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A photoactive complex [Ir(3m-ppy)2(dppm)Cl] (1; dppm = bis(diphenylphosphino)methane, 3 m-Hppy = 3-methyl-2-phenylpyridine), which shows a green luminescence band at 517 nm in DMSO was synthesized from reaction of the dimeric [Ir2(3m-ppy)4Cl2] with dppm under an inert atmosphere. Complex 1 was characterized by 1H NMR, FT-IR, ESI-MS spectroscopies and CHN analysis. Single-crystal X-ray analysis of 1 revealed a distorted octahedral geometry comprising an IrIII center with monodentate dppm, bidentate-C,N 3 m-ppy and chlorido ligands. The electrochemistry of 1 was studied by cyclic voltammetry in 0.1 M NaClO4 in acetonitrile on a glassy carbon working electrode, displaying an oxidation peak of IrIII/IV at 1.2 V. Complex 1 showed anticancer activity against MDA-MB-231, MCF-7 and HCC1937 cell lines of human breast cancer; the respective cytotoxicity factors of 160, 32 and 25 were significantly greater than the cytotoxicity factors obtained with cisplatin. [ABSTRACT FROM AUTHOR]

[Display omitted] • [Ir(3m-ppy) 2 (dppm)Cl] was used for modification of carbon paste electrode (CPE). • Ir based spherical particles were self-assembled on CPE surface as proved by SEM. • After electrochemical activation, modified electrode was tested for amperometric determination of H 2 O 2. • For practical applicability, H 2 O 2 content in color cream developers was determined. • Proposed method allows rapid, sensitive and reliable sensing of H 2 O 2. In this work, a simple strategy of carbon paste electrode (CPE) modification with previously synthesized iridium(III) complex i.e. [Ir(3m-ppy) 2 (dppm)Cl] (3m-ppy = 3-methyl-2-phenylpyridine, dppm = bis(diphenylphosphino)methane) was elaborated together with first application of [Ir(3m-ppy) 2 (dppm)Cl] as working electrode component for H 2 O 2 amperometric determination. The electrode with iridium(III) complex (Ir/CPE) was prepared in one step using optimized drop coating procedure. The characterization of Ir/CPE by scanning electron microscopy in combination with energy dispersive spectrometry confirmed the presence of densely populated Ir(III) complex based microspherical particles self-assembled on the electrode surface. Comparative cyclic voltammetric responses of the Ir/CPE and pristine CPE in phosphate (pH 7.50) and acetate (pH 4.50) buffer solution proved that in both supporting electrolytes in the case of the modified electrode one irreversible oxidation peak is present with maximum close to 1.2 V vs. SCE. Comparative measurements were performed with both electrodes in the presence of H 2 O 2 target analyte, and it was found that after appropriate electrochemical activation at 1.20 V, during 60 min, the Ir complex containing electrode is a promising sensor for analytical purposes offering the possibility for the analysis of H 2 O 2 at working potentials in anodic range from 0.30 to 0.60 V and in cathodic range from −0.05 to −0.30 V in phosphate buffer pH 7.50 (0.1 M) as supporting electrolyte. The optimized amperometric protocol which included stirred solution, electrochemical activation of the electrode and working potential as 0.60 V vs. SCE showed acceptable linearity of the calibration curve for the investigated H 2 O 2 concentration range from 51.5 to 508.2 µM, and with evaluated LOQ as 8.8 µM. Additionally, this electrode exhibited good stability and reproducibility with relative standard deviation lower than 3%. The optimized and simple amperometric method was successfully applied for determination of H 2 O 2 content in commercially available color cream developers and obtained results were in a good agreement with declared values by the producers indicating the reliability of prepared H 2 O 2 sensor. [ABSTRACT FROM AUTHOR]