Sheet-like 2D Manganese(IV) Complex with High Photothermal Conversion Efficiency

Abstract

We report a stable, water-soluble, mononuclear manganese­(IV) complex [MnIV(H2 L)]·5H2O (Mn-HDCL) that acts as an efficient photothermal material. This system is based on a hexahydrazide clathrochelate ligand (L/HDCL) and is obtained via an efficient one-pot templated synthesis that avoids the need for harsh reaction conditions. Scanning tunneling microscopy images reveal that Mn-HDCL exists as a 2D sheet-like structure. In Mn-HDCL, the manganese­(IV) ion is trapped within the cavity of the cage-like ligand. This effectively shields the Mn­(IV) ion from the external environment while providing adequate water solubility. As a result of orbital transitions involving the coordinated manganese­(IV) ion, as well as metal-to-ligand charge transfer effects, Mn-HDCL possesses a large extinction coefficient and displays a photothermal performance comparable to single-wall carbon nanotubes in the solid state. A high photothermal conversion efficiency (ca. 71%) was achieved in aqueous solution when subjected to near-infrared 730 nm laser photo-irradiation. Mn-HDCL is paramagnetic and provides a modest increase in the T 1-weighted contrast of magnetic resonance images both in vitro and in vivo. Mn-HDCL was found to target tumors passively and allow tumor margins to be distinguished in vivo in a mouse model. In addition, it also exhibited an efficient laser-triggered photothermal therapy effect in vitro and in vivo. We thus propose that Mn-HDCL could have a role to play as a tumor-targeting photothermal sensitizer.

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

“…Since silica-cored Au nanoshells served as the first photothermal nanomaterials for clinical use, more and more inorganic agents with strong absorption in the NIR region, high chemical stability, adjustable water solubility, and minimal cytotoxicity have entered clinical trials. , Clinical trials have also been underway for small organic molecules due to their good biodegradability, good repeatability, and simple preparation. , Nevertheless, the major challenges for the clinical implementation of photothermal nanomaterials are the complex metabolism and excretion behaviors . The representative works on PTT with diverse photothermal nanomaterials in recent years − are summarized in Table .…”

Crystal structure and Hirshfeld surface analysis of poly[[tetraaqua(μ-1,3,4,7,8,10,12,13,16,17,19,22-dodecaazatetracyclo[8.8.4.13,17.18,12]tetracosane-5,6,14,15,20,21-hexaonato)iron(IV)dilithium] tetrahydrate]

“…A search in the Cambridge Structural Database (CSD version 5.43, update of November 2022; Groom et al, 2016) resulted in nine hits dealing with hydrazide-based clathrochelates of 3dmetals. There are three structures of Mn IV clathrochelates (Shylin et al, 2021;Xu et al, 2022), three structures of Fe IV clathrochelates (Tomyn et al, 2017) and three hits dealing with…”

“…The MOFs reveal a 1D coordination polymer topology: the Fe IV clathrochelate complex anions being connected by Mn 2+ (Xu et al, 2020b) or Cu 2+ (Xu et al, 2020a(Xu et al, , 2022 cations, forming zigzag hetero-bimetallic chains, and being bimetallic helps to understand the link with Mn 2+ and Cu 2+ .…”

Syntheses, Characterization, and X-ray Crystal Structure of Mn(III) Coordination Polymer of 2-((2-Hydroxyethylimino) Methyl)-6-Methoxyphenol

“…ii , 178.31 (18)°. The ranges of equatorial cissoid angles [88.8(2)°90.9(2)°] and the values of the transoid angles [178.4(2)° and 179.18 (19)°] reflect the slightly distortion of the N 2 O 4 environment from the ideal octahedral geometry. In each ligand molecule, the phenyl ring of the Schiff base lies in a plane including its phenolate oxygen (rms 0.0805 Å and 0.0212 Å).…”

“…It has been reported that in these enzymes, manganese is involved in complex redox cycles with diverse oxidation states [14][15][16][17]. In coordination chemistry, many complexes in which manganese is found in various environments have shown good redox properties with oxidation states ranging from Mn 2+ to Mn 5+ [18][19][20][21]. These phenomena are very useful for understanding and modeling the functioning of active enzymes.…”