Electronic spectroscopy of flavins in a cryogenic 22 - pole ion trap

Flavins are of great biological relevance, but little information is known about the isolated flavins. This dissertation deals with the electronic photodissociation spectroscopy of cryogenically cooled flavins. The optical spectra are recorded with a tandem mass spectrometer coupled to a cryogenic 22 - pole ion trap and an electrospray ionization source. Here, the first high-resolution vibronic spectra of protonated and alkali metalated flavins isolated in the gas phase are reported. A joined approach of quantum chemistry and cryogenic ion spectroscopy is employed to reveal intrinsic information of the complexes including lumichrome, lumiflavin, and riboflavin. The systematic investigation provides accurate trends of the geometric, vibrational, and electronic properties. Precisely, all measured spectra are assigned to S1-S0 (pi pi*) transitions. The experimentally extracted S1 origin transitions are either blue- or red-shifted to those obtained for neutral flavins, which is connected to a decrease and increase in the intermolecular interaction strength upon pi pi* excitation, respectively. Importantly, the isomers are investigated in an isomer-selective fashion because the spectral absorption range is sensitive to the site of metalation and protonation. The intramolecular vibrational structure is similar for all investigated complexes, because the orbitals contributing to the electronic excitation do not cover the relevant functional group or the metal/proton. In contrast, the intermolecular structures is highly sensitive to the size and site of metalation, and the site of protonation. Finally, while the metals bind mostly electrostatic to the flavins, the smaller proton binds covalently to them.

Author dc:creator

• Müller, David

Advisor dc:contributor.advisor

• Dopfer, Otto

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.14279/depositonce-12332

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/13548