Assemblies of iron and TPPS porphyrins investigated by TEM, AFM and UV/vis spectroscopy

Valentinas Snitka 2Raminta Rodaite Mindaugas Rackaitis 1

1. Bridgestone/Firestone Research, LLC, 1200 Firestone Parkway, Akron, OH 44317-000, United States
2. Kaunas University of Technology, Research Center for Microsystems and Nanotechnology (RCMN KTU), Studentu 65 - 203, Kaunas 3031, Lithuania

Abstract

Porphyrins and related macrocycles provide an extremely versatile nanometer sized synthetic component for a variety of materials applications. The exploration of porpfyrins and metalloporphyrins molecules as building blocks for tailored materials has found rapid growth during the last decade. Films, solids, microporous solids have been explored as field-responsive materials. Assembling molecular functional components into supramolecular architecture is envisioned to yield artificial devices of technological relevance, such as sensors, molecular sieves, energy cells.
In this work an aggregates of the tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and Fe(III)TPPS, formed in acid aqueous solutions were deposited onto hydrophilic(mica, glass) and hydrophobic (graphite) substrates and imaged using Transmission Electron Microskopy (TEM), Scanning Atomic Force Microscopy (AFM) and absorbtion spectra was investigated by UV/vis spectroscopy. The AFM and TEM studies reveald an nanoroads like structures formed on the surface from the TPPS solution. The TEM study revealed aggregate geometries, ranging from spherical with diameters 20-100 nanometers and rodlike structures with the diameter 5-7 nanometers and 1micron length.The nanoroads tend to form a bundles of individual roads. The AFM investigation have shown the flat structures with the thickness of 5-7 nanometres and the wide up to 20-70 nm. It suggest that the flat structure, unlike the previous model developed by authors1 , consist of the bundle of parallel nanoroads, formed by attractive forces of single nanoroads or it is an interplay of nucleation sites of nanoroads. Iron-porphyrins consist of 20-50 nanometer size particles which are dispersed or form fractal like structures around the nucleation centers on the surface. Some fractals have a well defined crystals shape.

1 R. Rotomskis,R. Augulis,V.Snitka,.Valiokas,B.Liedberg J.Phys.Chem.B2004, 108,2833-2838

 

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Presentation: oral at E-MRS Fall Meeting 2004, Symposium A, by Valentinas Snitka
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-01 22:05
Revised:   2009-06-08 12:55