Solvent-dependent energy and charge transfer dynamics in hydroporphyrin-BODIPY arrays

Area of Science:

• Photochemistry and Photophysics
• Supramolecular Chemistry
• Materials Science

Background:

• Hydroporphyrin-BODIPY arrays are promising for biomedical imaging and solar energy.
• Their photophysical properties and solvent effects remain largely unexplored.

Purpose of the Study:

• To elucidate solvent-dependent energy and electron transfer processes in chlorin- and bacteriochlorin-BODIPY arrays.
• To understand the mechanisms governing energy transfer and fluorescence quenching.

Main Methods:

• Time-resolved fluorescence spectroscopy
• Femtosecond transient absorption spectroscopy
• Density-functional-theory calculations

Main Results:

• Excitation of BODIPY leads to ultrafast energy transfer to hydroporphyrin, irrespective of solvent.
• Förster (through-space) and Dexter (through-bond) mechanisms dominate energy transfer in toluene and DMF, respectively.
• Hydroporphyrin fluorescence is quenched in DMF due to photoinduced charge transfer, unlike in toluene.

Conclusions:

• Solvent polarity significantly impacts energy transfer mechanisms and fluorescence properties in hydroporphyrin-BODIPY arrays.
• Photoinduced charge transfer in DMF leads to fluorescence quenching, suggesting potential limitations for applications requiring high emission efficiency.
• The findings provide crucial insights into the photophysics of these arrays for optimizing their use in imaging and energy conversion.