Temperature‐Controlled Pathway Complexity in Self‐Assembly of Perylene Diimide‐Polydiacetylene Supramolecule

Abstract

Self‐assembly process represents one of the most powerful and efficient methods for designing functional nanomaterials. For generating optimal functional materials, understanding the pathway complexity during self‐assembly is essential, which involves the aggregation of molecules into thermodynamically or kinetically favored pathways. Herein, a functional perylene diimide (PDI) derivative by introducing diacetylene (DA) chains (PDI‐DA) is designed. Temperature control pathway complexity with the evolution of distinct morphology for the kinetic and thermodynamic product of PDI‐DA is investigated in detail. A facile strategy of UV‐induced polymerization is adopted to trap and capture metastable kinetic intermediates to understand the self‐assembly mechanism. PDI‐DA showed two kinetic intermediates having the morphology of nanosheets and nanoparticles before transforming into the thermodynamic product having fibrous morphology. Spectroscopic studies revealed the existence of distinct H‐ and J‐aggregates for kinetic and thermodynamic products respectively. The polymerized fibrous PDI‐DA displayed reversible switching between J‐aggregate and H‐aggregate.

2D Nanomaterial-Directed Molecular Aggregation and Energy Transfer between Edge-Bound Donor–Acceptor Pairs

“…The enhancement of PDI water dispersibility in the present study is due to the tetraethyleneglycol end-groups of Lap-PDI4O . A decrease in fluorescence intensity was observed as the water content increased (Figure b), which was attributed to π–π stacking of perylene structures in an H-type aggregate. − The UV–vis spectra of Lap-NDI2O (Figure c) showed slightly redshifted absorption bands and an increase in the baseline absorbance due to scattering as the water content increased, indicating aggregation. As the water content increased, a new and intense band (λ max = 485 nm) appeared in the fluorescence spectra (Figure d), which was attributed to the formation of NDI excimers. , Such aggregation-induced emission is favorable for energy transfer applications in high water content systems .…”

Self-Assembly of Amphiphilic PDI and NDI Derivatives with Opposite Thermoresponsive Fluorescent Behaviors in Aqueous Solution

“…When PDI is aggregated in water, its fluorescent intensity increases with increasing temperature; conversely, the fluorescent intensity of NDI decreases under the same conditions. The decrease in the aggregation degree of PDIs in water at high temperatures is a specific phenomenon and could be employed to explain the improved fluorescence upon temperature rising using the ACQ effect. , Furthermore, this study highlights the significant role of molecular π-nuclei and molecular periphery fine structure modifications in the assembly process, which were observed through methods such as UV–visible (UV–vis) and 2D NMR. The results were dependent on hydrophilic and hydrogen bonding interactions as well as phase transition processes in supramolecular systems exhibiting LCST properties.…”

“…The driving forces behind supramolecular self-assembly include hydrogen bonding, van der Waals interaction, π–π stacking, host–guest interactions, charge-transfer interactions, hydrophobic interactions, and various other noncovalent interactions . In recent years, self-assembly has become an effective approach to developing smart functional materials. − Self-assembly is a phenomenon in which molecules with relatively simple or small structures are triggered from a disordered state to aggregate and organize themselves into regular structures through interactions. Therefore, assembly could be produced by the act of molecular aggregation; in other words, the aggregation of molecules may also be accompanied by self-assembly.…”

Non-destructive real-time monitoring and investigation of the self-assembly process using fluorescent probes

“…The self-assembly process is driven by both thermodynamics and kinetics, and understanding the kinetics of self-assembly is benecial for predicting the assembly behavior and designing hierarchical structures. 161,162 However, due to a lack of effective approaches for morphological evolution tracking during the assembly process, few researchers have systematically considered the kinetic process since existing research was mostly focused on the structural changes between aggregates. 7 The proposal of a uorescent probe provides a new idea for kinetic characterization.…”