Surface Pressure Driven Supramolecular Architectures from Mixed H-Aggregates of Dye-Capped Azobenzene Derivative

Abstract

We demonstrate a soft chemical approach for the synthesis of dimensionally dictated functionalized mesostructures by continuous tuning of the surface molecular density of a photoreceptable molecule (E)-1-(3-chloro-4-(octyloxy)phenyl)-2-phenyldiazene (compound 1) with Rhodamine B (Rh B). Highly oriented cylindrical microtubules with a hollow center running the entire distance of the assembly in a parallel-packed configuration were formed at the air-water interface. The surface tension driven self-organized structures were evidenced from electronic absorption and steady-state fluorescence spectroscopy in conjunction with optical, polarizing, and epifluorescence microscopy and microspectroscopy; the structural building blocks were identified to be mixed H-aggregates from compound 1 and Rh B of 1:1 stoichiometry, corroborated by a blue shift in the characteristic absorption features. The appearance of a crossover point (apparent isosbestic point) instead of a sharp defined isosbestic point in the absorption spectra signified the formation of mixed H-aggregates from trans-azobenzenes in ion-dipole interaction with the charged Rh B. Increasing the temperature induced an end-to-end self-assembly of the hollow tubules, and photoisomerization of compound 1 did not serve as a trigger to induce self-organization. A nonfluorescent planar crystalline morphology with irregular topology was observed for its isomer (E)-1-(4-chlorophenyl)-2-(4-(octyloxy)phenyl) diazene (compound 2).

Formation and Photoresponsive Properties of Giant Microvesicles Assembled from Azobenzene‐Containing Amphiphilic Diblock Copolymers

“…For the spin-coated film, the shift is larger than that for the vesicle, which means that the aggregation number (the number of azobenzene units within an aggregate) increased during the drying process, according to BenisiHildebrand kinetics. [20] This explanation can be further confirmed by the dialysis experiment of the self-assembled microvesicles. In Figure 3, the blue-shift induced by H-aggregation was found to gradually increase with the elongation of the dialyzing time, during which the water content gradually increased and the polarity of the solution increased at the same time.…”

“…H-aggregation is one kind face-to-face packing of molecules with a plane shape, and such a packing state would result in an energy rise (dipole parallel, transition permitted) and an energy decrease (dipole anti-parallel, transition forbid- den), showing the maximum-absorption peak blueshifting. [8] Although the azobenzene derivatives were thought to form enthalpically pre-micellar ordered H-aggregates, [20] some works showed that within a spherical micelle containing azobenzene surfactants, H-aggregation did not occur. [21] The difference between surfactants and polymers is mainly caused by the length of the molecules' tethered azobenzene units.…”

Solvent‐Polarity‐Tunable Dimeric Association of a Fullerene (C60)–N,N‐Dimethylaminoazobenzene Dyad: Modulated Electronic Coupling of the Azo Chromophore with a Substituted 3D Fullerene

“…[28][29][30] Among the molecular entities capable of forming ordered aggregates, azobenzenes are unique because of their intrinsic photoresponsive property. [31][32][33][34][35][36][37][38] Azobenzenes of donor-acceptor type have been found to form characteristic aggregates depending on the solvent composition, polarity, and the solute concentration.…”

Assembly of π‐Conjugated Nanosystems for Electronic Sensing Devices

“…[26] Consequently, patterned nanoarrays, nanostripes, nanofibers, nanoparticles, nanotubes, and even chiral assemblies could be fabricated. [24,[27][28][29][30] For example, Chen et al reported that by taking the advantage of their thinner and flexible gold nanowires (AuNWs) building blocks, giant superlattice nanomembranes could be fabricated via LB techniques. [31,32] It was found that high transparency, conductivity, and stretchability could be achieved simultaneously in such single-layer AuNWs superlattice nanomembrane, which make them facile to be integrated into lightweight, foldable optoelectronic devices with low consumption of materials and energy.…”

“…Nevertheless, recent investigations found that uniaxial compression of a nanocrystal or nanowire monolayer floating on an aqueous subphase could cause such nanostructures to assemble and pack over a large area, just like “logs‐on‐a‐river” showing in Figure A . Consequently, patterned nanoarrays, nanostripes, nanofibers, nanoparticles, nanotubes, and even chiral assemblies could be fabricated . For example, Chen et al reported that by taking the advantage of their thinner and flexible gold nanowires (AuNWs) building blocks, giant superlattice nanomembranes could be fabricated via LB techniques .…”