%0 Journal Article
%A Ortiz-Mahecha, Carlos
%A Schwob, Lucas
%A Leroux, Juliette
%A Bari, Sadia
%A Meissner, Robert
%A Bande, Annika
%T X-ray absorption spectroscopy reveals charge transfer in π-stacked aromatic amino acids
%J Physical chemistry, chemical physics
%V 27
%N 16
%@ 1463-9076
%C Cambridge
%I RSC Publ.
%M PUBDB-2025-04829
%P 8202 - 8211
%D 2025
%X X-ray absorption spectroscopy (XAS) and quantum mechanical calculations bear great potential to unravel π stacking side-chain interaction properties and structure in, e.g., proteins. However, core-excited state calculations for proteins and their associated interpretation for π–π interactions are challenging due to the complexity of the non-covalent interactions involved. A theoretical analysis is developed to decompose the core-to-valence transitions into their atomic contributions in order to characterize the π stacking of aromatic amino acids as a function of their non-covalent distance change. Three models were studied as a non-covalent mixed dimers of the phenylalanine, tyrosine and tryptophan amino acids. We found that there are carbon 1s → π* charge transfer transitions associated with the non-covalently paired aromatic amino acids through their side chains. The atomic-centered contributions to the electronic transition density quantify the excited state charge transfer of the pairing amino acid models, highlighting the π stacking interactions between their aromatic side chains.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1039/D4CP04615C
%U https://bib-pubdb1.desy.de/record/640689