We used
quantum mechanical (QM) nonlocal gradient electron correlation
interactions density functional theory (DFT) methods (
i.e. high precision quantum
mechanical simulations) to investigate various self-assembled
photoactive bioorganic systems of artificial minimal living cells
[1-8].
Visualization of the last one hundred steps of geometry optimization of squarine molecule based micelle done by quantum mechanical methods. Carbon atoms and their associated covalent bonds are shown as grey spheres and sticks, hydrogens are in light grey, oxygens - red, nitrogens - blue.
The cell systems studied are based on peptide nucleic acid (PNA)
and consisted of up to 360 atoms (not including the associated water or
methanol solvent shells) and are up to 3.0-4.2 nm in diameter. The
electron correlations interactions originating the hydrogen bonds and
Van der Waals weak chemical bonds that increase due to the addition of
a polar solvent (water or methanol) molecules, and fatty acid (FA) and
precursor fatty acid (pFA) molecules play a critical role in the QM
interaction based self-assembly of the photosynthetic center and
functioning of the photosynthetic processes of the artificial minimal
living cells. The distances between the separated sensitizer, precursor
fatty acid, and water or methanol molecules are comparable to Van der
Waals and hydrogen bonding radii. As a result these nonlinear quantum
interactions compress the overall system resulting in a smaller gap
between the HOMO and LUMO electron energy levels and photoexcited
electron tunneling occurs from the sensitizer (either 1,4-bis(N,N-dimethylamino) naphthalene
or a squarine, or a [Ru(bpy)2(4,4'-Me-2-2'-bpy)]2+) to pFA molecules (notation used: Me = methyl; bpy = bipyridine).
With the exception of the fatty acid molecules, the main parts of one of LANL artificial minimal living cell include a PNA double helix molecule which is covalently bonded to the 1,4-bis(N,N-dimethyl-amino)naphthalene sensitizer molecule shown at bottom-left, a pFA molecule (bottom-right), an SH anion molecule (center left). Carbon atoms and their associated covalent bonds are shown as green spheres and sticks, hydrogens are in light grey, oxygens - red, nitrogens - blue, sulfur - gold. Hydrogen bonds are depicted by dashed lines.
