Axial Cl Research Articles

First Subphthalocyanine Analogue with Fused 6H‐1,4‐diazepine Ring and its Conversion to Aminobenzamide Derivative

AbstractMixed cyclization of 5,7‐diphenyl‐6H‐1,4‐diazepine 2,3‐dicarbonitrile and tetrafluorophthalonitrile in the presence of boron trichloride affords along with symmetrical perfluorinated subphthakocyanine, [F12sPc], two novel subporphyrazine‐type products which were isolated by column chromatography and characterized by mass‐sprectometry, NMR, IR, UV‐VIS and fluorescent spectroscopy. It was established that co‐cyclomerization of dinitriles is accompanied by electrophilic chlorination of 1,4‐diazepine ring by evolved Cl2 resulting in formation of dibenzosubporphyrazine [F8sPc1] with fused 6‐chloro‐5,7‐diphenyl‐6H‐1,4‐diazepine fragment. According to DFT modelling and 1H NMR data, a more stable diastereomer with an axial Cl atom is formed and no inversion of the 1,4‐diazepine ring is observed. Hydrolytic cleavage of the 1,4‐diazepine fragment in [F8sPc1] is observed upon chromatography or in the presence of a strong acid (CF3COOH) and leads to 2‐amino‐3‐benzamide substituted dibenzo subporphyrazine [F8sPc2]. Fluorescence of [F8sPc1] (ΦF=0.03) is ca 10 times lower than for [F12sPc] (ΦF=0.28) due to the combined effect of intramolecular charge transfer (ICT) from the donor diazepine ring to the acceptor sPc macrocycle and heavy atom effect of chlorine. Fluorescence of [F8sPc2] is almost completely quenched by ICT from −NH2 group to the electron‐deficient subporphyrazine core (ΦF<0.001), but addition of acid leads to protonation of the amino group and switch‐ON the fluorescence. Therefore, aminobenzamide substituted subporphyrazines can be considered as perspective pH‐sensitive fluorophores.

Cs-Symmetric, Peripherally Fluorinated Boron Subphthalocyanine–Subnaphthalocyanine Hybrids: Shedding New Light on Their Fundamental Photophysical Properties and Their Functionality as Optoelectronic Materials

Hybridization of boron subphthalocyanine (BsubPc) and boron subnaphthalocyanine (BsubNc) has been modestly explored in the past, and was therefore carried out herein to access a subclass of these chromophores denoted as Ra-FxBsub(Pc3–p-Ncp) hybrids, where Ra is the axial halide substituent (axial chloride, Cl-, or axial fluoride, F-), x = 8, and p = 1. These chromophores were targeted as new candidate materials for organic electronic applications due to their Cs symmetry, in-plane dipole moment, and unique photophysical properties. Cl-/F- F8Bsub(Pc2-Nc1) hybrids were compared to Cl-/F- F8BsubPc hybrids, which are analogous compounds with an identical number of peripheral fluorine atoms but lower degree of π-conjugation. Upon photoexcitation of dilute toluene solutions and doped thin films with polystyrene as a nonemissive host, F8Bsub(Pc2-Nc1) hybrids exhibited distinctively broad absorption spectra and narrow emission profiles with red-shifted peak photoluminescence wavelengths in the 618–623 nm region compared to F8BsubPc hybrids (581–584 nm). Electroluminescence properties were probed in simple solution-cast organic light-emitting diodes (OLEDs) in which all four hybrids were diluted within an F8BT emissive polymer host. Upon electronic excitation, electroluminescence (EL) of Cs-symmetric hybrids followed the same trends as photoluminescence (PL), with OLED devices displaying narrow EL in the orange region (588–592 nm) for F8BsubPc hybrids and in the near-red region for F8Bsub(Pc2-Nc1) hybrids (627–632 nm). The photophysical processes important to OLEDs moderately improved with less π-conjugation in the periphery of the Cs-symmetric hybrids [F8Bsub(Pc2-Nc1) vs F8BsubPc; EQEMax: 0.099% vs 0.129%; luminance: 500 cd/m2 vs 1000 cd/m2 at maximum current density; relative PL quantum yields (QYs) ≈ 17–22% vs ≈ 35–44%]. Electrochemical data showed that Cs symmetry introduces reversibility or quasi-reversibility in the oxidation regime at potentials >1 V, and peripheral fluorination enables reversibility in the reduction process. Overall, F8Bsub(Pc2-Nc1) hybrids embody several unique physical characteristics into one: broad absorption spectra (full width at half-maximum height, FWHMsolabs = 53–55 nm, FWHMfilmabs = 71 nm), narrow near-red electroluminescence (FWHMOLEDEL = 33 nm), and photoluminescence (FWHMsolPL = 25–26 nm, FWHMfilmPL = 32 nm) emission, small energy band gaps (1.95–1.96 eV), high extinction coefficients (ε ≈ (5.65–6.16) × 104 M–1 cm–1), and dual electrochemical versatility. These results provide new physical insights into the material properties of Cs-symmetric macrocycles and advance the consideration of F8Bsub(Pc2-Nc1) and F8BsubPc hybrids for optoelectronic applications.

Axial chlorine coordinated iron-nitrogen-carbon single-atom catalysts for efficient electrochemical CO2 reduction

Iron-nitrogen-carbon single-atom catalysts (Fe-N-C SACs) are promising low-cost catalysts for electrochemical CO2 reduction reaction (CO2RR) to achieve carbon neutrality. However, their relatively low selectivity and activity are related to the strong binding of reaction intermediates (e.g., CO*) on single Fe atoms. Here, combining experimental and theoretical studies, we show that introducing axial chlorine (Cl) atom can modulate the electronic structure of Fe atoms in catalytically active FeN4 sites, which facilitates the desorption of CO* and inhibits the adsorption of H*, resulting in improved activity and selectivity in CO2RR. The Cl modified Fe-N-C SAC embedded in nitrogen-doped carbon nanosheets (FeN4Cl/NC) was synthesized in two steps: pyrolyzing Fe-loaded two-dimensional zeolite imidazole framework nanosheets and low-temperature incubation in hydrochloric acid solution. X-ray absorption spectroscopy results reveal that most atomically dispersed Fe atoms are coordinated with one axial Cl atom at 2.26 Å and four N atoms at 2.02 Å. The optimized FeN4Cl/NC exhibits a CO Faradaic efficiency of 90.5%, a high current density of 10.8 mA cm−2 at a low overpotential of 490 mV, and a high turnover frequency of 1566 h−1, one of the best among recently reported Fe-based CO2RR catalysts. FeN4Cl/NC was further applied as a bifunctional catalyst to construct rechargeable zinc-CO2 batteries, delivering a power density of 0.545 mW cm−2 with excellent stability over 15 h. Tailoring the coordination environment of metal atoms in M-N-C SACs by introducing axial atoms may be further extended as an efficient general approach to design advanced catalysts for various electrochemical applications, such as fuel cells, nitrogen fixation, and lithium-sulfur batteries.

Anion-Responsive Manganese Porphyrin Facilitates Chloride Transport and Induces Immunogenic Cell Death

Anion-Responsive Manganese Porphyrin Facilitates Chloride Transport and Induces Immunogenic Cell Death

New Dinuclear Methoxo-Bridged Manganese(III) complex: Synthesis, Characterization and Usage as New Precursor for Synthesis of Mn2O3 Particles

New dinuclear methoxo-bridged manganese(III) complex [Mn2((MeO-bph)en)2Cl2(m-CH3O)2] (1) was synthesized by template reaction of 2-hydroxy-4-methoxybenzophenone, 1,2-ethanediamine and MnCl2×6H2O with molar ration (1:1:1) in methanol as solvent. The title compound 1 was characterized by elemental analyses (CHN), Fourier Transform infrared spectroscopy (FT-IR) and single crystal X-ray diffraction. X-ray result reveal that 1 is dimeric with methoxo bridges between two symmetry equivalent manganese ions. The Mn ions are surrounded in a distorted octahedral geometry influenced by Jahn-Teller effect. The tridentate Schiff base ligand MeO-bp-en and one of the methoxo-bridges bind in the equatorial mode, whereas in the axial positions, other metoxo-bridge and Cl atom bind to the Mn ions. Thermogravimetric analysis of 1 was studied and display the title compound 1 decompose in three stages. Finally, by calcination of 1 at 500 °C for 3 h, we prepared Mn2O3 particles and characterized by FT-IR, XRD and SEM.

Biotransformation of hexachlorocyclohexanes contaminated biomass for energetic utilization demonstrated in continuous anaerobic digestion system

Lindane, the γ-hexachlorocyclohexane (HCH) isomer, was among the most used pesticides worldwide. Although it was banned in 2009, residues of Lindane and other HCH-isomers are still found with high concentrations in contaminated fields. For clean-up, phytoremediation combined with anaerobic digestion (AD) of contaminated biomass to produce biogas and fertilizer could be a promising strategy and was tested in two 15 L laboratory-scale continuous stirred tank reactors. During operation over one year by adding HCH isomers (γ, α and β) consecutively, no negative influence on conventional reactor parameters was observed. The γ- and α-HCH isomers were transformed to chlorobenzene and benzene, and transformation became faster along with time, while β-HCH was not removed. Genus Methanosaeta and order Clostridiales, showing significant enhancement on abundance with HCH addition, may be used as bioindicators for HCH dehalogenation in AD process. The potential for HCH degradation in AD system was restricted to axial Cl atoms of HCH and it showed slight enantioselective preference towards transformation of (+) α-HCH. Moreover, metabolite benzene was mineralized to CO2 and methane, deducing from tracer experiments with benzene-13C6. Overall, AD appears to be a feasible option for treatment of γ and α-HCHs contaminated biomass.

New insight into the reactions of organoplatinum(II) complexes with diorganotin dichloride and diisothiocyanate: Oxidative addition, reductive elimination and α-elimination

The reaction of electron rich [PtMe2(NN)] with SnMe2Cl2 in a 1:3/Pt:Sn mole ratio resulted in formation of Pt(IV) complexes [PtMe2(SnMe2Cl)Cl(NN)] {NN = 4,4′-Me2bpy (4,4′-dimethyl-2,2′-bipyridine) (7); 5,5′-Me2bpy (5,5′-dimethyl-2,2′-bipyridine) (8); bphen (4,7-diphenyl-1,10-phenanthroline) (9)}. NMR data show that the resulting complexes exist as the sole product corresponding to that of trans oxidative addition of SnMe2Cl2. The yellow polymorph of complex [PtCl2(5,5′-Me2bpy)] (10) was characterized by X-ray crystallography from the reaction of [PtMe2(5,5′-Me2bpy)] and excess of SnMe2Cl2 due to the reductive elimination of 8. On the other hand, the reaction of [PtMe2(NN)] with SnEt2Cl2 in a 1:3/Pt:Sn mole ratio resulted in formation of new complexes [PtMe2(SnEt2Cl)Cl(4,4′-Me2bpy)] (11), [PtMe2(SnEt2Cl)Cl(5,5′-Me2bpy)].SnEt2Cl2 (12) and [PtMe2(SnEt2Cl)Cl(bu2bpy)].SnEt2Cl2 (bu2bpy = 4,4′-di-tert-butyl-2,2′-dipyridine) (13). NMR data indicate that the PtSnEt2Cl bond is weaker than the PtSnMe2Cl bond. The X-ray crystal structure of 13 reveals that organoplatinum(IV) complex acts as a donor to the SnEt2Cl2 to form an adduct in a distorted trigonal bipyramid with the axial Cl⋯SnCl and equatorial SnEt2Cl units. Moreover, the X-ray crystal structure of the new yellow form of [PtClMe(4,4′-Me2bpy)] (14), which has been formed by the crystallization of a mixture of [PtMe2(4,4′-Me2bpy)] and excess of SnEt2Cl2, is described. The reaction of dimethylplatinum(II) complexes with dimethyltin diisothiocanate are reported for the first time which occur via Sn-NCS bond cleavage to afford the organoplatinum(IV) complexes [PtMe2(SnMe2NCS)(SCN)(NN)] {NN = bpy (17); phen (18); 5,5′-Me2bpy (19); bu2bpy (20); bphen (21)}. The crystal structures of the novel thiocyanatoplatinum(IV) complexes [PtMe2(SCN)2(bpy)] (22) and [PtMe2(SCN)2(5,5′-Me2bpy)]. H2O (23) are discussed which have been obtained due to the α-elimination of SnMe2. The crystal structures of 22–23 show that platinum adopts a slightly distorted octahedral geometry with trans- Pt(SCN)2 configuration in which SCN is bonded through sulfur atom while the nitrogen atom is coordinated to tin. NMR data indicate that the products dissociate via α-elimination of SnMe2 or reductive elimination of organotin(IV) compound and the stability of the organoplatinum(IV) compounds varies according to the trends [PtMe2(SnMe2Cl)Cl(NN)]>[PtMe2(SnMe2NCS)(SCN)(NN)]>[PtMe2(SnEt2Cl)Cl(NN)].

Ab initio study of ligand dissociation/exchange and the hydrogen production process of the Co(dmgH)2(py)Cl cobaloxime in the acetonitrile-water solvent

Density functional theory (DFT) calculations and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent were carried out to study the ligand dissociation/exchange process and hydrogen production pathway of a common cobaloxime complex, Co(dmgH)2(py)Cl (py = pyridine). Our results show that the axial Cl− is readily replaced by a water molecule which is a key step for the subsequent proton transfer in the hydrogen production cycle. Moreover, the py ligand also dissociates readily from the complex at a later stage. The alternate two electrons and two protons addition pathway was identified to be the favorable one for hydrogen production. The rate determining step of the hydrogen production by Co(dmgH)2(py)Cl is the first protonation of the Co ion, which competes with the proton transfer to the O of the side group of the complex.

Molecular structures of cobalt complexes of 2-aza-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-carbaporphyrin: [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)L] (L = Cl−, N*CS−)

Two experimentally well characterized four-coordinate complexes of the general formula [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)L] (with L = Cl− and N*CS− for 3 and 4) are considered for this study. The crystal structures of the paramagnetic chloro(2-aza-2-[p-methyl benzyl]-5,10,15,20-tetraphenyl-21-m-xylyl-21-carbaporphyrinato-N,N′,N″) cobalt(II) octane solvate [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)Cl]·0.5C8H18 (3·0.5 C8H18) and thiocyanato-N-(2-aza-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-m-xylyl-21-carbaporphyrinato-N,N′,N″) cobalt(II) [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)(NCS)] (4) were established. The geometry around the Co2+ ion in 3·0.5 C8H18 (or 4) is a distorted tetrahedron, with C2v symmetry. The magnitude of the zero-field splitting (ZFS) parameter (D) was reported to change from 44.5 cm−1 in 3 to 30.0 cm−1 in 4 through DC magnetic susceptibility determinations. The |D| value can be related to the magnitude of the ligand-field splitting parameter of the axial k-donating Cl− ligand of 3 and the axial π-accepting NCS− ligand of 4 at the cobalt sites.

Novel iridium-pentafluorophenyl porphyrin complex

The novel iridium-pentafluorophenyl porphyrin complex (TPFPPIrCl(CO)) was successfully synthesized by chemical reaction with the iridium (I) metal precursor [Ir(COD)Cl]2. The final complex was identified linked to the axial Cl and CO ligands by UV–Visible, 1H, 13C NMR spectroscopy as well the 1H/13C correlated techniques and by mass spectrometry.

A neutral paddlewheel-type diruthenium(III) complex with benzamidinato ligands: Synthesis, crystal structure, magnetism, and electrochemical and absorption properties

A new neutral diruthenium(III) complex coordinated with benzamidinato (bam) ligands, [Ru2(bam)4Cl2]·H2O (1), was synthesized and characterized, and its electronic structure was closely investigated via magnetic susceptibility, absorption spectrum, cyclic voltammetry, and density functional theory (DFT) calculations. Single crystal X-ray diffraction analysis revealed that complex 1 has a typical paddlewheel-type structure with a RuRu bond (bond length: 2.342(1)Å), in which the diruthenium (Ru2) core is coordinated by four equatorially μ-bridging bam ligands and two axial Cl− ions. The magnetic study and DFT calculations proved that complex 1 has a triplet spin state (S=1) and a unique electronic structure (π4δ2π*2σ2). Absorption spectral feature and electrochemical property of complex 1 were also carefully investigated both experimentally and theoretically in this study.

Structural Dependence of the Ising-type Magnetic Anisotropy and of the Relaxation Time in Mononuclear Trigonal Bipyramidal Co(II) Single Molecule Magnets.

This paper describes the correlation between Ising-type magnetic anisotropy and structure in trigonal bipyramidal Co(II) complexes. Three sulfur-containing trigonal bipyramidal Co(II) complexes were synthesized and characterized. It was shown that we can engineer the magnitude of the Ising anisotropy using ligand field theory arguments in conjunction with structural parameters. To prepare this series of compounds, we used, on the one hand, a tetradentate ligand containing three sulfur atoms and one amine (NS3tBu) and on the other hand three different axial ligands, namely, Cl-, Br-, and NCS-. The organic ligand imposes a trigonal bipyramidal arrangement with the three sulfur atoms lying in the trigonal plane with long Co-S bond distances. The magnetic properties of the compounds were measured, and ab initio calculations were used to analyze the anisotropy parameters and perform magneto-structural correlations. We demonstrate that a smaller axial zero-field splitting parameter leads to slower relaxation time when the symmetry is strictly axial, while the presence of very weak rhombicity decreases the energy barrier and speeds the relaxation of the magnetization.

Studies on the G Factors and Superhyperfine Parameters of the Tetragonal [Fe(CN)4·(CN)Cl]5–Group in NaCl

The g factors and superhyperfine parameters of the tetragonal (Fe(CN)4·(CN)Cl) 5�¬ group in NaCl are theoretically investigated from the perturbation formulas of these parameters for a tetragonally elongated octahedral low spin (S=1/2) 3d 7 cluster. This center is ascribed to the substitutional Fe + on host Na + site associated with one of the axial ligands CN - replaced by Cl - . Since the crystal-fields arising from the axial Cl - and CN - ions are weaker than those of the four planar CN - , the impurity center is characterized as the tetragonally elongated octahedron. The calculated g factors and superhyperfine parameters show reasonable agreement with the measured values. The results are discussed.

Conformation preference and related intramolecular noncovalent interaction of selected short chain chlorinated paraffins

Short chain chlorinated paraffins (SCCPs) are not only research focus of environmental issues but also interesting model molecules for organic chemistry which exhibit diverse conformation preference and intramolecular noncovalent interactions (NCIs). A systematic study was conducted to reveal the conformation preference and the related intramolecular NCIs in two C10-isomers of SCCPs, 5,5,6,6-tetrachlorodecane and 4,4,6,6-tetrachlorodecane. The overall conformation profile was determined on the basis of relative energies calculated at the MP2/6-311++G(d,p) level with the geometries optimized by B3LYP/6-311++G(d,p) method. Then, quantum theory of atoms in molecules (QTAIM) has been adopted to identify the NCIs in the selected conformers of the model molecules at both B3LYP/6-311++G(d,p) and M06-2X/aug-cc-pvdz level. Different chlorine substitution modes result in varied conformation preference. No obvious gauche effect can be observed for the SCCPs with chlorination on adjacent carbon atoms. The most stable conformer of 5,5,6,6-tetrachlorodecane (tTt) has its three dihedral angles in the T configuration, and there is no intramolecular NCIs found in this molecule. On the contrary, the chlorination on interval carbon atoms favors the adoption of gauche configuration for the H–C–C–Cl axis. Not only intramolecular H···Cl contacts but also H···H interactions have been identified as driving forces to compensate the instability from steric crowding of the gauche configuration. The gggg and g′g′g′g′ conformers are the most popular ones, while the populations of tggg and tg′g′g′ conformer are second to those of the gggg and g′g′g′g′ conformers. Meanwhile, the M06-2X method with large basis sets is preferred for identification of subtle intramolecular NCIs in large molecules like SCCPs.

Tuning the Magnetic Anisotropy of Single Molecules.

The magnetism of single atoms and molecules is governed by the atomic scale environment. In general, the reduced symmetry of the surrounding splits the d states and aligns the magnetic moment along certain favorable directions. Here, we show that we can reversibly modify the magnetocrystalline anisotropy by manipulating the environment of single iron(II) porphyrin molecules adsorbed on Pb(111) with the tip of a scanning tunneling microscope. When we decrease the tip-molecule distance, we first observe a small increase followed by an exponential decrease of the axial anisotropy on the molecules. This is in contrast to the monotonous increase observed earlier for the same molecule with an additional axial Cl ligand ( Nat. Phys. 2013 , 9 , 765 ). We ascribe the changes in the anisotropy of both species to a deformation of the molecules in the presence of the attractive force of the tip, which leads to a change in the d level alignment. These experiments demonstrate the feasibility of a precise tuning of the magnetic anisotropy of an individual molecule by mechanical control.

Chemical structure and reactions of axially coordinated iridium(III) porphyrins

Effect of modification of the axial (fifth and sixth) coordination sites on the physicochemical properties and reactivity of iridium(III) complexes with 5,10,15,20-tetraphenyl-21H,23H-porphine was studied. Oxidation reactions of (Cl)(H2O)IrTPP in protic solvents by atmospheric oxygen (on assistance of protons at high concentration) preceded by ligand substitution at the axial position were studied. It was found that (Cl)(H2O)IrTPP in 100% AcOH undergoes slow one-electron oxidation at the aromatic ligand to form π cation radical (CH3COO)(CH3COOH)IrTPP·+. The reaction was studied in 100% AcOH (H2O content 0.078%) at 288–308 K, its kinetic parameters were obtained. The (Cl)(H2O)IrTPP reaction product in CF3COOH was identified as complex (CF3COO)2IrIVTPP oxidized at the central metal cation. It was experimentally confirmed that the reaction in 99% CF3COOH at 298 K proceeds in two stages: the substitution of axial Cl− and H2O by excess CF3COO− (keff = (1.8 ± 0.1) × 10−3 s−1) and the oxidation of iridium to Ir(IV) (keff = (8.0 ± 0.5) × 10−5 s−1). Data on similar Re(III) complexes (PhO)ReTPP and (Cl)ReTPP are presented for comparison.

Properties of chemically generated π-radical cations and molecules of (meso-phenyl-β-octaethylporphyrinato)rhenium(V) with axial molecular oxygen

The state of existence and reactions of stable rhenium(V) complexes with β-octaethylporphin (O=Re(OPh)OEP, O=Re(Cl)OEP) and its meso-diphenyl-substituted derivatives (O=Re(Cl)5,15DPOEP) in concentrated H2SO4 at 318–348 K were studied. It was found that O=Re(Cl)5,15DPOEP undergoes slow single-electron oxidation at the aromatic ligand to give π-radical cation. The oxidation is accompanied by replacement of the axial Cl− ligand by the hydrogen sulfate ion present in excess. Full kinetic description of the intricate oxidation reaction of the complex involving atmospheric oxygen was obtained and parameters of simple reactions that constitute the intricate process were determined. In the case of O=Re(Cl)OEP and O=Re(OPh)OEP, the reaction stops after the formation of the cationic complex with axially coordinated oxygen and outer-sphere chloride ion O=Re(O2)OEP+ Cl−. The effect of the nature of axial and macrocyclic ligands in rhenium(V) porphyrins on the processes in sulfuric acid solutions of these compounds was established.

Impact of solvent models and van der Waals corrections on DFT geometric and 57Fe Mössbauer parameters of trans-[FeCl2(iPrOH)4

Geometric parameters of an iron(II) octahedral complex trans-[FeCl2(iPrOH)4] (Nunes et al., 2004), showing the Cl2O4 donor set (iPrOH=propan-2-ol), were investigated by a series of quantum-chemical calculations based on density functional theory (DFT), with the aim to quantify the influence of geometry and various corrections on the accuracy of the calculated 57Fe Mössbauer parameters, i.e. isomer shift, δ, and quadrupole splitting, ΔEQ. The B3LYP hybrid functional was used in combination with the Polarized Continuum Model (PCM), Conduktor-like screening model (COSMO) and van der Waals (VDW) corrections, involving the Wachters original full-electron, 6–311G(d) and TZVP basis sets. On the basis of the obtained data analysis it may be concluded that the overall good agreement between the experimental and theoretical results has been found for calculations performed at the B3LYP/Wachters/6–311G(d)/COSMO+VDW level of theory, showing the mean errors 0.0164Å and 0.0315Å for Fe–O and Fe–Cl bond lengths, respectively, 2.85° for the axial Cl–Fe–Cl and O–Fe–O angles, and absolute errors 0.09mms−1 for δ and 0.07mms−1 for ΔEQ.

Organotin(IV) derivatives with 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidine and their cytotoxic activities: The importance of being conformers

The organotin(IV) compounds Me2SnCl2(dbtp)(1), Me2SnCl2(dbtp)2 (2), Et2SnCl2(dbtp) (3), Et2SnCl2(dbtp)2 (4), Et2SnCl2(dptp) (5), nBu2SnCl2(dbtp)2 (6), nBu2SnCl2(dptp) (7), Ph2SnCl2(dbtp) (8), Ph2SnCl2(EtOH)2(dptp)2 (9), where dbtp=5,7-di-tert-butyl-1,2,4-triazolo[1,5-a]pyrimidine and dptp=5,7-diphenyl-1,2,4-triazolo [1,5-a]pyrimidine, have been tested by MTT for their cytotoxic activity on three tumor cell lines, HepG2 (human hepatocellular carcinoma), HeLa (human cervix adenocarcinoma) and MCF-7 (human breast cancer). Except for 1 and 2, which were ineffective, all compounds significantly showed a dose-dependent anti-proliferative effect against the three cell lines. By calculated IC50 values, the cytotoxicity of the complexes followed the order nBu>Ph>Et>Me for all the selected tumor cells. The cell death of HepG2, induced by organotin(IV) compounds 6–9, was considered to be apoptotic by measuring the exposure of phosphatidylserine to the outer membrane and observing the typical apoptotic morphological change by acridine orange/ethidium bromide staining. Flow cytometric analysis of propidium iodide-stained cells also demonstrated that organotin(IV) complexes caused apoptosis of HepG2 cells through cell arrest at G0–G1 phase. The crystal structure of 7, investigated by X-ray diffraction study, exhibited a distorted trigonal bipyramidal geometry with N, Cl as axial atoms and Cl and butyl groups in the equatorial plane. The triazolopyrimidine unit coordinates to the Sn atom through N(3) in a monodentate mode. Two conformational isomers (molecule A and B in the crystallographic independent unit) are co-crystallized in the solid state, a phenomenon that has been observed only occasionally. Conformational mobility of the cytotoxic complex 7 can sum up to the ligands ability to form H-bonds and π⋯π stacking, facilitating its intracellular uptake.

Photoactivation of Molecular Oxygen by an Iron(III) Porphyrin with a Magnesium Aluminum Layered Double Hydroxide for the Aerobic Epoxidation of Cyclohexene

AbstractThe photocatalytic aerobic epoxidation of cyclohexene proceeded under visible‐light irradiation only if 5,10,15,20tetrakis(pentafluorophenyl)porphyrin iron(III) chloride ([FeIII(TPFPP)Cl]) was combined with Mg‐Al layered double hydroxide (Mg‐Al LDH) as a solid base in chloroform. The OH groups in the Mg‐Al LDH exchanged with the axial Cl ligands in [FeIII(TPFPP)Cl] to afford [FeIII(TPFPP)OH], which functioned photocatalytically in the presence of Mg‐Al LDH but was inactive in its absence. The band in the action spectrum agreed well with the Soret band in the UV/Vis absorption spectrum of [FeIII(TPFPP)OH]. The spectral changes indicated the reduction of [FeIII(TPFPP)OH] to [FeII(TPFPP)] under visible‐light irradiation, which in turn activates O2 that could be used for the epoxidation of cyclohexene.