Synthesis and characterization of new coordination compounds containing functionalized pyrazole ligands

Autor: Dias, Isac Marinho
Přispěvatelé: Guedes, Guilherme Pereira, Neves, Amanda Porto Neves, Vaz, Maria das Gra?as Fialho
Jazyk: portugalština
Rok vydání: 2019
Předmět:
Zdroj: Biblioteca Digital de Teses e Dissertações da UFRRJ
Universidade Federal Rural do Rio de Janeiro (UFRRJ)
instacron:UFRRJ
Popis: Submitted by Leticia Schettini (leticia@ufrrj.br) on 2021-09-23T15:06:03Z No. of bitstreams: 1 2019 - Isac Marinho Dias.pdf: 5845934 bytes, checksum: 437b109380ab6b4dbe11d8d33b167215 (MD5) Made available in DSpace on 2021-09-23T15:06:03Z (GMT). No. of bitstreams: 1 2019 - Isac Marinho Dias.pdf: 5845934 bytes, checksum: 437b109380ab6b4dbe11d8d33b167215 (MD5) Previous issue date: 2019-03-13 CAPES - Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior Aromatic heterocycles such as pyrazoles are widely used in the construction of new molecular architectures when coordinated to ions of the d block leading to interesting biological and technological properties. In this work we describe the synthesis and characterization of two functionalized pyrazole ligands: potassium 5-amino-1-(benzothiazol-2-yl)-1H-pyrazole-4-carboxylate (L1) and potassium 5-amino-1-(pyrazin-2-yl)-1H-pyrazole-4-carboxylate (L2). The syntheses of the ligands were performed in three steps: (1) formation of the pyrazole nucleus with an ester group, (2) hydrolysis and (3) neutralization. In addition, a new azo (N=N-) photosensitive compound (E)-diazene-1,2-diylbis(4,1 phenylene)bis(hydrazinecarboxylate) (L3) was obtained. The synthesis of L3 was performed by reduction of 4-nitrophenol in alkaline conditions, affording the azo group, followed by two additions reactions in the phenol and carbonyl groups. All reactions steps were characterized by infrared, 1H-NMR and 13C-NMR spectroscopies, as well as melting point and GC-MS analyzes. The L1 and L2 ligands were used to synthesize new coordination compounds containing CoII, FeII, MnII, CuII and NiII ions. By using the slow diffusion methodology, two new families of coordination compounds wereobtained, with molecular formulas cis-[M(L1)2(OH2)4] (M= FeII, CoII and NiII) and trans-[M(L2)2(OH2)4] (MnII and CoII). The crystal structures of these complexes were solved by X ray diffraction and it was observed that the ligands are coordinated in a monodentate fashion. The crystal packing of these systems is stabilized by intra and intermolecular hydrogen bonds. The complexes cis-[M(L1)2(OH2)4] were studied by cyclic voltammetry, which theoxidation and reduction peaks were observed with respect to the FeII, CoII and NiII ions. The M?ssbauer spectroscopy for cis-[Fe(L1)2(OH2)4] showed a high spin state for the FeII ion in the emperature range 4-300 K. The magnetic measurements for the compounds cis-[Fe(L1)2(OH2)4] (M = CoII, FeII) showed a key role played by the axial and rhombic anisotropy from the metal ion, since the exchange interactions are negligible. Furthermore, this family was evaluated against the inhibition of the acetylcholinesterase showing good inhibition rates in aconcentration of 10 ?mol L-1. Through the slow diffusion methodology, new coordination compounds [Cu(L1)2(Py)2] and [Co(L1)2(Py)2] were obtained. The crystal structures of the compounds were elucidated by single crystal X-ray diffraction; in the [Co(L1)2(Py)2] complex, the metal ion lies on a distorted tetrahedral geometry, coordinated to two pyridine molecules and two oxygen atoms from different carboxylate groups in a monodentate fashion. The complex [Cu(L1)2(Py)2] presented the CuII ion in a distorted octahedral geometry, with two L1 ligands coordinated in a bidentate fashion the coordination sphere of the metal ion was completed by two coordinated pyridine molecules. Heterociclos arom?ticos como os piraz?is s?o amplamente utilizados na constru??o de novas arquiteturas moleculares quando coordenados a ?ons do bloco d, levando a interessantes propriedades biol?gicas e tecnol?gicas. Desta forma, o presente trabalho visou a s?ntese e a caracteriza??o de dois pr?-ligantes piraz?licos funcionalizados: 5-amino-1-(benzotiazol-2-il)- 1H-pirazol-4-carboxilato de pot?ssio (L1) e 5-amino-1-(pirazin-2-il)-1H-pirazol-4-carboxilato de pot?ssio (L2). Para a forma??o de cada pr?-ligante foram realizadas tr?s etapas reacionais, a saber: (1) forma??o do n?cleo piraz?lico funcionalizado com um grupamento ?ster, (2) hidr?lise e (3) uma etapa de neutraliza??o. Al?m disto, foi realizada a s?ntese de um terceiro ligante in?dito, contendo cont?m o grupamento fotossens?vel azo (-N=N-), (E)-diazeno-1,2-diilbis(4,1- fenileno)bis(hidrazinocarboxilato), chamado de L3. A s?ntese deste composto foi realizada atrav?s da redu??o do 4-nitrofenol em meio b?sico para a forma??o do grupamento azo, seguida de duas rea??es envolvendo adi??es ? carbonila. Todas as etapas reacionais para a forma??o dos compostos L1-L3 foram devidamente caracterizadas por espectroscopias na regi?o do infravermelho, RMN 1H e RMN 13C, al?m de an?lises como ponto de fus?o e CG-MS. Ap?s a forma??o dos pr?-ligantes L1 e L2, estes foram utilizados na s?ntese de novos compostos de coordena??o contendo os ?ons de CoII, FeII, MnII , CuII e NiII. Atrav?s da metodologia de difus?o lenta foram obtidas duas novas fam?lias de compostos de coordena??o cuja f?rmula molecular ? cis-[M(L1)2(OH2)4] (M= FeII, CoII e NiII) e trans-[M(L2)2(OH2)4] (MnII e CoII). A estruturas cristalinas destes complexos foram elucidadas por difra??o de raios X por monocristal, verificando-se que ligante se coordenou de forma monodentada e que a esfera de coordena??o do ?on met?lico foi completada por quatro mol?culas de ?gua. Foi verificado que os ret?culos cristalinos destes sistemas s?o estabilizados por liga??es de hidrog?nio intra e intermoleculares. Os complexos da fam?lia cis-[M(L1)2(OH2)4 ainda foram estudados por voltametria c?clica onde foram observados picos de oxida??o e redu??o referentes aos ?ons de FeII, CoII e NiII . A espectroscopia M?ssbauer para o complexo cis-[Fe(L1)2(OH2)4] evidenciou o estado alto spin para o ?on FeII no intervalo de temperatura de 4-300 K. As medidas magn?ticas para os compostos cis-[Fe(L1)2(OH2)4] (M=CoII e FeII) mostraram um comportamento oriundo da anisotropia magn?tica axial e r?mbica para estes sistemas, uma vez que as intera??es de troca s?o desprez?veis devido ? grande dist?ncia entre os s?tios met?licos no empacotamento cristalino. A resposta frente ? inibi??o da enzima acetilcolinesterase dos complexos da fam?lia cis-[M(L1)2(OH2)4] revelou taxas de inibi??o entre 35 - 55% na concentra??o de 10 ?mol L-1 . Utilizando a metodologia de difus?o de vapor foram obtidos compostos de coordena??o in?ditos [Cu(L1)2(Py)2] e [Co(L1)2(Py)2]. Estes compostos tamb?m tiveram sua estrutura elucidada por difra??o de raios X por monocristal, sendo verificado que o complexo [Co(L1)2(Py)2] possui uma geometria tetra?drica distorcida onde o centro met?lico e est? coordenado a duas mol?culas de piridina e dois ?tomos de grupos carboxilato de ligantes diferentes na forma monodentada. O complexo [Cu(L1)2(Py)2] possui um ?on de CuII em uma geometria octa?drica distorcida, verificando-se a coordena??o de dois ligantes L1 e duas mol?culas de piridina.
Databáze: OpenAIRE
Externí odkaz: