Role of molecular geometry, valence charge distribution and vibrational modes in bioactivity of cyclodiene insecticides
1Industrial Toxicology Research Centre, Lucknow, India.
Abstract:
Fourier transform infrared spectral measurement and complete normal mode calculations have been carried out for heptachlor and wedge modes have been identified. In addition, valence charge distributions have been obtained for aldrin, endrin, heptachlor, beta-endosulfan, cis-chlordane, trans-chlordane, photo-cis-chlordane and photo-trans-chlordane using CNDO/2 (complete neglect of differential overlap) molecular orbital calculations. A toxicity parameter has been defined as the product of the charge distribution and surface area of the corresponding active wedges, depending on the interacting structural features. The variation of this toxicity parameter is generally in order and in agreement with the reported measurements based on the corresponding order of observed LD50 values. Because of the structural features, the toxicity in these cases is a surface phenomenon rather than a volume effect as in the case of Gammexane, wherein the insecticide binds itself to membrane channels. Because the biological activity is a dynamic rather than a static phenomenon, it is expected that the normal modes involving the wedge atoms play an important role.
Related Concept Videos
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
Aromatic Hydrocarbon Anions: Structural Overview
Due to the absence of continuous overlap of p...
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Stereoisomerism of Cyclic Compounds
