Light-Triggered Metal Coordination Dynamics in Photoswitchable Dithienylethene-Ferrocene System

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Organometallic Chemistry

Background:

• Photochromic molecules, such as dithienylethenes (DTEs), are crucial for molecular switches.
• Ferrocene-containing compounds offer unique electronic and redox properties.
• Metal ion sensing requires selective and responsive molecular probes.

Purpose of the Study:

• To synthesize and characterize a novel C2-symmetric photochromic molecule integrating DTE and ferrocene units.
• To investigate the interaction of this molecule with mercury ions (Hg2+).
• To explore the impact of metal binding on the photoisomerization dynamics of the DTE core.

Main Methods:

• UV-Vis spectroscopy to study binding constants and photoisomerization.
• Density Functional Theory (DFT) calculations for theoretical insights.
• Electrochemical studies to probe redox properties.
• Synthesis and characterization of the C2-symmetric molecule 3.

Main Results:

• The molecule 3 binds Hg2+ through the sulfur atoms of the DTE moiety in both open (3o) and closed (3c) states.
• The open isomer (3o) exhibits stronger binding affinity for Hg2+ compared to the closed isomer (3c).
• Photoisomerization is preserved in the Hg2+-complexed form, albeit at a significantly reduced rate (photocyclization quantum yield decreased 8.2-fold).

Conclusions:

• The developed molecule functions as a responsive probe for Hg2+ detection.
• Metal coordination effectively modulates the photoswitching rate of the DTE core.
• This work highlights the potential for designing metal-modulated photochromic systems.