The heavy atom effect on Zn(ii) phthalocyanine derivatives: a theoretical exploration of the photophysical properties

Abstract

Absorption electronic spectra, singlet-triplet energy gaps and spin-orbit matrix elements have been computed at DFT and TDDFT levels of theory for a series of substituted Zn(ii)-phthalocyanines (ZnPcs), recently proposed as potential photosensitizers in photodynamic therapy (PDT). Their photophysical properties have been rationalized in the light of the substitution pattern which includes the position, the donor or withdrawing nature, and the relative donating force of peripheral and non-peripheral ligands. Moreover, the effects of heavy substituents on these properties have been investigated by introducing a different number of iodine atoms on the phthalocyanine macrocycle. The results show that the substitution pattern significantly affects the absorption spectra, but just slightly modifies the ΔES-T values. The presence of heavy atoms produces a significant effect on the photophysical properties of the investigated compounds enhancing the spin-orbit coupling (SOC) values.

Synergistic Effects in PtII–Porphyrinoid Dyes as Candidates for a Dual‐Action Anticancer Therapy: A Theoretical Exploration

“…The amount of energy required to excite the molecular oxygen has been previously computed to be 0.90 eV at the same level of theory used herein, which is in good agreement with the experimental value of 0.98 eV. Therefore, to evaluate the feasibility of the energy‐transfer process, we computed the singlet–triplet energy gap for all the investigated porphyrinoid dyes (Figure a).…”

Theoretical Insights into the Switching Off/On of 1O2 Photosensitization in Chemicontrolled Photodynamic Therapy

“…in which is the employed spin–orbit Hamiltonian and n = x , y , z . This protocol was successfully applied to study the photophysical properties of several dyes . The standard redox potential in solution was calculated in acetonitrile by using one of the most popular methods based on the Born–Haber cycle to derive the standard Gibbs free energy ( G ) for the reaction .…”

“…This protocol was successfully applied to study the photophysical properties of several dyes. [31,41,[66][67][68][69][70][71][72][73][74][75][76][77][78] The standard redox potential in solution was calculated in acetonitrile by using one of the most popular methods based on the Born-Haber cycle to derive the standard Gibbs free energy (G)f or the reaction. [79] The G value of the redox half-reaction, DG (sol) ,c onsists of the free energy change in the gas phase (DG (gas) )a nd the solvation free energies of the oxidized and reduced species.…”

Some examples on the performance of density functional theory in the description of bioinorganic systems and processes

“…For that reason, interactions of platinum anticancer drugs with DNA have been extensively investigated, aiming at disentangling the mechanism of action and toxicity [29][30][31]. Less attention, however, has been devoted to the formation of adducts between platinum drugs with biological ligands other than DNA.…”