Halogen Bonding in the Design of Organic Phosphors

Abstract

Halogen bonding as a new strategy for introducing heavy atom perturbers in defined stoichiometry in the design of organic phosphors is reviewed. Considering ten novel cocrystals assembled by polyaromatic hydrocarbons (PAHs) and their heterocyclic analogues and haloperfluorobenzenes using the new strategy, apart from biphenyl cocrystals they all phosphoresce strongly, showing that the new methodology can induce phosphorescence by a heavy atom effect. More interesting, the phosphorescence properties, including excitation/emission wavelengths and decay dynamics, show dependence on the structure of the PAHs and interaction patterns, which is very important and valuable in modulation of the expected colors of luminescent materials.

The Halogen Bond

“…Parallel to the work of Kim et al., the XB-based design of organic phosphors has been intensively studied by the group of Prof. Wei Jun Jin, as has been recently reviewed in a book chapter. 1012 Their main target has been to harness halogen···π interactions, the type of XB that was quantified already in the 1940s and 1950s, 51 , 58 , 59 to engineer phosphorescent crystals. Two types of fluorophores were employed: (i) fluorene and its heterocyclic analogues 1013 − 1015 and (ii) polycyclic aromatic hydrocarbons, 649 , 1016 − 1018 typically cocrystallized with 1,4-diiodotetrafluorobenzene (DITFB).…”

“…Parallel to the work of Kim et al., the XB-based design of organic phosphors has been intensively studied by the group of Prof. Wei Jun Jin, as has been recently reviewed in a book chapter . Their main target has been to harness halogen···π interactions, the type of XB that was quantified already in the 1940s and 1950s, ,, to engineer phosphorescent crystals.…”

Cocrystal assembled by 1,4-diiodotetrafluorobenzene and phenothiazine based on C—I...π/N/S halogen bond and other assisting interactions

“…1,4-DITFB can simultaneously act as an XB (-hole bond)/-hole bond donor and acceptor (Wang et al, 2016) originating from the strong electron-withdrawing group (F atom) attached to the benzene ring. Besides being considered as a tecton, 1,4-DITFB can also act as an efficient metal-free heavy-atom perturber to design strongly organic phosphors using XB, which has been shown by mainly combining bent and rigid planar polyaromatic hydrocarbons and their heterocyclic analogues (Gao, Shen et al, 2012;Shen et al, 2012;Zhu et al, 2014;Wang et al, 2014;Pang & Jin, 2015). However, the combination of different functionalized synthons may affect the luminescence properties of cocrystals.…”

Multicomponent Crystals with Two Fast Reorienting Constituents Over Perpendicular Noncovalent Axes

“…In recent years, the supramolecular chemistry and crystal engineering fields have undergone colossal progress due to the construction of complex systems for fundamental studies of intermolecular interactions. − These systems are also relevant when searching for new organic materials with interesting properties such as emission, thermal expansion, or dielectric properties, − and potential applications as sensors or the separation and storage of vapors and gases . From work on cryptophanes and cryptands to cages and capsules, and more recently molecular rotors, , directional interactions such as hydrogen bonds are used to assemble frameworks of increasing complexity.…”