Solvent Assisted Tuning of Morphology of a Peptide-Perylenediimide Conjugate: Helical Fibers to Nano-Rings and their Differential Semiconductivity

Abstract

Understanding the regulatory factors of self-assembly processes is a necessity in order to modulate the nano-structures and their properties. Here, the self-assembly mechanism of a peptide-perylenediimide (P-1) conjugate in mixed solvent systems of THF/water is studied and the semiconducting properties are correlated with the morphology. In THF, right handed helical fibers are formed while in 10% THF-water, the morphology changes to nano-rings along with a switch in the helicity to left-handed orientation. Experimental results combined with DFT calculations reveal the critical role of thermodynamic and kinetic factors to control these differential self-assembly processes. In THF, P-1 forms right handed helical fibers in a kinetically controlled fashion. In case of 10% THF-water, the initial nucleation of the aggregate is controlled kinetically. Due to differential solubility of the molecule in these two solvents, elongation of the nuclei into fibers is restricted after a critical length leading to the formation of nano-rings which is governed by the thermodynamics. The helical fibers show superior semi-conducting property to the nano-rings as confirmed by conducting-AFM and conventional I-V characteristics.

Solute–Solvent Interactions in Modern Physical Organic Chemistry: Supramolecular Polymers as a Muse

“… 150 Diverse pathways were also observed in the aqueous polymerization of N -phenylalanyl decorated PDIs. 151 In aqueous solutions containing 10 vol % THF, the monomers assembled into concentric rings of left-handed supramolecular polymers due to the poor solubility of the growing polymers. In contrast, in THF, long fibers with a right-handed helicity were obtained, as the growing polymers remained soluble in the more apolar solvent.…”

Self-Assembly Assisted Tandem Sensing of Pd2+and CN−by a Perylenediimide-Peptide Conjugate

“…It is worth mentioning here that the A 0‐0 /A 0‐1 ratio is commonly considered as a tool to monitor the aggregation. For perylene chromophores in aggregated state, typical values for the absorption ratio A 0−0 /A 0−1 are <0.7 while monomerically solubilized PDIs show Franck−Condon progression with a ratio A 0−0 /A 0−1 of ∼ 1.6 ,. When excited at 490 nm, compound 1 showed an intense emission at 545 nm in 1:1 DMF‐water (Supporting Information).…”

A DNA-NDI Hybrid to Efficiently Detect Histone in Parts per Trillion (ppt) Level

“…Unless otherwise mentioned all the reported experiments are carried out in 10 mM phosphate buffer pH 7.4. The absorption spectra of all NDIs showed two prominent vibronic bands at ∼ 380, 360 and a shoulder at 340 nm attributed to the 0–0, 0–1 and 0–2 vibrational transitions (Figures S1‐5, Supporting Information) . The emission spectra of these NDI derivatives are mirror images of the respective absorption spectra and show two prominent bands at ∼393 and ∼412 nm (Figures S1‐5, Supporting Information) .…”