Electronic properties of tetrathiafulvalene‐modified cyclic‐β‐peptide nanotube

Abstract

Cyclic tri-β-peptide having tetrathiafulvalene (TTF) at the side chain was synthesized to prepare a peptide nanotube aligning TTF side chains along the nanotube. The polarized light microscopic observations revealed crystallization of the cyclic peptide by the vapor diffusion method. Fourier-transform infrared and electron diffraction measurements of the crystals clarified formation of homogeneous hydrogen bonds making a columnar structure with a layer spacing of 4.9 Å. Electronic measurements of the peptide crystals on a gold mica substrate were carried out by the current sensing AFM. The current-voltage curves showed a rectification behavior, whose profile was consistent with a metal and p-type semiconductor junction. The p-type property is supported by the first principle calculations, which showed the HOMO orbital delocalizing fully over the plane of the TTF ring with the energy level of -5.1 eV. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 275-282, 2016.

Synthesis, Characterization, and Self-Assembly of a Tetrathiafulvalene (TTF)–Triglycyl Derivative

“…TTF moiety can be consecutively oxidized to the radical cation TTF + and dication TTF 2+ by either electrochemical or chemical processes. Due to the reversibility of these transformations [13], TTF has become a general building block for the fabrication of switchable functional materials [14][15][16][17], including supramolecular self-assembled nanostructures [18][19][20][21].…”

Engineering pH-responsive switching of donor–π–acceptor chromophore alignments along a peptide nanotube scaffold

“…This prole suggests a parallel b-sheet-like structure similarly to the previous reports on cyclic tri-b-peptide nanotubes. 10,24,25 Furthermore, the N-H stretching band was strongly observed at 3288 cm À1 , suggesting homogeneous hydrogen bonds forming in CP3Npi molecular assemblies. 26 Consequently, CP3Npi in HFIP/water is concluded to self-assemble into peptide nanotube owing to hydrogen bond formation.…”

“…Since the height prole indicates around 4 nm thickness which corresponds to the diameter of CP3Npi, single nanotube is considered to be generated without bundle formation, which makes a vivid contrast to the bundle formation of other PNTs due to anti-parallel dipole-dipole interaction between PNTs. 10,24 It is considered that the bulky Npi moieties should hinder close contact of macrodipoles of PNTs, and the large D-p-A dipoles may be arranged to cancel out partly the macrodipole of the PNT.…”

Chiral and random arrangements of flavin chromophores along cyclic peptide nanotubes on gold influencing differently on surface potential and piezoelectricity

“…4), which conrms the peptide nanotube formation through stacking the cyclic b-peptides. 17,24 The distances between the peptide nanotubes were found to be 24Å and 20Å for the C3FAA and C3FES nanotube bundles, respectively. The tight packing of the C3FES nanotubes may be ascribable to the regular arrangement of the avin groups on the peptide nanotube surfaces.…”

“…These absorptions indicate parallel b-sheet like structures and homogeneous hydrogen bond formations. 12,18,24 The crystal rods were identied by observations with the polarized microscopy under a cross Nicol conguration with a tint plate between the two crossed polarizers. The refractive indices along the long axis of the both peptide nanotubes were found to be larger than that along the short axis (Fig.…”