Investigation of the inclusion of the herbicide metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry

Vincent J. Smith, Natalia M. Rougier, Rita H. de Rossi, Mino R. Caira, Elba I. Buján, Mariana A. Fernández, Susan A. Bourne, Vincent J. Smith, Natalia M. Rougier, Rita H. de Rossi, Mino R. Caira, Elba I. Buján, Mariana A. Fernández, Susan A. Bourne

Index: Carbohydr. Res. 344(17) , 2388-93, (2009)

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Abstract

We report the formation of inclusion complexes between the phenylurea herbicide metobromuron [3-( p-bromophenyl)-1-methoxy-1-methylurea] and β- and γ-cyclodextrin in the solid state. Formation of crystalline inclusion complexes by the kneading method was confirmed by powder X-ray diffraction and further structural characterization using the principles of isostructurality followed. In addition, Δ H°, Δ S°, Δ G° and the association constants ( K) at 298 K were determined for complex formation in solution using isothermal titration calorimetry. The magnitudes of K for the formation of 1:1 complexes between metobromuron and α-, β- and γ-CD were estimated as 598, 310 and 114, respectively.