Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

Abstract

The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

Influence of Odd and Even Alkyl Chains on Supramolecular Nanoarchitecture via Self-Assembly of Tetraphenylethylene-Based AIEgens

“…However, when heating was applied, while the luminescent state was insignificantly altered, the luminescent colours of both TPE-Pi and TPE-Az changed from bright blue to light green. The TPE-Se also showed significant mechanochromic properties, as reported in our previous work [34]. These results confirm that these AIGs are relatively sensitive to molecular stacking in the crystal structure.…”

“…However, similar to TPE-Az and TPE-Pi, only TPE-Su nanobeads were observed upon further addition of water (fw = 90%) (ESI Figure S3C). With an alkyl chain of 10 carbons, we recently reported the morphologies of dumbbell shaped TPE-Se in THF/water at different water fractions [34]. Herein, at fw = 80%, self-assembly of TPE-Se led to flower-like aggregates several micrometers in diameter ( Figure 4D).…”

“…Synthesis of TPE-Se: This was molecule prepared following our reported paper [34]. Sebacic acid (0.1 g, 0.5 mmol) and amino-TPE (0.407 g, 1.08 mmol) were added to DMF (8 mL) at 0 • C and stirred for 10 min under nitrogen atmosphere, followed by addition of EDCI (0.230 g, 1.48 mmol), DMAP (0.181 g, 1.48 mmol) and TEA (0.2 mL, 1.40 mmol) at once.…”

“…We recently reported the self-assembly of a dumbbell-shaped TPE derivative connecting to an alkyl chain via an amide bond [34]. Scanning Electron Microscopy (FE-SEM) images revealed that this compound had self-organised into a flower-like assembly through a combination of amidehydrogen bonding and van der Waals interactions.…”

Synthesis, characterization, aggregation-induced emission, solvatochromism and mechanochromism of fluorinated benzothiadiazole bonded to tetraphenylethenes

“…[6][7][8] Recently, the aggregation induced emission (AIE) characteristics of small molecules and polymers has been proposed. [9][10][11][12] Tetraphenylethene (TPE) [13][14][15] with its propellershaped structure is one of the most studied examples for aggregation induced emission characteristics. Very recently, the TPE based molecules have been synthesized and investigated by Misra et al [16][17][18] The rational molecular design of the TPE based molecules makes it potential uses in non-doped OLEDs with a good color contrast.…”