Dataset Information

Mechanisms and applications of cyclometalated Pt(ii) complexes in photoredox catalytic trifluoromethylation.

ABSTRACT: The incorporation of a trifluoromethyl group into an existing scaffold can provide an effective strategy for designing new drugs and agrochemicals. Among the numerous approaches to trifluoromethylation, radical trifluoromethylation mediated by visible light-driven photoredox catalysis has gathered significant interest as it offers unique opportunities for circumventing the drawbacks encountered in conventional methods. A limited understanding of the mechanism and molecular parameters that control the catalytic actions has hampered the full utilization of photoredox catalysis reactions. To address this challenge, we evaluated and investigated the photoredox catalytic trifluoromethylation reaction using a series of cyclometalated Pt(ii) complexes with systematically varied ligand structures. The Pt(ii) complexes were capable of catalyzing the trifluoromethylation of non-prefunctionalized alkenes and heteroarenes in the presence of CF3I under visible light irradiation. The high excited-state redox potentials of the complexes permitted oxidative quenching during the cycle, whereas reductive quenching was forbidden. Spectroscopic measurements, including time-resolved photoluminescence and laser flash photolysis, were performed to identify the catalytic intermediates and directly monitor their conversions. The mechanistic studies provide compelling evidence that the catalytic cycle selects the oxidative quenching pathway. We also found that electron transfer during each step of the cycle strictly adhered to the Marcus normal region behaviors. The results are fully supported by additional experiments, including photoinduced ESR spectroscopy, spectroelectrochemical measurements, and quantum chemical calculations based on time-dependent density functional theory. Finally, quantum yields exceeding 100% strongly suggest that radical propagation significantly contributes to the catalytic trifluoromethylation reaction. These findings establish molecular strategies for designing trifluoromethyl sources and catalysts in an effort to enhance catalysis performance.

SUBMITTER: Choi WJ

PROVIDER: S-EPMC5811153 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Mechanisms and applications of cyclometalated Pt(ii) complexes in photoredox catalytic trifluoromethylation.

Choi Won Joon WJ Choi Sungkyu S Ohkubo Kei K Fukuzumi Shunichi S Cho Eun Jin EJ You Youngmin Y

Chemical science 20141124 2

The incorporation of a trifluoromethyl group into an existing scaffold can provide an effective strategy for designing new drugs and agrochemicals. Among the numerous approaches to trifluoromethylation, radical trifluoromethylation mediated by visible light-driven photoredox catalysis has gathered significant interest as it offers unique opportunities for circumventing the drawbacks encountered in conventional methods. A limited understanding of the mechanism and molecular parameters that contro ...[more]

PMID: 29560234

Similar Datasets

Project description:The photophysical and photobiological properties of a new class of cyclometalated ruthenium(II) compounds incorporating ?-extended benzo[ h]imidazo[4,5- f]quinoline (IBQ) cyclometalating ligands (C^N) bearing thienyl rings ( n = 1-4, compounds 1-4) were investigated. Their octanol-water partition coefficients (log Po/w) were positive and increased with n. Their absorption and emission energies were red-shifted substantially compared to the analogous Ru(II) diimine (N^N) complexes. They displayed C^N-based intraligand (IL) fluorescence and triplet excited-state absorption that shifted to longer wavelengths with increasing n and N^N-based metal-to-ligand charge transfer (MLCT) phosphorescence that was independent of n. Their photoluminescence lifetimes (?em) ranged from 4-10 ns for 1IL states and 12-18 ns for 3MLCT states. Transient absorption lifetimes (?TA) were 5-8 ?s with 355 nm excitation, ascribed to 3IL states that became inaccessible for 1-3 with 532 nm excitation (1-3, ?TA = 16-17 ns); the 3IL of 4 only was accessible by lower energy excitation, ?TA = 3.8 ?s. Complex 4 was nontoxic (EC50 > 300 ?M) to SK-MEL-28 melanoma cells and CCD1064-Sk normal skin fibroblasts in the dark, while 3 was selectively cytotoxic to melanoma (EC50= 5.1 ?M) only. Compounds 1 and 2 were selective for melanoma cells in the dark, with submicromolar potencies (EC50 = 350-500 nM) and selectivity factors (SFs) around 50. The photocytotoxicities of compounds 1-4 toward melanoma cells were similar, but only compounds 3 and 4 displayed significant phototherapeutic indices (PIs; 3, 43; 4, >1100). The larger cytotoxicities for compounds 1 and 2 were attributed to increased cellular uptake and nuclear accumulation, and possibly related to the DNA-aggregating properties of all four compounds as demonstrated by cell-free gel mobility-shift assays. Together, these results demonstrate a new class of thiophene-containing Ru(II) cyclometalated compounds that contain both highly selective chemotherapeutic agents and extremely potent photocytotoxic agents.

Dataset Information

Mechanisms and applications of cyclometalated Pt(ii) complexes in photoredox catalytic trifluoromethylation.

Publications

Mechanisms and applications of cyclometalated Pt(ii) complexes in photoredox catalytic trifluoromethylation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets