Magneto-structural versatility of copper(ii)-3-phenylpropionate coordination polymers with N-donor coligands

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A novel series of copper(II) coordination polymers [Cu-2(O2CC8H9)(4)(pyz)](n) (1), [Cu-2(O2CC8H9)(4)(dps)](n) (2), {[Cu(O2CC8H9)(2)(dps)(H2O)]center dot H2O}(n) (3), {[NaCu(O2CC8H9)(2)(bpm)(NO3)]center dot H2O}(n) (4), and [Cu-4(O2CC8H9)(6)-(OH)(2)(bpp)(2)](n) (5) [O2CC8H9- = 3-phenylpropionate anion, pyz = pyrazine, dps = di(4-pyridyl)sulfide, bpm = 2,2'-bipyrimidine, and bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and magneto-structurally investigated. Compounds 1 and 2 belong to a large group of copper(II) carboxylates where bis-monodentate pyz (1) and dps (2) ligands connect the paddle-wheel [Cu-2(II)(mu-O2CC8H9)(4)] units leading to alternating copper(II) chains. The structure of 3 consists of uniform chains of trans-[Cu-II(O2CC8H9)(2)] units linked by the bis-monodentate dps ligand. Compound 4 consists of heterobimetallic chains where [(Na2Cu2II)-Cu-I(mu-O2CC8H9)(4)(NO3)(2)] units are doubly bridged by bis-bidentate bpm ligands. Compound 5 is also a chain compound whose structure is made up by tetranuclear [Cu-4(II)(mu(3)-OH)(2)(mu-O2CC8H9)(4)(O2CC8H9)(2)] units which are doubly bridged by bis-monodentate bpp ligands. The magnetic properties were investigated in the temperature range 1.8-300 K. Strong antiferromagnetic interactions across the quadruple syn-syn carboxylate are observed in 1 and 2 [J = -378 (1) and -348 cm(-1) (2)] whereas a weak ferromagnetic coupling through the double out-of-plane oxo(carboxylate) bridge occurs in 4 [J = +2.66 cm(-1)], the spin Hamiltonian being defined as H = -JS(1).S-2 with S-1 = S-2 = S-Cu = 1/2. A quasi Curie law is observed for 3 (theta = -0.36 cm(-1)), the bis-monodentate dps ligand being a very poor mediator of magnetic interactions. The analysis of the magnetic properties of 5 is quite complex because of the presence of two crystallographically independent tetracopper(II) units with single-mu-hydroxo, di-mu-hydroxo, mu(3)-hydroxo and single-mu-hydroxo plus double syn, syn carboxylate bridges in each one. The nature and values of the magnetic couplings for 5 obtained by fitting (intermediate, strong and weak antiferromagnetic interactions for the three former exchange pathways respectively, and intermediate ferromagnetic interactions for the latter one) were substantiated by DFT type calculations.A novel series of copper(II) coordination polymers [Cu2(O2CC8H9)4(pyz)]n (1), [Cu2(O2CC8H9)4(dps)]n (2), {[Cu(O2CC8H9)2(dps)(H2O)]·H2O}n (3), {[NaCu(O2CC8H9)2(bpm)(NO3)]·H2O}n (4), and [Cu4(O2CC8H9)6(OH)2(bpp)2]n (5) [O2CC8H9− = 3-phenylpropionate anion,451172189CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)sem informaçãosem informaçãosem informaçãoThe authors thank the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq), the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), FINEP (ref. 134/08

Natural polyprenylated benzophenones: keto-enol tautomerism and stereochemistry

The keto-enol tautomerism and stereochemistry study of a HIV-inhibitory natural benzophenone, (1R,5R,7R,8S)-(+)-3-(10-(3,4-dihydroxyphenyl)-10-hydroxymethylene)-8-methyl -1,5,7-tris(3-methyl-2-butenyl)-8-(4-methyl-3-pentenyl)-bicyclo[3.3.1]nonane-2,4,9-trione (a), isolated from Garcinia brasiliensis seeds is presented. The crystal structure of (a), which is also know as guttiferona A, was determined by X-ray diffraction and its intra and inter-molecular geometries discussed and compared with two analogue natural benzophenones: clusianone and epiclusianone. In (a), the hydroxyl H atom from enolizable 2,4,10-trione moiety is linked in the oxygen atom bonded to 10-(3,4-dihydroxyphenyl)methylene group, in opposition to the related natural benzophenones, where this analogue H-atom is placed in different O-atoms from bicyclo[3.3.1]nonane ring system. Such behaviour can be explained by the presence of aromatic OH6 group in (a) that origins a further delocalized resonance path along of 3,4-dihydroxyphenyl-C10-OH2 group. In addition, the (a) stereochemistry around C7 atom is compared with known structures of clusianone and epiclusianone and the influence from configuration in this chiral C-atom to structural features found in the enolizable system is proposed

Preparation Of Achiral And Chiral (e)-enaminopyran-2,4-diones And Their Phytotoxic Activity.

A short and efficient approach to a range of new chiral and achiral functionalized (E)-enaminopyran-2,4-diones starting with commercially available dehydroacetic acid is described. The phytotoxic properties of these (E)-enaminopyran-2,4-diones were evaluated by their ability to interfere with the growth of Sorghum bicolor and Cucumis sativus seedlings. A different sensitivity of the two crops was evident with the (E)-enaminopyran-2,4-diones. The most active compounds were also tested against two weeds, Ipomoea grandifolia and Brachiaria decumbens. To the best of our knowledge, this is the first report describing enaminopyran-2,4-diones as potential plant growth regulators.571399-40

Solid-State Self-Assembly of a Linear Hexanuclear Copper(II) Oxamate Complex with Alternating Antiferro- and Ferromagnetic Coupling

In this work, we describe the synthesis, crystal structure and magnetic properties of the neutral hexacopper(II) complex of formula {[Cubpca)]2[Cu(dmopba)(H2O)]}2·4H2O (1), where Hbpca = bis(2-pyridylcarbonyl)-amide and dmopba = 4,5-dimethyl-1,2-phenylenebis(oxamato). Single crystals of 1 were obtained from the stoichiometric reaction (1:2 molar ratio) of the mononuclear copper(II) complexes (n-Bu4N)2[Cu(dmpba)] and [Cu(bpca)(H2O)2]NO3·2H2O through slow diffusion techniques in water as a solvent. The crystal structure of 1 shows that two neutral {[Cu(bpca)]2[Cu(dmopba)(H2O)]} trinuclear units are connected through double out-of-plane copper to outer carboxylate oxygen atoms resulting in a unique oxamate-bridged linear hexanuclear complex. Hydrogen bonds among adjacent entities involving the non-coordinated water molecules result in a supramolecular 3D network. Magnetic measurements on 1 show the occurrence of moderate antiferromagnetic intratrinuclear interactions between the copper(II) ions from the [Cu(bpca)]+ and [Cu(dmopba)(H2O)]2− fragments across the oxamate bridge and a weak intertrinuclear ferromagnetic interaction between the copper(II) ions that occurs between the two central [Cu(bpca)]+ fragments mediated by the carboxylate groups from the oxamate bridge [J = −31.96(2) cm−1 and J′ = +1.34(2) cm−1; H = J (S1·S2 + S2·S3 + S1′·S2′ + S2′·S3′) + J′ (S1·S1′)]