Iron-based photosensitizers for sustainable generation of reactive oxygen species

Overview

This technology offers a sustainable alternative to expensive ruthenium- and iridium-based photosensitizers traditionally used in photocatalytic processes. The solution features novel iron(II) coordination complexes that broadly absorb visible light and form exceptionally long-lived triplet excited states, enabling efficient generation of reactive oxygen species (ROS) from dissolved dioxygen. By replacing scarce and costly precious metals with earth-abundant iron, this approach dramatically reduces material costs while supporting environmental sustainability goals.

The primary application targeted is home disinfection, where surfaces functionalized with these iron-based dyes can produce ROS upon exposure to ambient sunlight or focused LED light sources to kill pathogenic microorganisms. This offers a low-cost, energy-efficient disinfection method accessible to everyday consumers without reliance on chemical disinfectants.

Technical specifications

Key features:

• Iron(II) coordination complexes with custom-designed ligands enabling broad visible-light absorption (panchromatic)
• Exceptionally long-lived triplet excited states confirmed via advanced spectroscopic techniques including RIXS (Resonant Inelastic X-ray Scattering) and X-ray absorption spectroscopy
• Tunable ligand design methodology allowing incorporation of functional groups for property control and surface tethering
• Air- and moisture-stable analogs that selectively react with dissolved dioxygen only in the presence of visible light
• Capability to generate reactive oxygen species (ROS) under ambient sunlight or LED illumination

How it works:

The complexes absorb visible light, promoting electrons into excited states that intersystem cross to long-lived triplet excited states. These triplet states can then transfer energy to dissolved molecular oxygen (triplet dioxygen), generating reactive oxygen species capable of killing microorganisms. The ligand scaffold provides structural control over absorption profiles and excited-state lifetimes while enabling chemical attachment to surfaces.

Technology readiness level

The technology is currently at an early-to-mid stage of development. The fundamental photophysics have been validated: spectroscopic monitoring has confirmed reactivity with triplet dioxygen, and synchrotron-based techniques (RIXS and X-ray absorption spectroscopy) have validated the structural basis for the long-lived triplet excited states. Synthetic methodology has been demonstrated through the preparation of air- and moisture-stable analogs with controllable properties.

Future work includes constructing prototype disinfection devices featuring optically transparent surfaces functionalized with the iron-based dyes, quantitatively analyzing ROS generation under sunlight and LED exposure (including wavelength dependence), and collaborating with biosystems engineering colleagues to evaluate efficacy against pathogenic microorganisms. The technology is ready for collaborative development toward prototype validation and eventual commercialization.