A new nicotine-based organocatalyst supported on silica nanoparticles (Fe(III)-NicTC@nSiO(2)) was prepared and characterized by different techniques. A series of 1,5-benzodiazepines derivatives were smoothly synthesized via the tandem process, starting from o-phenylenediamine and dimedone (or 1,3-cyclohexanedione), followed by addition of aldehyde in the presence Fe(III)-NicTC@nSiO(2) catalyst in water at room temperature. The Fe(III)-NicTC@nSiO(2) was also applied as an efficient catalyst for the selective synthesis of mono- and bis-1,5-benzodiazepines. Excellent yields and selectivity, short reaction time, mild conditions, and reusability of the catalyst are valuable features of this method.