor1,2N(CN)2 solvents. The structures of two representative products have been confirmed by X-ray diffraction analysis.

A Palladium-Catalyzed Carbonylation Approach to Eight-Membered Lactam Derivatives with Antitumor Activity.

The reactivity of 2-(2-alkynylphenoxy)anilines under PdI2 /KI-catalyzed oxidative carbonylation conditions has been studied. Although a different reaction pathway could have been operating, N-palladation followed by CO insertion was the favored pathway with all substrates tested, including those containing an internal or terminal triple bond. This led to the formation of a carbamoylpalladium species, the fate of which, as predicted by theoretical calculations, strongly depended on the nature of the substituent on the triple bond. In particular, 8-endo-dig cyclization preferentially occurred when the triple bond was terminal, leading to the formation of carbonylated ζ-lactam derivatives, the structures of which have been confirmed by XRD analysis. These novel medium-sized heterocyclic compounds showed antitumor activity against both estrogen receptor-positive (MCF-7) and triple negative (MDA-MB-231) breast cancer cell lines. In particular, ζ-lactam 3 j' may represent a novel and promising antitumor agent because biological tests clearly demonstrate that this compound significantly reduces cell viability and motility in both MCF-7 and MDA-MB-231 breast cancer cell lines, without affecting normal breast epithelial cell viability.

Selective Guest Inclusion in Oxalate-Based Iron(III) Magnetic Coordination Polymers.

The preparation and structural characterization of four novel oxalate-based iron(III) compounds of formulas {(MeNH3)2[Fe2(ox)2Cl4]·2.5H2O}n (1), K(MeNH3)[Fe(ox)Cl3(H2O)] (2), {MeNH3[Fe2(OH)(ox)2Cl2]·2H2O}n (3), and {(H3O)(MeNH3)[Fe2O(ox)2Cl2]·3H2O}n (4) (MeNH3+ = methylammonium cation and H2ox = oxalic acid) are reported here. 1 is an anionic waving chain of oxalato-bridged iron(III) ions with peripheral chloro ligands, the charge balance being ensured by methylammonium cations. 2 is a mononuclear complex with a bidentate oxalate, three terminal chloro ligands, and a coordinated water molecule achieving the six-coordination around each iron(III) ion. Its negative charge is balanced by potassium(I) and methylammonium cations. 3 and 4 are made up of oxalate-bridged and either hydroxo (3)- or oxo-bridged (4) iron(III) chiral three-dimensional (3D) networks of formulas [Fe2(OH)(ox)2Cl2]nn- (3) and [Fe2O(ox)2Cl2]n2n- (4) with methylammonium (3 and 4) and hydronium (4) as counterions. The common point these compounds share is related to their synthetic strategy, which consists of the use of mixed alkaline/alkylammonium cations as templating agents for the growth of the 1D or 3D iron(III) motifs. Interestingly, even in the presence of any given alkaline cation in the reaction solutions, the resulting coordination polymers (1, 3, and 4) exclusively contain the methylammonium cation, revealing the highly selective character of the 1D and 3D networks. Furthermore, the isolation of the very unstable compound 1 could be only achieved in the presence of the KCl salt, suggesting a probable templating effect of the potassium(I) cations. Finally, a study of the variable-temperature magnetic properties of the 3D compounds 3 and 4 showed the occurrence of weak ferromagnetic ordering due to a spin canting, the value of the critical temperature (Tc) being as high as 70 K.

Heterotrimetallic coordination polymers: {Cu(II)Ln(III)Fe(III)} chains and {Ni(II)Ln(III)Fe(III)} layers: synthesis, crystal structures, and magnetic properties.

The use of the [Fe(III) (AA)(CN)4](-) complex anion as metalloligand towards the preformed [Cu(II) (valpn)Ln(III)](3+) or [Ni(II) (valpn)Ln(III) ](3+) heterometallic complex cations (AA=2,2'-bipyridine (bipy) and 1,10-phenathroline (phen); H2 valpn=1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu(II) (valpn)Ln(III) (H2O)3 (µ-NC)2 Fe(III) (phen)(CN)2 {(µ-NC)Fe(III) (phen)(CN)3}]NO3 ⋅7 H2O}n (Ln=Gd (1), Tb (2), and Dy (3)) and the trinuclear complex [Cu(II) (valpn)La(III) (OH2 )3 (O2 NO)(µ-NC)Fe(III) (phen)(CN)3 ]⋅NO3 ⋅H2O⋅CH3 CN (4) were obtained with the [Cu(II) (valpn)Ln(III)](3+) assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[Ni(II) (valpn)Ln(III) (ONO2 )2 (H2 O)(µ-NC)3 Fe(III) (bipy)(CN)]⋅2 H2 O⋅2 CH3 CN}n (Ln=Gd (5), Tb (6), and Dy (7)) resulted with the related [Ni(II) (valpn)Ln(III) ](3+) precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [Cu(II) (valpn)La(III) (OH2)3 (O2 NO)(µ-NC)Fe(III) (phen)(CN)3 ](+), nitrate counterions, and non-coordinate water and acetonitrile molecules. The heteroleptic {Fe(III) (bipy)(CN)4} moiety in 5-7 acts as a tris-monodentate ligand towards three {Ni(II) (valpn)Ln(III)} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the Cu(II)-Ln(III) (1-3) and Ni(II)-Ln(III) (5-7) units, as well as through the single cyanide bridge between the Fe(III) and either Ni(II) (5-7) or Cu(II) (4) account for the overall ferromagnetic behavior observed in 1-7. DFT-type calculations were performed to substantiate the magnetic interactions in 1, 4, and 5. Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out-of-phase ac signals below 4.0 K in the lack of a dc field, the values of the pre-exponential factor (τo) and energy barrier (Ea ) through the Arrhenius equation being 2.0×10(-12)  s and 29.1 cm(-1), respectively. In the case of 7, the ferromagnetic interactions through the double phenoxo (Ni(II)-Dy(III)) and single cyanide (Fe(III)-Ni(II)) pathways are masked by the depopulation of the Stark levels of the Dy(III) ion, this feature most likely accounting for the continuous decrease of χMT upon cooling observed for this last compound.

Ferromagnetic Coupling in "Double-Bridged" Dihydrogenpyrophosphate Complexes of Cobalt(II) and Nickel(II).

Three isostructural compounds of the formula {[M(bipy)(H2O)(H2P2O7)]2·2H2O} [bipy = 2,2'-bipyridine; M = Ni (1), Co (2), Mn (3)] have been isolated from aqueous solutions containing the corresponding metal(II) chloride hydrate with a bipy and sodium pyrophosphate solution in a 1:1:2 molar ratio, and their structures were determined by single-crystal X-ray diffraction. The structures of 1-3 consist of neutral aqua(2,2'-bipyridine)metal(II) dinuclear units bridged by two dihydrogenpyrophosphate groups adopting a bidentate/monodentate mode. Each metal ion in 1-3 is six-coordinate in a distorted octahedral geometry, with the reduced value of the angle subtended by the chelating bipy at the metal ion [79.6(1)° (1), 77.32(7)° (2), and 72.9(1)° (3)] being the main source of this distortion. The values of the intramolecular metal-metal separation are 5.271(1) Å (1), 5.3065(8) Å (2), and 5.371(1) Å (3). Magnetic susceptibility measurements on polycrystalline samples of 1-3 in the temperature range 1.9-300 K shows weak intramolecular ferromagnetic [J = +1.86(2) cm(-1) (1) and +0.25(1) cm(-1) (2)] and antiferromagnetic [J = -0.48(1) cm(-1) (3)] coupling, with the spin Hamiltonian being defined as H = -JSM1·SM1a. This rarely observed coordination mode for dihydrogenpyrophosphate leads to ferromagnetic coupling in complexes of nickel(II) or cobalt(II).

Dihydrogen tetrametaphosphate, [P4O12H2]2-: synthesis, solubilization in organic media, preparation of its anhydride [P4O11]2- and acidic methyl ester, and conversion to tetrametaphosphate metal complexes via protonolysis.

Dihydrogen tetrametaphosphate [P4O12H2](2-) (1) can now be synthesized and isolated as its PPN salt ([PPN](+) = [N(PPh3)2](+)) via treatment of [PPN]4[P4O12] with trifluoroacetic anhydride in wet acetone; this simple procedure affords the oxoacid salt in 94% yield. A pKa of 15.83 ± 0.11 in acetonitrile was determined. [P4O12H2](2-) reacts with the dehydrating agent N,N'-dicyclohexylcarbodiimide to afford tetrametaphosphate anhydride [P4O11](2-) (2) in 82% yield, also as the PPN salt. From 2 a monohydrogen tetrametaphosphate ester [P4O10(OH)(OMe)](2-) (3, 96%) was derived by addition of methanol, illustrating that 2 can function as a reagent for chemical phosphorylation. Addition of water to 2 regenerates 1 quantitatively. Deprotonation of 1 by metal amides in the +2 oxidation state led to the unconventional monomeric tin(II) κ(4) tetrametaphosphate [Sn(P4O12)](2-) (4, 78%, a molecular analog of SnO) and binary dimeric chromium(II) bis(µ2,κ(2),κ(2)) derivative [Cr2(P4O12)2](4-) (5, 82%). Structural data stemming from single-crystal X-ray diffraction studies for the PPN salts of anions 1-5 are also reported.

Divergent palladium iodide catalyzed multicomponent carbonylative approaches to functionalized isoindolinone and isobenzofuranimine derivatives.

2-Alkynylbenzamides underwent different reaction pathways when allowed to react under PdI2-catalyzed oxidative carbonylation conditions, depending on the nature of the external nucleophile and reaction conditions. Thus, oxidative carbonylation of 2-ethynylbenzamides, bearing a terminal triple bond, carried out in the presence of a secondary amine as external nucleophile, selectively led to the formation of 3-[(dialkylcarbamoyl)methylene]isoindolin-1-ones through the intermediate formation of the corresponding 2-ynamide derivatives followed by intramolecular nucleophilic attack by the nitrogen of the benzamide moiety on the conjugated triple bond. On the other hand, 3-[(alkoxycarbonyl)methylene]isobenzofuran-1(3H)imines were selectively obtained when the oxidative carbonylation of 2-alkynylbenzamides, bearing a terminal or an internal triple bond, was carried out in the presence of an alcohol R'OH (such as methanol or ethanol) as the external nucleophile and HC(OR')3 as a dehydrating agent, necessary to avoid substrate hydrolysis. In this latter case, the reaction pathway leading to the isobenzofuranimine corresponded to the 5-exo-dig intramolecular nucleophilic attack of the oxygen of the benzamide moiety on the triple bond coordinated to the metal center followed by alkoxycarbonylation. The structures of representative products have been confirmed by X-ray crystallographic analysis.

Ligand effects on the structure and magnetic properties of alternating copper(II) chains with 2,2'-bipyrimidine- and polymethyl-substituted pyrazolates as bridging ligands.

A novel series of heteroleptic copper(II) compounds of formulas {[Cu2(µ-H2O)(µ-pz)2(µ-bpm)(ClO4)(H2O)]ClO4·2H2O}n (1), {[Cu2(µ-H2O)(µ-3-Mepz)2(µ-bpm)](ClO4)2·2H2O}n (2), and {[Cu2(µ-OH)(µ-3,5-Me2pz)(µ-bpm)(H-3,5-Me2pz)2](ClO4)2}n (3) [bpm = 2,2'-bipyrimidine, Hpz = pyrazole, H-3-Mepz = 3-methylpyrazole, and H-3,5-Me2pz = 3,5-dimethylpyrazole] have been synthesized and structurally characterized by X-ray diffraction methods. The crystal structures of 1 and 2 consist of copper(II) chains with regular alternating bpm and bis(pyrazolate)(aqua) bridges, whereas that of 3 is made up of copper(II) chains with regular alternating bpm and (pyrazolate)(hydroxo) bridges. The copper centers are six- (1) or five-coordinate (2) in axially elongated, octahedral (1) or square-pyramidal (2) environments in 1 and 2, whereas they are five-coordinate in distorted trigonal-bipyramidal surroundings in 3. The values of the copper-copper separations across the bpm/pyrazolate bridges are 5.5442(7)/3.3131(6) (1), 5.538(1)/3.235(1) (2), and 5.7673(7)/3.3220(6) Å (3). The magnetic properties of 1-3 have been investigated in the temperature range of 25-300 K. The analysis of their magnetic susceptibility data through the isotropic Hamiltonian for an alternating antiferromagnetic copper(II) chain model [H = -J∑i=1-n/2 (S2i·S2i-1 + αS2i·S2i+1), with α = J'/J and Si = SCu = 1/2] reveals the presence of a strong to moderate antiferromagnetic coupling through the bis(pyrazolate)(aqua) [-J = 217 (1) and 215 cm(-1) (2)] and (pyrazolate)(hydroxo) bridges [-J = 153 cm(-1) (3)], respectively, whereas a strong to weak antiferromagnetic coupling occurs through the bis-bidentate bpm [-J' = 211 (1), 213 (2), and 44 cm(-1) (3)]. A simple orbital analysis of the magnetic exchange interaction within the bpm- and pyrazolate-bridged dicopper(II) fragments of 1-3 visualizes the σ-type pathways involving the (dx(2)-y(2)) (1 and 2) or d(z(2)) (3) magnetic orbitals on each metal ion, which account for the variation of the magnetic properties in these three novel examples of one-dimensional copper(II) compounds with regular alternating intrachain antiferromagnetic interactions.

Magnetocaloric efficiency tuning through solvent-triggered 3D to 2D interconversion in holmium(III)-based dynamic MOFs.

The neutral holmium(III) oxalate octadecahydrate {[Ho2(ox)3(H2O)6]·12H2O}n of mixed hexagonal/decagonal (63·103) 3D net topology shows important changes in the magnetocaloric efficiency upon dehydration/rehydration by heating and water vapor exposition to give the holmium(III) oxalate decahydrate {[Ho2(ox)3(H2O)6]·4H2O}n of hexagonal (63) 2D net topology through the intermediacy of the elusive amorphous anhydrous compound {Ho2(ox)3}n.

Cubane-type Cu(II)4 and Mn(II)2Mn(III)2 complexes based on pyridoxine: a versatile ligand for metal assembling.

By using Vitamin B6 in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine], two tetranuclear compounds of formula [Mn4(PN-H)4(CH3CO2)3Cl2]Cl·2CH3OH·2H2O (1) and [Cu4(PN-H)4Cl2(H2O)2]Cl2 (2) have been synthesized and magneto-structurally characterized. 1 crystallizes in the triclinic system with space group P1 whereas 2 crystallizes in the orthorhombic system with Fdd2 as space group. They exhibit Mn(II)2Mn(III)2 (1) and Cu(II)4 (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting as chelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally bound chloride anions (1 and 2) plus two coordinated water molecules (2). The electroneutrality is achieved by the presence of chloride counterions in both compounds. Tri- [Mn(1) and Mn(3)] and divalent [Mn(2) and Mn(4)] manganese centers coexist in 1, all being six-coordinate with distorted Mn(1/3)O6 and Mn(2/4)O5Cl octahedral surroundings, respectively, the equatorial Mn-O bonds being about 0.2 Å shorter at the former ones. The two crystallographically independent copper(II) ions in 2 are five-coordinate in somewhat distorted CuO5 [Cu(1)] and CuO4Cl [Cu(2)] square pyramidal geometries. The values of the intracore metal-metal separation cover the ranges 3.144(1)-3.535(1) (1) and 2.922(6)-3.376(1) Å (2). The magnetic properties of 1 and 2 were investigated in the temperature range 1.9-300 K, and they correspond to an overall antiferromagnetic behavior with susceptibility maxima at 5.0 (1) and 65.0 K (2). The analysis of the magnetic susceptibility data showed the coexistence of intracore antiferro- and ferromagnetic interactions in the two compounds. Their values compare well with those existing in the literature for the parent systems.

LAT1 (SLC7A5) catalyzes copper(histidinate) transport switching from antiport to uniport mechanism.

LAT1 (SLC7A5) is one of the most studied membrane transporters due to its relevance to physiology in supplying essential amino acids to brain and fetus, and to pathology being linked to nervous or embryo alterations; moreover, LAT1 over-expression is always associated with cancer development. Thus, LAT1 is exploited as a pro-drug vehicle and as a target for anti-cancer therapy. We here report the identification of a new substrate with pathophysiological implications, i.e., Cu-histidinate, and an unconventional uniport mechanism exploited for the Cu-histidinate transport. Crystals of the monomeric species Cu(His)2 were obtained in our experimental conditions and the actual transport of the complex was evaluated by a combined strategy of bioinformatics, site-directed mutagenesis, radiolabeled transport, and mass spectrometry analysis. The LAT1-mediated transport of Cu(His)2 may have profound implications for both the treatment of copper dysmetabolism diseases, such as the rare Menkes disease, and of cancer as an alternative to platinum-based therapies.

Pyro without fire: synthesis, structure, and reactivity of a dimeric vanadyl pyrophosphate coordination complex.

The complex {[(V(IV)O)bipy(H(2)O)](2)(µ-P(2)O(7))}·3H(2)O (2) was readily obtained as a nanocrystalline powder by one-pot synthesis under mild conditions. Single crystals of 2 were grown at room temperature over 2 months, and its structure was determined. Fundamental catalytic activity was proven for this species by testing for oxidation of benzyl alcohol in air.

Synthesis, structure, and magnetic properties of regular alternating µ-bpm/di-µ-X copper(II) chains (bpm = 2,2'-bipyrimidine; X = OH, F).

The preparation and X-ray crystal structure of four 2,2'-bipyrimidine (bpm)-containing copper(II) complexes of formula {[Cu(2)(µ-bpm)(H(2)O)(4)(µ-OH)(2)][Mn(H(2)O)(6)](SO(4))(2)}(n) (1), {[Cu(2)(µ-bpm)(H(2)O)(4)(µ-OH)(2)]SiF(6)}(n) (2), {Cu(2)(µ-bpm)(H(2)O)(2)(µ-F)(2)F(2)}(n) (3), and [Cu(bpm)(H(2)O)(2)F(NO(3))][Cu(bpm)(H(2)O)(3)F]NO(3)·2H(2)O (4) are reported. The structures of 1-3 consist of chains of copper(II) ions with regular alternation of bis-bidentate bpm and di-µ-hydroxo (1 and 2) or di-µ-fluoro (3) groups, the electroneutrality being achieved by either hexaaqua manganese(II) cations plus uncoordinated sulfate anions (1), uncoordinated hexafluorosilicate anions (2), or terminally bound fluoride ligands (3). Each copper(II) ion in 1-4 is six-coordinated in elongated octahedral surroundings. 1 and 2 show identical, linear chain motifs with two bpm-nitrogen atoms and two hydroxo groups building the equatorial plane at each copper(II) ion and the axial position being filled by water molecules. In the case of 3, the axial sites at the copper atom are occupied by a bpm-nitrogen atom and a bis-monodentate fluoride anion, producing a "step-like" chain motif. The values of the angle at the hydroxo and fluoro bridges are 94.11(6) (1), 94.75(4) (2), and 101.43(4)° (3). In each case, the copper-copper separation through the bis-bidentate bpm [5.428(1) (1), 5.449(1) (2), and 5.9250(4) Å (3)] is considerably longer than that through the di-µ-hydroxo [2.8320(4) (1) and 2.824(1) Å (2)] or di-µ-fluoro [3.3027(4) Å (3)] bridges. Compound 4 is a mononuclear species whose structure is made up of neutral [Cu(bpm)(H(2)O)(2)F(NO(3))] units, [Cu(bpm)(H(2)O)(3)F](+) cations, uncoordinated nitrate anions, and crystallization water molecules, giving rise to a pseudo-helical, one-dimensional (1D) supramolecular motif. The magnetic properties of 1-3 have been investigated in the temperature range 1.9-300 K. Relatively large, alternating antiferro- [J = -149 (1) and -141 cm(-1) (2) across bis-bidentate bpm] and ferromagnetic [αJ = +194 (1) and +176 cm(-1) (2) through the dihydroxo bridges] interactions occur in 1 and 2 [the Hamiltonian being defined as H = -J∑(i=1)(n/2) (S(2i)·S(2i-1) - αS(2i)·S(2i+1))]. These values compare well with those previously reported for parent examples. Two weak intrachain antiferromagnetic interactions [J = -0.30 and αJ = -8.1 cm(-1) across bpm and the di-µ-fluoro bridges, respectively] whose values were substantiated by density functional theory (DFT)-type calculations occur in 3.

Trifluoracetic acid-assisted crystallization of vitamin B12 results in protonation of the phosphate group of the nucleotide loop: insight into the influence of crystal packing forces on vitamin B12 structures.

In the course of experiments concerning our ongoing project on the synthesis of vitamin B(12) (cyanocobalamin, CNCbl) bioconjugates for drug-delivery purposes, we observed the formation of well-shaped red parallelepipeds from a concentrated aqueous solution of the HPLC-purified vitamin. The X-ray structural investigation (MoK(α)) at 98 K on these crystals revealed a CNCbl-TFA salt of formula [CNCbl(H)](TFAc)·14H(2)O (1, where TFA = trifluoracetic acid; TFAc(-) = trifluoracetate anion), in which a proton transfer from the trifluoracetic acid to the phosphate-O4P oxygen atoms is observed. 1 crystallizes in the standard orthorhombic P2(1)2(1)2(1) space group, a = 16.069(2) Å, b = 20.818(2) Å, c = 24.081(2) Å, Z = 4. The final full-matrix least-squares refinements on F(2) converged with R(1) = 4.1% for the 18957 significant reflections, a very low crystallographic residual for cobalamins, which facilitated the analysis of the extensive network of hydrogen bonds within the lattice. To the best of our knowledge, this is the first cobalamin structure to show protonation of the phosphate group of the cobalamin nucleotide loop. In this work, the crystal structure of 1 is analyzed and compared to other CNCbls reported in the literature, namely, CNCbl·3PrOH·12H(2)O (2, PrOH = propyl alcohol), CNCbl·acetone·20H(2)O (3), CNCbl·2LiCl·10.2H(2)O (4), and CNCbl·2KCl·10.6H(2)O (5). The analysis confirmed that protonation of the phosphate leaves the major CNCbl structural parameters unaffected, so that 1 can be considered an "unmodified" Cbl solvate. However, comparison between 1-5 led to interesting findings. In fact, although the cobalt(III) coordination sphere in 1-5 is similar, significant differences could be noted in the upward fold angle of the corrin macrocycle, a parameter commonly related to the steric hindrance of the axial lower "α" nucleotide-base and the electronic trans influence of the upper "ß" substituent. This suggests that crystal-packing forces may influence the corrin deformation as well. Herein we explore, on the basis of the newly acquired structure and reported crystallographic data, whether the incongruities among 1-5 have to be attributed to random crystal packing effects or if it is possible to associate them with specific crystal packing (clusters).