Chiral-Induced Spin Selectivity Regulates Triplet formation in Heliobacterial Photosynthesis

TL;DR

This study uses quantum simulations to show how chirality-induced spin selectivity (CISS) suppresses triplet formation in heliobacterial photosynthesis, revealing a natural spin-based protective mechanism.

Contribution

It introduces a theoretical model combining CISS with the radical pair mechanism to explain triplet regulation in heliobacterial reaction centers.

Findings

CISS significantly reduces triplet formation in the model.

Hyperfine coupling and recombination rates influence triplet regulation.

Quantum spin dynamics provide an intrinsic protective mechanism.

Abstract

Triplet formation and its regulation have always been of central interest in understanding the photophysical behavior of living systems. In organic systems, excessive triplet formation poses significant challenges, as it can promote photochemical damage and reduce the efficiency of charge separation processes, making its regulation critically important.Here, we present a theoretical investigation of the intrinsic quantum spin dynamics governing triplet formation in the heliobacterial reaction center, a system that operates without any internal magnetic field. Using an open quantum systems approach based on the Lindblad formalism, we simulate the spin-correlated radical pair dynamics occurring during charge separation in the heliobacterial reaction center. The study systematically examines how triplet formation is regulated by variations in two key parameters, hyperfine coupling strengths and recombination rates, and how this regulation is further influenced by the inclusion of chirality-induced spin selectivity (CISS) in conjunction with the radical pair mechanism (RPM). Our results demonstrate that the CISS effect significantly suppresses triplet formation across the parameter space relevant to the heliobacterial molecular environment, revealing an intrinsic quantum protective mechanism operating through spin control in heliobacterial photosynthesis.