SÃntese, caracterizaÃÃo e propriedades fotocrÃmicas da sais derivados do Ãcido N-(3,5-dinitrobenzoil)-α-fenilglicina

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The preparation and characterization of salts derived from N-(3,5- dinitrobenzoyl)-α-phenylglycine was carried out by using protonated amines as counter-ion, as follows: NH4 + (DNBAm), (CH3-CH2-)2NH2 + (DNBD), (CH3-CH2-CH2- )NH3 + (DNBP), (CH3-CH2-CH2-CH2-)NH3 + (DNBBu) and (CH3-CH2-)3NH+ (DNBT). These salts showed photocromic effect with ultraviolet (UV) or solar radiation exposure, both in the solid state and DMSO solution. The salts were prepared from N-(3,5-dinitrobenzoyl)-α-phenylglycine in good yields, following the same synthetic route. Several techniques of analysis were used to characterize the synthesized products: 1H-NMR, 13C-NMR, infrared (IR), elemental analysis (EA), TGA and UV-Vis spectroscopy. Spectroscopic assays indicate the formation of a intramolecular charge-transfer complex after ultraviolet radiation exposure. A photochromic efficiency study in DMSO medium also indicates that the salt counter-ion of N-(3,5- dinitrobenzoyl)-α-phenylglycine has almost no influence on photochemical reaction efficiency to the formation of the charge-transfer complex, these results are correlated to pKBH+ values o the respective protonated bases, used as counter-ion (aqueous and DMSO media). Some conductivity measurements were carried out for DNBAm and DNBT (in DMSO), indicating that dissociation occurs to both salts, being the DNBAm solution the most conductor. The initial assessment of the prepared salts in solid state was carried out through the irradiation of controlled UVC light. The test for visual color change (white - pink) point out the following color intensity order: DNBT>DNBD>DNBP>DNBBu>DNBAm

ASSUNTO(S)

materiais fotocrÃmicos dosimeter ciencias exatas e da terra dosÃmetros uv protection proteÃÃo uv photochromic materials

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