Effect of Side-Chain Substituents on Self-Assembly of Perylene Diimide Molecules:  Morphology Control

Abstract

Effect of side-chain substitutions on the morphology of self-assembly of perylene diimide molecules has been studied with two derivatives modified with distinctly different side-chains, N,N'-di(dodecyl)-perylene-3,4,9,10-tetracarboxylic diimide (DD-PTCDI) and N,N'-di(nonyldecyl)-perylene-3,4,9,10-tetracarboxylic diimide (ND-PTCDI). Due to the different side-chain interference, the self-assembly of the two molecules results in totally different morphologies in aggregate: one-dimensional (1D) nanobelt vs zero-dimensional (0D) nanoparticle. The size, shape, and topography of the self-assemblies were extensively characterized by a variety of microscopies including SEM, TEM, AFM, and fluorescence microscopy. The distinct morphologies of self-assembly have been obtained from both the solution-based processing and surface-supported solvent-vapor annealing. The nanobelts of DD-PTCDI fabricated in solution can feasibly be transferred to both polar (e.g., glass) and nonpolar (e.g., carbon) surfaces, implying the high stability of the molecular assembly (due to the strong pi-pi stacking). The side-chain-dependent molecular interaction was comparatively investigated using various spectrometries including UV-vis absorption, fluorescence, X-ray diffraction, and differential scanning calorimetry. Compared to the emission of ND-PTCDI aggregate, the emission of DD-PTCDI aggregate was significantly red-shifted (ca. 30 nm) and the emission quantum yield decreased about three times, primarily due to the more favorable molecular stacking for DD-PTCID. Moreover, the aggregate of DD-PTCDI shows a pronounced absorption band at the longer wavelength, whereas the absorption of ND-PTCDI aggregate is not significant in the same wavelength region. These optical spectral observations are reminiscent of the previous theoretical investigation on the side-chain-modulated electronic properties of PTCDI assembly.

Orientational Organization of Organic Semiconductors within Periodic Nanoscale Silica Channels: Modification of Fluorophore Photophysics through Hierarchical Self‐Assembly

“…As a result, the fluorescence of the molecule is significantly quenched due to the p-p electronic coupling and the symmetry-forbidden transition. [44] The fluorescence decay curve of 1 a in "good" solvent DMF is fitted well to the single exponential profile of the anthracene monomer ( Figure S3, Supporting Information), which further confirms the transformation of the anthracene excimer to monomer by the solvent-guest molecular interactions. In contrast, faster decay of 1 a was observed in the "poor" solvent hexane ( Figure S3, Supporting Information), suggesting an aggregation-induced quenching effect.…”

“…The dramatic spectral changes induced by the solvent molecules with different polarity could be attributed to the different aggregation magnitude of the guest aromatic species, which in turn determines the optical spectral property of the aromatic molecules. [9,44,46] For example, as An-C10 was insoluble in hexane, molecules of An-C10 tended to aggregate gradually in the hexane/2-propanol mixture when the hexane concentration was increased, as did most of the organic aromatic species, which quenched the emission mainly due to the symmetry-forbidden transition involving the lower-energy p-stacking state. [9,44,46] Evidently, small-molecule analytes were able to generate effectively a responsive fluorescence change.…”

Self-assembled multicolor nanoparticles based on functionalized twistacene dendrimer for cell fluorescent imaging

“…However, OTPy nanoparticles showed the same absorption maximum at 380 nm but much broader absorption contour than that in THF, which might result from the weak electronic coupling of molecule OTPy. 56,57 As shown in Figure 4g, a 27-nm bathochromic shift in fluorescence spectra was observed between TTPy (484 nm) and OTPy nanoparticles (511 nm), which was larger than that (6 nm) in THF. More importantly, one can notice that the full width at half maximum became smaller than those in THF.…”

Programmed self-assembly of largeπ-conjugated molecules into electroactive one-dimensional nanostructures

“…SEM, TEM and atomic force microscopy (AFM) images reveal uniform crystalline nanobelts with an average thickness of 100 nm and a ratio of width to height of ∼4. The effect of the side chains on the morphology of the self-assembled objects has been studied with PDIs 10b and 10c having different alkyl substituents ( figure 11(a)) [30]. N , N ;-dodecyl-PDI 10b self-assembles into 1D nanobelts by phase-transfer self-assembly between excess of hexane and a concentrated CHCl 3 solution, due to the favorable π-π stacking of 10b.…”