@article{article_201812, title={PHOTOINDUCED ELECTRON TRANSFER BETWEEN PYRENE/HYDROXYPYRENE AND AROMATIC AMINO ACIDS}, journal={Journal of the Turkish Chemical Society Section A: Chemistry}, volume={2}, pages={8–11}, year={2015}, DOI={10.18596/jotcsa.03120}, author={Acar, Nursel}, keywords={Electron transfer, DFT, pyrene, aromatic amino acid}, abstract={Photoinduced  electron  transfer  systems  have  optical applications  such  as  sensory photoreceptors and light-emitting diodes. The photonic energy which is harvested by an antenna  is  transformed  into  ground  state  chemistry  utilizing  photoinduced  electron transfer  or  photochemical  bond  reorganization  [1].  Amino  acids  often  possess  particular properties, such as weak van der Waals and hydrogenbonds, wide transparency ranges in the visible regions and zwitterionic nature of the  molecules which are very important in materials  science  [2].  In  order  to  be  able  to  optimize  the  efficiency  of  organic  optical devices, it is an advantage to understand completely the physical behaviour of compounds in gas phase and in solution. <br />We  have  studied  geometrical  structure,  electronic  structure  and  optical  excitation  of pyrene(Py)/1-hydroxypyrene  (PyOH)  with  aromatic  amino  acids  in  vacuum  and  in  water using DFT and TD-DFT calculations. The density functional theory (DFT) computations have been performed at ωB97XD/6-31G(d,p) level using Gaussian 09 program [3]. <br />Pyrene and hydroxypyrene were chosen as molecular antenna and aromatic amino acids were chosen as electron donors. Our results show that more stable complexes are formed in  vacuum.  Tryptophan  (Trp)  complexes  are  the  most  stable  among  all  optimized complexes.  Significant  geometrical  changes  have  been  observed  for  the  optimized complexes  between  gas  phase  and  water.  Pyrene/hydroxypyrene-aminoacid  interactions via  π-π stacking  promote  the  photoinduced  transfer  reactions.  Calculated  HOMO-LUMO <br />energies confirm that charge-transfer occurs between the molecules. The most significant charge transfer is observed for Trp complexes between HOMO-1 and LUMO. It is concluded that  the  lowering  of  highest  occupied  orbital  (HOMO)  and  lowest  unoccupied  molecular <br />orbital (LUMO) energy gap appears to be cause of its enhanced charge transfer.}, number={2}, publisher={Turkish Chemical Society}