Modulation of Properties by Ion Changing Based on Luminescent Ionic Salts Consisting of Spirobi(boron ketoiminate)

Abstract

We report development of luminescent ionic salts consisting of the boron ketoiminate structure, which is one of the robust skeletons for expressing aggregation-induced emission (AIE) properties. From the formation of the boron-centered spiro structure with the ketoiminate ligands, we obtained stable ionic salts with variable anions. Since the ionic salts show Tms below 100 °C, it was shown that these salts can be classified as an ionic liquid. By using PF6 anion, the single crystal—which is applicable for X-ray crystallography—was obtained. According to the optical measurements, it was proposed that electronic interaction should occur through the boron center. Moreover, intense emission was observed both in solution and solid. Finally, we demonstrated that the emission color of the PF6 salt was altered from crystal to amorphous by adding mechanical forces. Based on boron complexation and intrinsic solid-state luminescent characters, we achieved obtainment of emissive ionic materials with environmental responsivity.

Design for a Pure-Blue-Emissive Polymer Film through the Selective Perturbation of the Energy Level of the Highest Occupied Molecular Orbital in a Boron Complex

“…Similarly to common AIE-active molecules, these motions were effectively suppressed in the aggregation. As a result, solid-state luminescence was observed from the series of boron complexes and polymers. − More recently, by introducing the fused structure at these AIE-active complexes for suppressing molecular motions, it was confirmed that the resulting fused boron complexes (FBKIs, Figure ) showed not only similar luminescence efficiencies in solution, solid, and amorphous but also mechanochromic luminescent behaviors. − In particular, it was demonstrated that FBKIs are a platform for fabricating luminescent polymer films . The resulting polymers showed yellow emission, and red-shifts were observed in the films.…”

Photophysical Properties of Pyrene‐Substituted nido‐Carborate Anion and the Change of Luminescence Species by Counter Cations in Solution and Solid States

“…Moreover, the roles of counter ions in photoluminescent properties are not systematically examined. Although several cation‐based emitters were reported, [ 38–44 ] there are limited reports on anion‐based emitters. [ 45,46 ] Tohnai et.al .…”

“…Moreover, the roles of counter ions in photoluminescent properties are not systematically examined. Although several cation-based emitters were reported, [38][39][40][41][42][43][44] there are limited [17][18][19] and b) nido-carborate anion (PYnCA). The red hydrogen atom is μ-H. reports on anion-based emitters.…”

Frustrated element-blocks: A new platform for constructing unique stimuli-responsive luminescent materials

“…Various element-blocks with mechanochromic luminescent properties have been reported, and it is suggested that intermolecular interaction could be the major factor for modulating luminescent color in solid. 17,18 Actually, since molecular distribution and subsequently degree of intermolecular interaction would be considerably different between crystal and amorphous, mechanochromic luminescent behaviors appear when regular structures in the solid-state luminescent crystalline materials are collapsed by mechanical forces. On the other hand, in order to avoid ACQ usually caused by intermolecular interaction in the condensed state, the introduction of bulky substituents is one of conventional strategies.…”