Arene Ring Research Articles

Comparative structural description of five arene ruthenium(II) complexes of N,N-bidentate Schiff base ligands to related complexes from literature

A series of new half-sandwich Ru(II) complex salts of the general formula [(η6-arene)RuX(L)]PF6 (where arene = p-cymene, X = Br and ligand L1 = N-tert-butyl-N-(pyridyl methylene) amine (complex 1), ligand L2 = N-isopropyl-2-pyridine carbaldimine (complex 2), ligand L3 = (2,5-dimethyl-phenyl)-pyridin-2-yl methylene amine (complex 3), ligand L4 = (3,5-dimethyl-phenyl)-pyridin-2-yl methylene (complex 4) and arene = C6H6, X = I, ligand L5 = (4-bromo-phenyl)-pyridin-2-yl methylene (complex 5) have been synthesized by reacting the ruthenium arene precursors [(η6-arene)Ru(μ-X)X]2 with N,N-bidentate ligands in a 1:2 ratio. Full characterization of the complexes was accomplished by physicochemical and spectroscopic methods and X-ray structures of all the complexes 1–5. The crystal structures reveal that the ruthenium centers in 1–5 are coordinated to the N,N-bidentate ligand in a bidentate manner, to the respective halide, and to the arene ring to give a pseudo-tetrahedral geometry around them. The whole arrangement is referred to as the three-legged piano stool, in which the N,N-bidentate ligand and the halide (Br or I) serve as the base occupying three coordination sites, while the arene ring serves as the apex of the stool and occupy the remaining coordination sites.

Non‐emissive RuII Polypyridyl Complexes as Efficient and Selective Photosensitizers for the Photooxidation of Benzylamines

Five new Ru(II) polypyridyl complexes bearing N-(arylsulfonyl)-8-amidoquinolate ligands and three of their biscyclometalated Ir(III) congeners have been prepared and employed as photocatalysts (PCs) in the photooxidation of benzylamines with O 2 . In particular, the new Ru(II) complexes do not exhibit photoluminescence but they harvest visible light efficiently and are very stable in solution under irradiation with blue light. Their non-emissive behavior has been related to the low electrochemical energy gaps and rationalized on the basis of theoretical calculations (DFT analysis), which predict low S 0 ← T 1 energy values. Moreover, the Ru(II) complexes, despite being non-emissive, display excellent activities in the selective photocatalytic transformation of benzylamines into the corresponding imines. The presence of an electron withdrawing group (-CF 3 ) on the arene ring of the N-(arylsulfonyl)-8-amidoquinolate ligand improves the photocatalytic activity of the corresponding photocatalyst. Furthermore, all the experimental evidences, including Transient Absorption Spectroscopy measurements suggest that singlet oxygen is the actual oxidant. The Ir(III) analogues are considerably more photosensitive and consequently less efficient photosensitizers (PSs).

Moving substituents around arene rings

Rearrangement reactions are useful ways to make substituted aromatic molecules, but most of the methods that shift a substituent around an arene ring leave a functional group behind at the vacated ...

Positional Isomerism in the N^N Ligand: How Much Difference Does a Methyl Group Make in [Cu(P^P)(N^N)]+ Complexes?

The synthesis and structural characterization of 5,6′-dimethyl-2,2′-bipyridine (5,6′-Me2bpy) are reported, along with the preparations and characterizations of [Cu(POP)(5,6′-Me2bpy)][PF6] and [Cu(xantphos)(5,6′-Me2bpy)][PF6] (POP = bis(2-(diphenylphosphanyl)phenyl)ether, xantphos = 4,5-bis(diphenylphosphanyl)-9,9-dimethyl-9H-xanthene). Single-crystal X-ray structure determinations of [Cu(POP)(5,6′-Me2bpy)][PF6] and [Cu(xantphos)(5,6′-Me2bpy)][PF6] confirmed distorted tetrahedral copper(I) coordination environments with the 5-methylpyridine ring of 5,6′-Me2bpy directed towards the (C6H4)2O unit of POP or the xanthene unit of xantphos. In the xantphos case, this preference may be attributed to C–H…π interactions involving both the 6-CH unit and the 5-methyl substituent in the 5-methylpyridine ring and the arene rings of the xanthene unit. 1H NMR spectroscopic data indicate that this ligand orientation is also preferred in solution. In solution and the solid state, [Cu(POP)(5,6′-Me2bpy)][PF6] and [Cu(xantphos)(5,6′-Me2bpy)][PF6] are yellow emitters, and, for powdered samples, photoluminescence quantum yields (PLQYs) are 12 and 11%, respectively, and excited-state lifetimes are 5 and 6 μs, respectively. These values are lower than PLQY and τ values for [Cu(POP)(6,6′-Me2bpy)][PF6] and [Cu(xantphos)(6,6′-Me2bpy)][PF6], and the investigation points to the 6,6′-dimethyl substitution pattern in the bpy ligand being critical for enhancement of the PLQY.

Electronic Energy Relaxation in a Photoexcited Fully Fused Edge-Sharing Carbon Nanobelt.

Carbon nanobelts are cylindrical molecules composed of fully fused edge-sharing arene rings. Because of their aesthetically appealing structures, they acquire unusual optoelectronic properties that are potentially suitable for a range of applications in nanoelectronics and photonics. Nevertheless, the very limited success of their synthesis has led to their photophysical properties remaining largely unknown. Compared to that of carbon nanorings (arenes linked by single bonds), the strong structural rigidity of nanobelts prevents significant deformations away from the original high-symmetry conformation and, therefore, impacts their photophysical properties. Herein, we study the photoinduced dynamics of a successfully synthesized belt segment of (6,6)CNT (carbon nanotube). Modeling this process with nonadiabatic excited state molecular dynamics simulations uncovers the critical role played by the changes in excited state wave function localization on the different types of carbon atoms. This allows a detailed description of the excited state dynamics and spatial exciton evolution throughout the nanobelt scaffold. Our results provide detailed information about the excited state electronic properties and internal conversion rates that is potentially useful for designing nanobelts for nanoelectronic and photonic applications.

Comparative Structural Description of Five Arene Ruthenium(Ii) Complexes with N,N- Bidentate Schiff Base Ligands and Related Complexes from Literature

Isostructurality between certain pairs of complexes A series of new half-sandwich Ru(II) complex salts of the general formula [(η6-arene)RuX(L)]PF6 (where arene = p-cymene, X = Br and L = N-tert-butyl-N-(pyridyl methylene) amine (1), N-isopropyl-2-pyridine carbaldimine (2), (2,5-dimethyl-phenyl)-pyridin-2-yl methylene amine (3), (3,5-dimethyl-phenyl)-pyridin-2-yl methylene (4) and arene = C6H6, X = I, L = (4-bromo-phenyl)-pyridin-2-yl methylene (5) have been synthesized by reacting the ruthenium arene precursors [(η6-arene)Ru(μ-X)X]2 with N,N-bidentate ligands in a 1:2 ratio. Full characterization of the complexes was accomplished using 1H and 13C NMR, elemental analyses, UV-Vis, IR and X-ray structures of all the complexes 1 - 5. The crystal structures reveal that the ruthenium centers in 1 - 5 are coordinated to the N,N-bidentate ligand in a bidentate manner, to the respective halide and to the arene ring. The whole arrangement is referred to as the three-legged piano stool, in which the N,N-bidentate ligand and the halide (Br or I) serve as the base, while the arene ring serves as the apex of the stool. A comparison to related structures from the CSD reveal isostructurality amongst certain pairs of complexes.

A new photoluminescent coordination polymer constructed with an N-donor ligand having extended coordination capabilities derived from quinoline and pyridine.

Employment of the organic 2-(pyridin-4-yl)quinoline-4-carboxylic acid ligand with extended coordination capabilities leads to the formation of the one-dimensional copper(II) coordination polymer catena-poly[[diaquacopper(II)]-bis[μ-2-(pyridin-4-yl)quinoline-4-carboxylato]-κ2N2:O;κ2O:N], {[Cu(C15H9N2O2)2(H2O)2]·2H2O}n, under hydrothermal conditions. The ligand, isolated as its hydrochloride salt, namely, 4-(4-carboxyquinolin-2-yl)pyridinium chloride monohydrate, C15H11N2O2+·Cl-·H2O, reveals a pseudosymmetry element (translation a/2) in its crystal structure. The additional pyridyl N atom, in comparison with the previously reported analogues with an arene ring instead of the pyridyl ring in the present ligand molecule, promotes the formation of a one-dimensional coordination polymer, rather than discrete molecules. This polymer shows photoluminescent properties with bathochromic/hypsochromic shifts of the ligand absorption bands, leading to a single band at 479 nm. The CuII ions are involved in weak antiferromagnetic interactions within dimeric units, as evidenced by SQUID magnetometry.

Radiosynthesis, in vitro and preliminary in vivo evaluation of the novel glutamine derived PET tracers [18F]fluorophenylglutamine and [18F]fluorobiphenylglutamine

IntroductionGlucose has been deemed the driving force of tumor growth for decades. However, research has shown that several tumors metabolically shift towards glutaminolysis. The development of radiolabeled glutamine derivatives could be a useful molecular imaging tool for visualizing these tumors. We elaborated on the glutamine-derived PET tracers by developing two novel probes, namely [18F]fluorophenylglutamine and [18F]fluorobiphenylglutamine. Materials and methodsBoth tracers were labelled with fluorine-18 using our recently reported ruthenium-based direct aromatic fluorination method. Their affinity was evaluated with a [3H]glutamine inhibition experiment in a human PC-3 and a rat F98 cell line. The imaging potential of [18F]fluorophenylglutamine and [18F]fluorobiphenylglutamine was tested using a mouse PC-3 and a rat F98 tumor model. ResultsThe radiosynthesis of both tracers was successful with overall non-decay corrected yields of 18.46 ± 4.18% (n = 10) ([18F]fluorophenylglutamine) and 8.05 ± 3.25% (n = 5) ([18F]fluorobiphenylglutamine). In vitro inhibition experiments showed a moderate and low affinity of fluorophenylglutamine and fluorobiphenylglutamine, respectively, towards the human ASCT-2 transporter. Both compounds had a low affinity towards the rat ASCT-2 transporter. These results were endorsed by the in vivo experiments with low uptake of both tracers in the F98 rat xenograft, low uptake of [18F]FBPG in the mice PC-3 xenograft and a moderate uptake of [18F]FPG in the PC-3 tumors. ConclusionWe investigated the imaging potential of two novel PET radiotracers [18F]FPG and [18F]FBPG. [18F]FPG is the first example of a glutamine radiotracer derivatized with a phenyl group which enables the exploration of further derivatization of the phenyl group to increase the affinity and imaging qualities. We hypothesize that increasing the affinity of [18F]FPG by optimizing the substituents of the arene ring can result in a high-quality glutamine-based PET radiotracer.Advances in Knowledge and Implications for patient care: We hereby report novel glutamine-based PET-tracers. These tracers are tagged on the arene group with fluorine-18, hereby preventing in vivo defluorination, which can occur with alkyl labelled tracers (e.g. (2S,4R)4-[18F]fluoroglutamine). [18F]FPG shows clear tumor uptake in vivo, has no in vivo defluorination and has a straightforward production. We believe this tracer is a good starting point for the development of a high-quality tracer which is useful for the clinical visualization of the glutamine transport.

Arenesulfonyl Fluoride Synthesis via Copper-Catalyzed Fluorosulfonylation of Arenediazonium Salts.

We report herein a general and practical copper-catalyzed fluorosulfonylation reaction of a wide range of abundant arenediazonium salts to smoothly prepare various arenesulfonyl fluorides using the 1,4-diazabicyclo[2.2.2]octane-bis(sulfur dioxide) adduct as a convenient sulfonyl source in combination with KHF2 as an ideal fluorine source and without the need for additional oxidants. Interestingly, the electronic character of the arene ring in the starting arenediazonium salts has a significant impact on the reaction mechanistic pathway.

Cu(II) Ion Adsorption by Aniline Grafted Chitosan and Its Responsive Fluorescence Properties.

The detection and removal of heavy metal species in aquatic environments is of continued interest to address ongoing efforts in water security. This study was focused on the preparation and characterization of aniline grafted chitosan (CS-Ac-An), and evaluation of its adsorption properties with Cu(II) under variable conditions. Materials characterization provides support for the grafting of aniline onto chitosan, where the kinetic and thermodynamic adsorption properties reveal a notably greater uptake (>20-fold) of Cu(II) relative to chitosan, where the adsorption capacity (Qm) of CS-Ac-An was 106.6 mg/g. Adsorbent regeneration was demonstrated over multiple adsorption-desorption cycles with good uptake efficiency. CS-Ac-An has a strong fluorescence emission that undergoes prominent quenching at part per billion levels in aqueous solution. The quenching process displays a linear response over variable Cu(II) concentration (0.05–5 mM) that affords reliable detection of low level Cu(II) levels by an in situ “turn-off” process. The tweezer-like chelation properties of CS-Ac-An with Cu(II) was characterized by complementary spectroscopic methods: IR, NMR, X-ray photoelectron (XPS), and scanning electron microscopy (SEM). The role of synergistic effects are inferred among two types of active adsorption sites: electron rich arene rings and amine groups of chitosan with Cu(II) species to afford a tweezer-like binding modality.

Salicylic acid and aspirin stimulate growth of Chlamydomonas and inhibit lipoxygenase and chloroplast desaturase pathways

Chemical stimulants, used to enhance biomass yield, are highly desirable for the commercialisation of algal products for a wide range of applications in the food, pharma and biofuels sectors. In the present study, phenolic compounds, varying in substituents and positional isomers on the arene ring have been evaluated to determine structure-activity relationship and growth. The phenols, catechol, 4-methylcatechol and 2, 4-dimethyl phenol were generally inhibitory to growth as were the compounds containing an aldehyde function. By contrast, the phenolic acids, salicylic acid, aspirin and 4-hydroxybenzoate markedly stimulated cell proliferation enhancing cell numbers by 20–45% at mid-log phase. The order of growth stimulation was ortho > para > meta with respect to the position of the OH group. Both SA and aspirin reduced 16:3 in chloroplast galactolipids. In addition, both compounds inhibited lipoxygenase activity and lowered the levels of lipid hydroperoxides and malondialdehydes in the cells. The present study has demonstrated the possibility of using SA or aspirin to promote algal growth through the manipulation of lipid metabolising enzymes.

Tuning the catecholase activity of bis(pyrazolyl)methane-based copper(II) complexes by substitutions of the ligand core: unraveling a dual O2/H2O2 oxidation mechanism

Five new dinuclear copper(II) complexes based on dicompartmental ligands of the general formula R1R2R1-C6(OH)[C(O)-NH-CH2-CH(pz)2]2 (pz = pyrazolyl ring, R1 = R2 = H: HHH-Cu2; R1 = H, R2 = t-Bu: HButH-Cu2; R1 = Me, R2 = H: MeHMe-Cu2; R1 = Me, R2 = Br: MeBrMe-Cu2; R1 = Me, R2 = NO2: MeNO2Me-Cu2) were prepared and characterized in both solution and solid state. The phenoxide moiety acts as a bridge between two copper(II) centers; the remaining coordination sites of the metals are filled by the deprotonated N-amide atoms, the nitrogen atoms originating from the bis(pyrazolyl)methane groups and one exogenous hydroxide bridge. The catecholase-type activity of these dicopper complexes was studied in methanol, using a combination of aerobic and anaerobic methods. These investigations revealed that the substitution pattern of the central arene ring has an impact on the catalytic activity of our complexes, with the catalytic activity increasing in the following order: HHH-Cu2 <HButH-Cu2 <MeNO2Me-Cu2 <MeBrMe-Cu2 <MeHMe-Cu2. H2O2 was identified as the byproduct of O2 reduction. Its influence on the catalytic mechanism has been examined and found to have an impact on the catecholase-type reaction using these catalysts. Based on these findings, a dual mechanism for the catechol oxidation is proposed, where both molecular oxygen and the formed hydrogen peroxide act concurrently as oxidants.

A light-operated pillar[6]arene-based molecular shuttle.

A molecular shuttle comprising a pillar[6]arene macrocyclic ring and an axle with two equal-energy-level stations connected by an azobenzene unit was synthesised. The E isomer of the azobenzene functioned as "open gate", allowing the pillar[6]arene ring to rapidly shuttle back-and-forth between the two stations. Ultraviolet irradiation induced photo-isomerisation of the azobenzene from E to Z form. The Z isomer of the azobenzene functioned as a "closed gate", inhibiting shuttling of the pillar[6]arene ring.

BNN-1,3-dipoles: isolation and intramolecular cycloaddition with unactivated arenes.

The mono-base-stabilized 1,2-diboranylidenehydrazine derivatives featuring a 1,3-dipolar BNN skeleton are obtained by dehydrobromination of [ArB(Br)NH]2 (Ar = 2,6-diphenylphenyl (Dpp), Ar = 2,6-bis(2,4,6-trimethylphenyl)phenyl (Dmp) or Ar = 2,4,6-tri-tert-butylphenyl (Mes*)) with N-heterocyclic carbenes (NHCs). Depending on the Ar substituents, such species can be isolated as a crystalline solid (Ar = Mes*) or generated as reactive intermediates undergoing spontaneous intramolecular aminoboration of the proximal arene rings via [3 + 2] cycloaddition (Ar = Dpp or Dmp). The latter reactions showcase the 1,3-dipolar reactivity toward unactivated arenes at ambient temperature. In addition, double cycloaddition of the isolable BNN species with two CO2 molecules affords a bicyclic species consisting of two fused five-membered BN2CO rings. The electronic structures of these BNN species and the mechanisms of these cascade reactions are interrogated through density functional theory (DFT) calculations.

Pillar[5]arene-based [3]rotaxanes: Convenient construction via multicomponent reaction and pH responsive self-assembly in water

Four pillar[5]arene based [3]rotaxanes (1-4) involving two 1,4-diethoxypillar[5]arene (DEP5) rings and a dumbbell-shaped component were successfully synthesized. The dumbbell-shape molecules contain one longer bridge, two triazole sites and two multicomponent stoppers. After threading DEP5 rings with linear guests (G1-G4) which contain two benzaldehyde units, the base catalyzed three-component reaction of dimedone, malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1–4. The structures of [3]rotaxanes and their self-assembly behaviors were characterized by 1H NMR, 13C NMR, NOESY, HR-ESI-MS, DLS and TEM technologies. We hope that pillar[5]arene based [3]rotaxanes may have potential applications in drug delivery systems and molecular devices.

Synthesis, characterization and adsorption studies of a novel triptycene based hydroxyl azo- nanoporous polymer for environmental remediation

Gradual increase in CO2 emission due to energy production from fossils fuels is a major contributor to global warming. Alternatively, “carbon free” nuclear energy generates radioactive and carcinogenic iodine vapors. Thus, the need to develop efficient sorbents for capture of CO2 and I2 is justified. Herein, we report a Triptycene-based-Hydroxyl-Azo-Polymer (TBHAP) derived from relatively inexpensive hydroquinone (one of the two monomers) and using water as a solvent. TBHAP is thermally stable and nanoporous with high surface area (SABET up to 824 m2 g−1). The presence of permanent porosity (due to triptycene), π-rich cavities (from abundant arene rings) and active functional groups [phenolic−OH and azo (NN)] in the polymeric network of TBHAP makes it effective for reversible iodine (188 wt%), H2 (8.9 mg g−1: 77 K, 1 bar) and CO2 (145 mg/g: 273 K, 1 bar) uptake with moderately high CO2/N2 selectivity (84 at 273 K). TBHAP is also an effective and selective adsorbent for toxic cationic dyes [Methylene blue (Qm = 250 mg g−1) and Rhodamine B (Qm = 588 mg g−1)] from an aqueous solution containing binary mixtures of cationic/anionic dyes. Thus, TBHAP is a versatile porous material with various applications in the domain of environmental remediation.

Additive-Free Nickel-Catalyzed Debenzylation Reactions via Hydrogenative C–O and C–N Bond Cleavage

C–O and C–N cleavage reactions play a fundamental role in synthetic chemistry and biomass valorization. Many efforts have been done in the past in order to develop efficient catalysts able to mediate these transformations. However, still some drawbacks are present: necessity for additives and occurrence of side reactions. Here, an array of Ni-based catalysts derived from the thermal decomposition of a Ni(II)/phenanthroline complex onto different supports was prepared. Ni–N–C@Al2O3-1000 material (pyrolyzed at 1000 °C) was the most efficient catalyst for both O- and N-debenzylation of various substrates (>20 examples) using dihydrogen as reductant. Advantageously, this process is water tolerant, proceeds free of any additive, and does not show overhydrogenation of the arene ring. The structure, morphology, and chemical composition of Ni–N–C@Al2O3-1000 have been elucidated. It is constituted by variously sized Al2O3-supported Ni(0)/NiOx nanoparticles (NPs) embedded by layers of nitrogen-doped carbon.

Effect of Alkyl Chain Length and Linker Atom on the Crystal Packing in 6,12-Dialkoxy- and 6,12-Dialkylsulfanyl-Benzo[1,2-b:4,5-b′]bis[b]benzothiophenes

The effect of varying the chain length on the solid state conformation and packing of 6,12-dialkoxy- and 6,12-dialkylsulfanyl-benzo[1,2-b:4,5-b’]bis[b]benzothiophenes has been studied. The compounds were prepared by SNAr reaction of 6,12-difluorbenzo[1,2-b:4,5-b’]bis[b]benzothiophene with alkoxides or alkanethiolates derived from C7-C10 alcohols and alkanethiols. Single crystal X-ray diffraction analysis revealed all but two compounds to crystallise in the triclinic space group P1. Two compounds were obtained as monoclinic crystals with space group P21/c. The alkoxy substituted compounds adopted a molecular conformation with a step from the core and a gauche conformation about the C1’-C2’ bond placing the alkyl chains close to parallel with the pentacyclic arene ring system, whereas in the alkylsufanyl derivatives, the alkyl chains were arranged strongly deviated from the plane of the ring, with the sulfur atom anti-periplanar to C3’ of the alkyl chain. NMR measurement of T1 relaxation in CDCl3 showed both the alkoxy and alkylsulfanyl substituents to be freely rotating at ambient temperature in solution indicating the orientation of the chains in the solid state was due to packing interactions during crystallization.

Coordinative versatility in main group complexes of C-2,6-terphenyl substituted amidinates

The synthesis and characterization of two C-2,6-terphenyl substituted amidines, N,N′-dicyclohexyl-2,6-di(4-tolyl)benzamidine and N,N′-dicyclohexyl-2,6-dimesitylbenzamidine, are described. Both crystallize as the E-syn isomer, though interconversion between the E-syn and Z-syn isomers is observed for both in solution. These amidines are readily deprotonated by either n-butyllithium in THF or AlMe3 in toluene, affording the THF solvated lithium and dimethylaluminium amidinate complexes respectively. These complexes have been characterized in the solid-state using single-crystal X-ray crystallography. The identity of the 2,6-substituents on the secondary arene rings of the terphenyl group plays a significant role in the coordination motif adopted by the amidinate, as well as the potential to access bis(amidinato)metal complexes.

Similarities and differences in d6 low-spin ruthenium, rhodium and iridium half-sandwich complexes: synthesis, structure, cytotoxicity and interaction with biological targets

In this paper, we discussed the similarities and differences in d6 low-spin half-sandwich ruthenium, rhodium and iridium complexes containing 2,2′-biimidazole (H2biim). Three new complexes, {[RuCl(H2biim)(η6-p-cymene)]PF6}2·H2O (1), [(η5-Cp)RhCl(H2biim)]PF6 (2), and [(η5-Cp)IrCl(H2biim)]PF6 (3), were fully characterized by CHN, X-ray diffraction analysis, UV–Vis, FTIR, and 1H, 13C and 15N NMR spectroscopies. The complexes exhibit a typical pseudooctahedral piano-stool geometry, in which the aromatic arene ring (p-cymene or Cp) forms the seat, while the bidentate 2,2′-biimidazole and chloride ion form the three legs of the piano stool. Moreover, the cytotoxic activities of the compounds were examined in the LoVo, HL-60, MV-4-11, MCF-7 human cancer cell lines and BALB/3T3 normal mouse fibroblasts. Notably, the investigated complexes showed no cytotoxic effects towards the normal BALB/3T3 cell line compared to cisplatin, which has an IC50 value of 2.20 µg. Importantly, 1 displayed the highest activity against HL-60 (IC50 4.35 µg). To predict a binding mode, we explored the potential interactions of the metal complexes with CT-DNA and protein using UV absorption and circular dichroism. The obtained data suggest that the complexes could interact with CT-DNA via an outside binding mode. Moreover, binding of the complexes with the GSH via UV–Vis and ESI mass spectra was determined. Comparative studies have shown that the rhodium complex (2) is the most GSH reactive, which is probably responsible for its deactivation towards LoVo and MCF-7 tumour cells. The influence of the metal ion on the biological activity of isostructural Rh(III) and Ir(III) complexes was an important goal of the presented investigation.