Host-guest complexes of phenoxy alkyl acid herbicides and cyclodextrins. MCPA and beta-cyclodextrin

• Type: Article in International Scientific Journal
• Date: 2012

Authors

Manuela Garrido, EM (Author) Other; Marcos Santos (Author) Other; Paulo Silva (Author) Other; Fernando Cagide (Author) FCUP; Jorge Garrido (Author) Other; Fernanda Borges (Author) FCUP

Journal

Title: Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes

Vol. 47

ISSN: 0360-1234

Publisher: Taylor & Francis

Indexing

ISI Web of Knowledge - 12 Citations

Scopus - 16 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

CORDIS: Physical sciences > Chemistry

Other information

Authenticus ID: P-002-G4X

Abstract (EN): The chlorophenoxy herbicide MCPA(4-chloro-2-methylphenoxyacetic acid), widely used for the control of broad-leaf weeds primarily in cereal and grass seed crops, still remains one of the most often used herbicides in Portugal. As the formation of inclusion complexes with cyclodextrins can improve its solubility properties, the interaction between the herbicide MCPA and beta-cyclodextrin was investigated. The stability constants describing the extent of formation of the complexes have been determined by phase-solubility studies. Different analytical techniques [ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (H-1 NMR)] were employed for a thorough investigation of the structural characteristics of the obtained complexes, which exhibited distinct features and properties from both "guest" and "host" molecules. FTIR and H-1 NMR data obtained for the MCPA/beta-CD complexes gave information about the interaction between MCPA and the nonpolar cyclodextrin cavity. The dramatic change observed in band frequency and proton displacements of OCH2 group and H6 aromatic proton confirmed the inclusion of MCPA in beta-CD. The formation of an inclusion complex between MCPA and beta-CD increased the aqueous solubility of this herbicide which could be a particularly advantageous property for some specific applications, namely to improve commercial formulation and for environmental protection.

Language: English

Type (Professor's evaluation): Scientific