Synthesis of Chiral 12-Phenyl(2H)dodecanoic Acids: Useful metabolic probes for the biosynthesis of 1-alkenes from fatty acids

The synthesis of chiral 12-phenyi(²H)dodecanoic acids as metabolic probes for the evaluation of the stereo-chemical course of the biosynthesis of 1-alkerses from fatty acids in plants and insects is described. The diastereoisomeric (2R, 3R)- or (2S, 3S)-12-phenyl(2,3?²H₂)dodecanoic acids 11 are obtained in high chemical and optical yield (>97% e.e.) from the readily available (E)-12-phenyl(2,3-²H₂)dodec-2-enoic acid ( 10 ) or (E)-12-phenyldodec-2-enoic acid ( 10a ) by microbial reduction with wet packed cells of Clostridium tyrobutyricum in either ²H₂O or H₂O buffer. (2R)- and (2S)-12-phenyl(2?²H)dodecanoic acids 9 (>97% e.e.) are accessible from the allylic alcohol 6 via Sharpless epoxidation with (+)-L- or (?)-D-diethyl tartrate, Synthetic routes to the (E)- and (Z)-11-phenyl(1?²H) undec-1-enes 16 and 16a as reference compounds are also included.     

Mono- and dinuclear Zn(II) complexes of Schiff-base ligands: syntheses,characterization and studies of photoluminescence

Six Schiff-bases HL¹-HL⁴, L⁵ and L⁶ [HL¹ = 2,6-bis[1-(2-aminoethyl)pyrolidine-iminomethyl]-4-methyl-phenol, HL² = 2,6-bis[1-(2-aminoethyl)piperidine-iminomethyl]-4-methyl-phenol, HL³ = N-{1-(2-aminoethyl)pyrolidine}salicylideneimine, HL⁴ = N-{1-(2-aminoethyl)piperidine}salicylideneimine, L⁵ = 2-benzoyl pyridine-N-{1-(2-aminoethyl)pyrolidine}, L⁶ = 2-benzoylpyridine-N-{1-(2-aminoethyl)piperidine}] have been synthesized and characterized. Zn(II) complexes of those ligands have been prepared by conventional sequential route as well as by template synthesis. The same complexes are obtained from the two routes as evident from routine physicochemical characterizations. All the Schiff-bases exhibit photoluminescence originating from intraligand (π–π*) transitions. Metal mediated fluorescence enhancement is observed on complexation of HL¹-HL⁴ with Zn(II), whereas metal mediated fluorescence quenching occurs in Zn(II) complexes of L⁵ and L⁶.     

Radiative lifetimes of the 6p 2 P 1 2/0 and 6p 2 P 3 2/0 levels in Yb II

Radiative lifetimes have been determined for the 6² P ₁ ^2/0 and 6² P ₃ ^2/0 levels in Yb II using the method of laser-induced fluorescence from sputtered metal vapour. The results, 8.0(2)ns (6² P ₁ ^2/0 ) and 6.3(3)ns (6² P ₃ ^2/0 ), are compared with lifetimes obtained from ab initio manybody perturbation calculations.     

Mononukleare und mehrfach verbrückte dinukleare Phthalocyaninate(1–/2–) des Yttriums durch Solvenz‐kontrollierte Kondensation; kleine Solvenz‐Cluster als Liganden

Mononuclear and Multiply Bridged Dinuclear Phthalocyaninates(1–/2–) of Yttrium by Solvent Controlled Condensation; Small Solvent Clusters as Ligands Green chlorophthalocyaninato(2–)yttrium(III), [Y(Cl)pc^2–] forms when yttrium chloride is heated with o‐phthalonitrile in 1‐chloronaphthalene. Black cis‐di(chloro)phthalocyaninato(1‐)yttrium(III), ^cis[Y(Cl)₂pc^–] is obtained as a stable intermediate by partial reduction. Both complexes are soluble in many O‐donor solvents and pyridine. The solubility in water is remarkable: [Y(Cl)pc^2–] dissolves with green, ^cis[Y(Cl)₂pc^–] with red‐violet color. Typical absorptions of the pc^2– ligand are observed at 14800 and 29700 cm^–1. A solvent dependent monomer‐dimer equilibrium is found for the pc^– radical. The monomer with absorptions at 12100 and 19900 cm^–1 is favored in non‐polar solvents, while in polar solvents the dimer with absorptions at 8700, 13200 and 18600 cm^–1 is preferred. cis‐Tri(dimethylformamide)chlorophthalocyaninato(2–)yttrium(III) etherate ( 1 ) crystallises from a solution of [Y(Cl)pc^2–] in MeOH/dmf, cis‐tetra(dimethylsulfoxide)phthalocyaninato(2–)yttrium(III) chloride etherate methanol disolvate ( 2 ) from thf/dmso, μ‐di(chloro)‐μ‐di〈di(pyridine)(μ‐water)〉di(phthalocyaninato(2–)‐ yttrium(III)) ( 5 ) from py, and cis‐(chloro)pyridine(triphenylphosphine oxide)phthalocyaninato(2–)yttrium(III) semi‐etherate ( 3 ) is obtained from a solution of [Y(Cl)pc^2–] and triphenylphosphine oxide in py. 1 condenses in MeOH yielding a (1 : 1)‐mixture ( 4 ) of μ‐di(chloro)di(〈trans‐(diwaterdimethanol)〉〈dimethanol〉phthalocyaninato(2–)yttrium(III)) ( 4 a ) and μ‐di(chloro)di(dimethylformamide〈dimethanol〉phthalocyaninato(2–)yttrium(III)) ( 4 b ); co‐ordinatively bound solvent clusters are in brakets. The structures of 1 – 5 have been established by X‐ray crystallography. Apart from 3 with hepta‐co‐ordinated yttrium, the metal ion prefers octa‐co‐ordination, and the bond arrangement around Y³⁺ is always a distorted quadratic antiprism. In the dinuclear complexes obtained by solvent controlled condensation both antiprisms share an edge by two μ‐Cl atoms in 4 , while in 5 the antiprisms are face‐shared by two trans positioned μ‐Cl atoms and μ‐O atoms, respectively. In 5 , the bent ^b〈{py}₂(μ‐H₂O)〉 cluster is stabilised by a combined interplanar bonding of pyridine by short N…H–O bonds (d(N…O) = 2.664(7) Å; 2.81(2) Å) and strong van‐der‐Waals interactions with the ecliptic pc^2– ligands. 4 a and 4 b contain the dimeric methanol cluster 〈(MeOH)₂〉, and 4 a in addition the cyclic heterotetrameric trans‐diwaterdimethanol cluster, trans^c〈(H₂O)₂(MeOH)₂〉. The neutral clusters co‐ordinatively bound to the Y atom are compared with structurally established cluster‐anions of type 〈(OMe)(MeOH)〉^–, linear ^l〈(OMe)(MeOH)₂〉^–, cyclic ^c〈(OH)₃(H₂O)₃〉^3–, ^b〈{H₂O}₂(μ‐O)〉^2–, and ^b{H₂O}₂(μ‐F)〉^–.     

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

The cationic cluster complexes [Ru₃(μ‐H)(μ‐κ²N,C‐L¹ Me)(CO)₁₀]⁺ ( 1 ⁺; HL¹ Me=N‐methylpyrazinium), [Ru₃(μ‐H)(μ‐κ²N,C‐L² Me)(CO)₁₀]⁺ ( 2 ⁺; HL² Me=N‐methylquinoxalinium), and [Ru₃(μ‐H)(μ‐κ²‐N,C‐L³ Me)(CO)₁₀]⁺ ( 3 ⁺; HL³ Me=N‐methyl‐1,5‐naphthyridinium), which contain cationic N‐heterocyclic ligands, undergo one‐electron reduction processes to become short lived, ligand‐centered, trinuclear, radical species ( 1 – 3 ) that end in the formation of an intermolecular C? C bond between the ligands of two such radicals, thus leading to neutral hexanuclear derivatives. These dimerization processes are selective, in the sense that they only occur through the exo face of the bridging ligands of trinuclear enantiomers of the same configuration, as they only afford hexanuclear dimers with rac structures (C₂ symmetry). The following are the dimeric products that have been isolated by using cobaltocene as reducing agent: [Ru₆(μ‐H)₂{μ₆‐κ⁴N₂,C₂‐(L¹ Me)₂}(CO)₁₈] ( 5 ; from 1 ⁺), [Ru₆(μ‐H)₂{μ₆‐κ⁴N₂,C₂‐(L² Me)₂}(CO)₁₈] ( 6 ; from 2 ⁺), and [Ru₆(μ‐H)₂{μ₄‐κ⁸N₂,C₆‐(L³ Me)₂}(CO)₁₈] ( 7 ; from 3 ⁺). The structures of the final hexanuclear products depend on the N‐heterocyclic ligand attached to the starting materials. Thus, although both trinuclear subunits of 5 and 6 are face‐capped by their bridging ligands, the coordination mode of the ligand of 5 is different from that of the ligand of 6 . The trinuclear subunits of 7 are edge‐bridged by its bridging ligand. In the presence of moisture, the reduction of 3 ⁺ with cobaltocene also affords a trinuclear derivative, [Ru₃(μ‐H)(μ‐κ²N,C‐L^3′ Me)(CO)₁₀] ( 8 ), whose bridging ligand (L^3′ Me) results from the formal substitution of an oxygen atom for the hydrogen atom (as a proton) that in 3 ⁺ is attached to the C⁶ carbon atom of its heterocyclic ligand. The results have been rationalized with the help of electrochemical measurements and DFT calculations, which have also shed light on the nature of the odd‐electron species, 1 – 3 , and on the regioselectivity of their dimerization processes. It seems that the sort of coupling reactions described herein requires cationic complexes with ligand‐based LUMOs.     

Mononitrosyl‐ und trans‐Dinitrosyl‐Komplexe von Phthalocyaninaten des Mangans und Rheniums

Mononitrosyl and trans ‐Dinitrosyl Complexes of Phthalocyaninates of Manganese and Rhenium Tetra(n‐butyl)ammonium or di(triphenylphosphane)iminium nitrosylacidophthalocyaninato(2–)manganate, (cat)[Mn(NO)(X)pc^2–] (X = ONO, NCO, N₃; cat = ⁿBu₄N, PNP) is prepared from acidophthalocyaninato(2–)manganese, [Mn(X)pc^2–], (cat)NO₂ and (ⁿBu₄N)BH₄ in CH₂Cl₂ or from nitrosylphthalocyaninato(2–)manganese, [Mn(NO)pc^2–] and (ⁿBu₄N)X (X = ONO, NCO, N₃, NCS) at T < 120 °C, respectively. [Mn(NO)(X)pc^2–]^– dissociates in methanol, and [Mn(NO)pc^2–] precipitates. Nitrito(O)phthalocyaninato(2–)manganese, (cat)NO₂ and hydrogensulfide yield trans‐di(nitrosyl)phthalocyaninato(2–)manganate, ^trans[Mn(NO)₂pc^2–]^–, isolated as red violet (PNP) and (ⁿBu₄N) complex salt. Nitrosyl(triphenylphosphane oxide)phthalocyaninato(2–)manganese, [Mn(NO)(OPPh₃)pc^2–] is obtained by addition of OPPh₃ to [Mn(NO)pc^2–] at 200 °C. Di(triphenylphosphane)phthalocyaninato(2–)rhenium(II) and (PNP)NO₂ in CH₂Cl₂ or in molten (PNP)NO₂ and PPh₃ at 100 °C yields green blue l‐di(triphenylphosphane)iminium nitrosylnitrito(O)phthalocyaninato(2–)rhenate, ^l(PNP)[Re(NO)(ONO)pc^2–]. Similarly, but with (ⁿBu₄N)NO₂ red plates of tetra‐(n‐butyl)ammonium trans‐di(nitrosyl)phthalocyaninato(2–)rhenate, (ⁿBu₄N)^trans[Re(NO)₂pc^2–] is isolated. Addition of (PNP)Br or (PNP)PF₆ to a concentrated solution of (ⁿBu₄N)^trans[Re(NO)₂pc^2–] in pyridine precipitates ^l(PNP)^trans[Re(NO)₂pc^2–]. (ⁿBu₄N)^trans[Re(NO)₂pc^2–] and PPh₃ at 300 °C yield blue green nitrosyl(triphenylphosphane oxide)phthalocyaninato(2–)‐ rhenium, [Re(NO)(OPPh₃)pc^2–], that is oxidised with iodine precipitating nitrosyl(triphenylphosphane oxide)phthalocyaninato(2–)rhenium triiodide, [Re(NO)(OPPh₃)pc^2–]I₃. The crystal structures of ^l(PNP)[Mn(NO)(ONO)pc^2–] ( 1 ), ^l(PNP)‐ [Mn(NO)(NCO)pc^2–] ( 2 ), ^l(PNP)^trans[Mn(NO)₂pc^2–] ( 3 ), ^l(PNP)^trans[Re(NO)₂pc^2–] ( 4 ) [Mn(NO)(OPPh₃)pc^2–] ( 5 ), [Re(NO)(OPPh₃)pc^2–] ( 6 ), and [Re(NO)(OPPh₃)pc^2–]I₃ · CH₂Cl₂ ( 7 ) have been determined. The M–N(NO) distance varies between 1.623(12) Å in 5 and 1.846(3) Å in 3 . The M–N–O moiety is almost linear. The UV‐Vis spectra with the B band at ca. 14500 cm^–1and the Q band at 30400 cm^–1 do not dependent significantly on the axial ligand and the metal atom and its oxidation state. N–O stretching vibrations are observed in the IR spectra between 1701 cm^–1 in 3 and 1753 cm^–1 in [Mn(NO)pc^2–] or for the Re series between 1571 cm^–1 in 4 and 1724 cm^–1 in 7 . M–N(NO) stretching and M–N–O deformation vibrations are assigned in the IR spectra and resonance Raman spectra between 486 cm^–1 in 4 and 620 cm^–1 in 1 .     

Alkane loss from collisionally activated alkylmethyleneimmonium ions

The collision-induced dissociation (CID) spectra of five alkylmethyleneimmonium ions (H₂C-N⁺R¹R², (a) R¹ = R² = C₂H₅, (b) R¹ = n-C₃H₇, R² = H, (c) R¹ = n-C₃H₇, R² = CH₃, (d) R¹ = n-C₃H₇, R² = C₂H₅, (e) R¹ = R² = n-C₃H₇) are reported and discussed in terms of the mechanism of alkane loss. The most abundant alkane losses result from 2-azaallylic bond cleavages within R¹ and R² leading to daughter ions of m/z 84. Ion d (R¹ = n-C₃H₇, R² = C₂H₅) was chosen for a deuterium-labelling study because it exhibited methane loss nearly free from interferences with other fragmentations. The methane lost consists to a great extent (95%) of the methyl moiety of R². Whereas the methyl moiety obviously stays intact during the fragmentation process, the hydrogen additionally needed originates from all positions of R¹ and the double-bonded methylene in an approximately random distribution, suggesting extensive hydrogen migrations preceding the transfer step.     

Rate coefficients and mechanisms of the reaction of cl‐atoms with a series of unsaturated hydrocarbons under atmospheric conditions

Rate coefficients and/or mechanistic information are provided for the reaction of Cl‐atoms with a number of unsaturated species, including isoprene, methacrolein ( MACR ), methyl vinyl ketone ( MVK ), 1,3‐butadiene, trans‐2‐butene, and 1‐butene. The following Cl‐atom rate coefficients were obtained at 298 K near 1 atm total pressure: k(isoprene) = (4.3 ± 0.6) × 10^?10cm³ molecule^?1 s^?1 (independent of pressure from 6.2 to 760 Torr); k( MVK ) = (2.2 ± 0.3) × 10^?10 cm³ molecule^?1 s^?1; k( MACR ) = (2.4 ± 0.3) × 10^?10 cm³ molecule^?1 s^?1; k(trans‐2‐butene) = (4.0 ± 0.5) × 10^?10 cm³ molecule^?1 s^?1; k(1‐butene) = (3.0 ± 0.4) × 10^?10 cm³ molecule^?1 s^?1. Products observed in the Cl‐atom‐initiated oxidation of the unsaturated species at 298 K in 1 atm air are as follows (with % molar yields in parentheses): CH₂O (9.5 ± 1.0%), HCOCl (5.1 ± 0.7%), and 1‐chloro‐3‐methyl‐3‐buten‐2‐one (CMBO, not quantified) from isoprene; chloroacetaldehyde (75 ± 8%), CO₂ (58 ± 5%), CH₂O (47 ± 7%), CH₃OH (8%), HCOCl (7 ± 1%), and peracetic acid (6%) from MVK ; CO (52 ± 4%), chloroacetone (42 ± 5%), CO₂ (23 ± 2%), CH₂O (18 ± 2%), and HCOCl (5%) from MACR ; CH₂O (7 ± 1%), HCOCl (3%), acrolein (≈3%), and 4‐chlorocrotonaldehyde (CCA, not quantified) from 1,3‐butadiene; CH₃CHO (22 ± 3%), CO₂ (13 ± 2%), 3‐chloro‐2‐butanone (13 ± 4%), CH₂O (7.6 ± 1.1%), and CH₃OH (1.8 ± 0.6%) from trans‐2‐butene; and chloroacetaldehyde (20 ± 3%), CH₂O (7 ± 1%), CO₂ (4 ± 1%), and HCOCl (4 ± 1%) from 1‐butene. Product yields from both trans‐2‐butene and 1‐butene were found to be O₂‐dependent. In the case of trans‐2‐butene, the observed O₂‐dependence is the result of a competition between unimolecular decomposition of the CH₃CH(Cl)? CH(O?)? CH₃ radical and its reaction with O₂, with k_decomp/k_O2 = (1.6 ± 0.4) × 10¹⁹ molecule cm^?3. The activation energy for decomposition is estimated at 11.5 ± 1.5 kcal mol^?1. The variation of the product yields with O₂ in the case of 1‐butene results from similar competitive reaction pathways for the two β‐chlorobutoxy radicals involved in the oxidation, ClCH₂CH(O?)CH₂CH₃ and ?OCH₂CHClCH₂CH₃. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 334–353, 2003     

P (VDF‐co‐CTFE)‐g‐P2VP amphiphilic graft copolymers: Synthesis,structure, and permeation properties

A series of amphiphilic graft copolymers of poly (vinylidene fluoride‐co‐chlorotrifluoroethylene)‐g‐poly(2‐vinyl pyridine), P (VDF‐co‐CTFE)‐g‐P2VP, with different degrees of P2VP grafting (from 26.3 to 45.6 wt%) was synthesized via one‐pot atom transfer radical polymerization (ATRP). The amphiphilic properties of P (VDF‐co‐CTFE)‐g‐P2VP graft copolymers allowed itself to self‐assemble into nanoscale structures. P (VDF‐co‐CTFE)‐g‐P2VP graft copolymers were introduced into neat P (VDF‐co‐CTFE) as additives to form blending membranes. When two different solvents, N‐methyl‐2‐pyrrolidone (NMP) and dimethylformamide (DMF), were used, specific organized crystalline structures were observed only in the NMP systems. P (VDF‐co‐CTFE)‐g‐P2VP played a pivotal role in controlling the morphology and pore structure of membranes. The water flux of the membranes increased from 57.2 to 310.1 L m^?2 h^?1 bar^?1 with an increase in the PVDF‐co‐CTFE‐g‐P2VP loading (from 0 to 30 wt%) due to increased porosity and hydrophilicity. The flux recovery ratio (FRR) increased from 67.03% to 87.18%, and the irreversible fouling (R_ir) decreased from 32.97% to 12.82%. Moreover, the pure gas permeance of the membranes with respect to N₂ was as high as 6.2 × 10⁴ GPU (1 GPU = 10^–6 cm³[STP]/[s cm² cmHg]), indicating their possible use as a porous polymer support for gas separation applications.     

Experimental study of the D + H2 (v = 1) reaction by CARS spectroscopy

The reactions D + H₂ (v = 0, 1) → HD (v = 0, 1) + H have been studiedin a discharge flow reactor by CARS-spectroscopy. For H₂(v = 0) molecules a rate constant of (4, 0 ± 1, 0) 10^?16 cm³ s^?1 is obtained at 310 K from measured HD (v = 0, 1) product yields. Keeping the degree of vibrational excitation of H₂in the microwave discharge in the range of 1% from the increase of the HD (v = 0, 1) CARS signals a rate of k_{2a, b} = (1, 0 ± 0, 4) 10^?13cm³ s^?1 is derived. The total consumption of H₂ (v = 1) in the presence of D atoms gives a rate k₂ = (1, 9 ± 0, 2) 10^?13 cm³ s^?1 at 310 K. The resultsare discussed in regard to previous measurements and theoretical treatments.     

Voltammetry of Dissolved Iron(III)–Nitrilotriacetate–Hydroxide System in Water Solution

The investigation of the dissolved iron(III)–nitrilotriacetate–hydroxide system in the water solution (I=0.1 mol L^?1 in NaClO₄; pH 8.0±0.1) using differential pulse cathodic voltammetry, cyclic voltammetry, and sampled direct current (DC) polarography, was carried out on a static mercury drop electrode (SMDE). The dissolved iron(III) ion concentrations varied from 2.68×10^?6 to 6×10^?4 mol L^?1 and nitrilotriacetate concentrations were 1×10^?4 and 5×10^?4 mol L^?1. By deconvoluting of the overlapped reduction voltammetric peaks using Fourier transformation, four relatively stable, dissolved iron(III) complex species were characterized, as follows: [Fe(NTA)₂]^3?, mixed ligand complexes [FeOHNTA]^? and [Fe(OH)₂NTA]^2?, showing a one‐electron quasireversible reduction, and binuclear diiron(III) complex [NTAFeOFeNTA]^2?, detected above 4×10^?4 mol L^?1 of the added iron(III) ions, showing a one‐electron irreversible reduction character. The calculations with the constants from the literature were done and compared with the potential shifts of the voltammetric peaks. Fitting was obtained by changing the following literature constants: log β₂([Fe(NTA)₂]^3?) from 24 to 27.2, log β₁([FeNTA]^?) from 8.9 to 9.2, log β₂([Fe(NTA)₂]^4?) from 11.89 to 15.7 and log β₂([Fe(OH)₂NTA]^3?) from 15.63 to 19. The determination of the electrochemical parameters of the mixed ligand complex [FeOHNTA]^?, such as: transfer coefficient (α), rate constant (k_s) and formal potential (E°') was done using a sampled DC polarography, and found to be 0.46±0.05, 1.0±0.3×10^?3 cm s^?1, and ?0.154±0.010 V, respectively. Although known previously in the literature, these four species have now for the first time been recorded simultaneously, i.e. proved to exist simultaneously under the given conditions.     

Synthesis and characterization of nickel(II) complexes with three potentially hexadentate Schiff-base ligands and polyamines: X-ray crystal structure determination of one nickel(II) complex

Three new potentially hexadentate N₄O₂ Schiff-base ligands (H₂L¹, H₂L² and H₂L³) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L¹), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L²) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L³), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)₃ gave the neutral complexes [NiL⁴], [NiL⁵] and [NiL⁶]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L¹)(MeCN)₂](ClO₄)₂·MeCN has been characterized through X-ray diffraction methods.     

Novel Octahedral Bis[2‐(1‐aziridinyl)ethanol‐κ2N,O] Complexes of Cobalt(II)

The synthesis and molecular structure of trans‐{bis[(acetato‐κO)‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 4 ) and cis‐{bis[chlorido‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 5 ) is reported. Both neutral chelate complexes are prepared from the corresponding Co^II salt [CoX₂; X = OAc ( 1 ), Cl ( 2 )] and 2‐(1‐aziridinyl)ethanol (azolH, 3 ) in dry dichloromethane. A third, ionic complex, cis‐{bis[aqua‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) diacetate ( 6 ) is formed from 4 in the presence of water and could be crystallized from aqueous dichloromethane. In all cases, 2‐(1‐aziridinyl)ethanol is coordinating as bidentate chelate ligand by the nitrogen and oxygen atom of the aziridinyl and hydroxy moiety. After purification, the compounds have been fully characterized using IR spectroscopy and FAB⁺‐MS. The single‐crystal X‐ray structure analysis revealed a distorted octahedral geometry for all complexes with either trans ( 4 ) or cis ( 5 , 6 ) configuration.     

Preparation and Properties of trans-[CoCl2(tmd>)2]Cl,and trans- and cis-[Co(NCS)2(tmd)2]NO3 (tmd: Tetramethylenediamine)

The cobalt(III) complexes [CoX₂(tmd)₂]⁺ (X: Cl^? or NCS^?, tmd: tetramethylenediamine), in which tmd forms a seven-membered chelate ring, have been prepared. Trans-[CoCl₂(tmd)₂]Cl was derived from [Co(NO₂)₂(tmd)₂]NO₃ in a fairly good yield. Two geometrical isomers, trans and cis, of [Co(NCS)₂-(tmd)₂]NO₃ were independently synthesized from trans-[CoCl₂(tmd)₂]Cl by different methods. The geometrical configurations of the isomeric pair of the NCS complex have been determined based on chromatographic behavior, electronic absorption spectra, and vibrational spectra. The d-d and CT absorption maxima of the NCS complex (18.7 x 10³cm^?1 (ε = 275) and 30.9 x 10³cm^?1 (ε = 3630) for the trans isomer, 19.3 x 10³cm^?1 (ε = 302) and 31.0 x 10³cm^?1 (ε = 4070) for the cis isomer) and the Co-N(amine) stretching frequency of trans-[CoCl₂(tmd)₂]Cl (418 cm^?1) have been compared with those of the corresponding ethylenediamine and trimethylenediamine complexes.     

Lanthanide(II) Complexes of the Dihydrotriazinido Ligand [N{C(Ph)=N}2C(tBu)Ph]−

The potassium dihydrotriazinide K(L^Ph,tBu) ( 1 ) was obtained by a metal exchange route from [Li(L^Ph,tBu)(THF)₃] and KOtBu (L^Ph,tBu = [N{C(Ph)=N}₂C(tBu)Ph]). Reaction of 1 with 1 or 0.5 equivalents of SmI₂(thf)₂ yielded the monosubstituted Sm^II complex [Sm(L^Ph,tBu)I(THF)₄] ( 2 ) or the disubstituted [Sm(L^Ph,tBu)₂(THF)₂] ( 3 ), respectively. Attempted synthesis of a heteroleptic Sm^II amido‐alkyl complex by the reaction of 2 with KCH₂Ph produced compound 3 due to ligand redistribution. The Yb^II bis(dihydrotriazinide) [Yb(L^Ph,tBu)₂(THF)₂] ( 4 ) was isolated from the 1:1 reaction of YbI₂(THF)₂ and 1 . Molecular structures of the crystalline compounds 2 , 3· 2C₆H₆ and 4· PhMe were determined by X‐ray crystallography.     

Metabolism of Deuterated threo‐Dihydroxy Fatty Acids in Saccharomyces cerevisiae: Enantioselective Formation and Characterization of Hydroxylactones and γ‐Lactones

Biotransformation of (±)‐threo‐7,8‐dihydroxy(7,8‐²H₂)tetradecanoic acids (threo‐(7,8‐²H₂)‐ 3 ) in Saccharomyces cerevisiae afforded 5,6‐dihydroxy(5,6‐²H₂)dodecanoic acids (threo‐(5,6‐²H₂)‐ 4 ), which were converted to (5S,6S)‐6‐hydroxy(5,6‐²H₂)dodecano‐5‐lactone ((5S,6S)‐(5,6‐²H₂)‐ 7 ) with 80% e.e. and (5S,6S)‐5‐hydroxy(5,6‐²H₂)dodecano‐6‐lactone ((5S,6S)‐5,6‐²H₂)‐ 8 ). Further β‐oxidation of threo‐(5,6‐²H₂)‐ 4 yielded 3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ), which were converted to (3R,4R)‐3‐hydroxy(3,4‐²H₂)decano‐4‐lactone ((3R,4R)‐ 9 ) with 44% e.e. and converted to ²H‐labeled decano‐4‐lactones ((4R)‐(3‐²H₁)‐ and (4R)‐(2,3‐²H₂)‐ 6 ) with 96% e.e. These results were confirmed by experiments in which (±)‐threo‐3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ) were incubated with yeast. From incubations of methyl (5S,6S)‐ and (5R,6R)‐5,6‐dihydroxy(5,6‐²H₂)dodecanoates ((5S,6S)‐ and (5R,6R)‐(5,6‐²H₂)‐ 4a ), the (5S,6S)‐enantiomer was identified as the precursor of (4R)‐(3‐²H₁)‐ and (2,3‐²H₂)‐ 6 ). Therefore, (4R)‐ 6 is synthesized from (3S,4S)‐ 5 by an oxidation/keto acid reduction pathway involving hydrogen transfer from C(4) to C(2). In an analogous experiment, methyl (9S,10S)‐9,10‐dihydroxyoctadecanoate ((9S,10S)‐ 10a ) was metabolized to (3S,4S)‐3,4‐dihydroxydodecanoic acid ((3S,4S)‐ 15 ) and converted to (4R)‐dodecano‐4‐lactone ((4R)‐ 18 ).     

Structural diversity,magnetic properties and luminescence of NiII,CoII and ZnII coordination polymers derived from 3,3′‐[(5‐carboxy‐1,3‐phenylene)bis(oxy)]dibenzoic acid and 1,10‐phenanthroline

Three novel coordination polymers (CPs), namely poly[[di‐μ‐aqua‐bis{μ₄‐3,3′‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ⁵O¹:O^1′,O³:O⁵:O^5′}bis(1,10‐phenanthroline‐κ²N,N′)trinickel(II)] dimethylformamide 1.5‐solvate trihydrate], {[Ni₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·1.5C₃H₇NO·3H₂O}_n, (I), poly[[di‐μ‐aqua‐bis{μ₄‐3,3′‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ⁵O¹:O^1′,O³:O⁵:O^5′}bis(1,10‐phenanthroline‐κ²N,N′)tricobalt(II)] diethylamine disolvate tetrahydrate], {[Co₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₂H₇N·4H₂O}_n, (II), and catena‐poly[[aqua(1,10‐phenanthroline‐κ²N,N′)zinc(II)]‐μ‐5‐(3‐carboxyphenoxy)‐3,3′‐oxydibenzoato‐κ²O¹:O³], [Zn(C₂₁H₁₂O₈)(C₁₂H₈N₂)(H₂O)]_n, (III), have been synthesized by the reaction of different metal ions (Ni²⁺, Co²⁺ and Zn²⁺), 3,3′‐[(5‐carboxy‐1,3‐phenylbis(oxy)]dibenzoic acid (H₃cpboda) and 1,10‐phenanthroline (phen) under solvothermal conditions. All the CPs were characterized by elemental analysis, single‐crystal and powder X‐ray diffraction, FT–IR spectroscopy and thermogravimetric analysis. Complexes (I) and (II) have isomorphous structures, featuring similar linear trinuclear structural units, in which the central Ni^II/Co^II atom is located on an inversion centre with a slightly distorted octahedral [NiO₆]/[CoO₆] geometry. This comprises four carboxylate O‐atom donors from two cpboda^3? ligands and two O‐atom donors from bridging water molecules. The terminal Ni^II/Co^II groups are each connected to the central Ni^II/Co^II cation through two μ_1,3‐carboxylate groups from two cpboda^3? ligands and one water bridge, giving rise to linear trinuclear [M₃(μ₂‐H₂O)₂(RCOO)₄] (M = Ni²⁺/Co²⁺) secondary building units (SBUs) and the SBUs develop two‐dimensional‐networks parallel to the (100) plane via cpboda^3? ligands with new (3²·4)₂(3²·8³·9)₂(3⁴·4².8²·9⁴·10³) topological structures. Zinc complex (III) displays one‐dimensional coordination chains and the five‐coordinated Zn atom forms a distorted square‐pyramidal [ZnO₃N₂] geometry, which is completed by two carboxylate O‐atom donors from two distinct Hcpboda^2? ligands, one O atom from H₂O and two N atoms from a chelating phen ligand. Magnetically, CP (I) shows weak ferromagnetic interactions involving the carboxylate groups, and bridging water molecules between the nickel(II) ions, and CP (II) shows antiferromagnetic interactions between the Co²⁺ ions. The solid‐state luminescence properties of CP (III) were examined at ambient temperature and the luminescence sensing of Cr₂O₇^2?/CrO₄^2? anions in aqueous solution for (III) has also been investigated.     

Bioactive Hydrogel Layers on Microdisk Electrode Arrays: Cyclic Voltammetry Experiments and Simulations

Poly(hydroxyethylmethacrylate)‐based hydrogel membranes were applied to microfabricated, microdisk electrode arrays (MDEAs) of 50 μm (5184 disks), 100 μm (1296 disks) and 250 μm (207 disks) (d/r=4; A= 0.1 cm²) and studied by cyclic voltammetry (CV) in 1.0 mM ferrocene monocarboxylic acid (FcCO₂H). The membrane produced an order of magnitude decrease in current densities and a shift to quasi reversibility due to a decrease in the D_appt of FcCO₂H, from 4.51×10^?6 cm² s^?1 to 1.42×10^?8 cm² s^?1, (2.18×10^?8 cm² s^?1 from release experiments). The MDEA050 (comprising 50 μm disks) maintained its enhanced current density attributes confirming its value as an effective electrode for biosensors. Finite element modeling (FEM) simulations successfully replicated the voltammograms of the MDEAs.     

A novel two‐dimensional cadmium(II) complex: poly[diaquatris(μ4‐cyclohexane‐1,4‐dicarboxylato)bis[2‐(pyridin‐4‐yl)‐1H‐benzimidazole]tricadmium(II)

The title compound, [Cd₃(C₈H₁₀O₄)₃(C₁₂H₉N₃)₂(H₂O)₂]_n or [Cd₃(chdc)₃(4‐PyBIm)₂(H₂O)₂]_n, was synthesized hydrothermally from the reaction of Cd(CH₃COO)₂·2H₂O with 2‐(pyridin‐4‐yl)‐1H‐benzimidazole (4‐PyBIm) and cyclohexane‐1,4‐dicarboxylic acid (1,4‐chdcH₂). The asymmetric unit consists of one and a half Cd^II cations, one 4‐PyBIm ligand, one and a half 1,4‐chdc²⁻ ligands and one coordinated water molecule. The central Cd^II cation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4‐chdc²⁻ ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric Cd^II cations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4‐PyBIm, five O atoms from three 1,4‐chdc²⁻ ligands and one O atom from an aqua ligand. The 1,4‐chdc²⁻ ligands possess two conformations, i.e.e,e‐trans‐chdc²⁻ and e,a‐cis‐chdc²⁻. The cis‐1,4‐chdc²⁻ ligands bridge the Cd^II cations to form a trinuclear {Cd₃}‐based chain along the b axis, while the trans‐1,4‐chdc²⁻ ligands further link adjacent one‐dimensional chains to construct an interesting two‐dimensional network.     

Multifunctionality in Bimetallic LnIII[WV(CN)8]3− (Ln=Gd,Nd) Coordination Helices: Optical Activity,Luminescence, and Magnetic Coupling

Two chiral luminescent derivatives of pyridine bis(oxazoline) (Pybox), (SS/RR)‐iPr‐Pybox (2,6‐bis[4‐isopropyl‐2‐oxazolin‐2‐yl]pyridine) and (SRSR/RSRS)‐Ind‐Pybox (2,6‐bis[8H‐indeno[1,2‐d]oxazolin‐2‐yl]pyridine), have been combined with lanthanide ions (Gd³⁺, Nd³⁺) and octacyanotungstate(V) metalloligand to afford a remarkable series of eight bimetallic CN^?‐bridged coordination chains: {[Ln^III(SS/RR‐iPr‐Pybox)(dmf)₄]₃[W^V(CN)₈]₃}_n ? dmf ? 4 H₂O (Ln=Gd, 1 ‐SS and 1 ‐RR; Ln=Nd, 2 ‐SS and 2 ‐RR) and {[Ln^III(SRSR/RSRS‐Ind‐Pybox)(dmf)₄][W^V(CN)₈]}_n ? 5 MeCN ? 4 MeOH (Ln=Gd, 3 ‐SRSR and 3 ‐RSRS; Ln=Nd, 4 ‐SRSR and 4 ‐RSRS). These materials display enantiopure structural helicity, which results in strong optical activity in the range 200–450 nm, as confirmed by natural circular dichroism (NCD) spectra and the corresponding UV/Vis absorption spectra. Under irradiation with UV light, the Gd^III‐W^V chains show dominant ligand‐based red phosphorescence, with λ_max≈660 nm for 1 ‐(SS/RR) and 680 nm for 3 ‐(SRSR/RSRS). The Nd^III‐W^V chains, 2 ‐(SS/RR) and 4 ‐(SRSR/RSRS), exhibit near‐infrared luminescence with sharp lines at 986, 1066, and 1340 nm derived from intra‐f ⁴F_3/2→⁴I_{9/2,11/2,13/2} transitions of the Nd^III centers. This emission is realized through efficient ligand‐to‐metal energy transfer from the Pybox derivative to the lanthanide ion. Due to the presence of paramagnetic lanthanide(III) and [W^V(CN)₈]^3? moieties connected by cyanide bridges, 1 ‐(SS/RR) and 3 ‐(SRSR/RSRS) are ferrimagnetic spin chains originating from antiferromagnetic coupling between Gd^III (S_Gd=7/2) and W^V (S_W=1/2) centers with J _{1 ‐(SS)}=?0.96(1) cm^?1, J _{1 ‐(RR)}=?0.95(1) cm^?1, J _{3 ‐(SRSR)}=?0.91(1) cm^?1, and J _{3 ‐(RSRS)}=?0.94(1) cm^?1. 2 ‐(SS/RR) and 4 ‐(SRSR/RSRS) display ferromagnetic coupling within their Nd^III‐NC‐W^V linkages.