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Thermo gravimetric analysis of supramolecular complexes of p-tert-butylcalix[6]arene and ammonium cations: crystal structure of diethylammonium complex
Authors:  rcio Lazzarotto,Francine Furtado Nachtigall,Eduardo Ernesto Castellano
Affiliation:a Departamento de Química Orgânica, UFRGS, Av. Bento Gonçalves 9500, CEP 91501 970, C.P. 15003, Porto Alegre, Rio Grande do Sul, Brazil
b Departamento de Química, Universidade Estadual de Ponta Grossa, Campus de Uvaranas, Av. General Carlos Cavalcanti 4748, CEP 84030 900 Ponta Grossa, Paraná, Brazil.
c Departamento de Física, Universidade de São Paulo, São Carlos, Av. Trabalhador Sãocarlense 400, Centro, CEP 13566-590, São Carlos, SP, Brazil
Abstract:
Thermo gravimetric analysis of ammonium-p-tert-butylcalix[6]arene salts were carried out to determine the stoichiometry of the inclusion compounds and the temperature of leaving of the ammonium cation, as amine, from the solid phase by a reverse proton transfer reaction to calixarene. The chain length of the amine molecules and their relative basicity order are the main factors which determine the decomplexation temperatures for the ammonium salts of piperidinium, diethylammonium, ethylenediammonium, morpholinium, s-butylammonium, butylammonium, hexylammonium and triethylammonium salts of p-tert-butylcalix[6]arene anion. The solid state structure of bis-diethylammonium-p-tert-butylcalix[6]arene dianion is reported. The calix moiety adopts a 1,2,3 alternate conformation, with one ammonium as exo-calix and other as endo-calix, with an intricate array of hydrogen bonds between phenol, phenolate and ammonium cations.
Keywords:Calixarenes   Supramolecular chemistry   Thermal analysis   Ammonium cations   Inclusion compounds
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