A Time-Dependent Density Functional Study of a Non-Aromatic [1.1.1.1.1]-Pentaphyrin and Its Lutetium Complex

Abstract

The molecular structures and absorption electronic spectra of two novel phototoxic pentapyrrolic expanded porphyrins (a isopentaphyrin derivative and its lutetium complex) have been studied at the density functional level and its time-dependent extension (TDDFT). The geometries were optimized with three different exchange-correlation functionals (PBE0, B3LYP, and ωB97XD) and the SV(P) basis set plus the pseudopotential method for the complex. With respect to the porphyrin, the structure of [1.1.1.1.1]-pentaphyrin and its lutetium complex are predicted much distorted due to the lack of conjugation. The lowest excitation energy band (experimental at 814 nm) for the free-base isopentaphyrin is well predicted by the ωB97XD at 772 nm. The possible photodynamic reaction mechanisms (types I and II) were studied through the calculation of the electron affinity and ionization potentials in solvent, using the COSMO model.

22π-Electrons [1.1.1.1.1] pentaphyrin as a new photosensitizing agent for water disinfection: experimental and theoretical characterization

“…This means that PCCox 4 is able to produce the cytotoxic agent. The comparison between the ΔES-T herein computed for 4 and that previously found for the reduced species 3 [25] (< 0.2 eV) can explain the observed differences between these two expanded porphyrins. [24] Actually, in view of the very small energy ΔES-T gap found for the isopentaphirin, the ability to generate singlet oxygen by means of a type II PDT mechanism was ruled out.…”

“…[ [24][25] Herein we report a joint experimental and theoretical investigation of the new 20-(4'carboxyphenyl)-2,13-dimethyl-3,12-diethyl- [22] pentaphyrin complex PCCox (4). The photoactivation properties of the novel expanded porphyrin were recently tested in water disinfection, using S. Aureus as a Gram-positive bacteria model and data showed that 4 was effective against these bacteria at nanomolar concentration [26][27].…”

“…Type I and type II photosensitized processes have been explored at DFT and its TDDFT [28] formulation. These methods have been previously and successfully employed to explain the structural and spectroscopic features of a large series of systems including different type of photosensitizers active in PDT [25,[29][30][31][32][33][34][35]. PCCox (m/z 592) showed two intense radical ions at m/z 577 and 563 corresponding to the loss of CH3 and C2H5 radicals, respectively, and two much less intense ions at m/z 483 and 471 due to the neutral displacing of one of the two dialkylated pyrrole moiety (C7H11N) and the benzoic acid radical (C7H5O2), respectively.…”

Synthesis, characterization, quantum chemical calculations and anticancer activity of a Schiff base NNOO chelate ligand and Pd(II) complex

“…Quartarolo and Russo applied PBE0 and ab initio multi-reference coupled cluster with the resolution of identity approximation (RICC2) approaches to predict the UV-Visible spectra of pyranoanthocyanins, a class of derived anthocyanin molecules; they showed that the use of larger basis sets results in little improvement of excitation energies, and that the conformational effect has a slight influence on the λMAX predictions [29]. In another study, Sousa et al (2012) tested B3LYP and PBE0, and long-range corrected ωB97X and ωB97XD hybrid functional to predict the absorption electronic spectra of the isopentaphyrin derivative and its lutetium complex; and they showed that ωB97XD is the most reliable to reproduce the absorption electronic spectra of the isopentaphyrin derivative and its lutetium complex [30]. In regard to the 1 H and 13 C chemical shift calculations, the gauge-independent atomic orbital (GIAO) method is one of the most common approaches used to predict nuclear magnetic shielding tensors (σiso) [31,32].…”

Electronic spectra and intersystem spin‐orbit coupling in 1,2‐ and 1,3‐squaraines

“…[ ] The good performance of these approaches in predicting molecular geometries and optical properties and in studying excited states of organic and metal‐containing systems, is well established in the literature. [ ]…”