Design of Conjugated Molecules Presenting Short‐Wavelength Luminescence by Utilizing Heavier Atoms of the Same Element Group

Abstract

The introduction of heavy atoms into conjugated molecules often induces a redshift in the emission spectra. Conversely, we report here a blueshifting effect in the absorption and emission bands of a conjugated organic dye by employing a heavier atom from the same element group. Boron complexes having oxygen- and sulfur-bridged structures in the ligand moiety were synthesized, and their optical properties were compared. Significant optical bands in the absorption and luminescence spectra of the sulfur-bridged complex were observed in a shorter wavelength region than those of the oxygen-bridged complex. Theoretical calculations suggest that replacement of the bridging atom by a heavier one should reduce molecular planarity because of the larger atom size. As a result, the degree of electronic conjugation decreases, and this is followed by a blueshift in the optical bands. Finally, a blue-emissive crystal is demonstrated.

Aggregation‐Induced Emission of Highly Planar Enaminone Derivatives: Unexpected Fluorescence Enhancement by Bromine Substitution

“…Enaminone compounds have been widely used for the formation of highly emissive metal or boron complexes . However, fluorescence properties of pure enaminone compounds have rarely been mentioned, especially in the solid states .…”

Modulation of the solid-state luminescent properties of conjugated polymers by changing the connecting points of flexible boron element blocks

“…Based on this idea, the pyridinoiminate complex BPI was obtained ( Figure 13). 73,74 A large difference between optimized structures in the ground and excited states, which can be obtained by the calculations with density functional theory (DFT) and time-dependent DFT methods, respectively, was proposed. 73 Therefore, it was expected that boron pyridinoiminate can work as an AIE behavior.…”

Aggregation-induced emission characteristics of o-carborane-functionalized fluorene and its heteroanalogs: the influence of heteroatoms on photoluminescence

“…However, recent studies have demonstrated that DBF shows better charge-transporting properties and solubility than DBT. 24,25 The small oxygen atom size endows DBF with smaller torsional angles and higher planarity, which is beneficial for orderly stacking and charge transport in the solid state. 24,26 Even more striking is that furan derivatives can avoid the heavy atom effect that occurs in thiophene-based luminogens.…”

“…24,26 Even more striking is that furan derivatives can avoid the heavy atom effect that occurs in thiophene-based luminogens. 25 Thus, they tend to exhibit stronger and short-wavelength luminescence and are promising candidates for fabricating advanced full-color display optoelectronic devices. o-Carborane was selected to tune the excited state of organic chromophores.…”