Click Synthesis, Aggregation-Induced Emission, E/Z Isomerization, Self-Organization, and Multiple Chromisms of Pure Stereoisomers of a Tetraphenylethene-Cored Luminogen

Abstract

It has been difficult to decipher the mechanistic issue whether E/Z isomerization is involved in the aggregation-induced emission (AIE) process of a tetraphenylethene (TPE) derivative, due to the difficulty in the synthesis of its pure E and Z conformers. In this work, pure stereoisomers of a TPE derivative named 1,2-bis{4-[1-(6-phenoxyhexyl)-4-(1,2,3-triazol)yl]phenyl}-1,2-diphenylethene (BPHTATPE) are successfully synthesized. Both isomers show remarkable AIE effect (α(AIE) ≥ 322) and high fluorescence quantum yield in the solid state (Φ(F) 100%). The conformers readily undergo E/Z isomerization upon exposure to a powerful UV light and treatment at a high temperature (>200 °C). Such conformational change, however, is not observed under normal fluorescence spectrum measurement conditions, excluding the involvement of the E/Z isomerization in the AIE process of the TPE-based luminogen. The molecules of (E)-BPHTATPE self-organize into ordered one-dimensional nanostructures such as microfibers and nanorods that show obvious optical waveguide effect. BPHTATPE shows rich chromic effects, including mechano-, piezo-, thermo-, vapo-, and chronochromisms. Its emission peak is bathochromically shifted by simple grinding and pressurization and the spectral change is reversed by fuming with a polar solvent, heating at a high temperature, or storing at room temperature for some time. The multiple chromic processes are all associated with changes in the modes of molecular packing.

Design amphiphilic dipolar π-systems for stimuli-responsive luminescent materials using metastable states

“…Recently, luminescent materials that are responsive to mechanical stimuli have attracted considerable attention because they have the unique ability to tune their molecular, physical or chemical properties via macroscopic stimulation [5][6][7][8] . Several mechanistic explanations for the mechanically stimulated changes in the colour of the luminescence have been proposed: a phase transformation of the solid structure [9][10][11][12][13][14][15][16] , excimer formation or dissolution [17][18][19] and mechanical stress-induced chemical changes 20,21 . However, the development of new materials with luminescent mechanochromism still depends heavily on serendipitous discovery or random screening; studies based on rationally designed luminophoric compounds and sensitivity to mechanical stimuli remains rare.…”

A stimuli-responsive double-stranded digold(i) helicate

“…rotation of phenyl functions, are restricted in the solid-state rendering the molecules emissive. 18,19 This AIE phenomenon is opposite to commonly observed aggregation-caused quenching. 18,19 However, there are 80 still no examples of metal complexes that simultaneously exhibit AIE activity, phase-dependent and stimuli-responsive luminescent properties.…”

“…18,19 This AIE phenomenon is opposite to commonly observed aggregation-caused quenching. 18,19 However, there are 80 still no examples of metal complexes that simultaneously exhibit AIE activity, phase-dependent and stimuli-responsive luminescent properties. Therefore, it is not astonishing that the general design principles of AIE active mechanochromic luminescent metal compounds, particularly those with 85 remarkably tuneable emission wavelength can not be found in the literature.…”

A Tetraphenylethylene-based Fluorescent Chemosensor for Cu2+ in Aqueous Solution and Its Potential Application to Detect Histidine

“…Since the phenomenon named aggregation-induced emission (AIE) was reported, 21 in which non-emissive dyes can be induced to emit efficiently by the aggregate formation, a large number of AIE-active dyes, such as tetraphenylethylene-based compounds, have been developed in the fields of organic light-emitting diodes and chemo/bioprobes. [22][23][24][25][26] Though some tetraphenylethylene-based sensors for metal ions have been reported, [27][28][29][30] and a tetraphenylethylene-based zinc complex was reported as a sensitive DNA probe by coordination interaction, 31 there is still few related studies on the detection of Cu 2+ or amino acids by the indicator-displacement assay with Cu 2+ . 32 In this report, a tetraphenylethene-based fluorescent compound 1 was synthesized and used to detect Cu 2+ in an aqueous solution.…”