Charge Transfer Metal‐Organic Framework Containing Redox‐Active TTF/NDI Units for Highly Efficient Near‐Infrared Photothermal Conversion

Abstract

Metal-organic frameworks (MOFs), as a class of new inorganic-organic hybrid crystal materials, could have important applications in near-infrared (NIR) photothermal conversion. Herein, a new charge-transfer MOF (Co-MOF) with mixed ligands of H 4 TTFTB and bpmNDI incorporating redox-active tetrathiafulvalene/naphthalene diimide (TTF/ NDI) units into one system is reported. Due to the presence of TTF/NDI oxidative and reductive couples, stable radicals can be observed in the MOF. In addition, charge transfer from the electron donor (TTF) to the acceptor (NDI) results in a broad absorption in the NIR region. The Co-MOF exhibited an efficient photothermal effect induced by irradiation with a NIR laser. Under the 808 nm laser (0.7 W cm À 2 ) illumination, the temperature of the Co-MOF increased from room temperature to 201°C in only 10 s. Furthermore, a series of polydimethylsiloxane (PDMS) films doped with trace amounts of Co-MOF showed efficient NIR photothermal conversion. When a Co-MOF@PDMS (0.6 wt %) film is irradiated by 808 nm laser with power of 0.5 W cm À 2 , it's temperature can reach a plateau at 62°C from 20°C within 100 s. Our experimental results from the Co-MOF@PDMS film demonstrate that the effectiveness and feasibility of the material is promising for photothermal applications.

Donor–acceptor systems in metal–organic frameworks: design, construction, and properties

“…In addition to the optical and electrical properties described above, D–A MOFs with CT or ET interaction may exhibit properties such as magnetism 67 and photothermal conversion. 68 There are plenty of reports with cogent results, simultaneously, exploring the additional properties. Fukunaga et al constructed a pillared layer D–A system, which was composed of [FeCp* 2 ] (decamethylferrocene) as the interlayer pillar and the 2D D 2 A type polymer formed by TCNQ (tetracyanoquinodimethane) and ruthenium (Ru) as a layer.…”

“…Several relative works demonstrated that D–A MOFs are excellent candidates for photothermal imaging and therapy, which discloses the potential applied value. Zuo et al reported a D–A charge transfer MOF, 68 which consisted of tetrathiafulvalene tetrabenzoate (H 4 TTFTB) and N , N ′-bis(4-pridylmethyl)-1,4,5,8-naphthalene diimide (BPMNDI) mixed ligands. Both ligands feature strong redox properties (Fig.…”

A Tetrathiafulvalene/Naphthalene Diimide-Containing Metal–Organic Framework with fsc Topology for Highly Efficient Near-Infrared Photothermal Conversion

“…Metal–organic frameworks (MOFs), one class of hybrid crystalline materials consisting of organic linkers and metal nodes/clusters, − have attracted much attention in recent decades due to their controllable structures, modular nature, and potential applications in molecule separation, − sensing, , luminescence, , catalysis, , energy-related fields, , etc. Recently, some MOFs have been applied as carriers for photothermal material encapsulation to achieve integration and synergistic enhancements, − but only a few MOFs with near-infrared photothermal conversion capability have been reported. − Thus, studying the design and synthesis of MOFs with near-infrared photothermal conversion behavior is worthwhile.…”

“…Both of them have reversible multistep redox activity. − In 2021, we reported one two-dimensional (2D) MOF, Co-MOF , constructed from organic ligands TTF and NDI, which showed good near-infrared photothermal conversion performance. In this material, the near-infrared photothermal conversion property resulted from interlamination π···π interactions between TTF and NDI units . On the basis of this previous work, we chose the same TTF ligand and the semirigid NDI ligand to construct a new MOF.…”

A radical photochromic metal–organic framework for boosting NIR-II photothermal conversion and therapy

“…Meanwhile, Yin and co-workers reported the first example of a MOF as a NIR photothermal material containing stable perylenediimide radical anions. 15 Xu et al prepared a viologencontaining coordination polymer, 16 and Zuo's group constructed a Co-MOF containing redox active tetrathiafulvalene/ naphthalene diimide units, 17 and both exhibited remarkable NIR photothermal effects. However, most reports of MOFs are on the bulk crystals with absorption in the visible or NIR-I windows.…”