Synthesis of BODIPY-Linked N-Heterocyclic Carbene Metal Complexes for Cancer Chemotheranostics and Catalysis Applications.

Fluorescent N-heterocyclic carbene (NHC) metal complexes are useful for various chemical and biological applications. In this study, we developed a simple strategy to synthesize BODIPY-linked NHC metal complexes involving Ag, Cu, Ni, and Pd. The synthesis began with the preparation of BODIPY-imidazolium salt as a precursor ligand. This ligand was used to obtain BODIPY-imidazolium silver carbene complex, which subsequently facilitated the syntheses of BODIPY-linked NHC transition metal complexes (Cu, Ni, and Pd) via the transmetalation method. This approach offers a versatile pathway for the synthesis of various other fluorescent carbene metal complexes. The applications of these BODIPY-linked NHC metal complexes were also explored. Chemotherapeutic anti-cancer activity of BODIPY-imidazolium silver carbene complex showed high cancer cell killing efficacy as compared to its precursor ligand. This outcome confirmed that the attachment of the silver atom is essential to enhance the cytotoxic activities. Additionally, the fluorescence property of the BODIPY moiety is highly useful for cellular imaging, which establishes the silver complex as a potential chemotheranostic agent for cancer management. Furthermore, BODIPY-imidazolium copper carbene complex was explored as a non-noble metal-based catalyst for ammonia borane (AB) hydrolysis to generate hydrogen. This catalytic system was further applied for chemoselective reduction of the aromatic formyl groups in the presence of other reducible functional groups. Overall, this investigation presents a simple and efficient design strategy for the synthesis of different BODIPY-linked metal carbene complexes with potential applications in catalysis, cellular imaging, and cancer therapy.