Copper and Manganese Complexes of Pyridinecarboxaldimine Induce Oxidative Cell Death in Cancer Cells.

Leveraging the versatile redox behavior of transition metal complexes with heterocyclic ligands offers significant potential for discovering new anticancer therapeutics. This study presents a systematic investigation of a pyridinecarboxaldimine ligand (PyIm) with late 3d-transition metals inhibiting cancer cell proliferation and the mechanism of action. Synthesis and thorough characterization of authentic metal complexes of redox-active late 3d-transition metals enabled the validation of antiproliferative activity in liver cancer cells. Notably, (PyIm)2Mn(II) (1) and (PyIm)2Cu(II) (5) complexes exhibited a good inhibitory profile against liver cancer cells (EC50: 4.0 µM for 1 and 1.7 µM for 5) with excellent selectivity over normal kidney cells (Selectivity index, SI = 17 for 5). Subsequently, evaluation of these complexes in cancers cell lines from four different sites of origin (liver, breast, blood, and bone) demonstrated a predominant selectivity to liver and a moderate selectivity to breast cancer and leukemia cells over the normal kidney cells. The mechanism of action studies highlighted no expected DNA damage in cells, rather, the enhancement of extracellular and intracellular reactive oxygen species (ROS) resulting in mitochondrial damage leading to oxidative cell death in cancer cells. Notably, these complexes potentiated the antiproliferative effect of commercially used cancer therapeutics (cisplatin, oxaliplatin, doxorubicin, and dasatinib) in liver cancer cells. These findings position redox-active metal complexes for further evaluation as promising candidates for developing anticancer therapeutics and combination therapies.

Mixed-Valent Stellated Cuboctahedral Cu(2,4-Imdb)-MOF for Trace Water Detection.

Developing an economical and robust sensor using an earth-abundant metal-based metal-organic framework (MOF) to detect trace water content rapidly is crucial for laboratories and chemical industries. Herein, a mixed-valent chiral [{Cu+Cu32+(2,4-Imdb)3(H2O)3}·Cl]∞ MOF manifests atypical quantitative detection of a trace amount of water [0.016% (v/v)] in organic solvents. Single-crystal X-ray diffraction and time-correlated single-photon counting supported the mechanism for turn-on fluorescence.

Cyclic Palladium Formamidinate: Synthesis, Structure, Reactivity, and Application to Suzuki-Miyaura Cross-Coupling.

The deprotonation of acyclic palladium amidine chloride (1) with potassium tert-butoxide in tetrahydrofuran results in palladium bis(formamidinate) (2). 2 undergoes a nucleophilic addition reaction with acetonitrile in the presence of PdCl2 or Pd(OAc)2 (OAc = acetate) to give dinuclear cyclic six-membered (triazapentadiene)palladium complexes (4a and 4b). These compounds are also prepared from cyclic six-membered (tap)PdCl2 (5; tap = triazapentadiene) or formamidinium salts (6a-6c) with Pd(OAc)2/NaOAc in acetonitrile, whereas the direct reaction of 2 with acetonitrile or acrylonitrile resulted in palladium black or an acyclic C-N-coupled product (3). A comparison of structure 4 from 2 suggests a possible intermediate dinuclear palladium complex whose structure was identified through theoretical calculations. Further, Suzuki-Miyaura cross-coupling reactions were carried out under different solvents notably in an ethanol/water medium at room temperature.

Cuboctahedral [In36(µ-OH)24(NO3)8(Imtb)24]MOF with Atypical Pyramidal Nitrate Ion in SBU: Lewis Acid-Base Assisted Catalysis and Nanomolar Sensing of Picric Acid.

A robust and multifunctional cuboctahedral [In36(µ-OH)24(NO3)8(Imtb)24] MOF (In(Imtb)-MOF) with an atypical pyramidal nitrate ion-containing hitherto unknown SBU core [In9(µ-OH)6(NO3)] is reported. The intra- and interlayer nitrate ions adopt pyramidal and inverted pyramidal shapes, which separates the active indium site [(In3(µ-OH)2)NO3-(In3(µ-OH)2)] and linear In3(µ-OH)2 by 0.5 and 0.9 nm, respectively. Additionally, the high density of active metal sites shows remarkable catalytic activity with higher TOF even for sterically hindered substrates in Strecker synthesis and CO2 cycloaddition. Moreover, the luminescence behavior of In(Imtb)-MOF and the presence of uncoordinated nitrogen atoms are exploited for selective sensing of explosive trinitrophenol (TNP) with a detection limit (LOD) of 2.3 ppb.