Highly Solid‐State Emissive Pyridinium‐Substituted Tetraphenylethylene Salts: Emission Color‐Tuning with Counter Anions and Application for Optical Waveguides

Abstract

In this paper seven salts of pyridinium-substituted tetraphenylethylene with different anions are reported. They show typical aggregation-induced emission. Crystal structures of three of the salts with (CF(3)SO(2))(2) N(-), CF(3) SO(3)(-), and SbF(6)(-) as the respective counter anions, are determined. The emission behavior of their amorphous and crystalline solids is investigated. Both amorphous and crystalline solids, except for the one with I(-), are highly emissive. Certain amorphous solids are red-emissive with almost the same quantum yields and fluorescence life-times. However, some crystalline solids are found to show different emission colors varying from green to yellow. Thus, their emission colors can be tuned by the counter anions. Furthermore, certain crystalline solids are highly emissive compared to the respective amorphous solids. Such solid-state emission behavior of these pyridinium-substituted tetraphenylethylene salts is interpreted on the basis of their crystal structures. In addition, optical waveguiding behavior of fabricated microrods is presented.

AIE active pyridinium fused tetraphenylethene: Rapid and selective fluorescent “turn-on” sensor for fluoride ion in aqueous media

“…[44] Thus, considering the AIE feature of TPE units, we speculate that this 27-fold increase in fluorescence intensity is due to both the formation of less soluble amorphous aggregates of N-methylpyridinium fused TPE and annihilation of deleterious heavy atom effect of iodide ion by displacement of fluoride ion with iodide ion. [44] These suggestions are evidently justified in view of the previously reported literatures by Tang [44] and Zhang [45]. Besides increasing in fluorescence intensity, the addition of fluoride anion to the aqueous solution of 1 is also recorded as a blue shift.…”

“…Thus, a decrease in π-conjugation between pyridinium, phenyl and ethylene units, that leads to blue shifted emission spectra, occurs. [45] The proposed sensing mechanism was illustared in Figure 2. The detection limit is also determined with this experiment by establishing the minimum level at which fluorescence initially increased at 470 nm upon addition of fluoride ion and recorded as 6x10 -4 M. The UV/Vis absorption spectra of DMSO and aqueous solution of 1 before and after addition of 3.0 mM fluoride anion is shown in Figure S1.…”

Emissive nanoparticles from pyridinium-substituted tetraphenylethylene salts: imaging and selective cytotoxicity towards cancer cells in vitro and in vivo by varying counter anions

“…In addition, it is expected that the bulky anions in NanoTPES 2 , 3 and 4 may allow the tetraphenylethylene frameworks to possess more planar conformations, which can lead to the red-shifts of the emission according to our previous report. 16 …”

Tuning the Solid State Emission of the Carbazole and Cyano‐Substituted Tetraphenylethylene by Co‐Crystallization with Solvents

“…Furthermore, the controllable formation of three emissive forms of di( p ‐methoxylphenyl) dibenzofulvene was realized in the presence of cetyl trimethylammonium bromide (CTAB). [17b] We also found that the emission colors and quantum yields of crystalline solids of pyridinium‐substituted tetraphenylethylene with different anions could be tuned by the respective counter anions . In this case, the counter anions influence the packing of pyridinium‐substituted tetraphenylethylene in the crystals and thus the conformations of the tetraphenylethylene framework are affected.…”