Design of Hückel–Möbius Topological Switches with High Nonlinear Optical Properties

Abstract

The macrocyclic ring of expanded porphyrins presents a conformational versatility that leads to original structural motifs and generates unique Hückel-to-Möbius topological switches. These systems can act as optoelectronic materials and their range of applicability depends on the high values of the nonlinear optical properties (NLOP) and the large differences between the Hückel and Möbius structures. With the aim to design new topological switches with the optimum NLOP, we have performed a DFT computational study on the effect of three different geometric and electronic factors of the meso-substituents: i) their electron-withdrawing and -releasing character; ii) their distribution along

Aromaticity as a Guiding Concept for Spectroscopic Features and Nonlinear Optical Properties of Porphyrinoids

“…In this section, it is important to note that our goal is to assess if the devised structure-property relationships hold for real-world meso -substituted porphyrinoids. A detailed investigation of the effect of peripheral substituents on the NLO properties is out of the scope of the present article, although it is expected that the presence of strong electron-withdrawing and -releasing groups located on opposite sides of the porphyrinoid skeleton will led to a dramatic increase of the NLO responses [ 22 ]. Here, only a subset of porphyrinoids is considered, namely 16N , 18P , 20O , 22I and 22S .…”

“…Relative to the parent porphyrin, expanded porphyrins exhibit spectacularly high TPA cross-section values [ 7 , 18 , 19 ], so they are very promising candidates for biomedical applications, such as photodynamic therapy [ 20 ]. Moreover, several studies found a close relationship between molecular topology, aromaticity and NLO properties in expanded porphyrins [ 11 , 12 ] and demonstrate that Hückel-to-Möbius topological switches behave as efficient optical switches [ 21 , 22 , 23 ]. Besides NLO properties, our recent work highlights the importance of the macrocyclic aromaticity in determining the electron transport properties of expanded porphyrins; so redox-triggered aromaticity switches act as efficient conductance switching elements for molecular electronic devices [ 24 ].…”

Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime: Hückel–Möbius Interconversions in Expanded Porphyrins

“…Expanded porphyrins have drawn much attention over the past few decades due to their facile redox interconversions, novel metal coordination behaviors, versatile electronic states, and conformational flexibility. 1 The latter is responsible for the rich chemistry associated with such systems, which has led to various applications such as near-infrared dyes, 2 nonlinear optical materials, 3 magnetic resonance imaging contrast agents 4 and molecular switches. 5 Such changes may involve a Hückel-Möbius aromaticity switch within a single molecule, which can easily be induced by, inter alia, an appropriate solvent, pH, temperature and metalation conditions.…”

Reversible π-system switching of thiophene-fused thiahexaphyrins by solvent and oxidation/reduction

“… 9 , 10 In particular, noteworthy are their optical and photophysical properties that can be altered greatly by their topologies and π-systems. 11 In addition, topology and aromaticity switches based on expanded porphyrins have attracted much interest. 11d , e Thus, expanded porphyrins could be ideal platforms for exploring novel functions as well as addressing fundamental aspects of chemical topology by rational molecular design.…”