Morphologically Diverse Micro- and Macrostructures Created via Solvent Evaporation-Induced Assembly of Fluorescent Spherical Particles in the Presence of Polyethylene Glycol Derivatives

Abstract

The creation of fluorescent micro- and macrostructures with the desired morphologies and sizes is of considerable importance due to their intrinsic functions and performance. However, it is still challenging to modulate the morphology of fluorescent organic materials and to obtain insight into the factors governing the morphological evolution. We present a facile bottom-up approach to constructing diverse micro- and macrostructures by connecting fluorescent spherical particles (SPs), which are generated via the spherical assembly of photoisomerizable azobenzene-based propeller-shaped chromophores, only with the help of commercially available polyethylene glycol (PEG) derivatives. Without any extra additives, solvent evaporation created a slow morphological evolution of the SPs from short linear chains (with a length of a few micrometers) to larger, interconnected networks and sheet structures (ranging from tens to >100 µm) at the air–liquid interface. Their morphologies and sizes were significantly dependent on the fraction and length of the PEG. Our experimental results suggest that noncovalent interactions (such as hydrophobic forces and hydrogen bonding) between the amphiphilic PEG chains and the relatively hydrophobic SPs were weak in aqueous solutions, but play a crucial role in creating the morphologically diverse micro- and macrostructures. Moreover, short-term irradiation with visible light caused fast morphological crumpling and fluorescence switching of the obtained structures.

Light-Responsive Hexagonal Assemblies of Triangular Azo Dyes

“…For instance, compound 4 forms one-dimensional (1D) fibrous structures, regardless of the solvent polarity [ 69 ]. By contrast, compound 2 has a strong tendency to assemble into spherical objects in THF-H 2 O mixed solutions [ 70 ], whereas the substitution of sterically crowded t -Bu groups leads to the formation of hexagonal structures such as short nanorods and long sticks. Notably, after the molecular assemblies, the fluorescence efficiencies for 1 and 2 improved by approximately 2–3%.…”

Environmentally Friendly Synthesis and Self‐Catalytic Hydrolysis of Triazole‐Modified Organosilanes for Polysiloxane Production

“…Organotrialkoxysilanes are the most important representatives of organosilicon molecules, which are the precursors of a wide range of oligomeric, polymeric structures of great practical importance, as well as interest in academic research. [1][2][3][4][5][6][7] Thus, organotrialkoxysilanes are key reagents for obtaining such valuable products and materials as polyhedral oligomeric silsesquioxanes (POSS), [8,9] hyperbranched silsesquioxanes and siloxane dendrimers, [10][11][12][13] cyclic organosilsesquioxanes, various polysiloxane oligomeric and polymeric resins and copolymers, [2,14] as well as surface modifiers. [5,[15][16][17] Currently, the traditional methods for the preparation of such alkoxysilanes are cross-coupling, hydrosilylation, transmetalation, and substitution reactions.…”

“…Organotrialkoxysilanes are the most important representatives of organosilicon molecules, which are the precursors of a wide range of oligomeric, polymeric structures of great practical importance, as well as interest in academic research [1–7] …”

Solvent- and Light-Sensitive AIEE-Active Azo Dye: From Spherical to 1D and 2D Assemblies

“…Fluorescent molecular assembly systems provide an exciting platform for constructing reversibly stimuli-responsive assembled nano-and microstructures whose optical, electronic, and sensing functions can be regulated by contact and non-contact stimuli such as light, chemicals, temperature, and pressure . Many studies have reported the self-assembly of π-conjugated organic chromophores into versatile fluorescent nano-and microstructured materials with such desired functions [1][2][3][4][5][6]12,14,21]. A sufficient understanding of (i) the design of small component molecules, (ii) specific and non-specific interactions of the molecules with surrounding solvents, and (iii) three-dimensional molecular arrangements is critical to elicit responses to stimuli from the self-assembled systems.…”