Synthesis, optical properties and helical self-assembly of a bivaline-containing tetraphenylethene

Abstract

A chiral tetraphenylethene derivative with two valine-containing attachments (TPE-DVAL), was synthesized by Cu(I)-catalyzed azide-alkyne “click” reaction. The optical properties and self-assembling behaviours of TPE-DVAL were investigated. The molecule is non-emissive and circular dichroism (CD)-silent in solution, but shows strong fluorescence and Cotton effects in the aggregation state, demonstrating aggregation-induced emission (AIE) and CD (AICD) characteristics. TPE-DVAL exhibits good circularly polarized luminescence (CPL) when depositing on the surface of quartz to allow the evaporation of its 1,2-dichloroethane solution. SEM and TEM images of the molecule show that the molecule readily self-assembles into right-handed helical nanofibers upon the evaporation of its solvent of DCE. The molecular alignments and interactions in assembling process are further explored through XRD analysis and computational simulation. The driving forces for the formation of the helical fibers were from the cooperative effects of intermolecular hydrogen bonding, π-π interactions and steric effect.

Circularly‐Polarized Luminescence (CPL) from Chiral AIE Molecules and Macrostructures

“…Furthermore, Li et al investigated the impact of two‐fold substitution with l ‐valine ( Figure ), which gave helical fibers when a 0.1 m m DCE solution was allowed to slowly evaporate . Unexpectedly, these fibers possessed opposite screw‐sense, although the amino acid derivatives had the same chirality.…”

“…Copyright 2014, The Royal Society of Chemistry. Reproduced with permission . Copyright 2016, Macmillan Publishers Limited.…”

Self‐Assembly of Aggregation‐Induced‐Emission Molecules

“…Molecular self‐assembly is the oriented association of molecules into nano‐ or microscopic structures through noncovalent interactions . AIE molecules offer great advantages as ideal building blocks for the construction of luminescent micro‐/nanostructures because of their high fluorescence efficiency in the solid state and variable emission colors . Due to their unique properties, AIE molecules can be designed as a new kind of functional material that has broad applications in fields such as biology, the environment, materials, pharmacy, and agriculture.…”

Self‐assembled chiral nanostructures of amphiphilic peptide: from single molecule to aggregate

“…Circular dichroism (CD) and ultraviolet–visible (UV–vis) spectroscopy are used to probe the optical activity of self‐assembled aggregates as they grow in dimensions. As well known, if molecules form chiral aggregates with differential absorption of circularly polarized light, CD spectra can provide useful structural information . At a low concentration (0.02 mg/ml), A 6 R 1 molecules are predominantly in random coil conformation, which is demonstrated by CD spectrum with a negative peak at 196 nm (Figure (A), black curve), no chiral architecture being evident in dilute solution.…”