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Updated: May 6, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Unravelling the molecular structure and packing of a planar molecule by combining nuclear magnetic resonance and
Gustavo A M Sáfar1, Angelo Malachias, Rogério Magalhães-Paniago
1Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil. gamsafar@yahoo.com.br.
Abstract:
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.
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