Perylene-naphthalene systems: Efficient intramolecular and supramolecular electron transfer in water

Abstract

This study explores novel perylene (PTCA) – naphthalene (SANS) systems for efficient electron transfer in aqueous medium, utilizing both intramolecular and supramolecular architectures. We synthesized a new covalently linked PTCA-SANS dyad, demonstrating highly efficient intramolecular electron transfer (rate: 1.50 × 10⁹ s⁻¹, efficiency: 0.96) from the electron-donating naphthalene unit (SANS) to the electron-accepting perylene core (PTCA) upon photoexcitation. Furthermore, a novel supramolecular system was designed using cationic perylenediimide derivative (TAIPDI) and anionic SANS. Spectroscopic analyses confirmed stable conjugate formation via π−π stacking and ionic interactions (K = 6.11 × 10³ M⁻¹). Fluorescence lifetime measurements of TAIPDI upon photoexcitation and subsequent titration with SANS indicated efficient supramolecular electron transfer, characterized by a rate of 7.89 × 10⁸ s⁻¹ and an efficiency of 0.80. In comparison, the photoexcitation of SANS followed by titration with TAIPDI yielded exceptionally fast and efficient supramolecular electron transfer, with a rate of 5.26 × 10¹¹ s⁻¹ and an efficiency of 0.99. Electrochemical measurements and molecular orbital calculations both confirmed this electron transfer characteristic. Both systems are easily synthesized, exhibit broad light absorption and good stability, and achieve rapid, efficient electron transfer in water. These properties highlight their potential for diverse optical and photonic applications.