Porphyrin arrays responsive to additives. Fluorescence tuning

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Effective antenna systems are crucial for utilizing low-flux sunlight.
• Optimized dye orientation is key for efficient energy transfer in light-harvesting systems.

Purpose of the Study:

• To synthesize and characterize peptide-linked porphyrin arrays (Boc-(Por(Zn,S))(n)-OBu(t)) with tunable dye orientation.
• To investigate the effect of additive reagents on the fluorescence and absorption properties of these arrays.

Main Methods:

• Synthesis of porphyrin arrays with varying numbers of porphyrin units (n=2, 4, 8).
• Spectroscopic analysis (UV-Vis absorption, fluorescence emission, circular dichroism) in organic solvents.
• Investigation of the impact of 1,2-diaminoethane (en) addition on spectroscopic properties.

Main Results:

• Porphyrin arrays exhibited blue shifts in B-band absorption compared to the monomer.
• Fluorescence yield decreased with increasing array length (n), following Phi' = 0.03/n(1.5).
• Addition of 1,2-diaminoethane (en) dramatically enhanced fluorescence (up to >730 times for n=8) and induced red shifts in absorption bands, altering dye orientation.

Conclusions:

• Peptide-linked porphyrin arrays demonstrate tunable fluorescence emission through additive-induced changes in dye orientation.
• These materials show significant potential for developing advanced, responsive light-harvesting systems.
• The ability to a posteriori optimize dye orientation and fluorescence emission is a key feature for practical applications.