Self‐Assembled Metal–Organic Framework Stabilized Organic Cocrystals for Biological Phototherapy

• Published in: Angewandte Chemie International Edition Vol. 60; no. 44; pp. 23569 - 23573
• Main Authors: Zeng, Le, Huang, Ling, Wang, Zhonghe, Wei, Jianwei, Huang, Kai, Lin, Wenhai, Duan, Chunying, Han, Gang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 25.10.2021
• Edition: International ed. in English
• Subjects: Aqueous solutions; Biocompatibility; Biocompatible Materials - chemistry; Calcium - chemistry; Calcium ions; Catalysis; Charge transfer; charge-transfer interaction; Crystal structure; Crystals; Diimide; Imides - chemistry; Metal-organic frameworks; Metal-Organic Frameworks - chemical synthesis; Metal-Organic Frameworks - chemistry; metal–organic framework; Naphthalene; Naphthalenes - chemistry; organic co-crystal; Phototherapy; Photothermal conversion; photothermal therapy; Pyrene; Pyrenes - chemistry; self-assembly; self-assembly; charge-transfer interaction; photothermal therapy; metal-organic framework; organic co-crystal
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202108076

Organic self‐assembled co‐crystals have garnered considerable attention due to their facile synthesis and intriguing properties, but supramolecular interactions restrict their stability in aqueous solution, which is especially important for biological applications. Herein, we report on the first biological application of aqueous dispersible self‐assembled organic co‐crystals via the construction of metal–organic framework (MOF) ‐stabilized co‐crystals. In particular, we built an electron‐deficient MOF with naphthalene diimide (NDI) as the ligand and biocompatible Ca2+ as the metal nodes. An electron donor molecule, pyrene, was encapsulated to form the host–guest MOF self‐assembled co‐crystal. We observed that such MOF structure leads to uniquely high‐density ordered arrangement and the close intermolecular distance (3.47 Å) of the charge transfer pairs. Hence, the concomitant superior charge transfer interaction between pyrene/NDI can be attained and the resultant photothermal conversion efficiency of Py@Ca‐NDI in aqueous solution can thus reach up to 41.8 %, which, to the best of our knowledge, is the highest value among the reported organic co‐crystal materials; it is also much higher than that of the FDA approved photothermal agent ICG as well as most of the reported MOFs. Based on this realization, as a proof of concept, we demonstrated that such a self‐assembled organic co‐crystal platform can be used in biological applications that are exemplified via highly effective long wavelength light photothermal therapy. Organic co‐crystals are solid‐state multifunctional materials with intriguing properties whereas the supramolecular interactions within co‐crystals limited their stability in solution and their application in biology. Utilizing metal–organic framework to stabilize and strengthen the charge‐transfer interaction between electron donor and electron acceptor, a water‐dispersible co‐crystal was obtained and applied in photothermal therapy.