A multifunctional photoswitch: 6π electrocyclization versus ESIPT and metalation

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Materials Science

Background:

• Development of molecular switches with tunable photochemical properties is crucial for advanced materials.
• Understanding excited state intramolecular proton transfer (ESIPT) and electrocyclization mechanisms is key to designing functional molecules.
• Metal-organic interactions can significantly alter molecular photophysical behavior.

Purpose of the Study:

• To synthesize and characterize a novel terthiazole-based molecular switch.
• To investigate the photochemical and photophysical properties of the switch and its metal complexes.
• To elucidate the effect of nickel and copper metalation on the switch's photoresponsive behavior.

Main Methods:

• Synthesis of a terthiazole-based molecular switch.
• Steady-state and ultrafast absorption spectroscopy for photochemical and photophysical analysis.
• Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations for theoretical rationalization.

Main Results:

• The terthiazole-based molecule acts as a biphotochrome with time-dependent photochemical outcomes.
• Efficient fluorescence photoswitching based on ESIPT was observed.
• Nickel and copper metalation effectively suppressed the photochemical reactions, particularly electrocyclization.

Conclusions:

• The designed terthiazole-based molecular switch exhibits complex photochromic behavior.
• Metalation provides a strategy to control and potentially inhibit specific photochemical pathways.
• The study offers valuable insights into the interplay between molecular structure, photochemistry, and metal coordination.