New class of aggregates in aqueous solution: an NMR, thermodynamic, and dynamic light scattering study.
We investigated the aggregation properties of two classes of aromatic and hydrophobic compounds, namely chloroacetamides and ethyl 3-phenyl-2-nitropropionates, in moderately concentrated aqueous solution (millimolar range). The identification of all species present in solution under specific experimental conditions was performed by 1D and 2D NMR, pulsed gradient spin-echo NMR, and dynamic light scattering techniques. Some physical-chemical properties (viscosity, surface tension, and colligative properties) of the aqueous solutions were also determined. Both classes of compounds behave quite similarly: in solution, three distinct species, namely a monomeric species, small and mobile aggregates, and large and stiff aggregates, are observed. The results give insight into a new class of aggregates, held together by pi-pi interactions, which show an unusual associative behavior in water.
Sanna
Cecilia
C
Institute of Chemical Methodologies, CNR, Via Salaria km 29.3, 00016 Monterotondo Stazione, Italy.
La Mesa
Camillo
C
Mannina
Luisa
L
Stano
Pasquale
P
Viel
Stéphane
S
Segre
Annalaura
A