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Aryloxazolines represents potential building blocks in the synthesis of precursors of ESIPT-active sensors. Here we describe the Sonogashira cross-coupling reaction between iodo-containing 2-aryloxazolines and terminal alkynes. The reaction occurs under mild conditions and a range of alkynes was employed leading the formation of a small library of functionalized aryloxazolines.

Despite the serious public health problems caused by Chagas disease in several countries, the available therapy remains with only two drugs that are poorly active during the chronic phase of the disease in addition to having severe side effects. In search of new trypanocidal agents, herein we describe the synthesis and biological evaluation of eleven new 1,6-diphenyl-1H-pyrazolo[3,4-b]pyridine compounds containing the carbohydrazide or the 2,3-dihydro-1,3,4-oxadiazole moieties. Two of them showed promising in vitro activity against amastigote forms of T. cruzi and were evaluated in vivo in male BALB/c mice infected with T. cruzi Y strain. Our results suggest that the substitution at the C-2 position of the phenyl group connected to the carbohydrazide or to the 2,3-dihydro-1,3,4-oxadiazole moieties plays an important role in the trypanocidal activity of this class of compounds. Moreover, the compound containing the 2,3-dihydro-1,3,4-oxadiazole moiety has demonstrated more favorable structural requirements for in vivo activity than its carbohydrazide analog.

The transformation of $$\hbox {CO}_2$$ to more reactive and value-added chemical species is a crucial way of reducing environmental impact. The $$\hbox {CO}_{2}\,+ \hbox { M}^{+}\,\rightarrow \hbox { MO}^{+}\,+$$ CO reaction, with $${\mathrm{{M}}}=\hbox {transition}$$ metal, is an important channel in gas phase, and it has been accomplished by the $$\hbox {Sc}^{+}$$ species. Besides being a better choice for sustainable transformations, early transition metals, such as scandium, can open new routes for a variety of novel reactions. In this context, DFT calculations are employed to explore N-heterocyclic olefins (NHOs) molecules as a ligand for scandium complexes in the $$\hbox {CO}_2$$ to CO reduction. As revealed by the energetics of the process, the described NHO-Sc systems are able to convert $$\hbox {CO}_2$$ to CO in an exoergic way, therefore showing great potential for $$\hbox {CO}_2$$ conversion.

Pentacyanidoferrate(II) complexes of aromatic N-heterocycles, such as 4-cyanopyridine, exhibit characteristic colors and strong metallochromism associated with the donor-acceptor interactions of the metal ions with the cyanide ligands. In the presence of transition metal ions insoluble polymeric complexes are formed, displaying bright yellow, red, brown and green colors with zinc(II), nickel(II), copper(II) and iron(III) ions, respectively. Such metallochromic response is better observed on filter paper, allowing applications in analytical spot tests. The effects can be explored visually and probed by means of modern instrumental facilities, including spectrophotometric and resonance Raman techniques. In this way, by using the cyanopyridinepentacyanidoferrates, the Prussian Blue test for ferric ions can be extended to the entire row of transition metal elements, providing a new and modern insight of such classical Feigl’s spot tests.

Two novel indole-based N-aryl substituted thiosemicarbazones (3a and 3b) have been synthesized by the condensation reaction of 3-acetylindole with respective thiosemicarbazide. The SC-XRD and first-principles DFT approach was then used to comprehensively elucidate the structures of both 3a and 3b after initial spectral analysis. The SC-XRD geometric parameters displayed a reasonable agreement with computed geometric parameters. Hirshfeld surface analysis (HSA) has been employed for counting the non-covalent interactions (NCIs) in the crystalline framework. Entire computational calculations were executed for 3a and 3b at DFT/B3LYP/6-311G(d,p) functional. Further, FMO and UV-Vis spectral calculation are carried out at TD-DFT/B3LYP/6-311G(d,p) functional. The most significant potential transitions were observed in 3a with higher stabilization energy value 22.17 kcal/mol and in 3b with 20.95 kcal/mol stabilization energy, explored by NBO analysis. The calculated energy gaps were determined as 4.07 and 3.897 eV for 3a and 3b, respectively. Global reactivity descriptors including electronegativity, softness, hardness, electron affinity, ionization potential and electrophilicity was estimated with assistance of HOMO and LUMO energies. The possible suitable positions for the nucleophilic or electrophilic attack on the chemical structures of investigated molecules were determined using MEP analysis. The simulated spectral data was found in good agreement with experimental based spectral findings.

Chagas disease, caused by Trypanosoma cruzi, is a parasitosis that predominates in Latin America. It is estimated that 25 million people are under the risk of infection and, in 2008, more than 10 thousand deaths were registered. The only two drugs available in the therapeutics, nifurtimox and benznidazole, showed to be more effective in the acute phase of the disease. However, there is no standard treatment protocol effective for the chronic phase. Nitrofurazone (NF), an antimicrobial drug, has activity against T. cruzi, although being toxic. Considering the need for new antichagasic drugs, the existence of promising new therapeutic targets, as 14α-sterol demethylase and cruzain, and employing the bioisosterism and molecular hybridization approaches, four novel compounds were synthesized, characterized by melting point range, elemental analysis, IR and NMR spectroscopy. The compounds were tested against T. cruzi amastigotes in infected U2OS cells. All compounds showed selectivity towards T. cruzi and showed trypanomicidal activity in low micromolar range. The compound 3 showed potency similar to benznidazole, but lower efficacy. These results highlight the importance of the 1,2,4-triazole, thiosemicarbazonic and nitro group moieties for designing new efficient compounds, potentially for the chronic phase of Chagas disease.

A theoretical investigation has been performed on nickel– and palladium–N-heterocyclic carbene (NHC) complexes in the Mizoroki–Heck (MH) reaction. A density functional theory (DFT) comparison of reaction pathways in cationic and neutral catalytic cycles for both metals was made using the M06 functional. The oxidative addition barrier is much lower for NHC–Ni than that for NHC–Pd for both mono- and bis-ligand pathways; the bis-ligand pathway (i.e., where both NHCs remain coordinated) is energetically more favorable for both metals. The migratory insertion steps have lower free energy barriers for NHC–Ni than for NHC–Pd complexes for both neutral and cationic pathways. β-Hydride elimination is computed as thermodynamically difficult for NHC–Ni complexes, indicating a possible reluctance in the elimination of the Ni-based hydride intermediate and formation of the Heck adduct at room temperature. The base-assisted reductive elimination is easier for NHC–Pd than for NHC–Ni complexes in the neutral and cationic...

A microwave-assisted synthesis of novel N-acylhydrazone and semicacarbazone-7-hidroxy-coumarins derivatives, starting from 3-acetyl-7-hydroxy-2H-chromen-2-one, is described. This optimized protocol led to higher yields and considerable reduction in reaction time from ∼24 to ∼1 hour. Aqueous solutions of these compounds showed bright blue to cyan emission and maximum quantum yields of 0.244. The stereoelectronic effects of the attached groups led to modulation of the spectral characteristics by favoring syn or anti amide conformers. The synthesized compounds showed pH dependent luminescence and a strong batochromic shift up to 65 nm in a low polarity medium (methanol) due to a better stabilization of the syn-conformer promoting this redshifted emission. These characteristics can be exploited for designing new luminescent probes for pH as well as polar microenvironments.

The chalcones have been cyclized into the N-propionyl-2-pyrazolines using propionic acid with hydrazine hydrate. The structures of pyrazolines were determined by FT-IR, NMR spectroscopy, and confirmed by single crystal X-ray diffraction (SC-XRD) study. Further, a combined experimental and density functional theory (DFT) based study of these pyrazolines has been reported. A comprehensive DFT investigation was performed with the level of theory as B3LYP/6-311 + G(d,p), investigating the electronic structure characteristics, FMOs and non-linear optical features of said compounds. However, the UV absorption spectra of 2a, 2b and 2c were calculated in acetone by Polarizable Continuum Model (PCM) at TD-B3LYP/6-311+G(d,p), and TD-Cam-B3LYP/6-311+G(d,p), levels. The AIM calculations were performed to explore the non-covalent interactions (NCIs). The calculated bond lengths and bond angles of said compounds are in good agreement with the SC-XRD determined parameters. The computed alignment of the frontier molecular orbitals of the derivatives with smaller energy gap provides additional information into the electronic features which enhancing the nonlinear optical (NLO) efficiency of the derivatives. Besides, synthesized compounds were applied for antibacterial activity and found compound 2c was most significant antibacterial agent. It has an antibacterial efficiency in the form of zone inhibition 20 ± 0.50 and 21 ± 0.25 mm against Gram-positive bacterial strains S. aureus and B. subtilis and 19 ± 0.35 and 18 ± 0.40 mm against Gram-negative bacterial strains E. coli and P. peli. Overall, antibacterial activity of synthesized compounds was significant against bacteria, though variable against Gram-positive and negative bacterial strains.

Made available in DSpace on 2018-11-26T16:32:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-05-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) INCT-Catalise Two new copper(II) complexes with the deprotonated ligand 3-hydroxypicolinic acid (3-HPA) and heterocyclic bases (1,10-phenanthroline - phen or 2,2'-bipyridine -bpy) were synthesized. [Cu(3-HPA)(phen)ClO4] I and [Cu(3-HPA)(bpy)ClO4] II were characterized by elemental analyses, conductivity measurements, FT-IR, UV-Vis, EPR and High-resolution Electrospray Ionization Mass Spectrometry (HRESIMS). The results indicate that the geometry around the copper ion is distorted square-pyramidal, and that the copper ion is coordinated to 3-HPA via oxygen and nitrogen atoms, and to heterocyclic bases via their two nitrogen atoms. A perchlorate ion weakly bonded occupies the apical position, completing the metal coordination sphere. In this work, the compound [Cu(3-HPA)(2)] III was also synthesized using a new method, different from that described in the literature. The cytotoxic activity of these compounds against tumor and normal cell lines was investigated. Complex I exhibited a strong antitumor activity, being the most active in the series of studied complexes. The compounds were also evaluated for activity against Mycobacterium tuberculosis, and the complex I displays good antimycobacterial activity, while compounds II and III were only moderately active. (C) 2016 Elsevier B.V. All rights reserved. Univ Fed Uberlandia, Inst Quim, Joao Naves de Avila Ave,2121,Campus Santa Monica, BR-38400902 Uberlandia, MG, Brazil Univ Fed Minas Gerais, Dept Quim, Belo Horizonte, MG, Brazil Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, NPPNS, BR-14040903 Ribeirao Preto, SP, Brazil Univ Sao Paulo, Inst Quim, Sao Paulo, SP, Brazil Univ Estadual Paulista, Dept Ciencias Biol, Fac Ciencias Farmaceut, Campus Araraquara, BR-14801902 Araraquara, SP, Brazil Univ Estadual Paulista, Dept Ciencias Biol, Fac Ciencias Farmaceut, Campus Araraquara, BR-14801902 Araraquara, SP, Brazil FAPEMIG: APQ-00330-14 FAPEMIG: CEX - RED-00010-14