Unravelling the molecular structure and packing of a planar molecule by combining nuclear magnetic resonance and scanning tunneling microscopyElectronic supplementary information (ESI) available: Infrared and optical absorption spectra of the substances. See DOI: 10.1039/c3cp53542h

• Main Authors: Sáfar, Gustavo A. M, Malachias, Angelo, Magalhães-Paniago, Rogério, Martins, Dayse C. S, Idemori, Ynara M
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c3cp53542h

The determination of the molecular structure of a porphyrin is achieved by using nuclear magnetic resonance (NMR) and scanning tunneling microscopy (STM) techniques. Since macroscopic crystals cannot be obtained in this system, this combination of techniques is crucial to solve the molecular structure without the need for X-ray crystallography. For this purpose, previous knowledge of the flatness of the reagent molecules (a porphyrin and its functionalizing group, a naphthalimide) and the resulting molecular structure obtained by a force-field simulation are used. The exponents of the I - V curves obtained by scanning tunneling spectroscopy (STS) allow us to check whether the thickness of the film of molecules is greater than a monolayer, even when there is no direct access to the exposed surface of the metal substrate. Photoluminescence (PL), optical absorption, infrared (IR) reflectance and solubility tests are used to confirm the results obtained here with this NMR/STM/STS combination. No mass spectrometry, no X-ray diffraction, just STM and NMR were used for structural determination of a new porphyrin molecule.