Intrinsic Characterization Method on the Heavy Atom Effect of Metalloporphyrins

Abstract

The presence of room temperature phosphorescence emission in metalloporphyrin, via the transition from the excited triplet state (T1) to the ground state (S0), relies on the chelated heavy metal ions, which is known as the heavy atom effect (HAE). Despite the HAE being a reliable method to tune the phosphorescence process widely, the realization of the HAE nature is a tough task as the induced phosphorescence process is sensitive to not only the specie of bonded heavy atoms but also chemical environments such as the oxygen quenching and solvent effect. In this study, we have aimed at a quantitative determination of the intrinsic phosphorescent transition rate (k P) in metalloporphyrin gadolinium-labeled hematoporphyrin monomethyl ether (Gd-HMME). After the theoretical analysis based on the rate equation model to remove the nonintrinsic contribution and the experimental results of phosphorescence, the k P is calculated to be ∼2.4 × 10–4 μs–1. This study enables us to approach the intrinsic energy characteristic of metalloporphyrins; moreover, our work provides an effective pathway for the further optimization of the varied functional metalloporphyrin.

Tumor-penetrating nanoplatform with ultrasound “unlocking” for cascade synergistic therapy and visual feedback under hypoxia

“…H(Gd) is a metalloporphyrins that undergoes an energy level transition under sound energy to stimulate the valence change and finally catalytically release excess of ROS, especially 1 O 2 . [ 34 , 35 ] The ESR spectra results (Fig. 2 f) and the absorption peak intensity of SOSG (Fig.…”

Insight into the Heavy Atom Effect Induced by Environmental Heavy Atoms for Gadolinium-Labeled Hematoporphyrin Monomethyl Ether

“…k P0 was fitted to be 2.1 × 10 2 s −1 , which coincides with our previous work. 23 The second term k P1 , which is [Gd 3+ ] dependent, is the role played by the external HAE and determined through a slope κ and [Gd 3+ ]. To better illustrate the significance of the slope, the κ is further deduced using eq 6…”

“…The Gd-HMME, surrounded by environmental Gd 3+ , is written as Gd 3+ : Gd-HMME for short, and the concentration of environmental Gd 3+ is denoted by [Gd 3+ ]. According to our previous work, 23 k P could be calculated using eq 1 = k P P T P (1) and Φ P , τ P , and Φ T could be obtained in the following ways. Φ P is obtained by a relative method using eq 2 i k j j j y { z z z i k j j j j j y…”

“…Φ T can be given by the singlet oxygen quantum yield (Φ Δ ) under air conditions, 23 which is determined by a relative method as follows i k j j j y…”

“…Recently, a quantitative method of evaluating the HAE by way of the phosphorescent transition rate ( k P ) was proposed in our previous work . In this work, an investigation of the intrinsic external HAE induced by environmental metal ions is performed via the concentration evolution of k P .…”