Thymine-Induced Dynamic Switching of Self-Assembled Nanofibers in Diaminotriazine-Functionalized Tetraphenylethylene Derivatives: Implications for One-Dimensional Molecular Devices

Abstract

One-dimensional (1D) supramolecular polymers of aggregation-induced emission (AIE)-active chromophores belong to an in-demand group of functional materials because of their potential applications in optoelectronic devices like optical waveguides, lasers, displays, photodetectors, field-effect transistors, and solar cells. Herein, we report the hydrogen (H)-bondingdirected self-assembly of diaminotriazine-appended tetraphenylethylene derivatives (TPE-DAT) into 1D-fibers, hierarchical organogels and their thymine-induced structural transitions. The intermolecular H-bonding ability of diaminotriazine (−DATDAT−) leads to the formation of TPE dimers, which upon subsequent cooperative self-assembly via π–π stacking forms micrometer-long, blue-emissive, bundled nanofibers. Further, we exploit the molecular recognition property of thymine nucleobase toward the diaminotriazine unit to tune the properties of this 1D assembly. In the presence of a thymine derivative (T-C12), the blue-emissive, bundled nanofibers of TPE-DAT having a width of 70–80 nm changes to green-emissive nanofibers of TPE-DATT-C12 with 30–40 nm width. This transition from blue- to green-emissive nanofibers and hierarchical gels was ascribed to the change in monomeric units, their molecular planarity, and packing in the self-assembly, which was further probed by UV–visible absorption, atomic force microscopy (AFM), transmission electron microscopy (TEM), and fluorescence properties. In addition, to gain more insights into the mechanism of these 1D-assemblies, we explored the self-assembly properties of chiral and racemic derivatives of TPE-DAT and the gelation properties of TPE-DAT and TPE-DATT-C12. In short, this work demonstrates the use of the molecular recognition property of nucleobase and nucleobase analogues in constructing and controlling the formation of rarely reported 1D-assemblies of AIE-active TPE chromophores.

Aggregation-Induced Emission-Active Nanostructures: Beyond Biomedical Applications

“…The former formed blue-emissive flexible-bundled fibers, whereas the latter formed green-emissive rigid-random fibers. Reproduced from ref . Copyright 2022 American Chemical Society.…”

“…Recently, Saraswathi and Joseph reported the self-assembly of diaminotriazine-functionalized TPE derivatives (11a−c) in the presence of thymine into micrometer-long 1-D nanofibers of variable widths to form hierarchical gels with bright green fluorescence. 109 Intermolecular hydrogen bonding between diaminotriazine units enables the formation of homodimers, which packs in hexagonal columnar structures in the absence of thymine to afford blue-emissive flexible-bundled fibers. The presence of thymine, however, disrupted the formation of homodimers by forming heterodimers, which packs in a tetragonal columnar structure to afford green-emissive rigidrandom fibers (Figure 5).…”

“…Among the general reviews in biomedical applications, the preparation of various AIE-active nanoarchitectures and nanomaterials has been reviewed. ,, AIE-active polymers including FNPs, amphiphilic AIE-active polymers, and their nanoprobes for biomedical applications have also been summarized. There are a number of reviews with focus on particular applications, for example, theranostics. , Specifically, the applications of AIE nanomaterials for photodynamic therapy and cancer diagnosis and treatment , and bioimaging and biosensing − were reviewed. Some other interesting works on AIE polymeric FNPs and carbon dots − and drug delivery have also been summarized.…”

Two-dimensional self-assembly and co-assembly of two tetracarboxylic acid derivatives investigated by STM

“…Supramolecular self-assembly has been a wide concern in many elds such as nanopattern fabrication and heterogeneous nanomaterials ascribed to its ability to guide simple molecular components to spontaneously form complicated and wellorganized molecular aggregation states via molecular noncovalent interactions. [1][2][3][4] Supramolecular self-assembly is promising in the preparation of diverse functional nanostructures through designing the chemical structures of functional building blocks at the molecular level and controlling the connection of building blocks. The precise construction of multi-component self-assembly systems anticipated to possess functions that cannot be achieved using mono-component systems has attracted attention and yet remains challenging.…”

Fatty Acids/Tetraphenylethylene Conjugates: Hybrid AIEgens for the Preparation of Peptide-Based Supramolecular Gels

“…Tetraphenylethylene (TPE) is the prototype AIEgens due to its easy synthesis and a wide range of possibilities to modify the scaffold (Feng H.T. et al, 2018;Liu Q et al, 2018;Yang et al, 2018;García-González et al, 2021;Ma et al, 2021;Saraswathi and Joseph, 2022). Although some debate still exists, both restriction of intramolecular rotation and intramolecular π-π stacking interactions have been generally recognized as the mechanism of the TPE intense bluish emission (Chen et al, 2019).…”