Investigation of the inclusion of the herbicide metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry.
We report the formation of inclusion complexes between the phenylurea herbicide metobromuron [3-(p-bromophenyl)-1-methoxy-1-methylurea] and beta- and gamma-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, DeltaH degrees , DeltaS degrees , DeltaG degrees and the association constants (K) at 298K 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 alpha-, beta- and gamma-CD were estimated as 598, 310 and 114, respectively.
Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.
Vincent J
VJ
Smith
Natalia M
NM
Rougier
Rita H
RH
de Rossi
Mino R
MR
Caira
Elba I
EI
Buján
Mariana A
MA
Fernández
Susan A
SA
Bourne
D002151:Calorimetry; D006540:Herbicides / Q000737:chemistry*; D010671:Phenylurea Compounds / Q000737:chemistry*; D013816:Thermodynamics; D014961:X-Ray Diffraction; D047392:beta-Cyclodextrins / Q000737:chemistry*; D047408:gamma-Cyclodextrins / Q000737:chemistry*
D006540:Herbicides; D010671:Phenylurea Compounds; D047392:beta-Cyclodextrins; D047408:gamma-Cyclodextrins; C008770:metobromuron