Bipyridyl derivatives as photomemory devices: a comparative electronic-structure study

Area of Science:

• Photochemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Isoelectronic bipyridyl derivatives, [2,2 -bipyridyl]-3,3 -diamine (BP(NH(2))(2)) and [2,2 -bipyridyl]-3,3 -diol (BP(OH)(2)), display significantly different excited-state double proton transfer dynamics.
• These differences in fluorescence quantum yields, varying by four orders of magnitude, are attributed to potential energy surface topography and conical intersections.

Purpose of the Study:

• Investigate the photochemical properties of "dark" states in bipyridyl derivatives.
• Explore the potential of these "dark" states for photomemory device applications.
• Analyze the photochemical behavior of a hybrid bipyridyl compound, [2,2 -bipyridyl]-3-amin-3 -ol (BP(OH)(NH(2))).

Main Methods:

• Density Functional Theory (DFT) calculations.
• Time-Dependent DFT (TDDFT) methods.
• Complete Active Space Self-Consistent Field (CASSCF) calculations.

Main Results:

• Characterized a family of "dark" states accessible via light irradiation.
• Identified [2,2 -bipyridyl]-3,3 -diamine (BP(NH(2))(2)) as exhibiting properties suitable for photomemory applications.
• The hybrid compound BP(OH)(NH(2)) shows intermediate photochemical characteristics.

Conclusions:

• BP(NH(2))(2) demonstrates significant potential for development into photomemory devices due to its accessible "dark" states.
• Computational analysis provides insights into the structure-property relationships governing excited-state proton transfer in bipyridyl systems.
• The study highlights the role of theoretical calculations in predicting material functionalities for advanced applications.