Aggregation-induced emission enhancement in boron difluoride complexes of 3-cyanoformazanates

Abstract

Boron difluoride (BF2) complexes of 3-cyanoformazanates exhibit aggregation-induced emission enhancement in THF–water mixtures due to their severely twisted N-aryl substituents which restrict intramolecular motion and π stacking upon aggregation.

Near‐Infrared Photoluminescence and Electrochemiluminescence from a Remarkably Simple Boron Difluoride Formazanate Dye

“…[26] However,w ec annot rule out excimer formation [27] as BF 2 complexes of formazanate ligands have been shown to aggregate through p-type interactions. [28] The l ECL observed during these studies is at least 85 nm (1132 cm À1 )r ed-shifted compared to all other ECL organic dyes reported to date.…”

Methoxy‐Substituted Difluoroboron Benzoylacetonate Complexes with Color‐Tunable Phosphorescence

“…Substitution at the ortho‐ position induced a twist around the Ar−CO bond (40°). Gilroy and co‐workers observed similar results from boron difluoride complexes of 3‐cyanoformazanates with aggregation‐induced emission . This helps to explain the diminished fluorescence quantum yield in solution for compound 4 .…”

“…Compound 4 showed the lowest extinction coefficient, and the most red fluorescence wavelength ( λ F=495 nm); however, the dye is barely emissive in CH 2 Cl 2 (Figure S1). This is likely due to geometry changes and steric interactions of the ortho‐ substituted methoxy groups preventing planarization with the dioxaborine ,. Because of the importance of planar structures in activating the red‐shifted phosphorescence,, the dramatic changes in luminescence through these subtle changes in substitution should be good models for studying RTP emitting materials.…”

“…Gilroy and co-workers observed similar results from boron difluoride complexes of 3-cyanoformazanates with aggregation-induced emission. [43] This helps to explain the diminished fluorescence quantum yield in solution for compound 4. The twisted molecular geometry will likely have an influence on the delayed emission properties in PLA blends.…”

“…This is likely due to geometry changes and steric interactions of the ortho-substituted methoxy groups preventing planarization with the dioxaborine. [42,43] Because of the importance of planar structures in activating the red-shifted phosphorescence, [44,45] the dramatic changes in luminescence through these subtle changes in substitution should be good models for studying RTP emitting materials.…”