# Local Environmental Effects on Light-Driven CO2 Reduction in Liposomes

## TL;DR

This study explores how different lipid environments in liposomes affect the efficiency of light-driven CO2 reduction using molecular components.

## Contribution

The paper provides design principles for optimizing light-driven CO2 reduction in liposomes by analyzing lipid membrane properties and molecular interactions.

## Key findings

- Catalyst efficiency increases with distance from the membrane center and is linked to vertical reduction energies.
- DMPC and DPPG-based liposomes showed the highest quenching efficiency and best photocatalytic performance.
- Variation in cations did not significantly influence the performance, unlike electrochemical studies.

## Abstract

We report the governing
principles that regulate the
activity of
light-driven CO2 reduction by a molecular photosensitizer
bis­(2,2′-bipyridine)-(4,4′-dinonyl-2,2′-bipyridine)-ruthenium­(II)
(RuC

9
) and a molecular catalyst
(5,10,15,20-tetra­(4-methylphenyl)­porphinato)­cobalt­(II) (CoTTP) in supramolecular assembly within the lipid bilayers of liposomes
suspended in water. We tested six different lipids with membranes
in either the gel phase, fluid phase, or at the transition between
both states, as well as zwitterionic or negatively charged headgroups.
The correlation of the membrane rigidity with light-driven catalysis
performance is not conclusive for the investigated set of lipid membranes,
but molecular dynamics simulations elucidate how catalyst efficiency
increases with the distance from the membrane center as well as their
calculated vertical reduction energies. Luminescence quenching studies
revealed that mainly dynamic quenching was observed with the highest
quenching efficiency found with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol)­(sodium salt) (DPPG)-based
liposomes, in agreement with the results of the best performance in
photocatalysis and the computational insights. A variation of cations
did not show any significant influence on the performance, as opposed
to electrochemical studies. The overall mechanistic findings of this
study provide design principles for light-driven CO2 reduction
by molecular components in liposomes.