Browsing by Author "Salla, Cristian A. M."

Now showing 1 - 2 of 2

The Effect of Substituents and Molecular Aggregation on the Room Temperature Phosphorescence of a Twisted Π-System
(Royal Society of Chemistry, 2022) Salla, Cristian A. M.; Farias, Giliandro; Sturm, Ludmilla; Dechambenoit, Pierre; Durola, Fabien; Murat, Aydemir; Bechtold, Ivan H.
Considering the relevance of room temperature phosphorescent (RTP) materials, we discuss the influence of donor and acceptor groups substituted on to a twisted three-fold symmetric hydrocarbon homotruxene, which presents a persistent RTP, even in the absence of donor or acceptor moieties, under ambient conditions as a result of the twisted pi-system. Compared to a fluorine acceptor, a donor methoxy group increases the phosphorescence decay rate in solution, while in the solid-state, molecular aggregation and packing yield a very persistent phosphorescence visible by the eye. The RTP of the intrinsically apolar homotruxene is found to be modulated by polar substituents, whose main impact on the solid-state emission is due to altered packing in the crystal.
Halogenation of a Twisted Non-Polar Π-System as a Tool to Modulate Phosphorescence at Room Temperature
(Royal Soc Chemistry, 2021) Farias, Giliandro; Salla, Cristian A. M.; Aydemir, Murat; Sturm, Ludmilla; Dechambenoit, Pierre; Durola, Fabien; Bechtold, Ivan H.
Halogenation of a twisted three-fold symmetric hydrocarbon with F, Cl or Br leads to strong modulation of triplet-triplet annihilation and dual phosphorescence, one thermally activated and the other very persistent and visible by eye, with different relative contributions depending on the halide. The room temperature phosphorescence is highly unusual given the absence of lone-pair-contributing heteroatoms. The interplay between the spin-orbit coupling matrix elements and the spatial configuration of the triplet state induces efficient intersystem crossing and thus room temperature phosphorescence even without relying on heteroatomic electron lone pairs. A ninefold increase of the ISC rate after introduction of three bromine atoms is accompanied by a much higher 34-fold increase of phosphorescence rate.