Correlating elastic properties and molecular organization of an ionic organic nanostructure

Abstract

Mechanical and structural properties of ionically self-assembled nanostructures of meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) and meso-tetra(4-pyridyl)porphyrin (TPyP) are presented. This is the first time that elastic modulus of an ionic porphyrin nanostructure has been reported. X-ray photoelectron spectroscopy (XPS), UV-visible spectra, and elemental analysis all support a stoichiometric 1 : 1 TSPP to TPyP composition. Atomic force microscopy (AFM) revealed that the porphyrin nanostructure is composed of stacked ribbons about 20 nm tall, 70 nm wide, and several microns in length. High resolution transmission electron microscopy (HRTEM) images showed clear lattice fringes 1.5 ± 0.2 nm in width aligned along the length of the nanorod. Selected area electron diffraction (SAED) and powder X-ray diffraction patterns of TSPP:TPyP are consistent with an orthorhombic system and space group Imm2 with lattice parameters a = 26.71 Å, b = 20.16 Å, and c = 8.61 Å. Crystallographic data is consistent with an arrangement of alternating face-to-face TSPP and TPyP molecules forming ordered columns along the length of the nanorods. The structural integrity of the solid is attributed to combined noncovalent interactions that include ionic, hydrogen bonding, and π-π interactions. The values of Young's modulus obtained for the crystalline TSPP:TPyP nanorods averaged 6.5 ± 1.3 GPa. This modulus is comparable to those reported for covalently bonded flexible polymeric systems. The robust bonding character of the TSPP:TPyP nanostructures combined with their mechanical properties makes them excellent candidates for flexible optoelectronic devices.

A Noble‐Metal‐Free Heterogeneous Photosensitizer‐Relay Catalyst Triad That Catalyzes Water Oxidation under Visible Light

“…Infrared studies also confirm the complexation and the formation of a Prussian blue network (Supporting Information, Figure S3). XPS spectra of N 1s and Fe 2p bands (Supporting Information, Figures S4–S6 and Table S1) are also in good agreement with the expected structures . The corresponding SEM‐EDX elemental mapping reveals the homogenous distribution of the elemental species (Supporting Information, Figures S7 and S8) in [Fe‐TPyP] and [CoFe‐TPyP].…”

Surface Chemistry of Vitamin: Pyridoxal 5′‐Phosphate (Vitamin B6) as a Multifunctional Compound for Surface Functionalization

“…The presence of this quaternary amine can be proven using the core N1s photoelectron. In general, binding energy of the N1s electron is upshifted when protonated . The quaternary ammonium on PLP at pH 4 has an bond; NH peak at 400 eV (Figure d, black), which decreases at pH 8 (Figure d, red) and disappears at pH 12 (Figure d, blue).…”

Mechanical behavior of crystalline ionic porphyrins

“…Detailed procedures for the ISA crystal preparation and isolation are described elsewhere [30,35,36]. The different porphyrin crystals were all prepared at 65 °C in neutral or acidic (HCl) aqueous media from positive and negative tecton ion combinations in 1:1 ratios.…”

“…The different porphyrin crystals were all prepared at 65 °C in neutral or acidic (HCl) aqueous media from positive and negative tecton ion combinations in 1:1 ratios. By controlling the acidity/basicity of the reaction medium, one can manipulate the charges (using pKa values) of the tectons in solution and thereby influence the stoichiometry [18,35]. The following solids were synthesized: H 2 TMPyP: H 2 TSPP (pH 5,7), NiTMPyP:H 2 TSPP (pH 7), H 2 TMPyP: NiTSPP (pH 7), CuTMPyP:H 2 TSPP (pH 7), H 2 TMPyP: CuTSPP (pH 7), H 2 [H 2 TPyP]:H 4 TSPP (pH 3), and H 4 TAPP:H 4 TSPP (pH 2.9 for sheaves; pH 3.6 for rods).…”

“…Thus, this report is the first to relate the elastic modulus of single crystal ionic BPs to their molecular organization within the lattice of these anisotropic crystals. A single mechanical propertystructure correlation study of an ionic BP reported earlier by Esklesen et al relied on a powder X-ray diffraction-based molecular arrangement [35].…”