[en] Complete text of publication follows. Bridged bifunctional molecules of general structure X-(CH₂)_n-Y represent an interesting class of models for experimental and theoretical investigations of the early stages of radiation-induced processes in complex organic molecules and macromolecules, including those of biological importance. Variations in ionization energy of functional groups (X and Y), bridge length and conformation may affect crucially the electronic structure and reactivity of primary ionized molecules, which can be described in terms of 'fine tuning'. This contribution gives an overview of our recent studies on a number of bifunctional radical cations (in particular, diketones amidoesters, amidoamines and aminoethers) using EPR, optical spectroscopy and quantum-chemical calculations [1 - 3]. The criterion of localization of spin density in bridged radical cations will be formulated. The effect of 'magic bridge' (or 'conformational lock') on the reactivity of radical cations will be considered in detail. Several examples of selective and specific reactions for radical cations with a 'magic bridge' (n = 3) will be presented. In addition, preliminary data on the properties of bridged bifunctional radical anions will be discussed. This work was supported by the Russian Foundation for Basic Research (project no. 09-03-00848).