Singlet oxygen generation by porphyrins and metalloporphyrins revisited: A quantitative structure-property relationship (QSPR) study

Abstract

Porphyrins and metalloporphyrins are used as photosensitizers in photocatalysis, photodynamic therapy (PDT), disinfection, degradation of persistent pollutants and other applications. Their mechanism of action involves intersystem crossing to triplet excited state followed by formation of singlet oxygen (1 O2), which is a highly reactive species and mediates various oxidative processes. The design of advanced sensitizers based on porphyrin compounds have attracted significant attention in recent years. However, it is still difficult to predict the efficiency of singlet oxygen generation for a given structure. Our goal was to develop a quantitative structure-property relationship (QSPR) model for the fast virtual screening and prediction of singlet oxygen quantum yields for pophyrins and metalloporphyrins. We performed QSPR analysis of a dataset containing 32 compounds, including various porphyrins and their analogues (chlorins and bacteriochlorins). Quantum-chemical descriptors were calculated using Density Functional Theory (DFT), namely B3LYP and M062X functionals. Three different machine learning methods were used to develop QSPR models: random forest regression (RFR), support vector regression (SVR), and multiple linear regression (MLR). The optimal QSPR model «structuresinglet oxygen generation quantum yield» obtained using RFR method demonstrated high determination coefficient for the training set (R 2 = 0.949) and the highest predicting ability for the test set (pred_R 2 = 0.875). This proves that the developed QSPR method is realiable and Manuscript File Click here to view linked References 2 can be directly applied in the studies of singlet oxygen generation both for free base porphyrins and their metal complexes. We believe that QSPR approach developed in this study can be useful for the search of new poprhyrin photosensitizers with enhanced singlet oxygen generation ability.

Single-Atom Catalysis for Efficient Sonodynamic Therapy of Methicillin-Resistant Staphylococcus aureus-Infected Osteomyelitis

“…From Figure S8 and Figure S9, the generation of • OH and • O 2 − is negligible in all groups, suggesting that the sonodynamic mechanism of HNTM-Pt@ Au was similar to that of the type II PDT. 39,40 As shown in Figure 2F, the sonocatalytic mechanism can be summarized as the following two points: (i) Au NRs can enhance the ultrasonic cavitation and improve the absorption of ultrasonic energy in the system; (ii) Au NRs and Pt single atoms acted as electron acceptors to promote the transfer of electrons generated from HNTM, improving the separation efficiency of electron−hole pairs. Sonocatalytic Activity of Different Metal Single Atoms and Theoretical Calculations.…”

Quantitative Structure‐Property Relationship Modelling for the Prediction of Singlet Oxygen Generation by Heavy‐Atom‐Free BODIPY Photosensitizers**

“…For instance, models reported for pteridines, furicoumarins and porphyrins showed RMS Φ Δ errors of 5.7–24.8 %. [ 47 , 48 , 49 ] It should be noted that in these studies the values of singlet oxygen quantum yields were measured in identical conditions for all compounds in the dataset. In the current study we used larger datasets (>40 BODIPYs for each model) with Φ Δ values measured using different 1 O 2 traps and reference photosensitizers.…”

“… [46] However, earlier we showed that QSPR may be used for the analysis of 1 O 2 production by pterins and flavins, [47] psoralens and angelicins, [48] porphyrins and metalloporphyrins. [49] In this regard, applying QSPR for the prediction of Φ Δ values for heavy‐atom‐free BODIPYs in solvents of different polarity offers a means to estimate SOCT‐ISC efficiency in these systems. Hence, we started to search BODIPY structures which undergo SOCT‐ISC to correlate molecular features to singlet oxygen quantum yields with the aid of machine learning methods.…”

Quantitative Structure–property Relationship Modelling for the Prediction of Singlet Oxygen Generation by Heavy-Atom-Free BODIPY Photosensitizers

“…46 However, earlier we showed that QSPR may be used for the analysis of 1 O 2 production by pterins and flavins, 47 psoralens and angelicins, 48 porphyrins and metalloporphyrins. 49 In this regard, applying QSPR for the prediction of  Δ values for heavy-atom-free BODIPYs in solvents of different polarity offers a means to estimate SOCT-ISC efficiency in these systems. Hence, we started to search BODIPY structures which undergo SOCT-ISC to correlate molecular features to singlet oxygen quantum yields with the aid of machine learning methods.…”