Quantum processes in 8-Oxo-Guanine-Ru(bipyridine)32+ photosynthetic systems of artificial minimal cells

Abstract

Abstract:Density functional theory methods were used to investigate various self-assembled photoactive bioorganic systems of interest for artificial minimal cells. The cell systems studied are based on nucleotides or their compounds and consisted of up to 123 atoms (not including the associated water or methanol solvent shells) and are up to 2.5 nm in diameter. The electron correlation interactions responsible for the weak hydrogen and Van der Waals chemical bonds increase due to the addition of a polar solvent (water or methanol). The precursor fatty acid molecules of the system also play a critical role in the quantum mechanical interaction based self-assembly of the photosynthetic center and the functioning of the photosynthetic processes of the artificial minimal cells. The distances between the separated sensitizer, fatty acid precursor, and methanol molecules are comparable to Van der Waals and hydrogen bonding radii. As a result the associated electron correlation interactions compress the overall system, resulting in an even smaller gap between the highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) electron energy levels and photoexcited electron tunnelling occurs from the sensitizer (either Ru(bpy) 2+ 3 or [Ru(bpy) 2 (4-Bu-4'-Me-2,2'-bpy)] 2+ + derivatives) to the precursor fatty acid molecules (notation used: Me = methyl; Bu = butyl; bpy = bipyridine). The shift of the absorption spectrum to the red for the artificial protocell photosynthetic centers might be considered as the measure of the complexity of these systems. 31.10.+z, 31.15.A-, 31.15.ae, 33.15.-e, 33.20.- PACS (2008):

Photoinduced Self-Organization in “Semiconductor World”: Part I. from Protophotosynthesis to Protomembranes

“…Such small ultrasystems (≈ 5 nm) containing a photosensitizer [72,73] and a minimal amount of fatty acid (due to which they fit well with the abiogenetic "fatty acid world" model [74]), are typically characterized by the quantum self-assembly (including photo-induced one and photo-induced electron tunneling [75][76][77]. The small size of such structures relative to the mean free path of the charge carriers explains the possibility of spintronics control over photoinduced transport phenomena in them, and therefore over the processes of elementary photosynthesis [78].…”