Heteropoly acids triggered self-assembly of cationic peptides into photo- and electro-chromic gels

Abstract

A series of cationic peptides with alternating lysines and hydrophobic residues were designed and synthesized. These kinds of short peptides with protonated lysines can complex with anionic heteropoly acids (HPAs) to form a stable gel in water/ethanol mixed solution. Circular dichroism spectroscopy showed that the short peptides adopted a mixed conformation (β-sheet and random-coil) within the gel matrix. Scanning and transmission electron microscopy revealed that the heteropoly acids, acting as nanosized cross-linkers, first initiated the self-assembly of the cationic peptides into spherical nanostructures. Then these nanospheres accumulated with each other through hydrogen bonds and hydrophobic interactions to form large sheet-like assemblies, which further interconnected with each other forming continuous 3D network structures. Fourier-transform infrared spectroscopy showed that the structural integrity of the HPAs was maintained during the gelation process. The resultant hybrid gels showed reversible photo- and elecrtro-chromic properties. X-ray photoelectron spectroscopy revealed that the hybrid gels, capable of persistent and reversible changes of their colour, are attributed to the intervalence charge-transfer transition of the HPAs. Reversible information writing and erasing were demonstrated through a repeated photo-lithograph or electric stimuli without significant loss of the gel performance.

Highly Crystalline Mesoporous Phosphotungstic Acid: A High‐Performance Electrode Material for Energy‐Storage Applications

“…[17b] This observation suggests that a partial tungsten ions are reduced during the self-assembly process to be stabilized on the dangling bonds of mesoporous structure in 2.5-mPTA. [19] The O 1s XPS spectrum of 2.5-mPTA shows a peak at 532.1 eV, which is slightly lower binding energy than that of pristine PTA ( Figure S4, see SI). The decrease of W-O binding energy in 2.5-mPTA might be attributed to the weakness of W-O bond upon connecting PTA clusters to form microchannels.…”

Highly Crystalline Mesoporous Phosphotungstic Acid: A High‐Performance Electrode Material for Energy‐Storage Applications

“…Interestingly, 2.5‐mPTA exhibits additional peaks at 33.9 and 36.4 eV, which represent W 5+ 4f 7/2 and W 5+ 4f 5/2 states of tungsten, respectively . This observation suggests that a portion of the tungsten ions are reduced during the self‐assembly process to be stabilized on the dangling bonds of the mesoporous structure of 2.5‐mPTA . The O 1s XPS spectrum of 2.5‐mPTA shows a peak at 532.1 eV, which is a slightly lower binding energy than that of pristine PTA (see Figure S4).…”

Polyoxometalate‐Based Photochromic Supramolecular Hydrogels with Highly Ordered Spherical and Cylindrical Micellar Nanostructures

“…Because this device takes al onger time to erase colored patterns, the device has a potentialapplication in recording rewritable information. [12]…”

“…Only al imited number of POM-based photochromic gel systemsh ave been described in the literature. [12] Gao et al developed ap hotochromic hydrogel by introducing ammonium molybdate as ap hotochromic unit into ap olyacrylamide network. [12a] The hydrogele xhibitsg ood photochromic abilities.…”