IONIC-SOLUTIONS AND THEIR PIVOTAL ROLES IN ORGANIC AND BIOLOGICAL-SYSTEMS

Ionic solutions are known to affect the static and dynamic behaviour o f organic and biological systems through ion-solvent interactions. Wit h respect to organic systems, spectacular enhancement in both the reac tion rates and stereoselectivities in the Diels-Alder (D-A) reactions are noted in presence of ionic solvent media. Several D-A reactions ot herwise were not possible or were very sluggish. Application of ultrah igh external pressure could be obviated by using the ionic solutions. In the case of biological systems, the thermal stabilities of the DNA duplexes have been noted to vary with the type of counterions availabl e ill system. Variations in the rates Of D-A reactions and thermal sta bility of DNA duplexes in ionic solutions have been discussed in terms of internal pressure, a ion-solvent interaction quantity and a volume parameter. Useful correlations are noted between internal pressure an d reaction rates of the D-A reactions. More significantly, the correla tions exposed in connection with the thermal stability of DNA duplexes are simple, thought-provoking and present radical departure from our current understanding on the ion-DNA interactions.