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Previous issue date: 2014-01-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Metal Organic Frameworks (MOFs) are supramolecular structures consisted of
ions or metal clusters coordinated to organic ligands which are repeated in two or three
dimensions. These structures have atracted much attention due to their properties such
as low density, high specific surface area and large volume of pores. In this work,
MOFs consisted of zinc clusters connected by ditopic ligands, terephthalic acid (1,4-
H2BDC) or isophthalic acid (1,3-H2BDC) were synthesized. To obtain the proposed
materials, different routes and synthetic parameters were tested, such as the molar ratio
of the precursors, the addition of template molecules, the type of solvente, the addition
of organic base or the type of a counter-ion of Zn salt. It was found that the variation of
these parameters led to the formation of different metalorganic structures. The solids
obtained were characterized by XRD, SEM and IR. For the samples identified as MOF-
5, it was verified that the structure was composed of both interpenetrated and non
interpenetrated structures. These samples showed a low stability, becoming totally
transformed into another structure within less than 72 hours. The addition of the nickel
and/or cobalt was found to be a promissing method for increasing the stability of MOF-
5, which in this case, still remained unconverted to another structure even after 15 days
of exposure to air. The samples prepared from 1,3-H2BDC were probably new, still
unknown Metal Organic Frameworks / Redes Metalorg?nicas (MOFs) s?o estruturas supramoleculares constitu?das de
?ons ou clusters met?licos coordenados com ligantes org?nicos que se repetem em duas
(2D) ou tr?s (3D) dimens?es. Essas estruturas t?m atra?do muita aten??o devido ?s suas
propriedades, como por exemplo, baixa densidade, elevada ?rea superficial espec?fica e
elevado volume de poro livre. Neste trabalho foram sintetizadas MOFs formadas por
clusters met?licos de zinco conectados por ligantes dit?picos, ?cido tereft?lico (1,4-
H2BDC) ou isoft?lico (1,3-H2BDC). Para a obten??o dos materiais propostos foram
testadas diferentes rotas e par?metros de s?ntese, tais como, raz?o molar dos
precursores, adi??o de mol?culas de molde, tipo de solvente, adi??o de base org?nica ou
do contra-?on do sal de Zn. Constatou-se que a varia??o destes par?metros pode
conduzir a forma??o de diferentes estruturas metalorg?nicas. Os s?lidos obtidos foram
caracterizados por DRX, MEV e IV e TG. Para as amostras onde foi identificada a rede
metalorg?nica MOF-5 verificou-se a exist?ncia de por??es de estrutura interpenetrada,
assim como de estrutura n?o interpenetrada. Estas amostras apresentaram baixa
estabilidade, convertendo-se totalmente em outra estrutura num per?odo de tempo
inferior a 72 h. A adi??o de n?quel e/ou cobalto mostrou-se promissora para o aumento
de estabilidade da MOF-5, a qual foi identificada mesmo ap?s 15 dias de exposi??o ao
ar. Dentre as amostras preparadas com 1,3-H2BDC apenas uma estrutura foi
identificada, com base nos bancos de dados de estruturas conhecidas, levando a crer que
tr?s redes metalorg?nicas obtidas apresentam estruturas in?ditas
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17771 |
| Date | 24 January 2014 |
| Creators | Campos, Viviane de Oliveira |
| Contributors | CPF:00735018405, Gasparotto, Luiz Henrique da Silva, CPF:21859095844, http://lattes.cnpq.br/2649423643904707, Kulesza, Joanna Elzbieta, CPF:70134641477, http://lattes.cnpq.br/1568423340359601, Alves J?nior, Severino, CPF:81408307472, http://lattes.cnpq.br/9563158536061549, Barros, Br?ulio Silva |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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