Experimental data were obtained on the effect of adsorbed organic molecules (naphthalene, stearone, benzene, xylene, aluminum oxyquinoline and mixtures of some aliphatic compounds) on the conductivity of gold island films. Nanoisland structures were realized which exhibit non-linear conduction current-voltage characteristics and a sharp switching effect in the presence of adsorbed organics. The conditions for the occurrence of the voltage-controlled negative resistance in such nanocomposite systems are discussed. Some data are also given on electroluminescence of the nanocomposites. Two theoretical models are suggested to describe the conduction current-voltage characteristics of organic molecular structures under various conditions.