Separation and Identification of Lutein Derivatives in Processed Foods

In the present work, we show that in processed sorrel, the lutein (1) can convert to 3’-epilutein (2) – 3’-stereoisomer of lutein – by epimerisation reaction, as well as to anhydrolutein I (3) and II (4) by dehydration reaction. The newly formed anhydrolutein I (3) and II (4) were detected and identified by HPLC-DAD and HPLC-MS techniques and co-chromatography with authentic samples. The compounds 1 and 2 were also isolated from cooked sorrel by column chromatography and characterized by NMR spectroscopy.     

Four supramolecular transition metal(II) complexes based on triazole-benzoic acid derivatives: crystal structure,Hirshfeld surface analysis,and spectroscopic and thermal properties

Four new complexes [M(3-tba)₂(H₂O)₄] (1–3) and [Co(4-tba)₂(H₂O)₄] (4) {M = Zn (1), Ni (2), Co (3), 3-Htba = 3-(1H-1,2,4-triazol-1-yl)benzoic acid, 4-Htba = 4-(1H-1,2,4-triazol-1-yl)benzoic acid} have been synthesized under solvothermal conditions and structurally characterized by single crystal X-ray diffraction. Complexes 1–4 are also determined by elemental analysis, X-ray powder diffraction, IR and electronic spectroscopy. Single crystal X-ray diffraction reveals that complexes 1–3 are isostructural and they crystallize in the orthorhombic space group of Pbca, while complex 4 belongs to triclinic system with Pī space group. Based on different intermolecular hydrogen bonding and π···π stacking interactions, complexes 1–4 further assembled into 3D supramolecular frameworks. Hirshfeld surface analysis was used to further study the intermolecular interactions of the complexes. The thermogravimetric analyses (TGA) reveal that these complexes possess good thermal stability, and the differential scanning calorimetry (DSC) analyses show intense exothermic phenomena in the decomposition processes of triazole groups. Besides, the photoluminescence property of complex 1 in the solid state is also determined.     

Neutral and cationic (pyrazolylmethyl)pyridine palladium(II) complexes: kinetics and chemoselectivity studies in hydrogenation of alkenes and alkynes

Reactions of (3,5-dimethylpyrazolylmethyl)pyridine (L1) and (3,5-diphenylpyrazolylmethyl)pyridine (L2) with either [PdCl₂(NCMe)₂] or [PdClMe(COD)] afforded the respective neutral palladium complexes, [PdCl₂(L1)] (1), [PdCl₂(L2)] (2) and [PdClMe(L1)] (3). Treatment of complex 1 with equimolar amounts of PPh₃ or PPh₃/NaBAr₄ produced the corresponding cationic complexes [Pd(L1)ClPPh₃]Cl (4) and [Pd(L1)ClPPh₃]BAr₄ (5), respectively. Complexes 1–5 formed active catalysts in hydrogenation of alkenes and alkynes. Isomerization reactions were predominant in the hydrogenation reactions of terminal alkenes, while hydrogenation of alkynes involved a two-step process via alkene intermediates prior to the formation of the respective alkenes. The lack of induction periods in the hydrogenation reactions in addition to pseudo-first-order kinetics with respect to the substrates established the homogeneous nature of the active species.     

Ring-opening polymerization of ε-caprolactone catalysed by (pyridyl)benzoazole Zn(II) and Cu(II) complexes

This paper describes the synthesis of (pyridyl)benzoazole Zn(II) and Cu(II) complexes and their applications as catalysts in ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). Reactions of 2-(3-pyridyl)-1H-benzimidazole (L1), 2-(2-pyridyl)-1H-benzothiazole (L2) and 2-(2-pyridyl)-1H-benzimidazole (L3) with Zn(II) and Cu(II) acetates produced the corresponding complexes; [Zn₂(L1)₂(OAc)₄)] (1), [Cu₂(L1)₂(OAc)₄] (2), [Zn(L2)(OAc)₂)] (3), [Zn(L3)(OAc)₂)] (4) and [Cu(L3), (OAc)₂)] (5). Molecular structures of complexes 2 and 5a revealed that while L1 adopts a monodentate binding mode, through the pyridyl nitrogen atom, L3 exhibits a bidentate coordination mode. All the complexes formed active catalysts in the ROP of ε-CL to afford moderate molecular weight polymers. The kinetics of the ROP reactions of ε-CL were pseudo-first-order with respect to monomer and catalysts.     

The synthesis and structural characterization of transition metal coordination complexes of coumarilic acid

The coumarilate (coum^?) complexes of Co^II(1), Ni^II(2) Cu^II(3) and Zn^II(4) were synthesized and characterized by elemental analysis, magnetic susceptibility, solid-state UV–Vis, FTIR spectra, thermoanalytical TG–DTG/DTA and single-crystal X-ray diffraction methods. It was found that all of the complex structures have 2 mol (coum^?) ligand bonded as monoanionic monodentate in the structures of 1 and 2 while they were coordinated to metal cations as monoanionic bidentate in the complexes 3 and 4. There was not any hydrate water in the metal complexes. The complexes of 1 and 2 have four moles of aqua ligand, and the other complexes have two moles. Thermal decomposition of each complex starts with dehydration, and then the decomposition of organic parts goes. The thermal dehydration of the complexes takes place in one (for the compounds of 2, 3, 4) or two (for the compound 1) steps. The decomposition mechanism and the thermal stability of the complexes under investigation were determined on the basis of their structures. Metal oxides were obtained as the final decomposition product.     

One-pot multicomponent synthesis of novel 1-thiazolyl-5-coumarin-3-yl-pyrazole derivatives and evaluation of their cytotoxic activity

A series of novel 1-thiazolyl-5-coumarin-3-yl-pyrazole derivatives (4a–l) were synthesized via one-pot multicomponent reaction of 5-substituted salicylaldehydes (1a–c), 4-hydroxy-6-methyl-2H-pyran-2-one (2) and 2-hydrazinyl-4-arylthiazoles (3a–d) in acetonitrile using a catalytic amount of piperidine under reflux conditions. This multicomponent approach has advantages such as reduced reaction time and a high product yield percentage when compared with corresponding multistep approaches. All the synthesized compounds were evaluated for their cytotoxic activity against Hep G2 (hepatocellular liver carcinoma) and MCF-7 (breast cancer) cell lines and compared with the standard drug Doxorubicin. Among all the compounds, compounds 4d against Hep G2, 4k against MCF-7 and 4e against both Hep G2 & MCF-7 showed excellent cytotoxic activity.     

Tuning the regioselectivity of (benzimidazolylmethyl)amine palladium(II) complexes in the methoxycarbonylation of hexenes and octenes

Reactions of N-(1H-benzoimidazol-2-ylmethyl-2-methoxy)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl-2-bromo)aniline (L2) with p-TsOH, Pd(AOc)₂ and two equivalents of PPh₃ or PCy₃ produced the corresponding palladium complexes, [Pd(L1)(OTs)(PPh₃)] (1), [Pd(L2)(OTs)(PPh₃)] (2) and [Pd(L1)(OTs)(PCy₃)] (3), respectively, in good yields. The new palladium complexes 1–3 and the previously reported complexes [Pd(L1)ClMe] (4) and [Pd(L2)ClMe] (5) gave active catalysts in the methoxycarbonylation of terminal and internal olefins to produce branched and linear esters. The effects of complex structure, nature of phosphine derivative, acid promoter and alkene substrate on the catalytic activities and selectivity have been studied and are herein reported.     

Copper complexes of pyridyl–tetrazole ligands with pendant amide and hydrazide arms: synthesis,characterization, DNA-binding and antioxidant properties

Pyridyl–tetrazole ligands 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetamide (L1), 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetamide (L2), 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetohydrazide (L3) and 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetohydrazide (L4) have been prepared and coordinated with CuCl₂·2H₂O to furnish the corresponding complexes [Cu(L1) ₂ ]–[Cu(L4) ₂ ]. EPR spectra of the complexes are characteristic of square planar geometries, with nuclear hyperfine spin 3/2. DNA-binding studies using UV–Vis absorption spectroscopy, viscosity and thermal denature studies revealed that all of these complexes are avid binders of calf thymus DNA. The antioxidant properties of the free ligands and the Cu(II) complexes were investigated using the p-nitrosodimethyl aniline hydroxyl radical scavenging method, and [Cu(L4) ₂ ] was found to show the highest activity.     

Copper(I) complexes of 2-(benzen-1-yl)methyleneamino-3-aminomaleonitrile and triphenylphosphine ligands: synthesis,characterization, luminescence and catalytic properties

Some mixed ligand copper(I) complexes of general formula [Cu(L)(PPh₃)₃]X (X = Cl (1), ClO₄ (2), BF₄ (3) or PF₆ (4); L = 2-(benzen-1-yl)methyleneamino-3-aminomaleonitrile) were prepared and characterized by physicochemical and spectroscopic methods. A single-crystal X-ray diffraction study of [Cu(L)(PPh₃)₃]CIO₄ (2) revealed that the copper atom is four coordinated in a distorted tetrahedral geometry. Electrochemical studies of complexes 1–4 show quasireversible redox behavior corresponding to the Cu(I)/Cu(II) couple. Room temperature luminescence is observed for all four complexes. These complexes proved to be effective catalysts for the Sonogashira coupling of terminal alkynes with aryl halides at 90 °C.     

Mono-, Di- and Tetranuclear Complexes and Clusters With Bromine-Functionalized Bis(diphenylphosphino)amine Ligands

We report the preparation of bromo-aryl functionalized bis(diphenylphosphino)amine ligands of the type Ph₂PNArPPh₂ (1, Ar = p-BrC₆H₄; 2, Ar = p-BrC₆H₄–C₆H₄) and their coordination properties. Mono- and dinuclear complexes were formed with Cu(I), Au(I), Pd(II), Pt(II) and tetranuclear cobalt carbonyl clusters were obtained. The crystal structures of [PdCl₂(1)] (3), [PdCl₂(2)] (4), [(AuCl)(μ-1)] (6), [Co₄(CO)₅(μ-CO)₃(μ-dppa)(μ-1)] (dppa = Ph₂PNHPPh₂) (8) and [Co₄(CO)₅(μ-CO)₃(μ-dppm)(μ-1)] (dppm = Ph₂PCH₂PPh₂) (9) have been determined by X-ray diffraction. Whereas the diphosphine ligands chelate the metal center in 3 and 4, and in the Pt(II) complex 5 which is analogous to 3, ligand 1 acts as a bridge in 6 where the separation between the two Au(I) centers is 3.0402(5) Å. In the tetranuclear clusters 8 and 9, and in the cluster 10 analogous to 9 with 2 as bridging ligand, two orthogonal Co–Co edges are bridged by a diphosphine ligand and each cobalt center is thus coordinated by one P donor. Complex 3 was shown to react with the Pd(0) complex [Pd(dba)₂] (dba = dibenzylideneacetone) to afford a tetranuclear complex resulting from both the insertion of Pd(0) into the ligand C–Br bond and Pd(II)/Pd(0) comproportionation to form a doubly ligand-bridged Pd(I)–Pd(I) core.     

Conformational isomerism of the seven-membered heterocycle in a single crystal of [η<Superscript>2</Superscript>-Ph<Subscript>2</Subscript>P(O)(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>C(O)NМе<Subscript>2</Subscript>]TiF<Subscript>4</Subscript> adduct

The crystal structure of TiF₄[(Ph₂P(O)CH₂CH₂C(O)NMe₂)] chelate (I) was studied by X-ray crystallography, which revealed four crystallographically independent complex molecules of similar structure (1–4). It was found that the molecules are only slightly different in the bond lengths between the coordinated atoms and the central titanium ion and considerably different in the geometry of the seven-membered TiOPCCCO chelate ring. The geometry of the chelate rings was found to be almost identical in each pair of complexes 1, 2 (A) and 3, 4 (B), and a conclusion was drawn on the presence of two conformational isomers (A and B) of the chelate complex. Quantum chemical calculations of the relative thermodynamic stability of molecules 1–4 were performed, and their geometry optimization led to one theoretical structure. The comparison of the chelate ring geometry in the theoretical structure and in conformers A and B revealed that the conformation of the theoretical chelate ring coincides with that of conformer A.     

Directed assembly of cobalt(II) 1-H-indazole-3-carboxylic acid coordination networks by bipyridine and its derivatives: structural versatility,electrochemical properties,and antifungal activity

This paper describes the hydrothermal synthesis, full characterization, and architectural diversity of three intriguingly bioactive cobalt–organic frameworks, namely, 3D [Co(HL ^? )₂(BPY)] _n ·4nH₂O (1), 2D [Co(HL ^? )₂(BPE)] _n (2), and 2D [Co(HL ^? )₂(DPP)] _n (3) coordination polymers, synthesized through a mixed ligand strategy using H ₂ L (1-H-indazole-3-carboxylic acid) as a main structural block and the flexible bipyridine and its derivatives (BPY = 4,4′-bipydine, BPE = 1,2-bis(4-pyridyl)ethane, DPP = 1,3-bis(4-pyridyl)propane) as auxiliary ligand sources. Complexes 1–3 were isolated as air stable and slightly soluble crystalline solids and characterized using elemental analysis, FT-IR, electrochemical technique, thermogravimetric analysis, powder X-ray diffractometer, and single-crystal X-ray crystallography. The bipyridine derivatives played key roles in defining the structural space group and dimensionality feature of the obtained networks. The abundant H-bonding and π–π stacking interactions in complexes 1–3 gave rise to their intricate metal–organic structures of 3D (1), 2D (2), and 2D (3). In addition, the solutions of complexes 1–3 showed profound antifungal activities against the selected strain of Colletotrichum musae compared with the controlled group using benomyl as a traditional agrochemical fungicide.     

Dynamic in situ solvothermal reactions between ZnX<Subscript>2</Subscript> (X = Cl,ClO<Subscript>4</Subscript>) and a heterocyclic disulfide

Solvothermal reactions of 2-ppds (2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide) with ZnX₂ (X = Cl, ClO₄) in mixed CH₃OH–CH₂Cl₂ solvent have been investigated. To better understand these reactions, solution analysis was conducted in parallel with single-crystal X-ray diffraction analysis of the in situ generated coordination complexes. At 120 °C, solvothermal reaction of 2-ppds with ZnCl₂ resulted in a discrete mononuclear coordination complex formulated as [ZnCl₂(L1)] (1), in which the zwitterion L1 (1-methyl-4-(pyridin-2-yl)pyrimidin-1-ium-2-olate) was formed in situ from 2-ppds, and solution analyses based on TLC and ESI–MS further showed that the reaction solution also contains in situ transformed products of L2 (bis(4-(pyridin-2-yl)pyrimidin-2-yl)sulfane) and L3 (2-methoxy-4-(pyridin-2-yl)pyrimidine). At 90 °C, solvothermal reaction between 2-ppds and Zn(ClO₄)₂ led to a discrete mononuclear coordination complex formulated as [Zn(SH)(L2)]ClO₄ (2) that features a terminally bound –SH group, while the reaction solution was also found to contain a library of in situ reaction products of 2-ppds including L1, L2, L3 and L4 ((4-(pyridin-2-yl)pyrimidin-2-yl) 4-(pyridin-2-yl)pyrimidine-2-sulfonothioate). Thus, the heterocyclic disulfide 2-ppds is transformed in situ into various organic products in a series of reactions involving C–S/S–S bond cleavage.     

X-ray diffraction investigation of perfluoro-4-methylenecyclohexa-2,5-dienones

Perfluorinated 8-phenyl-7,8-diethylbicyclo[4.2.0]octa-1,4,6-trien-3-one (3), 2-(4-oxocyclohexa-2,5-dienylidene)-1,1-diethylbenzocyclobutene (4) and 2-(4-oxocyclohexa-2,5-dienylidene)-5-(2-phenyl-cis-1,2-diethylbenzocyclobuten-1-yloxy)-1,1-diethylbenzocyclobutene (5), including the 4-methylencyclohexa-2,5-dienone fragment, were prepared by the reaction of perfluoro-1,1-(1) and-1,2-diethylbenzocyclobutene (2) with pentafluorobenzene in SbF₅. Single crystal X-ray diffraction study of compounds 3–5 revealed that the oxygen atom of the C=O group participated in the formation of supramolecular architectures in all three compounds, and C=O…π bonding may be considered as the corresponding synthon (with increased separation in the case of compound 5). C-F…π bonding acts as a second synthon. F…F interactions in crystals 3–5 were classified as stabilizing or enforced.     

Synthesis of New Pyrano[2,3-<Emphasis Type="Italic">d</Emphasis>]Pyrazoles and Furochromones Derivatives Utilizing Amino Acids Derivatives

Hydrolysis of oxazolone derivatives (2b) yielded α-khellinoyl(amino)-cinnamic acid (3) as a good precursor to react with ethyl esters of glycine, L-methionine, and glycylglycine affording 4, 5, and 4, 5 respectively with minor product 7. Hydrolysis of oxazolone derivatives (2b) afforded α,β-dehydroamino acid derivatives (DDAA) (8). Interaction of oxazolone derivatives (2a,b) with active methylene compounds as ethyl acetoacetate, malononitrile, ethylcyanoacetate, and cyanoacetamide afforded 9–16 respectively     

Four Mixed 3d-4f 12-Metallacrown-4 Complexes: Syntheses,Structures and Magnetic Properties

The incorporation of Ln^III ions into the 12-metallacrown-4 topology affords the formation of four mixed 3d-4f pentanuclear complexes of compositions [NH(C₂H₅)₃]{[Ln(OAc)₄] [12-MC _Mn ^III _(N)shi-4]}·xH₂O (Ln = Sm (1), Gd (2), Tb (3), Dy (4); x = 0.5 for 1 and 3, x = 0.25 for 2, x = 0 for 4; H₃shi = salicylhydroxamic acid). Compounds 1–4 were obtained from the reactions of H₃shi with Mn(CH₃COO)₂·4H₂O and Ln(NO₃)₃·6H₂O, in the presence of N(C₂H₅)₃. They all contain a crown-like [Mn₄Ln(μ-NO)₄]¹¹⁺ core with four Mn^III atoms being at the rim of the crown and an Ln^III ion occupying the dome of the crown. The peripheral ligation about the core is provided by four η¹:η¹:µ acetate groups. The identity of the Ln^III ions slightly affects the 12-metallacrown-4 frameworks, as demonstrated by the gradual decrease of the distances between the Ln^III ions and the centres of the Mn₄ planes (1.85 Å for 1, 1.81 Å for 2, 1.80 Å for 3, and 1.77 Å for 4). Variable-temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4. Antiferromagnetic interactions are determined for complexes 1–4.     

Transition metal complexes of a hydrazone derived from hydralazine hydrochloride and 3,5-di-tert-butylsalicylaldehyde

Mononuclear Co(III), Ni(II) and Cu(II) coordination compounds of (E)-1-(3,5-di-tert-butyl-2-hydroxybenzylidene)-2-(phthalazin-1-yl)hydrazine (LH) were prepared and characterized by physicochemical and spectroscopic methods. The metal-to-ligand ratio was found to be 1:2 in [Co(L)₂]Cl·2H₂O (1) and [Ni(L)₂]·2H₂O (2), while it is 1:1 in [Cu(L)Cl]·2CH₃OH (3). The X-ray crystal structures of LH and complex 1 is are reported. LH shows monobasic behavior, coordinating through NNO donor atoms. The complexes were investigated for their antimicrobial properties. Complexes 1 and 3 show excellent antibacterial and antifungal activities, respectively.     

Co(II) and Ni(II) complexes with imidazole-containing ligands: Synthesis,structural characterization,and magnetic property

Hydrothermal reaction of Co(II) salt with 1,4-di(1-imidazolyl)benzene (L¹) and 4,4’-oxydiphthalic acid (H₄OA) yields a new complex [Co₃(HOA)₂(L¹)₄(H₂O)₄] (I). [Ni(L²)₂SO₄] · 0.5H₂O (II) can be obtained via the hydrothermal reaction of NiSO₄ · 6H₂O with 1,3-di(1H-imidazol-4-yl)benzene (L²). Complexes I and II have been characterized by single-crystal and powder X-ray diffraction (CIF files CCDC nos. 1019291 (I) and 1019292 (II)), IR, elemental, and thermogravimetric analyses. Complex I exhibits the uninodal six-connected 3D pcu framework structure of I with (4¹² · 6³) topology; Complex II consists of the uninodal four-connected 2D sql (4⁴ · 6²) networks. In addition, magnetic property of I was investigated.     

Tetraphenylantimony perrhenate and tetraphenylantimony chlorate: Syntheses and structures

The reaction of tetraphenylantimony chloride with sodium perrhenate or potassium chlorate yields tetraphenylantimony perrhenate (I) and tetraphenylantimony chlorate (II), respectively. Complex I was also synthesized from pentaphenylantimony and triphenylantimony diperrhenate in toluene. According to X-ray diffraction, crystals I and II consist of almost regular tetrahedral tetraphenylstibonium cations (CSbC, 109.4(2)°–109.5(7)° in I and 109.1(1)°–109.6(1)° in II) and [ReO₄]^? (OreO, 107.6(3)°–113.3(5)°) and [ClO₃]^? (OClO, 96.3(9)°, 116.4(5)°) anions, respectively. The average Sb-C bond lengths (2.094(3) Å in I, 2.097(2) Å in II) are close to the sum of the covalent radii of the Sb and C atoms. The average distances Re-O in complex I (1.672(4) Å) and Cl-O in complex II (1.315 Å) correspond to multiple bonds.     

Influence of the nature of the substituent in 3-(2-pyridyl)-1,2,4-triazole for complexation with Pd<Superscript>2+</Superscript>

The structure of four new palladium complexes [Pd(HL ² )Cl ₂ and Pd(L ^1–3 ) ₂ ] with 3-(2-pyridyl)-5-R-1,2,4-triazoles (R=H, CH₃, Ph respectively HL ¹ , HL ² , HL ³ ) was proposed based on IR, NMR, UV spectroscopy and MALDI mass spectrometry data analysis. It is found that the complexation of HL ² and HL ³ with Pd²⁺ ions results in a decrease of their fluorescence intensity and it is vice versa in case of HL ¹ . Furthermore, the influence of the substituent (R) in the 3-(2-pirydyl)-5-R-1,2,4-triazoles on the fluorescent and protolytic properties of HL ^1–3 was investigated.