Fluorine in Cyclometalated Platinum Compounds

Cycloplatinated (II) Complex Based on Isoquinoline Alkaloid Elicits Ferritinophagy-Dependent Ferroptosis in Triple-Negative Breast Cancer Cells

The development and optimization of metal-based anticancer drugs with novel cytotoxic mechanisms have emerged as key strategies to overcome chemotherapeutic resistance and side effects. Agents that simultaneously induce ferroptosis and autophagic death have received extensive attention as potential modalities for cancer therapy. However, only a limited set of drugs or treatment modalities can synergistically induce ferroptosis and autophagic tumor cell death. In this work, we designed and synthesized four new cycloplatinated (II) complexes harboring an isoquinoline alkaloid C∧N ligand. On screening the in vitro activity of these agents, we found that Pt-3 exhibited greater selectivity of cytotoxicity, decreased resistance factors, and improved anticancer activity compared to cisplatin. Furthermore, Pt-3, which we demonstrate can initiate potent ferritinophagy-dependent ferroptosis, exhibits less toxic and better therapeutic activity than cisplatin in vivo. Our results identify Pt-3 as a promising candidate or paradigm for further drug development in cancer treatment.

Fluorination Reactions at a Platinum Carbene Complex: Reaction Routes to SF3 , S(=O)F and Fluorido Complexes

The electron-rich Pt complex [Pt(IMes)2 ] (IMes: [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolinylidine]) can be used as precursor for the syntheses of a variety of fluorido ligand containing compounds. The sulfur fluoride SF4 undergoes a rapid oxidative addition at Pt0 to yield trans-[Pt(F)(SF3 )(IMes)2 ]. A photolytic reaction of SF6 at [Pt(IMes)2 ] in the presence of IMes gave the fluorido complexes trans-[Pt(F)2 (IMes)2 ] and trans-[Pt(F)(SF3 )(IMes)2 ] along with trans-[Pt(F)(SOF)(IMes)2 ] and trans-[Pt(F)(IMes')(IMes)] (IMes': cyclometalated IMes ligand), the latter being products produced by reaction with adventitious water. trans-[Pt(F)(SOF)(IMes)2 ] and trans-[Pt(F)2 (IMes)2 ] were synthesized independently by treatment of [Pt(IMes)2 ] with SOF2 or XeF2 . A reaction of [Pt(IMes)2 ] with a HF source gave trans-[Pt(H)(F)(IMes)2 ], and an intermediate bifluorido complex trans-[Pt(H)(FHF)(IMes)2 ] was identified. Compound trans-[Pt(H)(F)(IMes)2 ] converts in the presence of CsF into trans-[Pt(F)(IMes')(IMes)].

The impact of cyclometalated and phosphine ligands on the luminescence properties of cycloplatinated(ii) complexes: photophysical and theoretical investigations

The effects of various C^N cyclometalated and phosphine ligands on the photophysical properties of cycloplatinated(ii) complexes were investigated experimentally and theoretically.

Fluorinated Cycloplatinated(II) Complexes Bearing Bisphosphine Ligands as Potent Anticancer Agents

A family of cationic cycloplatinated(II) complexes [Pt(dfppy)(P^P)]Cl, dfppy = 2-(2,4-difluorophenyl)pyridine, incorporating bisphosphine ligands, P^P = bis(diphenylphosphino)methane (1, dppm), 1,2-bis(diphenylphosphino)ethane (2, dppe) and 1,2-bis(diphenylphosphino)benzene (3, dppbz), was prepared. The complexes were characterized by means of several analytical and spectroscopic methods. These complexes displayed acceptable stability in the biological environments which was confirmed by NMR, HR ESI-MS and UV-vis techniques. The antiproliferative properties of these complexes were evaluated by National Cancer Institute (NCI) at National Institutes of Health (NIH) against 60 different human tumor cell lines such as leukemia, melanoma, lung, colon, brain, ovary, breast, prostate and kidney. These complexes showed higher cytotoxicity than cisplatin against a wide variety of cancer cell lines such as K-562 (leukemia), HOP-92 (lung), HCT-116 (colon), OVCAR-8 (ovarian), PC-3 (prostate), MDA-MB-468 (breast), and melanoma cancer cell lines. Complex 3 as the most potent compound in this study furnished an excellent anti-proliferative activity compared to the cisplatin against Hela, SKOV3, and MCF-7 cancer cell lines. The main mode of the interaction of 1-3 with DNA was also determined using molecular docking studies.

A C^N Cycloplatinated(II) Fluoride Complex: Photophysical Studies and Csp3-F Bond Formation

This work reports the synthesis and characterization of a new C^N-based cycloplatinated(II) fluoride complex, [Pt(ppy)(PPh₃)F] (2; ppy = 2-phenylpyridinate), involving a Pt-F bond. The new complex is highly luminescent in the green area with a high quantum yield of 94.6% at 77 K. A comparison study of the heavier halogen derivatives reveals a descending emission quantum yield order of F > Cl > Br > I. Time-dependent density functional theory calculations ascribe the decreased emission efficiency to the decreasing trend of an intraligand (IL) transition from F to I, which accounts for the major radiative pathway. In addition, 2 is capable of the fluorinating alkyl halides, leading to C_sp³-F bond formation at room temperature.

Platinum Complexes from C-H Activation of Sterically Hindered [C^N] Donor Benzothiophene Imine Ligands: Synthesis and Photophysical Properties

Primary amines and benzothiophene-3-carboxaldehyde were reacted to give four large, bulky imine ligands. These imine ligands were reacted with a tetramethyl platinum dimer and by heteroatom-assisted C-H activation, both monometalated compounds and bismetalated compounds were synthesized. In all cases, five-membered platinacycles were formed. The compounds were characterized by NMR spectroscopy, and one bismetalated compound was characterized by single-crystal X-ray diffraction. The UV-vis absorption and emission spectra and the excited-state lifetimes were recorded for these complexes. Density functional theory (DFT) and time-dependent-DFT calculations were performed to aid in the assignment of the absorption and emission spectra of the newly synthesized complexes.

BF3·OEt2-TFAA Mediated Tetra-Functionalization of Amino Acids - Synthesis of Di- and Tri-Substituted 2-Trifluoromethyl Oxazoles in One Pot

A highly efficient, TFAA-BF₃·OEt₂ mediated multicomponent coupling of amino acid, TFAA, and aromatics provides a broad library of 2-trifluoromethyl equipped 2,5-disubstituted/2,4,5-trisubstituted oxazoles or N-(trifluoroacetyl)-β-aminoalkyl ketones. This amino acid tetra-functionalization approach involves amidation (C-N), anhydride (C-O), Friedel-Crafts acylation (C-C), and Robinson-Gabriel annulation (C-O) followed by dehydrative aromatization. This reaction takes place under operationally simple, mild, and metal-free conditions using readily available amino acids and aromatic compounds.

Simple tuning of the luminescence properties of the double rollover cycloplatinated(ii) structure by halide ligands

The luminescence properties of double rollover cycloplatinated(ii) complexes and the effects of halogen ligands on the luminescence properties are investigated.

A facile method for the synthesis of trifluoromethylthio-/chloro-homoallylic alcohols from methylenecyclopropanes

Trifluoromethylthiolated/chloro-homoallylic alcohols have been directly accessed by the reaction of (PhSO₂)₂NSCF₃/Cl with methylenecyclopropanes (MCPs) in DMF in moderate to good yields.

Highly Fluorinated Ir(III)-2,2':6',2″-Terpyridine-Phenylpyridine-X Complexes via Selective C-F Activation: Robust Photocatalysts for Solar Fuel Generation and Photoredox Catalysis

A series of fluorinated Ir(III)-terpyridine-phenylpyridine-X (X = anionic monodentate ligand) complexes were synthesized by selective C-F activation, whereby perfluorinated phenylpyridines were readily complexed. The combination of fluorinated phenylpyridine ligands with an electron-rich tri-tert-butyl terpyridine ligand generates a "push-pull" force on the electrons upon excitation, imparting significant enhancements to the stability, electrochemical, and photophysical properties of the complexes. Application of the complexes as photosensitizers for photocatalytic generation of hydrogen from water and as redox photocatalysts for decarboxylative fluorination of several carboxylic acids showcases the performance of the complexes in highly coordinating solvents, in some cases exceeding that of the leading photosensitizers. Changes in the photophysical properties and the nature of the excited states are observed as the compounds increase in fluorination as well as upon exchange of the ancillary chloride ligand to a cyanide. These changes in the excited states have been corroborated using density functional theory modeling.

Luminescence properties of some monomeric and dimeric cycloplatinated(ii) complexes containing biphosphine ligands

The starting complexes [PtCl(C^N)(dmso)], in which C^N is either ppy = 2-phenylpyridinate, , or bhq = 7,8-benzo[h]quinolinate, , were prepared by a known method using the reaction of [PtCl2(dmso)2] with ppyH or bhqH, respectively, in toluene under reflux conditions. The reaction of [PtCl(C^N)(dmso)], or , with 1 equiv. of a number of biphosphine ligands, P^P, gave the cationic monomeric complexes [Pt(ppy)(P^P)]Cl, for which P^P is either 1,2-bis(diphenylphosphino)ethane (dppe), , 1,3-bis(diphenylphosphino)propane (dppp), , or bis(diphenylphosphino)methane (dppm), ; the bhq analogous complex [Pt(bhq)(dppe)]Cl, , was prepared similarly. However, the complex [Pt(ppy)(dfppe)]Cl, , in which dfppe is 1,2-bis(dipentafluorophenylphosphino)ethane, was prepared by the reaction of with excess amount of dfppe. When each of the starting complexes [PtCl(C^N)(dmso)], or , were reacted with 0.5 equiv. of any of the P^P ligands, the dimeric complexes [Pt2Cl2(ppy)2(μ-P^P)], , or [Pt2Cl2(bhq)2(μ-P^P)], , were formed. The complexes were fully characterized using multinuclear ((1)H and (31)P) NMR spectroscopy and elemental analysis. The structures of typical complexes , , , and were also confirmed by X-ray crystallography. The effect of ligands on the luminescent properties of the complexes was investigated and DFT calculations were performed to confirm the assignments.

Competing reaction pathways of 3,3,3-trifluoropropene at rhodium hydrido, silyl and germyl complexes: C–F bond activation versus hydrogermylation

The reactivity of the Rh complexes [Rh(L)(PEt₃)₃] (L = H, Si(OEt)₃, GePh₃) towards CH₂CHCF₃ was investigated which involve C–F bond activation and germylation reactions.

Higher fluorescence in platinum(iv) orthometallated complexes of perylene imine compared with their platinum(ii) or palladium(ii) analogues

The reaction of 3-perylenylmethylen-4'-ethylaniline () with [Pt2Me4(μ-SMe2)2] (and subsequent addition of PPh3) or with [Pt2(η(3)-C4H7)2(μ-Cl)2] produced cyclometallated Pt(II) complexes [Pt(C^N)Me(PPh3)] () and, respectively, [Pt2(C^N)2(μ-Cl)2] () (HC^N = 3-C20H11CH[double bond, length as m-dash]NC6H4-p-C2H5), with Pt bound to the ortho site of the perylenyl fragment. From the mononuclear complexes [Pt(C^N)L2] (L2 = acac (); S2COMe (); S2CNEt2 () are easily formed. Oxidative addition of methyl iodide to the square-planar Pt(II) complexes , , and gave the corresponding cyclometallated Pt(IV) compounds [Pt(C^N)L2MeI] , and . The X-ray structures of , , and show that the perylenyl fragment remains essentially flat in and and slightly twisted in . Comparison of the optical properties of these Pt(II) complexes with those reported for similar Pd(II) derivatives reveals that the change of metal exerts a notable influence on the UV-vis spectra. In solution at room temperature, all the Pt complexes exhibit fluorescence associated with the perylene fragment with low emission quantum yields for the Pt(II) complexes (<1%) and remarkably higher emission values for the Pt(IV) complexes: up to 29%, with emission lifetimes of 1-5 ns. Time-dependent density functional theory (TD-DFT) calculations were performed on the perylene imine and on representative complexes [M(C^N)(acac)] (M = Pd, Pt) and [Pt(C^N)(acac)MeI] to analyse the absorption spectra. These calculations support a perylene-dominated intraligand π-π*emissive state based on the HOMO and LUMO orbitals of the perylene chromophore, and a ligand-to-ligand charge-transfer (more intense for the Pt(II) complex) that explains the observed influence of the metal on the absorption properties.

Synthesis and structure of rhodium(i) silyl carbonyl complexes: photochemical C-F and C-H bond activation of fluorinated aromatic compounds

The rhodium(i) silyl carbonyl complexes [Rh{Si(OEt)3}(CO)(dippp)] () and [Rh{Si(OEt)3}(CO)(dippe)] () (dippp = 1,3-bis(diisopropylphosphino)propane, dippe = 1,2-bis-(diisopropylphosphino)ethane) were synthesized on treatment of the methyl compounds [Rh(CH3)(CO)(dippp)] () or [Rh(CH3)(CO)(dippe)] () with HSi(OEt)3 at low temperature. The methyl complexes and were prepared starting from the binuclear complexes [{Rh(μ-Cl)(dippp)}2] () and [{Rh(μ-Cl)(dippe)}2] (), respectively. The silyl complexes and as well as the precursors [{Rh(μ-I)(dippp)}2] (), [Rh(X)(CO)(dippp)] (: X = CH3, : X = I) and [Rh(X)(CO)(dippe)] (: X = CH3, : X = Cl) were characterized by NMR and IR spectroscopy and the structures in the solid state were determined by X-ray crystallography. The silyl complex converts into the carbonyl-bridged complex [{Rh(μ-CO)(dippp)}2] () above temperatures of -30 °C by loss of the silyl ligand, whereas is more thermally stable and a reaction to the binuclear complex [{Rh(μ-CO)(dippe)}2] () was observed at 50 °C. The silyl complex reacted under irradiation with hexafluorobenzene and pentafluoropyridine to give the C-F activation products [Rh(C6F5)(CO)(dippe)] () and [Rh(2-C5F4N)(CO)(dippe)] (), respectively. As additional products the silyl dicarbonyl complex [Rh{Si(OEt)3}(CO)2(dippe)] () and the cationic complex [Rh2(μ-H)(μ-CO)2(dippe)2](+)[SiF5](-) () were identified. Compound was synthesized independently by treatment of with gaseous CO. In a similar manner, the dippp analogue [Rh{Si(OEt)3}(CO)2(dippp)] () was also prepared starting from . Photochemical reaction of with pentafluorobenzene and 2,3,5,6-tetrafluoropyridine resulted selectively in C-H bond activation to afford and [Rh(4-C5F4N)(CO)(dippe)] (), respectively.

Consecutive C-F bond activation and C-F bond formation of heteroaromatics at rhodium: the peculiar role of FSi(OEt)3

C-F activation of 2,3,5,6-tetrafluoropyridine at [Rh{Si(OEt)3}(PEt3)3] (1) yields [Rh{2-(3,5,6-C5F3HN)}(PEt3)3] (2) and FSi(OEt)3, but in an unprecedented consecutive reaction FSi(OEt)3 acts as a fluoride source to give [Rh(4-C5F4N)(PEt3)3] (4) by regeneration of the C-F bond and C-H activation. Analogous refluorination steps were observed for other 2-pyridyl rhodium complexes. NMR spectroscopic studies revealed a delicate balance between the feasibility for C-F bond formation accompanied by a C-H activation and the occurrence of competing reactions such as hydrodefluorinations induced by the intermediary presence of H2.

Photophysical and DFT studies on cycloplatinated complexes: modification in luminescence properties by expanding of π-conjugated systems

The luminescent properties of cycloplatinated complexes containing aryl and SMe₂ ligands, [Pt(p-MeC₆H₄)(ĈN)(SMe₂)], (ĈN = benzo[h]quinolate (bzq), 1, or 2-phenylpyridinate (ppy), 2), were investigated in solution and solid state.

Gold and silver catalysis: from organic transformation to bioconjugation

A summary of gold (including AuNPs, Au(i) and Au(iii) complexes) and silver(i) catalysis and their application in bioconjugation reactions.

Anticancer C,N-cycloplatinated(II) complexes containing fluorinated phosphine ligands: synthesis, structural characterization, and biological activity

A series of potent C,N-cycloplatinated(II) phosphine antitumor complexes containing fluorous substituents in the cyclometalated or the ancillary phosphine ligands [Pt(C-N)(PR3)Cl] or both have been synthesized and characterized. The crystal structure of [Pt(dmba){P(C6H4CF3-p)3}Cl]·2CH2Cl2 (dmba = dimethylaminomethyl)phenyl) has been established by X-ray diffraction. Values of IC50 of the new platinum complexes were calculated toward a panel of human tumor cell lines representative of ovarian (A2780 and A2780cisR) and breast cancers (T47D). Complexes containing P(C6H4CF3-p)3 as ancillary ligand (with a bulky and electronegative CF3 substituent in para position) were the most cytotoxic compounds in all the tested cancer cell lines. In some cases, the IC50 values were 16-fold smaller than that of cisplatin and 11-fold smaller than the non-fluorous analogue [Pt(dmba)(PPh3)Cl]. On the other hand, very low resistance factors (RF) in A2780cisR (cisplatin-resistant ovarian carcinoma) at 48 h were observed (RF ≈ 1) for most of the new compounds. Analysis of cell cycle was done for the three more active compounds in A2780. They arrest cell growth in G0/G1 phase in contrast to cisplatin (S phase) with a high incidence of late-stage apoptosis. They are also good cathepsin B inhibitors (an enzyme implicated in a number of cancer related events).