New electron delocalization tools to describe the aromaticity in porphyrinoids.

  title={New electron delocalization tools to describe the aromaticity in porphyrinoids.},
  author={irene casademont-reig and Tatiana Woller and Julia Contreras‐Garc{\'i}a and Mercedes Alonso and Miquel Torrent‐Sucarrat and Eduard Matito},
  journal={Physical chemistry chemical physics : PCCP},
  volume={20 4},
The role of aromaticity in porphyrinoids is a current subject of debate due to the intricate structure of these macrocycles, which can adopt Hückel, Möbius and even figure-eight conformers. One of the main challenges in these large π-conjugated structures is identifying the most conjugated pathway because, among aromaticity descriptors, there are very few that can be applied coherently to this variety of conformers. In this paper, we have investigated the conjugated pathways in nine… 

Fingerprint of Aromaticity and Molecular Topology on the Photophysical Properties of Octaphyrins

Expanded porphyrins are currently recognized as the ideal test bed to explore the correlation between molecular properties and (anti)aromaticity since they can adopt different π-conjugation

Local and macrocyclic (anti)aromaticity of porphyrinoids revealed by the topology of the induced magnetic field.

It is shown that the analysis of the bifurcation of the induced magnetic field, Bind, allows clear identification and quantification of both local, and macrocyclic aromaticity, in a representative group of porphyrinioids.

Electron Delocalization in Planar Metallacycles: Hückel or Möbius Aromatic?

The recently proposed electron density of delocalized bonds (EDDB) method can be used not only to quantify and visualize aromaticity in such difficult cases, but also to provide a great deal of information on the real role of d‐orbitals in metallacycles without the ambiguity of bookkeeping of electrons in the π‐subsystem of the molecular ring.

Origins of the Electronic Modulations of Bacterio- and Isobacteriodilactone Regioisomers.

Computational methods and mechanistic insights provide a basis for the systematic exploration of the physicochemical properties of porphyrinoids as a function of the number, relative orientation, and degree of macrocycle-π-conjugation of β-substituents, in general, and for dilactone-based poiryrinic chromophores, in particular.

Performance of Electronic Structure Methods for the Description of Hückel–Möbius Interconversions in Extended π-Systems

Examination of a variety of wave function methods and density functionals for describing the thermochemistry and kinetics of topology interconversions across a wide range of macrocycles finds that range-separated double hybrids, such as ωB97M(2) and B2GP-PLYP, outperform other functionals with RMSDs of 0.6 and 0.8 kcal mol–1, respectively.

Aromaticity Survival in Hydrofullerenes: The Case of C66H4 with its π-Aromatic Circuits.

The results show the presence of three π-aromatic circuits at the bottom boat section of C66H4 indicating the unique features of this hydrofullerene in comparison to pristine C60, and reveals that spherical-like cages can involve a complex magnetic response that heavily depends on the orientation of the applied field.

Assessment of the performance of six indices in predicating the aromaticity of planar porphyrinoids

Aromaticity is a fundamental chemical concept that has been widely used in explaining the reactivity, stability, structure, and magnetic properties of many molecules such as conjugated macrocycles,

Aromaticity of Hückel and Möbius Topologies Involved in Conformation Conversion of Macrocyclic [32]Octaphyrin( Refined Evidence from Multiple Visual Criteria

A comprehensive investigation of the aromaticity control process of expanded porphyrins was carried out using a variety of visual criteria for the first time. The results show that the indicators

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

A computational study focuses on a series of Hückel porphyrinoids to assess the relationship between aromaticity, UV/vis absorption spectra and nonlinear properties, finding that aromaticity dictates the photophysical properties in porphyrs, whereas it is not the only factor determining the magnitude of NLO properties.

Triplet State Baird Aromaticity in Macrocycles: Scope, Limitations, and Complications

The aromaticity of cyclic 4nπ-electron molecules in their first ππ* triplet state (T1), labeled Baird aromaticity, has gained growing attention in the past decade. Here we explore computationally the



Description of aromaticity in porphyrinoids.

The block-localized wave function (BLW)-derived aromatic stabilization energies (ASE) of several porphyrinoids reveal that, on a per atom basis, the appended 6π electron heterocycles of porphirinoids confer aromaticity much more effectively than the macrocyclic 4n+2 π electron conjugations.

Control and Switching of Aromaticity in Various All-Aza-Expanded Porphyrins: Spectroscopic and Theoretical Analyses.

Control of aromaticity in various expanded porphyrins from the spectroscopic point of view with assistance from theoretical calculations is described.

Understanding the molecular switching properties of octaphyrins.

Aromaticity is shown to be a key concept in expanded porphyrins, determining the electronic, magnetic and NLO properties of these macrocycles.

Figure eights, Möbius bands, and more: conformation and aromaticity of porphyrinoids.

The conformational processes occurring in porphyrin analogues are often coupled to other chemical phenomena, and can thus be exploited as a means of constructing functional molecular devices.

Evaluation of the nonlinear optical properties for an expanded porphyrin Hückel-Möbius aromaticity switch.

The obtained results indicate that the expanded porphyrins are promising systems to manufacture Hückel-to-Möbius topological switches and provide a correct qualitative description of the electronic and vibrational contributions for the NLOP of expanded poralin.

Theoretical study of the switching between Hückel and Möbius topologies for expanded porphyrins

The expanded porphyrins have become a useful tool to synthesize new Huckel-to-Mobius topological switches. Only applying small changes in the external conditions (temperature, solvent, redox

Predicting the degree of aromaticity of novel carbaporphyrinoids.

The studied porphyrinoid structures have been obtained by replacing the NH and N groups of porphin with formally isoelectronic moieties such as O, S, CH and CH2.

From small carbocyclic rings to porphyrins: a personal account of 50 years of research.

It is shown that neither radical nor ionic intermediates can be detected in their course, and that the structural change rests exclusively on a concerted reorganization of the sand p-electrons of their molecular skeleton, associated with corresponding changes of bond lengths and angles.

Understanding conductivity in molecular switches: a real space approach in octaphyrins.

It is shown that it is not always possible to reduce conductance changes to one bond, and in those molecules where a deep rearrangement occurs far from the structural perturbation, local measures show a limited efficiency.

Nucleus-Independent Chemical Shifts:  A Simple and Efficient Aromaticity Probe.

The use of absolute magnetic shieldings, computed at ring centers with available quantum mechanics programs, are proposed as a new aromaticity/antiaromaticity criterion to establish NICS as an effective aromaticity criterion.