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Photophysical Studies of a New Water Soluble Indocarbocyanine Dye Adsorbed onto Microcrystalline Cellulose and beta-Cyclodextrin
UMTP - Unidade de Materiais Têxteis e Papeleiros e Departamento de Química, Universidade da Beira Interior, Rua Marquês d'Ávila e Bolama, Covilhã 6200-001, Portugal
Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
CQFM - Centro de Química - Física Molecular e IN - Instituto de Nanociência e Nanotecnologias, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais 1049-001, Lisboa, Portugal
C3i - Coordenação Interdisciplinar de Investigação e Inovação, Instituto Politécnico de Portalegre, P-7300-110, Portalegre, Portugal
CICS - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal
* Author to whom correspondence should be addressed.
Received: 21 January 2013; in revised form: 26 April 2013 / Accepted: 9 May 2013 / Published: 15 May 2013
Abstract: A water-soluble indocarbocyanine dye was synthesized and its photophysics were studied for the first time on two solid hosts, microcrystalline cellulose and b-cyclodextrin, as well as in homogeneous media. The inclusion of the indocarbocyanine moiety onto microcrystalline cellulose increased the dye aggregation with both H and J aggregates being formed. Adsorption on b-cyclodextrin enhanced aggregation in a similar way. The fluorescence quantum yields were determined for the powdered samples of the cyanine dye on the two hosts and a significant increase was observed relative to homogeneous solution. A remarkable concentration dependence was also detected in both cases. A lifetime distribution analysis has shown that the indocarbocyanine dye mainly occupies the amorphous part of cellulose and is not entrapped in the crystalline part of this host. In the b-CD case, the adsorption occurs outside the host cavity. In both hosts a strong concentration quenching effect is observed and only monomers emit. Both adsorptions may be explained by stereochemical constraints imposed by the two long sulphoethyl tails linked to nitrogen atoms of the indocarbocyanine dye.
Keywords: indocarbocyanine; microcrystalline cellulose; b-cyclodextrin; solid powdered samples; diffuse reflectance; laser induced luminescence; fluorescence quantum yields of powdered samples; lifetime distribution analysis
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El-Shishtawy, R.M.; Oliveira, A.S.; Almeida, P.; Ferreira, D.P.; Conceição, D.S.; Ferreira, L.F.V. Photophysical Studies of a New Water Soluble Indocarbocyanine Dye Adsorbed onto Microcrystalline Cellulose and beta-Cyclodextrin. Molecules 2013, 18, 5648-5668.
El-Shishtawy RM, Oliveira AS, Almeida P, Ferreira DP, Conceição DS, Ferreira LFV. Photophysical Studies of a New Water Soluble Indocarbocyanine Dye Adsorbed onto Microcrystalline Cellulose and beta-Cyclodextrin. Molecules. 2013; 18(5):5648-5668.
El-Shishtawy, Reda M.; Oliveira, Anabela S.; Almeida, Paulo; Ferreira, Diana P.; Conceição, David S.; Ferreira, Luis F.V. 2013. "Photophysical Studies of a New Water Soluble Indocarbocyanine Dye Adsorbed onto Microcrystalline Cellulose and beta-Cyclodextrin." Molecules 18, no. 5: 5648-5668.