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Title: Quantum chemical insights into the dependence of porphyrin basicity on the meso-aryl substituents: thermodynamics, buckling, reaction sites and molecular flexibility
Authors: Presselt, Martin
Dehaen, Wim
MAES, Wouter 
Klamt, Andreas
Martinez, Todd
Beenken, Wichard
Kruk, Mikalai
Issue Date: 2015
Source: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17 (21), p. 14096-14106
Abstract: The chemical and sensing properties of porphyrins are frequently tuned via the introduction of peripheral substituents. In the context of the exceptionally fast second protonation step in the case of 5,10,15,20-tetraphenylporphyrin (TPP), as compared to porphin and 5,10,15,20-tetramesitylporphyrin (TMesP), we investigated the macrocycle-substituent interactions of these three porphyrin derivatives in detail. Using quantum chemical thermodynamics calculations, the analysis of geometric structures, torsional profiles, electrostatic potential distributions, and particularly the analysis of molecular flexibilities via ab initio molecular dynamics simulations, we obtained a comprehensive picture of the reactivities of the studied porphyrins and how these are influenced by the meso-substituents. As compared to porphin and TMesP the second protonation of TPP is energetically more favorable and is particularly energetically comparable to its first protonation, instead of being significantly less favorable like in the case of porphyrin and TMesP. Additionally, the second TPP protonation is facilitated by an interplay between out-of-plane (oop) distortion of the protonation site and a pronounced electrostatic binding spot at the protonation site. Furthermore, the second protonation is particularly facilitated in the case of TPP by the large oop-flexibility of the diprotonated species as unraveled by ab initio molecular dynamics simulations.
Notes: [Presselt, Martin] Univ Jena, Inst Phys Chem, D-07743 Jena, Germany. [Presselt, Martin; Martinez, Todd] Stanford Univ, Dept Chem, Stanford, CA 94305 USA. [Presselt, Martin; Martinez, Todd] Stanford Univ, PULSE Inst, Stanford, CA 94305 USA. [Presselt, Martin; Beenken, Wichard J. D.] Ilmenau Univ Technol, Inst Phys, D-98684 Ilmenau, Germany. [Dehaen, Wim] Katholieke Univ Leuven, Dept Chem, Mol Design & Synth, B-3001 Leuven, Belgium. [Maes, Wouter] Hasselt Univ, Inst Mat Res IMO IMOMEC, Design & Synth Organ Semicond DSOS, B-3590 Diepenbeek, Belgium. [Klamt, Andreas] COSMOlog GmbH&COKG, D-51379 Leverkusen, Germany. [Klamt, Andreas] Univ Regensburg, D-93040 Regensburg, Germany. [Martinez, Todd] SLAC Natl Accelerator Lab, Menlo Pk, CA 94309 USA. [Kruk, Mikalai] Belarusian State Technol Univ, Dept Phys, Minsk 220050, Byelarus.
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ISSN: 1463-9076
e-ISSN: 1463-9084
DOI: 10.1039/c5cp01808k
ISI #: 000354946200036
Category: A1
Type: Journal Contribution
Validations: ecoom 2016
Appears in Collections:Research publications

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