Fluorination-dependent molecular orbital occupancy in ring-shaped perfluorocarbons

Abstract

Perfluorocarbons are a family of molecules consisting mainly of carbon and fluorine atoms. They have interesting chemical properties and have diverse applications in biomedicine, physical chemistry and polymer science. In this work, carbon K-edge absorption and emission spectra of liquid decalin are presented and compared to perfluorodecalin. A comprehensive picture of the electronic structure of decalin is provided based on soft X-ray absorption and emission spectroscopies. Experimental data are compared to theoretical time-dependent density functional theory for the hydrocarbon, the perfluorocarbon and the stepwise fluorinated derivatives. We observed a molecular orbital change from unoccupied to occupied orbitals for perfluorodecalin, which was induced through the fluorination process.

Impacts of Conformational Geometries in Fluorinated Alkanes

“…In addition DFT calculations for the hydrocarbons, the stepwise fluorinated hydrocarbons and the perfluorocarbons were performed. Additional insights into the energy shift induced by fluorination, the so-called perfluoro effect, were drawn and these provided significant connections to previous works 22 23 . We observed changes in the electronic structure due to the conformation effect induced by the increase of (CH 2 )- and (CF 2 )-chains for the investigated molecules and detected that different conformational geometries mainly influence the chemical and electronic interaction between the molecules.…”

“…Through investigation of the X-ray emission (XE) spectra of both decalin and PFD the appearance of two features of similar character to the vanished ones was discovered in the XE region of PFD. From the surmised fluorination-dependent MO occupancy change from the unoccupied to the occupied MO-region we concluded a direct impact to the inertness of the perfluorinated molecule according to the frontier orbital model 23 44 . Under consideration of the missing XE data, we can hypothesize a similar effect occurring in the molecules reported in this work, but further investigation of the XE regime is needed to gain more insight into the nature of the orbital change and orbital character in these transitions.…”

“…A closer look at features α and β reveals that they disappear and don’t have a counterpart in the spectra of the perfluorocarbons. In a previous work we found that the first two features of the ring-shaped decalin also disappear upon fluorination to perfluorodecalin (PFD) 23 . Through investigation of the X-ray emission (XE) spectra of both decalin and PFD the appearance of two features of similar character to the vanished ones was discovered in the XE region of PFD.…”

“…They have a wide range of applications ranging from tissue oxygenation 1 14 15 to post-operative treatment 16 17 . Their wide range of extraordinary properties - high density, high viscosity, high biological and chemical inertness, high gas solubility 18 19 - offer opportunities for applications in biomedicine and physical chemistry 20 21 , therefore leading to a high interest in scientific development 2 18 19 22 23 24 25 .…”

Soft X-ray Absorption Spectroscopy of Liquids for Understanding Chemical Processes in Solution

“…30 We have also studied C K-edge XAS of liquid perfluorocarbons. 31,32 The nano particles in liquid phase such as nanodiamonds 33,34 and carbon dots 35 have been also studied by C and O K-edge XAS.…”