Ivo Vencato

Retired

O presente trabalho descreve as atividades antibacterianas e antifúngicas de diversas chalconas obtidas diretamente através da condensação aldólica tipo Claisen-Schmidt das quais se determinou a concentração inibitória mínima frente a diferentes microrganismos (bactérias Gram-positivas e Gram-negativas e fungos). Estruturas no estado sólido cristal...

This article describes an undergraduate experiment for the synthesis of p-nitrophenyldiazonium chloride and its coupling with acetylacetone and two enaminones, 4-phenylamino-pent-3-en-2-one and 4-amino-pent-3-en-2-one, in an adaptation of a previously reported synthetic protocol. The azo dyes 4-(E)-phenylamino-3-[(E)-2-(4-nitrophenylazo)]-3-penten-...

This study represents an integrated approach towards understanding the electronic and structural aspects of 2-benzylamino-1,4-naphthalenedione, a representative 2-amino-napfthoquinone. To this end, theoretical calculations performed at the B3PW91/6-31+G(d) level of density functional theory, electrochemical and X-ray structural investigation were e...

Avenaciolide, a natural product isolated from Aspergillus avenaceus H. Smith, possesses several interesting biological properties, such as antifungal and antibacterial activities and inhibition of glutamate transport in mitochondria. In a study aiming to discover new compounds with antifungal activity, a bis-gamma-lactone analogous to avenaciolide...

Guanil-hidrazonas poli-substituídas foram sintetizadas através da reação de guanilação de tiossemicarbazonas com aminas aromáticas e alifáticas, promovida HgCl2. Este método representa o primeiro emprego de tiossemicarbazonas como componente eletrofílico em reações de síntese de guanidinas mediadas por tiófilo, onde a introdução de cada substituint...

The reaction of the ambidentate ligand dibenzylsulfoxide (dbso) with Me2SnCl2 in 1:1 molar ratio leads to the formation of the five-coordinate adduct [Me2SnCl2(dbso)], whereas the same reaction conditions with Ph2SnCl2 provide the six-coordinate adduct trans-[Ph2SnCl2(dbso)2]. On the other hand, the reaction with nBu2SnCl2 forms the dimeric adduct...

Thiosemicarbazones were employed for the first time as electrophiles in the guanylation reaction promoted by HgCl2, affording polysubstituted guanylhydrazones, with regioselective introduction of each nitrogen substituent. The antibacterial and antifungal activities of guanylhydrazones were evaluated by determination of minimal inhibitory concentra...

The crystal structure of synthetic ferrous hureaulite, Fe5 2+ (H2O)4(PO4H)2(PO4)2, was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å, β=96.27(3)°, V=1463.6(6) Å3, Z=4 and D calc=3.327 g/cm3. This end member of the hureaulite series was crystallized under distinctly acidic cond...

A novel dinuclear copper(II) complex with the amino acid L-arginine (L-arg), with mono and bidentate HPO42- oxoanions and an OH- anion. [CU2(L-arg)(2)(mu-HPO4-O)(mu-HPO4-O,O')(mu-OH)](-) center dot (H3O)(+) center dot 6H(2)O (1) was prepared and its structure was determined by X-ray diffraction methods. The two independent copper ions are in a dist...

The title compound, C18H22N2O2S, is of interest with respect to antibacterial and anticancer activity and it has shown good trypanocidal activity. The molecular packing lacks classical hydrogen bonds, being mediated only by weak van der Waals forces.

The title compound, C16H18N2O3S, is of interest with respect to antibacterial and anticancer activity and shows some trypanocidal activity. The crystal packing displays O—H...N and C—H...S hydrogen bonds, forming a chain parallel to the [100] direction. The crystal structure also shows a short intermolecular C=O...π-ring interaction connecting cent...

The title compound, C18H22N2O2S, is of inter­est with respect to anti­bacterial and anti­cancer activity and it has shown good trypanocidal activity. The mol­ecular packing lacks classical hydrogen bonds, being mediated only by weak van der Waals forces.

The antimicrobial activity of six N-phenyl- and fourteen N-benzoylthiourea derivatives were evaluated from their Minimal Inhibitory Concentration (MIC) values using the microdilution procedure against ten microorganisms. Most of the compounds exhibited selective activity against fungi and Gram-positive bacteria, which were very effectively inhibite...

In this work we have prepared a manganese(II) complex using the tridentate ligand N,N-bis(2-pyridylmethyl)amine (bpma). The manganese complex was characterized by elemental analysis, conductivity measurements and infrared, electronic (UV–vis) and EPR spectroscopic techniques. The analysis of the complex obtained has shown that the formula is [Mn(bp...

This work describes a two-step, one-pot synthetic method for the formal aza-[3 + 3] cycloaddition between N-alkyl substituted enaminones and benzoyl isothiocyanate, which afforded 4-thioxopyrimidines in reasonable yields. Reaction of acyclic enaminone with a sterically hindered group attached to the nitrogen atom afforded pyridine-2-thione, yet in...

Apresentamos neste trabalho aspectos teóricos da difração de raios X procurando discutir os principais conceitos envolvidos neste fenômeno a partir da interação entre radiação e matéria. Desenvolve-se uma formulação da lei de Bragg para a difração considerando a interação da radiação X com a matéria cristalina. Aplicamos ainda a lei de Bragg em um...

The reaction of Fe(ClO4)3.nH2O with N,N'-bis[(2-hydroxybenzyl)-N,N' -bis(1-methylimidazole-2-yl-methyl)]ethylenediamine (H2bbimen) affords two geometric isomers, A and B, of the complex cation [Fe(bbimen)]+, which were fully characterized by IR and UV-visible spectroscopies, ESI mass spectrometry, molar conductivity measurements, cyclic voltammetry...

Complex [Fe2III(BPClNOL)2(SO4)] 3 was synthesized through the reaction of the pro-ligand N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine (H2BPClNOL) and FeSO4.7H2O. The maximum absorption for the oxidized compound was at 519 nm (e = 1.40´103 dm3 mol-1 cm-1) while that of the mixed-valence compound was at 439 nm (e = 9.8´10...

In the title enaminone, C13H13NO4, the 1,3-dioxane-4,6-dione ring exhibits a distorted boat conformation. The amino H atom has one intra­molecular contact to a carbonyl O atom, forming a six-membered ring. Mol­ecules related by an inversion center are linked into dimers by N—H⋯O and C—H⋯O hydrogen bonds.

In the title compound C15H14N2OS, centrosymmetric dimers are formed via intermolecular N-(HS)-S-... hydrogen bonds. The dimeric units are linked by a weak intermolecular C-(HS)-S-... hydrogen bond, forming infinite chains along [010]. Additionally, unprecedented C-H-...pi interactions, involving the benzoyl group of the thiourea group as donor-acce...

In the title compound C15H14N2OS, centrosymmetric dimers are formed via inter­molecular N—H⋯S hydrogen bonds. The dimeric units are linked by a weak inter­molecular C—H⋯S hydrogen bond, forming infinite chains along [010]. Additionally, unprecedented C—H⋯π inter­actions, involving the benzoyl group of the thio­urea group as donor–acceptor, connect...

In the crystal structure of the title compound [systematic name: (17R,20α,21β)-1,2-didehydro-1-demethyl-19-hydr­oxy-21-methyl-18-norajmalan-17-yl acetate], C21H24N2O3, an inter­molecular O—H⋯O hydrogen bond [2.810 (4) Å and 160°] stabilizes the mol­ecular packing as an infinite chain along the [100] direction.

In the title enaminone, C13H19N1O4, the Meldrum's acid group has a distorted boat conformation. The two independent mol­ecules of the asymmetric unit are dimerized about a pseudo inversion center through two inter­molecular N—H⋯O hydrogen bonds, with N⋯O distances of 3.049 (4) and 3.093 (4) Å. The dimers are stacked along the [010] direction.

The title compound, C20H18N4O, is an example of a recently described pyridinium N-benzoyl­guanidine. This work represents the second structural study of this kind of compound. The structure is stabilized by C—H⋯π, C—H⋯N and C—H⋯O inter­actions.

The title compound, C20H18N4O, is an example of a recently described pyridinium N-benzoyl­guanidine. This work represents the second structural study of this kind of compound. The structure is stabilized by C—H⋯π, C—H⋯N and C—H⋯O inter­actions.

The title compound, C17H14O4, shows satisfactory cytotoxic activity against Artemia salina. Two non-classical inter­molecular C—H⋯O hydrogen bonds [C⋯O = 3.273 (2) and 3.302 (3) Å] join the mol­ecules alternately head-to-head and tail-to-tail across crystallographic inversion centres, resulting in a linear chain along the [11] direction.

We describe herein the synthesis, crystal structure and ¹H NMR properties of the mononuclear [ZnII(L-Br)].2H2O complex containing the hexadentate H2L-Br ligand (H2L-Br = N,N'-bis-(5-bromo-2-hydroxybenzyl)-N,N '-bis-(pyridin-2-ylmethyl)-ethane-1,2-diamine). DFT calculations demonstrate very good agreement between parameters calculated and those dete...

Three new iron(III) complexes with the ligand N,N'-bis(2-hydroxybenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine, H2bbpen, containing electron-donating and -withdrawing groups (Me, Br, NO2) in the 5-position of the phenol rings were synthesized and fully characterized by IR spectroscopy, ESI mass spectrometry, and CHN elemental analyses. X-ray s...

The title compound, C21H22N2O3, (2S,12βS)-methyl 2-[(1E)-1-formyl-1-propen­yl]-1,2,6,7,12,12b-hexa­hydro­indolo[2,3-α]­quinolizine-3-carboxylic acid, exhibits a rare vallesiachotamane skeleton. Inter­molecular hydrogen bonding results in the formation of a chain.

The crystal structure of synthetic ferrous hureaulite, Fe(5)(2+) (H(2)O)(4)(PO(4)H)(2)(PO(4))(2), was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) angstrom, beta=96.27(3)degrees, V=1463.6(6) angstrom(3), Z=4 and D(calc)=3.327 g/cm(3). This end member of the hureaulite series wa...

Reaction of 4-aminoantipyrine with acetylacetone, ethyl acetoacetate, benzoyl isothiocyanate, phenyl isothiocyanate, maleic anhydride and methoxymethylene Meldrum's acid afforded a series of new antipyrine derivatives. The antibacterial activity of the synthesized compounds against Micrococcus luteus ATCC 9341, Staphilococcus aureus ATCC 29737, and...

This work describes the first successful synthesis of five pyridinium N-benzoylguanidines. These new pyridinium ylides were prepared in moderate to good yields through the guanylation reaction of N-iminopyridinium ylide with N-benzoylthioureas, using both bismuth nitrate and mercury chloride as inorganic thiophiles. X-ray analysis of one pyridinium...

The title compound, C14H10ClNO, is a nitro­gen derivative closely related to natural 3′,7-epoxy-8,4′-oxy­neolignans, which are of interest because of their cytotoxic activity. Centrosymmetric hydrogen bonding occurs between pairs of mol­ecules.

The title compound, C14H10ClNO, is a nitro­gen derivative closely related to natural 3′,7-epoxy-8,4′-oxy­neolignans, which are of interest because of their cytotoxic activity. Centrosymmetric hydrogen bonding occurs between pairs of mol­ecules.

The title compound, C16H16N2O5, is a β-ketoether derivative closely related to natural 8,4′-oxyneolignans, which are of interest because of their moderate antifungal activity against systemic mycosis. The nitro group is not coplanar with the aromatic ring, as shown by a torsion angle of 47.2 (4)°. The molecules are linked by two non-classical inter...

We report EPR measurements at 9.77 and 34.1 GHz in powder and single crystal samples of the ternary copper amino acid complex Cu(l-arginine)2(SO4)·(H2O)6. The single crystal Electron Paramagnetic Resonance spectra display a single resonance for all magnetic field orientations in the ca and cb crystal planes. In the ab plane they display two resonan...

We present here the syntheses of two dinuclear iron(III) complexes with the polydentate N,O-donor ligand H2BPClNOL (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2- hydroxy)]propylamine). The reaction between FeIII(ClO4)3 · 9H2O, the title ligand and two equivalents of NaOAc · 3H2O resulted in the complex . When the synthesis was performed wit...

1,7-dibydroxyxanthone was isolated from Weddellina squamilosa Tul. (Podostemaceae) and the crystal structure has been determined (C13H8O4), Mr = 228.19, a = 4.902(l), b = 13.593(4), c = 14.740(2) Angstrom, space group P2(1)2(1)2(1), Z = 4, and V = 982.2(4) Angstrom(3). The 1,7-dihydroxyxanthone molecule is planar with a strong intramolecular H-bond...

The solid-state structure of the title en­amino­ne, C15H17N1O7, the C adduct obtained from the reaction of 4-amino­pent-3-en-2-one with methoxy­methyl­ene Meldrum's acid, has been investigated by X-ray diffraction, and several structural features are different from the previously described structure of the corresponding N adduct. The carbonyl group...

The title compound, C16H15N1O5, is a -ketoether derivative, closely related to natural 8.4′-oxy­neolignans, which are of interest because of their antiprotozoal activity. The nitro group is not coplanar with the aromatic ring, as is shown by a torsion angle of 49.4 (3)°. The mol­ecules are connected in the crystal structure by two non-classical in...

The Cu atom of the title compound, [Cu(C4H7N2O3)(2)], is in a tetragonally distorted octahedral environment. A carboxyl O atom and the alpha-amino N atom from each ligand coordinate to Cu in a trans square-planar configuration [Cu-O = 2.003 (3) and 2.020 (3) Angstrom, and Cu-N = 2.029 (4) and 2.049 (4) Angstrom]. The octahedron is completed by brid...

The title compound, C11H12ClN3O, is composed of a planar azoen­amine skeleton, which forms a six-membered ring through an intramolecular hydrogen bond. In the solid state only the azoen­amine tautomer was observed. The molecular packing is through adjacent mol­ecules linked by N—H…O bonds, resulting in a two-dimensional sheet structure.

The title compound [systematic name: 21,24-di­methyl-3,12,21,24-tetra­aza­hexa­cyclo­[9.7.3.32,10.01,10.04,9.013,18]­tetracosa-4,6,8,13(18),14,16-hexaene monohydrate], C22H28N4·H2O, crystallizes in space group P212121 with Z = 4 and exhibits approximate C2 symmetry. Intermolecular hydrogen bonds [O—H⃛N = 2.872 (3)° and N—H⃛O = 3.062 (4) Å] form cha...

A new heterodinuclear mixed valence complex [FeIIINiII(BPBPMP)(OAc)2]ClO41 with the unsymmetrical N5O2 donor ligand 2-bis[{(2-pyridylmethyl)-aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)}-aminomethyl]-4-methylphenol (H2BPBPMP) has been synthesized and characterized. 1 crystallizes in the monoclinic system, space group P21/n, a=12.497(2), b=18....

The reaction of acyclic enaminones with methoxymethylene Meldrum's acid afforded N-adduct and/or C-adduct of enaminones in moderate to good yields. The regiochemistry of this reaction depends on the N-amino substituent of the enaminone. The C-adduct is a precursor to 2-pyridones. X-ray analysis of two N-adducts were investigated and the Z-s-Z confi...

Using electron paramagnetic resonance spectroscopy we studied single crystals Of L-arginine phosphate monohydrate doped with copper. The angular dependence of the spectrum in three orthogonal planes shows that the Cu2+ ions occupy two symmetry related sites in the structure. The Zeeman and hyperfine coupling tensors were determined. The principal v...

The reaction of N-(p-tolyl)-maleimide with enaminones afforded succinimide-containing enaminones in moderate to good yields, and these compounds were evaluated against E. coli and S. aureus, but no significant antibacterial activity was observed. The regiochemistry of the compounds was examined mechanistically within frontier molecular orbital cons...

The ligand N,N′-bis(2-hydroxybenzyl)-2-ol-1,3-propanediamine (H3bbpnol) reacts with iron(III) perchlorate forming two dinuclear bis-μ-alkoxo complexes, a ‘cis–trans’ isomer (complex 1) previously reported and a ‘cis–cis’ isomer (complex 2) characterized in this work. The main differences found in complex 2 structure are, (a) the four phenolic oxyge...

A new tridentate ligand [(2-hydroxybenzyl)(2-(imidazol-2-yl)ethyl)]amine (HBHA) and its first dinuclear FeIII complex have been synthesized. The crystal structures of HBHA and of the complex [Fe2III(BHA)2(μ-OCH3)2(μ-OAc)](ClO4) (1) have been solved by X-ray crystallography. In the cation of complex 1, each BHA− anion is arranged in a facial mode wh...

Starting from 1,3-dimethyl-5-aminopyrazole 1 and p-substituted benzaldehydes 2 (R=H, CH3, NO2), four different compounds have been obtained: the Schiff bases 4, a bis-pyrazolyl Schiff base 6a (R=H), the expected bispyrazolo[3,4-b;4′,3′-e]pyridine 7b (R=CH3) and the carbinol derived from the Schiff base 8c (R=NO2). The products have been characteris...

Jatrogrossidion, 4Z-jatrogrossidentadion, 15-epi-4Z-jatrogrossidentadion, 4E-jatrogrossidentadion,15-epi-4E-jatrogrossidentadion, 2-hydroxyisojatrogrossidion, 2-epi-hydroxyisojatrogrossidion and jatrowediol have been isolated from the stems of Jatropha weddelliana. The elucidation of the structure of the latter, a novel lathyrane, was accomplished...

In this work, it is demonstrated that the benzoyl group is an activating group for thioureas in the HgCl2-guanylation reaction. Thus N-benzoyl-thioureas containing electronically neutral and even electron-withdrawing or electron-releasing substituents are converted into guanidines with reasonable yields. In addition, NMR and X-ray structural analys...

The vinylogous Mannich addition of silyloxyfuran 5 to chiral five- and six-membered N-acyliminium ions derived from 3/4a,b occurred exclusively through the addition to the N-acyliminium Si face to provide threo-6/7a,b as the major isomer (73–84% yield, 2:1–7:1 diastereoisomeric ratio) which were converted to the corresponding bicyclic lactams 10 an...

N, N, N′-tris(2-pyridylmethyl)-1,3-diamino-2-propanol (HTPPNOL) has been synthesized and a novel tetranuclear antiferromagnetic iron(III) complex, containing bridging acetate, oxo, and alkoxo groups was characterized by X-ray crystallography, infrared, electronic, and Mössbauer spectroscopies and magnetic susceptibility measurements.

The new 5-(n-alkoxyphenyl)-2-n-alkyltetrazole (L¹) and alpha,omega-bis-[5-(4-pentoxyphenyl)-2-alkanetetrazoles] (L²) ligands and their Pd(II) complexes have been synthesized. The X-ray diffraction study of the palladium complex with L¹ reveals a mononuclear structure in which the geometry of the Pd(L¹)2Cl2 chromophore is planar as required by the i...

[GRAPHICS] The addition of the titanium enolates of N-acetyl, N-propionyl, and N-bromoacetyl (R)-oxazolidin-2-ones to gamma-lactol 2, derived from (S)-glutamic acid, afforded trans- and cis-2,5-disubstituted tetrahydrofurans (trans/cis ratio: R = H, 2:1; R = Me, 8:1; R = Br, 10:1) after desilylation with aqueous HF/CH3CN, Chromatographic separation...

[reaction: see text] The addition of the titanium enolates of N-acetyl, N-propionyl, and N-bromoacetyl (R)-oxazolidin-2-ones to gamma-lactol 2, derived from (S)-glutamic acid, afforded trans- and cis-2,5-disubstituted tetrahydrofurans (trans/cis ratio: R = H, 2:1; R = Me, 8:1; R = Br, 10:1) after desilylation with aqueous HF/CH3CN. Chromatographic...

The crystal structure and absolute configuration of the title compound, C17H21BrO8, have been determined by X-ray analysis. They confirmed the 1′R absolute configuration at the 1′-bromoethyl moiety which has been assigned previously on the basis of chemical and spectroscopic data. Cohesion of the crystal can be attributed to weak intermolecular C—H...

A new polidentade ligand, N-(2-hydroxybenzyl)-N-(2-pyridylmethyl) [(3-chloro)(2-hydroxy)]propylamine (H2BPClNOL), was synthesized and two Fe2III complexes containing the FeIII(m-alcoxo)2FeIII core were structurally and magnetically characterized. Complex [Fe2(BPClNOL)2(OAc)]ClO4 (1) differs from complex [Fe2(BPClNOL)2(H2O)2](ClO4)2.4H2O (2) by the...

The first diiron(III) complex of the ligand N,N′-bis(2-hydroxybenzyl)-2-hydroxypropane-1,3-diamine (H3bbpnol), [Fe2(bbpnol)2]·2H2O 1, was prepared and fully characterized in order to model diiron metalloenzymes. The X-ray crystal structure determination together with the electrochemical data of 1 gave us sufficient information to infer the number o...

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and...

In the title compound, [In-2(C35H33N4O3)(C2H3O2)(2)]-NO3. 2H(2)O, a new binuclear In-III complex, the metal centers are linked by one phenolate and two acetate bridging groups. The In-III ions are in a distorted octahedral environment and they are related by imposed crystallographic C-2 symmetry.

In the title compound, [In2(C35-SH33N4O3)(C 2H3O2)2]-NO 3·2H2O, a new binuclear InIII complex, the metal centers are linked by one phenolate and two acetate bridging groups. The InIII ions are in a distorted octahedral environment and they are related by imposed crystallographic C2 symmetry.

The synthesis, X-ray crystal structure and spectroscopic and electrochemical properties of the new dinuclear copper(II) complex [Cu2(Hbtppnol)CH3COO](ClO4)2 (1), employing the novel unsymmetric dinucleating ligand N-(2-hydroxybenzyl)-N,N′,N′-tris(2-pyridylmethyl)-1,3-diaminopropan-2-ol (H2btppnol), are presented. This complex could be a relevant mo...