Aminomethyl Pyridine Research Articles

Complexes possessing rare "tertiary" sulfonamide nitrogen-to-metal bonds of normal length: fac-[Re(CO)3(N(SO2R)dien)]PF6 complexes with hydrophilic sulfonamide ligands.

Tertiary sulfonamide nitrogen-to-metal bonds of normal length are very rare. We recently discovered such a bond in one class of fac-[Re(CO)3(N(SO2R)(CH2Z)2)](n) complexes (Z = 2-pyridyl) with N(SO2R)dpa ligands derived from di-(2-picolyl)amine (N(H)dpa). fac-[M(CO)3(N(SO2R)(CH2Z)2)](n) agents (M = (186/188)Re, (99m)Tc) could find use as radiopharmaceutical bioconjugates when R is a targeting moiety. However, the planar, electron-withdrawing 2-pyridyl groups of N(SO2R)dpa destabilize the ligand to base and create relatively rigid chelate rings, raising the possibility that the rare M-N(sulfonamide) bond is an artifact of a restricted geometry. Also, the hydrophobic 2-pyridyl groups could cause undesirable accumulation in the liver, limiting future use in radiopharmaceuticals. Our goal is to identify a robust, hydrophilic, and flexible N(CH2Z)2 chelate framework. New C2-symmetric ligands, N(SO2R)(CH2Z)2 with (Z = CH2NH2; R = Me, dmb, or tol), were prepared by treating N(H)dien(Boc)2, a protected diethylenetriamine (N(H)dien) derivative, with methanesulfonyl chloride (MeSO2Cl), 3,5-dimethylbenzenesulfonyl chloride (dmbSO2Cl), and 4-methylbenzenesulfonyl chloride (tolSO2Cl). Treatment of fac-[Re(CO)3(H2O)3](+) with these ligands, designated as N(SO2R)dien, afforded new fac-[Re(CO)3(N(SO2R)dien)]PF6 complexes. Comparing the fac-[Re(CO)3(N(SO2Me)dien)]PF6 and fac-[Re(CO)3(N(SO2Me)dpa)]PF6 complexes, we find that the Re(I)-N(sulfonamide) bonds are normal in length and statistically identical and that the methyl (13)C NMR signal has an unusually upfield shift compared to that in the free ligand. We attribute this unusual upfield shift to the fact that the sulfonamide N undergoes an sp(2)-to-sp(3) rehybridization upon coordination to Re(I) in both complexes. Thus, the sulfonamide N of N(SO2R)dien ligands is a good donor, even though the chelate rings are conformationally flexible. Addition of the strongly basic and potentially monodentate ligand, 4-dimethylaminopyridine, did not affect the fac-[Re(CO)3(N(SO2tol)dien)]PF6 complex, even after several weeks. This complex is also stable to heat in aqueous solution. These results indicate that N(SO2R)dien ligands form fac-[Re(CO)3(N(SO2R)dien)]PF6 complexes sufficiently robust to be utilized for radiopharmaceutical development.

Synthesis and Characterization of New Polymeric Chelates Derived from Modified Amberlite IR P69 Resin with Cr(III),Co(II),Ni(II) and Cu(II) Ions.

The Amberlite IR P69 was modified, in a two steps process with new Schiff base (HL) derived from 2-picolyl amine and 2-mercapto-4-methyl-benzyaldehyde. The new modified resin and its polymeric chelates with Cr (III), Co,Ni and Cu (II) have been isolated in the solid states and fully characterized on the basis of H, 13 C NMR,FTIR and UV-Visible spectroscopy. Furthermore the magnetic moments and molar conductance of their solutions in DMSO were recorded to investigate the stereo chemical structures of the prepared metal polymers. The results obtained from elemental analyses and the spectral measurements have deduced the coordination of nitrogen and sulphur atoms of Schiff base moiety to Amberlite IR P69 to the selected metal ions, as well as these data in communicated with thermal and magnetic susceptibilities measurements have confirmed the thermal stability and octahedral geometries for Cr III complex, tetrahedral symmetry for Co IIandsqure planner for NiII and Cu(II )polymeric metal chelates.

Synthesis and Structural Characterisation of Palladium(II) Complexes with N,N′,N-Tridentate N′-Substituted N,N-Di(2-picolyl)amines and their Application to Methyl Methacrylate Polymerisation

The reaction of [Pd(CH3CN)2Cl2] with N′-substituted N,N-di(2-picolyl)amine-based ancillary ligands, for example N,N-di(2-picolyl)cyclohexylmethylamine (L1), N,N-di(2-picolyl)benzylamine (L2), N,N-di(2-picolyl)aniline (L3), and 1,4-bis[bis(2-pyridylmethyl)aminomethyl]benzene (L4), in the presence of NaClO4 in ethanol yields a new series of [(NN′N)PdCl]X (X = ClO4, Cl) complexes, i.e. mononuclear [LnPdCl]ClO4 (Ln = L1, L2, L3) and binuclear [L4Pd2Cl2]Cl2. X-Ray crystallographic analysis determined that the Pd atom in complexes [(NN′N)PdCl]X showed a slightly distorted square-planar geometry involving three nitrogen atoms and a chlorido ligand. Moreover, the unit cell included a ClO4– or Cl– anion as the counterion. The complex [L1PdCl]ClO4 showed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane at 60°C among the mononuclear PdII complexes. Specifically, the activity of binuclear [L4Pd2Cl2]Cl2 was 2-fold higher than the corresponding mononuclear [L2PdCl]ClO4 per active palladium metal centre.

Synthesis of N-picolylcarboxamides via palladium-catalysed aminocarbonylation of iodobenzene and iodoalkenes

A systematic investigation of the palladium-catalysed aminocarbonylation of iodobenzene, 1-iodocyclohexene and 1′-iodostyrene in the presence of N-nucleophiles containing pyridyl moieties (2-, 3- and 4-picolylamine, N-ethyl-4-picolylamine, di-(2-picolyl)amine) was carried out. The two types of iodo substrates differ substantially regarding the selectivity towards carbonylation: while the aminocarbonylation of iodobenzene resulted in the formation of carboxamide and ketocarboxamide mixtures under various conditions, with the predominant formation of ketocarboxamide even at low carbon monoxide pressure, the aminocarbonylation of iodoalkenes under same conditions gave the corresponding unsaturated carboxamide exclusively. Most of the carboxamides and phenylglyoxylamides, obtained via single and double carbon monoxide insertion, respectively, were isolated in yields of synthetic interest (up to 86%). Low reaction rates and unexpected chemoselectivity towards carboxamide formation have been observed with di-(2-picolyl)amine as N-nucleophile in the aminocarbonylation of iodobenzene.

Syntheses, characterization, and SOD activity studies of barbital-based nickel(II) complexes with different chelating amines: The X-ray crystal structures of Barb-H and [Ni(Barb)2(en)2] (Barb = 5,5-diethylbarbiturate)

Four new mixed ligand nickel(II) complexes, viz., [Ni(Barb)2(H2O)4] 1, [Ni(Barb)2(en)2] 2, [Ni(Barb)2(pn)2] 3, and [Ni(Barb)2(BPA)(H2O)] 4 (Barb=5,5-diethylbarbiturate, en=ethylenediamine, pn=propylenediamine, and BPA=bis(2-picolyl)amine) have been synthesized and characterized by means of elemental analysis, spectroscopic (FT-IR, Raman, and UV–Vis), and thermal analysis measurements. The spectral techniques suggest that all the nickel(II) complexes (1–4) exhibit octahedral geometry. The very low electrical conductance of the complexes supports their neutral nature. The monomeric nature of the complexes was assessed from their electronic spectra. X-ray diffraction studies were performed for the drug Barb-H and its nickel(II) complex 2. Complex 2 crystallizes in monoclinic space group P21/c with Z=2. The barbital drug is N-coordinated and the en molecules act as bichelating ligands, leading to an NiN6 octahedral coordination. Molecules of complex 2 are connected via NH⋯O hydrogen bonds, involving hydrogen atoms of both Barb and en ligands. The redox behavior of all complexes was investigated by cyclic voltammetry. Superoxide dismutase activity of these complexes has also been measured.

BODIPY modified silica coated magnetite nanoparticles as fluorescent hybrid material for Cu (II) detection in aqueous medium

A novel ratiometric fluorescent sensor for copper II based on silica coated magnetite hybrid fluorescent material functionalized with boron-dipyrromethene containing a di (2-picolyl) amine was prepared and characterized. The binding abilities of the functionalized silica coated magnetite nanoparticles towards different metal ions have been examined by fluorescence spectroscopy, and displays high selectivity and sensitivity for Copper II among the all tested metals in Ethanol/water: 8:2.

A Method for Improving the Optical Properties of a Fluoregenic Di-metal Chelator as a Zn2+Ion Fluorescent Probe by Using a Bridging Substrate

Fluorescent probe based detection methods for metal ions are indispensable tools in many fields, including medical diagnostics, environmental monitoring, living cell studies, and electronics. These methods have multiple advantages over other methods, such as high sensitivity, low cost, ease of application, and versatility. Numerous fluorescent metal ion probes have been designed using many strategies, including fluorogenic metal chelators, fluorescent dye tagged oligonucleotides, catalytic signal amplification, and chemodosimetors. Fluorogenic metal chelators, which consist of a fluorogenic unit (signaling site) covalently linked to chelating moieties (receptor units) with an appropriate spacer, are a general type metal ion probe. The recognition of chelating moieties with metal ions induces a change in the photophysical properties of the fluorescent probe. This is converted into an optical signal expressed as an enhancement or quenching of the fluorophore emission. The recognition can be enhanced to utilize additive reagents that provide additional binding sites for metal ions. For example, 8-aminoquinolino-β-cyclodextrin, developed by Liu et al., exhibited cooperative binding to Zn ion with 1-adamatanoic acid. It also detected Zn ions more efficiently than without 1adamatanoic acid because 1-adamatanoic acid bound to βcyclodextrin to provide additional binding site for Zn ions. This strategy can easily expand to improve the optical properties of metal ion sensors with two metal binding sites. Di-metal complexes may include bridging substrates to complete the metal coordination sphere, and bridging substrates can modulate the properties of the resulting cascade complexes. In particular, bridging substrates provided additional metal ion binding sites and enhanced the binding properties of metal ions to metal ion ligands. Various fluorescent molecules with two metal binding sites have been synthesized as efficient probes for detecting metal ions, such as Zn and Ag. Scaffolds of di-metalic fluoregenic probes have also been devised to detect anions. Most of these molecules can be used as metal ion probes. The optical properties of these molecules can be improved by bridging substrates, which provide additional metal ion binding sites. To validate this concept, (9,10-bis[(2,2-dipicolylamino)methyl]anthracene) (1) was adapted as a Zn ion probe because [Zn2(1)] 4+ efficiently detects phosphate derivatives as potential bridging substrates to provide additional metal binding sites. In various phosphate derivatives, ATP was adapted as a bridging substrate to provide additional metal binding sites because [Zn2(1)] 4+ fluorescence is most enhanced by binding with ATP. Therefore, a combination of 1 and ATP (1/ATP) was prepared as a Zn fluorescent probe. The optical properties of 1/ATP, compared to those of 1, can be improved by providing additional binding sites for metal ions using ATP, as depicted in Scheme 1. To determine the optimal ratio of 1 and ATP, fluorescence titration of ATP was conducted using a 5 μM solution of 1 with 2 equivalents of Zn ions. The fluorescence emission spectra of [Zn2(1)] 4+ in the presence of varied ATP concentrations were evaluated. [Zn2(1)] 4+ fluorescence increased nearly proportionally to ATP concentration and was maximized at one equivalent of ATP (see Supporting information). A sensing system (1/ATP) consiting of 1 (5 μM) and ATP (5 μM) was prepared to evaluate the cooperative binding effect of the bridging substrate by providing additional binding sites for Zn ions. Fluorescence changes of 1/ATP in the presence of various concentrations of Zn were examined. The addition of Zn ions induced greatly enhanced fluorescence. The binding zinc ions within the bis-(2-picolyl)amine in 1 prevents the photo induced electron transfer process

Formation of a metal-to-nitrogen bond of normal length by a neutral sufonamide group within a tridentate ligand. A new approach to radiopharmaceutical bioconjugation.

We demonstrate that a tertiary sulfonamide group, N(SO2R)R'2, can rehybridize to form a M-N bond of normal length even when the group is in a linear tridentate ligand, such as in the new tridentate N(SO2R)dpa ligands derived from di-(2-picolyl)amine (N(H)dpa). N(SO2R)dpa ligands were used to prepare fac-[Re(CO)3(N(SO2R)dpa)](PF6 or BF4) complexes. Structural characterization of the new complexes established that the tertiary sulfonamide nitrogen atom binds to Re with concomitant sp(2)-to-sp(3) rehybridization, facilitating facial coordination. The new fac-[Re(CO)3(N(SO2R)dpa)]X structures provide the only examples for any metal with the sulfonamide as part of a noncyclic linear tridentate ligand and with a normal metal-to-nitrogen(tertiary sulfonamide) bond length. Rare previous examples of such normal M-N bonds have been found only in more constrained situations, such as with tripodal tetradentate ligands. Our long-term objectives for the new tridentate N(SO2R)dpa ligands are to develop the fundamental chemistry relevant to the eventual use of the fac-[M(I)(CO)3](+) core (M = (99m)Tc, (186/188)Re) in imaging and therapy. The sulfonamide group uniquely contributes to two of our goals: expanding ways to conjugate the fac-[M(I)(CO)3](+) core to biological molecules and also developing new symmetrical tridentate ligands that can coordinate facially to this core. Tests of our conjugation method, conducted by linking the fac-[Re(I)(CO)3](+) core to a new tetraarylporphyrin (T(N(SO2C6H4)dpa)P) as well as to a dansyl (5-(dimethylamino)naphthalene-1-sulfonyl) group, demonstrate that large molecular fragments can be tethered via a coordinated tertiary sulfonamide linkage to this core.

Metal complexes with functionalised 2,2′-dipicolylamine ligand containing an antioxidant 2,6-di-tert-butylphenol moiety: synthesis and biological studies

A series of Zn, Mn, Fe, Co, and Ni complexes ([MX2L], X = Cl, OAc) of the novel di-(2-picolyl)amine ligand L with an antioxidant 2,6-di-tert-butylphenol pendant were synthesized and characterized by elemental analysis, IR, multinuclear NMR spectroscopy, MALDI-TOF mass spectrometry and the molecular structures of [ZnCl2L] and [MnCl2L] were established by X-ray crystallography. The chemical oxidation of complexes with a 2,6-di-tert-butylphenol fragment to the phenoxyl radicals was studied by means of ESR method. The antioxidant radical scavenging activity of the complexes was measured spectrophotometrically using a DPPH-test and linoleic acid peroxidation. The electron transfer reactions were examined in CUPRAC tests and as the inhibition of an enzymatic reaction involving the generation of a reactive oxygen species (superoxide radical-anion) by xanthine oxidase. The lipoxygenase (LOX) inhibition activity of the studied compounds was evaluated. The in vitro biological experiments were performed by using rat brain homogenates. The role of the phenol fragment and metal was found to be essential in antioxidant activity.

Multifunctional BODIPY derivatives to image cancer cells and sense copper(ii) ions in living cells

Two multifunctional colorimetric and fluorescent chemosensors were synthesized by the conjugation of BODIPY (4,4-difluoro-1, 3, 5, 7-tetramethyl-4-bora-3a, 4a-diaza-s-indacene) and di(2-picolyl)amine with benzyl groups (para-substituted, L1; meta-substituted, L2) as spacers, for selectively sensing copper(II) ions in preference to a variety of other common metal ions in aqueous media. The two analogous compounds exhibit different cytotoxic behaviour and attenuate mitochondrial membrane potentials in HepG-2 cells. In vitro bioassay results demonstrate that only L2 causes the decrease of mitochondrial membrane potentials in HepG-2 cells with low toxicity. Furthermore, fluorescence imaging in vitro confirms that L2 is a low toxicity chemosensor for copper(II) ions in living cells.

Real time pharmaceutical reaction monitoring by electrospray ion mobility-mass spectrometry

Reaction monitoring is a critical step in the synthesis of new drug entities, and many pharmaceutical companies spend significant resources on equipment and new methods to perform this task. The potential of electrospray ion mobility-mass spectrometry (ESI-IMMS) as a method for monitoring pharmaceutical reactions in real time is demonstrated with a reductive amination reaction that is commonly used in the synthesis of amines for drug discovery but poses problems for detection with current analytical instrumentation. Data were collected on the timescale of 300s and reaction completion time was determined by monitoring the starting, intermediate and product materials during the reaction. The detection limits for nicotinaldehyde (starting material 1), 4-picolylamine (starting material 2), and di-(2-picolyl)amine (the product) were 0.32, 0.10 and 0.05μM, respectively, with a linear dynamic range of more than 2 orders of magnitude for each analyte. Starting materials were not separated by their mobility in a nitrogen buffer gas, but could be separated in a buffer gas of carbon dioxide. In the nitrogen buffer gas, the reduced mobility (Ko) values for the reaction starting materials (nicotinaldehyde, 4-picolylamine, 4-pyridinementhanol) were 1.86cm2/Vs and the reduced mobility value for the product (di-(2-picolyl)amine) was 1.69cm2/Vs. In carbon dioxide the Ko values for the reaction starting materials were 1.43cm2/Vs and 1.38cm2/Vs for nicotinaldehyde and 4-picolylamine, respectively. The coupling of IMS to MS enabled the discovery of a hemiacetal complex forming between nicotinaldehyde and methanol, limiting the availability of nicotinaldehyde for the reaction. Thus use of IMS in conjunction with MS provided information about the reaction mechanism that would not have been possible with MS alone. The complexation prevented the formation of the intermediate species, presumably due to the formation of the hemiacetal from SM1; however, the intermediate species could be formed when the nicotinaldehyde concentration was increased by 10-fold. While either IMS or MS alone could be used to monitor this and similar reactions, the combined ESI-IMMS approach offered more complete information about the reaction, demonstrating potential as a rapid and selective technique to aid pharmaceutical process control.

Guanine Nucleobase Adducts Formed by [Pt(di-(2-picolyl)amine)Cl]Cl: Evidence That a Tridentate Ligand with Only in-Plane Bulk Can Slow Guanine Base Rotation

Pt(II) complexes bind preferentially at N7 of G residues of DNA, causing DNA structural distortions associated with anticancer activity. Some distortions induced by difunctional cisplatin are also found for monofunctional Pt(II) complexes with carrier ligands having bulk projecting toward the guanine base. This ligand bulk can be correlated with impeded rotation about the Pt-N7(guanine) bond. Pt(N(H)dpa)(G) adducts (N(H)dpa = di-(2-picolyl)amine, G = 5'-GMP, 5'-GDP, 5'-GTP, guanosine, 9-EtG, and 5'-IMP) were used to assess whether a tridentate carrier ligand having bulk concentrated in the coordination plane can impede guanine nucleobase rotation. Because the Pt(N(H)dpa) moiety contains a mirror plane but is unsymmetrical with respect to the coordination plane, Pt(N(H)dpa)(G) adducts can form anti or syn rotamers with the guanine O6 and the central N-H of N(H)dpa on the opposite or the same side of the coordination plane, respectively. The observation of two sharp, comparably intense guanine H8 NMR signals provided evidence that these Pt(N(H)dpa)(G) adducts exist as mixtures of syn and anti rotamers, that rotational interchange is impeded by N(H)dpa, and that the key interactions involves steric repulsions between the pyridyl and guanine rings. The relative proximity of the guanine H8 to the anisotropic pyridyl rings allowed us to conclude that the syn rotamer was usually more abundant. However, the anti rotamer was more abundant for the Pt(N(H)dpa)(5'-GTP) adduct, in which a hydrogen bond between the 5'-GTP γ-phosphate group and the N(H)dpa central N-H is geometrically possible. In all previous examples of the influence of hydrogen bond formation on rotamer abundance in Pt(II) guanine adducts, these hydrogen bonding interactions occurred between ligand groups in cis positions. Thus, the role of a trans ligand group in influencing rotamer abundance, as found here, is unusual.

Metal–Bis(2‐picolyl)amine Complexes as State 1(T) Inhibitors of Activated Ras Protein

Allosteric interactions: Metal(II) cyclens inhibit Ras-effector interactions by stabilizing a weak effector-binding state of Ras, state 1(T), and binding directly in the active site. The novel state (1T) inhibitor Zn(2+)-BPA (BPA = bis(2-picolyl)amine) binds outside the nucleotide binding pocket but nevertheless allosterically stabilizes state 1(T) and thus inhibits the Ras-Raf interaction.

Role of Ligand Acidity in Chelating Adsorption and Desorption of Metal Salts

A method is proposed to establish useful operation conditions for solid separation of materials having different acidities. The effect of ligand acidity on competitive adsorption and desorption of metal salts was studied by using copper sulfate and sulfuric acid as model electrolytes. Adsorption equilibria with four commercial N-donor chelating adsorbents, WP-1 (functional group branched poly(ethyleneimine)), CuWRAM (functional group 2-(aminomethyl)pyridine), Reillex HP (functional group poly(4-vinylpyridine)), and Dowex M 4195 (functional group bis-2-(pyridylmethyl)amine) were measured using potentiometric and batch uptake methods. Moreover, formation of the complexes in the solid phase was studied with reflection UV–vis spectroscopy. Experimental data were correlated with a nonideal competitive adsorption (NICA) model, and the obtained parameters were used in mapping the operation conditions for the studied adsorbents. Acidity of the adsorbents was proved to increase in the order WP-1 < Reillex HP < CuW...

Construction of CN−-bridged molecular squares employing penta-, hexa- and octa-coordinated metal ions

Three new cyanido-bridged discrete bimetallic assemblies based on [W(CN)6(bpy)]2− building block have been synthesised and structurally characterised. Neutral molecular square {[Ni(bpy)2]2[W(CN)6(bpy)]2}·nH2O (1) (bpy=2,2′-bipyridine) has been constructed from [NiII(bpy)2(H2O)2]2+ complex. Since the attempt to obtain analogous structure with Cu(II) ion was unsuccessful, we introduced tetradentate blocking ligand tren (tren=tris(2-aminoethyl)amine) on Cu, which resulted in dinuclear molecule {[Cu(tren)][W(CN)6(bpy)]} (2). In order to create square cluster with Cu(II) ions we employed tridentate ligand di-(2-picolyl)amine (dpa), which yielded the desired structure of {[Cu(dpa)]2[W(CN)6(bpy)]2} (3). Compounds (1) and (3), the first molecular squares based on [W(CN)6(bpy)]2− building block, are paramagnetic and follow the Curie law.

Cu(II)-Promoted Methanolysis of N,N-Dipicolylacetamide. Multistep Activation by Decoupling of &gt;N̈–C═O Resonance via Cu(II)–N Binding, Delivery of the Cu(II):(−OCH3) Nucleophile, and Metal Ion Assistance of the Departure of the Leaving Group

The methanolysis of the Cu(II) complex of N-acetyl-N,N-bis(2-picolyl)amine (2) was investigated by a kinetic study as a function of pH in methanol at 25 °C and computationally by DFT calculations. The active species is the basic form of the complex (3(-)), or (1:Cu(II))((-)OCH(3))(HOCH(3))), and the rate constant for its solvolysis is k(max) = 1.5 × 10(-4) s(-1). The mechanism involves Cu(II) binding to the amide N lone pair, decoupling it from >N-C═O resonance, concomitant with Cu(II):((-)OCH(3)) delivery to the adjacent >N-C═O unit, followed by Cu(II)-assisted departure of the N,N-bis(2-picolyl)amide from a tetrahedral intermediate.

Synthesis and characterization of new trinuclear copper complexes

This report describes our approach towards modeling the copper cluster active sites of nitrous oxide reductase and the multicopper oxidases/oxygenases. We have synthesized two mesitylene-based trinucleating ligands, MesPY1 and MesPY2, which employ bis(2-picolyl)amine (PY1) and bis(2-pyridylethyl)amine (PY2) tridentate copper chelates, respectively. Addition of cuprous salts to these ligands leads to the isolation of tricopper(I) complexes [(Mes-PY1)CuI3(CH3CN)3](ClO4)3·0.25Et2O (1) and [(Mes-PY2)CuI3](PF6)3 (3). Each of the three copper centers in 1 is most likely four-coordinate, with ligated acetonitrile as the fourth ligand; by contrast, the copper centers in 3 are three-coordinate, as determined by X-ray crystallography. The synthesis of [(Mes-PY1)CuII3(CH3CN)2(CH3OH)2](ClO4)6·(CH3OH) (2) was accomplished by addition of three equivalents of the copper(II) salt, Cu(ClO4)2·6H2O, to the ligand. The structure of 2 shows that two of the copper centers are tetracoordinate (with MeCN solvent ligation), but have additional weak axial (fifth ligand) interactions with the perchlorate anions; the third copper is unique in that it is coordinated by two MeOH solvent molecules, making it overall five-coordinate. For complexes 2 and 3, one copper ion center is located on the opposite side of the mesitylene plane as the other two. These observations, although in the solid state, must be taken into account for future studies where intramolecular tricopper(I)/O2 (or other small molecules of interest) interactions in solution are desirable.

A binuclear chloride bridged copper(II) complex with a modified ligand structure and different coordination environment and mononuclear cobalt(II) complexes with a pyridylpyrazole ligand: Synthesis, structure and cytotoxic activity

One new binuclear chloride bridged copper(II) complex [L′(Cl)Cu-(μ-Cl)-Cu(pz)L′](PF6)2 (1) and two mononuclear cobalt(II) complexes [Co(Cl)L]BF4·1/2CH3OH (2) and [Co(Cl)L]PF6 (3) where L={N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)}(2-aminomethyl)pyridine, L′={N-(3,5-dimethylpyrazol-1-ylmethyl)}(2-aminomethyl)pyridine and pz=3,5-dimethyl-pyrazole have been synthesized and characterized by physico-chemical methods and single crystal X-ray diffraction studies. The crystal structure of the binuclear copper(II) complex [L′(Cl)Cu-(μ-Cl)-Cu(pz)L′](PF6)2 shows that the two square plane copper(II) moieties are joined through a single chloride (μ-Cl) bridge and the coordination environment around the two copper atoms are different, whereas the cobalt ion in [Co(Cl)L]BF4·1/2CH3OH has a trigonal bipyramidal geometry. The cytotoxic activity of the ligand, and the copper and cobalt complexes 1 and 2 were measured in vitro against the human lymphocyte HL-60 and it shows that the metal complexes have different cytotoxic activities to the organic ligand.

Immobilization of MoO2Cl2 on polystyrene via different linkers and oxidation of sulfides in the presence of hydrogen peroxide

Chloromethylated polystyrene was oxidized to aldehydic polystyrene and by reaction of this aldehydic polystyrene resin with furfuryl amine and 2-(amino methyl) pyridine, imine-bounded polystyrene resins 1a and 1b were obtained. Amine-bounded polystyrene resins 1c–1f were also prepared by direct reaction of chloromethylated polystyrene and amines. These functionalized polystyrene resins were used to immobilize MoO2Cl2 on polystyrene. These functionalized polystyrene resins were characterized with elemental analysis (CHN) and FT-IR spectrum. Polymer-supported catalysts were characterized with FT-IR and neutron activation analysis (NAA). These catalysts were used in oxidation of methyl phenyl sulfide in the presence of H2O2 as oxidant and the results showed that these catalysts were highly active and selective. The reusability of these heterogeneous catalysts was also investigated and the results showed that the supported MoO2Cl2 catalyst on polystyrene via imidazole liker was highly reusable as it was used 15 times in oxidation of methyl phenyl sulfide in the presence of environmental benign oxidant (H2O2) and solvent (H2O) without any decrease in its activity. Then the catalytic activity of these supported catalysts was investigated in oxidation of some aliphatic and aromatic sulfides. Almost all of these supported molybdenum-based catalysts were highly active and selective in the conversion of these sulfides to their corresponding sulfoxides.

Proton-transfer supramolecular salts resulting from 3,5-dinitrobenzoic acid and aminomethyl pyridine

Three hydrogen-bonding three-dimensional (3D) networks of ammonium carboxylate salts formed between 3,5-dinitrobenzoic acid and aminomethyl pyridine (2-, 3-, 4-) are described here. During solution crystallization, the hydrogen atom transfers from the carboxylic acid to the amine to yield ammonium carboxylate salts, which feature three charge-separated N+–H⋯O− hydrogen bonds to afford two types of one-dimensional (1D) hydrogen-bonding columns. Of the three structures, ((2-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (1) shows a hydrogen-bonding column which consists of alternating R12(4) and R24(8) rings whereas ((3-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (2) results in a hydrogen-bonding column which comprises repeating R34(10) rings. ((4-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (3) bears a unique shape of Chinese knot among four cations instead of the column constructed by rings. From this we can gather information about the possible position effects of functional groups on the overall packing.