Details

Autor(en) / Beteiligte

• Michels, Rolf
• Sinemus, Thomas
• Hoffmann, Jan
• Brutschy, Bernhard
• Huber, Klaus

Titel

Co-Aggregation of Two Anionic Azo Dyestuffs at a Well-Defined Stoichiometry

Ist Teil von

• The journal of physical chemistry. B, 2013-07, Vol.117 (28), p.8611-8619

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2013

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The present work investigates the formation of well-defined heteroaggregates from a binary mixture of a red and a yellow azo-dyestuff in the presence of Mg2+ ions. Combined static and dynamic light scattering together with laser induced liquid bead ion desorption mass spectrometry (LILBID-MS) has been applied to characterize the states of the pure red dye and the pure yellow dye as well as of their mixture in aqueous solution without Mg2+. These experiments indicated that a structural reorganization on a molecular scale takes place as soon as the two dyes are combined. Solutions of the combined red and yellow dye contain micelle-like mixed entities with a size of a few tenths of nanometers. Upon the addition of Mg2+, these micelles vanish in favor of elongated heteroaggregates, which grow by a stepwise addition of smaller building units. As unraveled by UV/vis spectroscopy, the heteroaggregates that are formed from the red and yellow azo dye in the presence of Mg2+ obey a stoichiometric ratio of the two components of 1:1. A new multiangle scattering instrument allowed us for the first time to follow this aggregation process at the stoichiometric ratio by time-resolved combined static and dynamic light scattering, thereby providing further aspects of the worm-like nature of the growing heteroaggregates.