Search

The title compound, C32H28F2N2O2, a highly functionalized tetrahydropyridine, was synthesized by a one-pot multi-component reaction of 4-fluoroaniline, ethyl acetoacetate and benzaldehyde at room temperature using sodium lauryl sulfate as a catalyst. The compound crystallizes with two molecules in the asymmetric unit. The tetrahydropyridine ring adopts a distorted boat conformation in both molecules and the dihedral angles between the planes of the fluoro-substituted rings are 77.1 (6) and 77.3 (6)°. The amino group and carbonyl O atom are involved in an intramolecular N--H• • •O hydrogen bond, thereby generating an S(6) ring motif. In the crystal, molecules are linked by C--H• • •F hydrogen bonds forming a three-dimensional network and C--H• • •π interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H• • •H (47.9%), C• • •H/H• • •C (30.7%) and F• • •H/ H• • •F (12.4%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311+G(2d,p) level is compared with the experimentally determined molecular structure in the solid state. The HOMO--LUMO behaviour was used to determine the energy gap and the Natural Bond Orbital (NBO) analysis was done to study donor-- acceptor interconnections. [ABSTRACT FROM AUTHOR]

The structure of a mono-amine PdII complex, [PdCl2(C7H9N)(C12H11NS)], which crystallizes in the triclinic space group, P1, is reported. The primary geometry around the PdII atom closely resembles square planar (4 0 = 0.069). In the (E)-1-(thiophen-2-yl)-N-(p-tolyl)methanimine ligand, the phenyl and thiophene rings are not coplanar, subtending a dihedral angle of 38.5 (1) because of steric effects. The PdCl2N2 coordination plane is almost perpendicular to the planes of the coordinated o-toluidine and the NC2 fragment [dihedral angles of 84.7 (1) and 72.50 (4), respectively]. The Pd--NH2 length of 2.040 (2) Å is slightly shorter than the observed mean value for other complexes involving a Pd atom attached to the nitrogen of an aniline derivative. The molecules display an interesting supramolecular synthon based on reciprocal intermolecular N-H...Cl hydrogen-bonding interactions of the p-toluidine amine fragment, which results in centrosymmetric dimeric units. These units are further linked by C--H...Cl interactions, resulting in chains in the c-axis direction where the meanplanes of the repeating fragment are oriented in the (110) plane. [ABSTRACT FROM AUTHOR]

The reaction of [Cu(CH3CN)4](BF4) with 1-methyl-1,3-imidazolidine-2-thione {SC3H4(NMe)NH}, under aerobic conditions at room temperature, yielded an unusual one-dimensional coordination polymer, namely, catena-poly[[[(1-methyl-1,3-imidazolidine-2-thione-kS)copper(I)]-μ-(1-methyl-1,3-imidazolidine-2-thione)-k2S:S-copper(I)-μ-[3,30-(sulfanediyl)bis(1-methyl-1,3-imidazolidine-2-thione)]-k5S,S0,S00:S,S00] bis(tetrafluoridoborate)], {[Cu2(C4H8N2S)2(C8H14-N4S3)](BF4)2}n or [Cu4(k5:L¹--N--S--N--L¹)2(k¹:L¹--NH)2(k²:L¹--NH)2]n-(BF4)4n 1 [L¹= SC3 H4(NMe)NH] with sulfur-bridged {CuI 4S10}n central cores. The in situ generated bis(1-methyl-1,3-imidazolidinyl-2-thione) sulfide [{SC3H4(NMe)NSN(NMe)C3H4S; abbrev. L¹--N--S--N--L¹] ligand, in combination with 1-methyl-1,3-imidazolidine-2-thione (L¹--NH) ligands, construct this coordination polymer. Each CuI ion is bonded to four sulfur donor atoms in a distorted tetrahedral geometry and the formation of this polymer solely by sulfur donor atoms with {CuI 4S10}n central cores, is the first such example in copper-heterocyclic-2-thione chemistry. [ABSTRACT FROM AUTHOR]

The goal of this study was to identify new compounds from a methanol extract of a polyherbal combination of Aristolochia indica L. and Piper nigrum L. (MECAIPN), two traditional medicinal plants used to cure envenomation, as well as to assess their antioxidant and antivenom properties. MECAIPN yielded EA1 (an essential oil), AA2 (4-(2-oxo-propyl)-cyclopentane-1,3-dione), and W3 ((2,5-dioxo-imidazolidin-4-yl)-urea) (Allantoin). Although EA1 had stronger radical scavenging activity, AA2 had higher DPPH and ferric ion radical scavenging activity, and W3 had higher molybdenum ion radical scavenging activity due to being a single molecule, the binding investigation revealed that EA1 has a greater Stern–Volmer quenching constant (Ksv) than AA2 and W3. Synchronous measurements indicated that EA1, AA2, and W3 bind to tryptophan and tyrosine residues in venom, causing denaturation of the secondary structure of the residue. Finally, the current study concludes that EA1 has more therapeutic antivenom potential, which could be related to the synergism of chemicals found in it. When it came to single compounds, AA2 had stronger antioxidant and antivenom capabilities than W3. To understand the mechanism of action and manufacture the green antivenom medication, more testing of the EA1 and compounds remains required. [ABSTRACT FROM AUTHOR]

[Display omitted] • The reaction of an imidazolidinylpyridine with Ni(II), Cu(II), Cd(II) and Zn(II) in the presence of protic and aprotic solvents were explored. • The imidazolidinylpyridine bound to Cu(II) and Ni(II) intact when the reaction was performed in acetonitrile but bound as ring opened hemiaminal ether when the reaction was in methanol. • The Cd(II) and Zn(II) ion stabilised the imidazolidinylpyridine as a face-capping tridentate ligand regardless of the nature of the solvent. • The ligand and complexes were characterised using NMR, ESI-MS and SCXRD techniques, appropriately. • The interesting structural features observed in the solid-state structure are intriguing. The coordination chemistry of the imidazolidinylpyridine ligand with Ni(II), Cu(II), Cd(II), and Zn(II) ions was investigated in both protic and aprotic solvents. Interestingly, the coordination environment around the metal center varied significantly depending upon the nature of metal ion and solvent used for synthesis. In acetonitrile the imidazolidinylpyridine bound to Cu(II) and Ni(II) remains intact, while in methanol it formed ring-opened hemiaminal ether. The Cd(II) and Zn(II) ion stabilized the imidazolidinylpyridine as a face-capping tridentate ligand regardless of the nature of the solvent. The imidazolidinylpyridine and the complexes formed were characterized by NMR spectroscopy, high resolution electrospray ionization mass spectrometry and single-crystal X-ray crystallography, appropriately. The structural features in the solid-state structures were particularly intriguing, shedding light on the complex interplay between the ligand, metal ions, and solvent environments in coordination chemistry. [ABSTRACT FROM AUTHOR]

In the structures of 1:1 and 1:2 adducts of phosphanetricarbo­nitrile (C3N3P) with 1,4-di­aza­bicyclo­[2.2.2]octane (C6H12N2), the 1:1 adduct crystallizes in the ortho­rhom­bic space group, Pbcm, with four formula units in the unit cell (Z′ = 0.5). The P(CN)3 unit lies on a crystallographic mirror plane while the C6H12N2 unit lies on a crystallographic twofold axis passing through one of the C—C bonds. The P(CN)3 moiety has close to C3v symmetry and is stabilized by forming adducts with two symmetry-related C6H12N2 units. The phospho­rus atom is in a five-coordinate environment. As a result of the symmetry, the two trans angles are equal so τ5 = 0.00 and thus the geometrical description could be considered to be square pyramidal. However, the electronic geometry is distorted octa­hedral with the lone pair on the phospho­rous occupying the sixth position. As would be expected from VSEPR considerations, the repulsion of the lone-pair electrons with the equatorial bonding electrons means that the trans angles for the latter are considerably reduced from 180° to 162.01 (4)°, so the best description of the overall geometry for phospho­rus is distorted square pyramidal. The 1:2 adduct crystallizes in the monoclinic space group, P21/m with two formula units in the asymmetric unit (i.e. Z' = 1/2). The P(CN)3 moiety lies on a mirror plane and one of the two C6H12N2 (dabco) mol­ecules also lies on a mirror plane. The symmetry of the P(CN)3 unit is close to C3v. There are three P···N inter­actions and consequently the mol­ecular geometry of the phospho­rus atom is distorted octa­hedral. This must mean that the lone pair of electrons on the phospho­rus atom is not sterically active. For the 1:1 adduct, there are weak associations between the phospho­rus atom and one of the terminal nitro­gen atoms from the C≡N moiety, forming chains in the a-axis direction. In addition there are weak C—H···N inter­actions between a terminal nitro­gen atoms from the C≡N moiety and the C6H12N2 mol­ecules, which form sheets perpendicular to the a axis. [ABSTRACT FROM AUTHOR]

In the title compound, [Al2Br4(CH2)(C4H10O)2], the mol­ecule lies on a crystallographic twofold axis passing through the bridging C atom. Each AlIII atom is four-coordinate, being bonded to two bromide ions, bridging the CH2 group as well as the oxygen atom of a diethyl ether ligand in a slightly distorted tetra­hedral arrangement with angles ranging from 101.52 (8) to 116.44 (5)°. The Al—CH2—Al angle, 118.4 (2)°, is the smallest observed for a structure where this moiety is not part of a ring. In the crystal, weak C—H⋯Br inter­actions, characterized as R²2(12) rings, link the mol­ecules into ribbons in the [101] direction. The title compound is monomeric and coordinatively saturated in the solid state, as each aluminum is four-coordinate, but in solution the ether mol­ecules from either or both Al atoms can dissociate, and would be expected to rapidly exchange, and this is supported by NMR data. [ABSTRACT FROM AUTHOR]

The title compound, C5D6ClN2O+⋅Cl-, crystallizes in the ortho-rhombic space group, Pbcm, and consists of a 4-chloro-2-methyl-6-oxo-3,6-dihydropyrimidin-1-ium cation and a chloride anion where both moieties lie on a crystallographic mirror. The cation is disordered and was refined as two equivalent forms with occupancies of 0.750 (4)/0.250 (4), while the chloride anion is triply disordered with occupancies of 0.774 (12), 0.12 (2), and 0.11 (2). Unusually, the bond angles around the C=O unit range from 127.2 (6) to 115.2 (3)° and similar angles have been found in other structures containing a 6-oxo-3,6-dihydropyrimidin-1-ium cation, including the monclinic polymorph of the title compound, which crystallizes in the monoclinic space group P21/c [Kawai et al. (1973 ). Cryst. Struct. Comm. 2, 663-666]. The cations and anions pack into sheets in the ab plane linked by N--H⋯Cl hydrogen bonds as well as C--H⋯O and Cl⋯O interactions. In graph-set notation, these form R3³(11) and R3²(9) rings. Theoretical calculations seem to indicate that the reason for the unusual angles at the sp² C is the electrostatic interaction between the oxygen atom and the adjacent N--H hydrogen. [ABSTRACT FROM AUTHOR]

The first title benzoyl amide, C17H20CINO5 (3a), crystallizes in the monoclinic space group P21/c with Z = 4 and the second, C19H24CINO5 (3b), also crystallizes in P21/c with Z = 8 (Z' = 2), thus there are two independent molecules in the asymmetric unit. In 3a, the phenyl ring makes a dihedral angle of 50.8 (3)° with the amide moiety with the C O group on the same side of the molecule as the C--Cl group. One methoxy group is almost in the plane of the benzene ring, while the ethoxy and other methoxy substituent are arranged on opposite sides of the ring with the ethoxy group occupying the same side of the ring as the C=O group in the amide moiety. For one of the two molecules in 3b, both the amide and 5,5-dimethyl-3-oxocyclohex-1-en-1-yl moieties are disordered over two sets of sites with occupancies of 0.551 (2)/0.449 (2) with the major difference between the two conformers being due to the conformation adopted by the cyclohex-2-en-1-one ring. The three molecules in 3b (i.e., the undisordered molecule and the two disorder components) differ in the arrangement of the subsituents on the phenyl ring and the conformation adopted by their 5,5-dimethyl-3-oxocyclohex-1-en-1-yl moieties. In the crystal of 3a, N--H…O hydrogen bonds link the molecules into a zigzag chain propagating in the [001] direction. For 3b a combination of C--H…O and N--H…O intermolecular interactions link the molecules into a zigzag ribbon propagating in the [001] direction. [ABSTRACT FROM AUTHOR]

The title compound, catena-poly[[tetra­kis­(1-methyl­pyrrolidin-2-one-κO)calcium(II)]-μ-(E)-1,1′-dimethyl-2,2′-dioxo-1,1′,2,2′-tetra­hydro-[3,3′-bipyrrolyl­idene]-5,5′-bis­(thiol­ato)-κ²O:O′], [Ca(C10H8N2O2S2)(C5H9NO)4]n, 1, crystallizes in the triclinic space group P. The crystal studied was twinned by non-merohedry via two different twofold operations, about the normals to (001) and (10), giving four twin domains with refined occupancies of 0.412 (4), 0.366 (4), 0.055 (1), 0.167 (4). The Ca atoms are located on centers of inversion. Each Ca is surrounded by four 1-methyl­pyrrolidin-2-one (NMP) ligands and coordinated through one of the two O atoms to two (E)-1,1′-dimethyl-2,2′-dioxo-1,1′,2,2′-tetra­hydro-[3,3′-bipyrrolyl­idene]-5,5′-bis­(thiol­ate), [C10H8N2O2S2]2−, dianions (abbreviation: DMTBT). This dianion thus facilitates the formation of a 1-D polymer, which propagates in the [011] direction. These ribbons are linked by inter­molecular C—HS inter­actions. Each Ca atom is in an octa­hedral CaO6 six-coordinate environment with Ca—O bond lengths ranging from 2.308 (6) to 2.341 (6) Å, cis bond angles ranging from 88.2 (2) to 91.8 (2)° and the trans angles all 180° due to the Ca atoms being located on centers of inversion. Theoretical calculations were carried out using density functional theory (DFT) and the results showed that although the central DMTBT dianion is planar there is likely some resonance across the central bond between both aza­pentyl rings, but this is not sufficient to establish a ring current. The calculated UV–vis spectrum shows a peak at 625 nm, which accounts for the deep blue–purple color of solutions of the complex. [ABSTRACT FROM AUTHOR]

This manuscript describes the syntheses, structures and magnetism of MnIII–CaII/SrII complexes which are compositionally relevant in the context of the oxygen evolving complex (OEC) of photosystem II (PS II). A series of trimetallic tetraoxo complexes containing redox-inactive metal ions CaII or SrII were synthesized using a tetranucleating ligand framework. The structural characteristics of these complexes, with the oxido ligands bridging the redox-inactive metals and the manganese centres, make them particularly relevant to biological and heterogeneous metal-oxido clusters. Electrochemical studies of these compounds show that the reduction potentials are highly dependent upon the Lewis acidity of the redox-inactive metal, identifying the chemical basis for the observed differences in electrochemistry. This correlation provides insights into the role of the CaII/SrII ion in modulating the redox potential of the OEC and of other redox-inactive ions in tuning the redox potentials of other metal-oxide electrocatalysts. Temperature dependent magnetic measurements have also been performed for the complexes. [ABSTRACT FROM AUTHOR]

Three new compounds, namely, 5‐fluorocytosine–urea (2/1), 2C4H4FN3O·CH4N2O, (I), 5‐fluorocytosine–5‐fluorocytosinium 3,5‐dinitrosalicylate–water (2/1/1), 2C4H4FN3O·C4H5FN3O+·C7H2N2O7−·H2O, (II), and 2‐amino‐4‐chloro‐6‐methylpyrimidine–6‐chloronicotinic acid (1/1), C6H4ClNO2·C5H6ClN3, (III), have been synthesized and characterized by single‐crystal X‐ray diffraction. In compound (I), 5‐fluorocytosine (5FC) molecules A and B form two different homosynthons [R22(8) ring motif], one formed via N—H...O hydrogen bonds and the second via N—H...N hydrogen bonds. In addition to this interaction, a sequence of fused‐ring motifs [R21(6), R33(8), R22(8), R43(10) and R22(8)] are formed, generating a supramolecular ladder‐like hydrogen‐bonded pattern. In compound (II), 5FC and 5‐fluorocytosinium are linked by triple hydrogen bonds, generating two fused‐ring motifs [R22(8)]. The neutral 5FC and protonated 5‐fluorocytosinum cation form a dimeric synthon [R22(8) ring motif] via N—H...O and N—H...N hydrogen bonds. On either side of the dimeric synthon, the neutral 5FC, 5‐fluorocytosinium cation, 3,5‐dinitrosalicylate anion and water molecule are hydrogen bonded through N—H...O, N—H...N, N—H...OW and OW—HW...O hydrogen bonds, forming a large ring motif [R1010(56)], leading to a three‐dimensional supramolecular network. In compound (III), 2‐amino‐4‐chloro‐6‐methylpyrimidine (ACP) interacts with the carboxylic acid group of 6‐chloronicotinic acid via N—H...O and O—H...O hydrogen bonds, generating an R22(8) primary ring motif. Furthermore, the ACP molecules form a base pair via N—H...N hydrogen bonds. The primary motif and base pair combine to form tetrameric units, which are further connected by Cl...Cl interactions. In addition to this hydrogen‐bonding interaction, compounds (I) and (III) are further enriched by π–π stacking interactions. [ABSTRACT FROM AUTHOR]

The structures of the 18‐membered diselenide‐linked macrocycle 10,27‐di‐tert‐butyl 11,28‐dioxo‐2,3,19,20‐tetraselena‐10,12,27,29‐tetraazapentacyclo[28.4.0.04,9.013,18.021,26]tetratriaconta‐1(30),4(9),5,7,13,15,17,21,23,25,31,33‐dodecaene‐10,27‐dicarboxylate, C36H34N4O6Se4, and its precursor di‐tert‐butyl 2,2′‐[diselane‐1,2‐diylbis(2,1‐phenylene)]dicarbamate, C22H28N2O4Se2, are reported. The precusor to the macrocycle contains two tert‐butyl phenylcarbamate arms connected to a diselenide group, with Se—C and Se—Se bond lengths of 1.914 (4) and 2.3408 (6) Å, respectively. The macrocycle resides on a crystallographic center of inversion in space group P with one molecule in the unit cell (Z′ =). It contains an 18‐membered macrocyclic ring with two diselenide linkages. In this macrocycle, there are two free and two protected amino groups. The structures of an 18‐membered azamacrocycle containing two disselenide linkages and its precusor are reported. [ABSTRACT FROM AUTHOR]

A straightforward synthetic route has been adopted to synthesize highly nonplanar electron deficient perchlorometallo-porphyrins. Herein, we report the synthesis and characterization of MTPP(NO2)Cl7 where M = CoII, NiII, CuII and ZnII. Further, we examined their optical and electrochemical redox properties and the results are compared with MTPPCl8. MTPP(NO2)Cl7 exhibited red-shifted (∼10–15 nm) absorption spectra relative to MTPPCl8 due to the strong electron withdrawing nature of the nitro group. Mixed β-substitution alters the electrochemical redox properties to such an extent that an appreciable increase in the anodic shift in reduction potential (200–300 mV) is observed for MTPP(NO2)Cl7 relative to MTPPCl8 whereas only a minimal shift (15–50 mV) in the oxidation potential is observed. Nonplanarity of the macrocyclic core was investigated by single crystal X-ray analysis and DFT calculations. A higher ΔCβ (0.706 Å) for 1d as compared to 2d (0.642 Å) undoubtedly signifies nonplanarity induced by the nitro group. To substantiate the effect of mixed substitution, we performed axial ligation studies of Zn(ii) complexes with nitrogenous bases and basic anions and found higher log β2 values as well as a linear relation between log β2 and pKa as compared to perbromoporphyrins. Highly electron deficient β-substituted Co(ii) porphyrins (1a and 2a) were utilized as novel sensors for selective rapid visual detection of CN− ions. [ABSTRACT FROM AUTHOR]

An asymmetrical Schiff base ligand, 4-bromo-2-(2-pyridylmethy liminomethyl)phenol (HL), and its copper(II) complex, [Cu(L)SCN] (1), have been synthesized. Complex 1 is experimentally characterized by elemental analysis, FT-IR and UV-vis spectroscopic techniques, and cyclic voltammetry. The structure of the complex has been established by single-crystal X-ray diffraction studies, which reveal a square planar geometry of the central copper(II) ion in 1. The neighboring molecules of the complex connect each other by Π-Π stacking interactions with centroid-to-centroid ring distance 3.653 A. The ligand can display two possible tautomeric forms; therefore, 1 can have an alternate molecular structure. DFT calculations have been employed to investigate the structure and relative stabilities of the suggested tautomeric forms of the ligand and its corresponding copper(II) complex. [ABSTRACT FROM AUTHOR]

An asymmetrical Schiff base ligand, 4-bromo-2-(2-pyridylmethyliminomethyl)phenol (HL), and its copper(II) complex, [Cu(L)SCN] (1), have been synthesized. Complex1is experimentally characterized by elemental analysis, FT-IR and UV–vis spectroscopic techniques, and cyclic voltammetry. The structure of the complex has been established by single-crystal X-ray diffraction studies, which reveal a square planar geometry of the central copper(II) ion in1. The neighboring molecules of the complex connect each other by π–π stacking interactions with centroid-to-centroid ring distance 3.653 Å. The ligand can display two possible tautomeric forms; therefore,1can have an alternate molecular structure. DFT calculations have been employed to investigate the structure and relative stabilities of the suggested tautomeric forms of the ligand and its corresponding copper(II) complex. [ABSTRACT FROM PUBLISHER]

Three distorted square antiprismatic eight coordinated neodymium acylpyrazolone complexes were synthesized having the compositions [Nd(L1)3(H2O)(EtOH)] (NdL1), [Nd(L2)3(H2O)(EtOH)] (NdL2), and [Nd(L3)3(H2O)(EtOH)] (NdL3). The structure of all three complexes was examined using ESI‐mass, FT‐IR, and thermogravimetric methods. According to the single crystal analysis of NdL1, the complex was found eight‐coordinated (NdO8) with a distorted square antiprismatic geometry. A powder XRD pattern confirmed a similar structural arrangement of the other two complexes. In electronic absorption spectra, the transition 4G5/2←4I9/2, which is close to the centre of the visible spectrum (~17,500 cm−1), exhibits hypersensitivity, which stands out in stark contrast to the behaviour of many other typically weak and reliably unchanging, typical 4f–4f transitions. Through a comparative analysis of calculated oscillator strength, Judd‐Ofelt parameters, root mean square deviation, radiative lifetime and covalency parameters in various solvents, hypersensitivity, symmetry characteristics, and covalency have been thoroughly investigated. The promotion of 4f–4f electric‐dipole intensity has been found to be particularly successful with ethanol, pyridine, DMF, and DMSO. Utilizing Judd‐Ofelt Ω4 values and Hirshfeld analysis, long‐range secondary π⋅⋅⋅π stacking or H‐bonding interactions were investigated. The intensity of emission spectra, quantum yield, stokes shift, and antenna effect energy diagram was examined using solid‐state emission spectra. [ABSTRACT FROM AUTHOR]

The Mn11 ion in the structure of the mononuclear title compound, [Mn(C4H3N2O2)2(H2O)4], is situated on an inversion center and is coordinated by two O atoms from two deprotonated 4,6-dihydroxypyrimidine ligands and by four O atoms from water molecules giving rise to a slightly distorted octahedral coordination sphere. The complex includes an intramolecular hydrogen bond between an aqua ligand and the non-protonated N ring atom. The extended structure is stabilized by intermolecular hydrogen bonds between aqua ligands, by hydrogen bonds between N and O atoms of the ligands of adjacent molecules, and by hydrogen bonds between aqua ligands and the non-coordinating O atom of an adjacent molecule. [ABSTRACT FROM AUTHOR]

Photoactive metal complexes have emerged as potential candidates in the photodynamic therapy (PDT) of cancer. We present here the synthesis, characterization and visible light-triggered anticancer activity of two novel mixed-ligand oxo-bridged iron(III) complexes, viz., [{Fe(L)(acac)} 2 (μ-O)](ClO 4 ) 2 ( 1 ) and [{Fe(L)(cur)} 2 (μ-O)](ClO 4 ) 2 ( 2 ) where L is bis-(2-pyridylmethyl)-benzylamine, acac is acetylacetonate and cur is the monoanion of curcumin (bis(4-hydroxy-3-methoxyphenyl)-1,6-diene-3,5-dione). The crystal structure of complex 1 (as PF 6 − salt, 1a ) shows distorted octahedral geometry of each iron(III) centre formed by the FeN 3 O 3 core. The 1:2 electrolytic complexes are stable in solution and retain their oxo-bridged identity in aqueous medium. Complex 2 has a strong absorption band in the visible region and shows promising photocytotoxicity in HeLa and MCF-7 cancer cells in visible light giving respective IC 50 values of 3.1 ± 0.4 μM and 4.9 ± 0.5 μM while remains non-toxic in the dark (IC 50 > 50 μM). The control complex 1 is inactive both in the light and dark. Complex 2 accumulates in cytoplasm of HeLa and MCF-7 cells as evidenced from fluorescence microscopy and triggers apoptotic cell death via light-assisted generation of reactive oxygen species (ROS). Taken together, complex 2 with its promising photocytotoxicity but negligible dark toxicity in cancer cells has significant photochemotherapeutic potential for applications in PDT. [ABSTRACT FROM AUTHOR]

Thiosemicarbazones of 2-formylpyridine, 2-aceylpyridine and 2-benzoylpyridine, abbreviated in general as HL-R (where H depicts the acidic hydrogen and R the fragment (R = H, Me and Ph) linked to the imine-carbon) react with [Pd(PPh 3 ) 2 Cl 2 ] in refluxing ethanol in the presence of triethylamine to afford complexes of the type [Pd(L-R)(PPh 3 )]Cl ( 1 , R = H; 2 , R = Me, 3 , R = Ph). Structures of the complexes 1 and 3 have been determined by X-ray crystallography, and the structure of complex 2 has been optimized by DFT. In all three the thiosemicarbazone ligand binds to the metal center as a monoanionic tridentate NNS-donor forming two adjacent five-membered chelate rings, the triphenylphosphine occupies the fourth coordination site on palladium. Complexes 1 – 3 display intense absorptions in the visible and ultraviolet regions, which have been analyzed by TDDFT calculations. All the complexes are found to efficiently catalyze Suzuki, Heck and Sonogashira type C–C cross-coupling, and C–N coupling reactions of aryl halides with primary and secondary amines. All the catalytic reactions are found to proceed under ligand-free condition. [ABSTRACT FROM AUTHOR]

The binding of 3d transition metals to maleic hydrazide (3,6-dihydroxypyridazine) has been investigated. Cobalt(II), copper(II), manganese(II) and nickel(II) complexes of maleic hydrazide have been prepared, crystallized and studied by various spectroscopic techniques. X-ray crystallographic structures of ML 2 · n H 2 O complexes with all four metal ions have been obtained. In all of the complexes two maleic hydrazides bind as unidentate ligands. Water molecules occupy the remaining coordination sites. In the cobalt(II) and nickel(II) complexes, which are isomorphous, the ligand binds through a single ligand nitrogen atom whereas in the manganese(II) and copper(II) complexes the ligand binds through a ligand oxygen atom. The metal ions all have six coordinate octahedral geometries except the copper(II) complex which has a five-coordinate square pyramidal geometry. [ABSTRACT FROM AUTHOR]

Abstract: The compound 4-methyl-2,6-bis[(2-(pyridin-2-yl)hydrazinylidene)methyl]phenol (H-PHMP) was prepared by the direct condensation of 2,6-diformyl-4-methylphenol (PCDA) and 2-hydrazinopyridine. It reacts with copper(II) nitrate to yield a self-assembled, both alkoxo- and hydroxo-bridged, tetranuclear homoleptic copper(II) complex, [Cu4(PHMP)2(μ3-OH)2(NO3)2](NO3)2·9H2O (1), with a [Cu4(μ-O)2(μ3-OH)2]4+ half-open cubane core. Compound 1 is composed of two dinuclear [Cu2(PHMP)] units linked by the two μ-bridging alkoxide oxygen atoms of the PCDA backbone. Variable temperature magnetic susceptibility measurements indicate the existence of antiferromagnetic exchange interactions (J 1 =−304.0cm−1, J 2 =−127.3cm−1 and g =2.05) in complex 1. The exchange pathway parameters were also evaluated from density functional theoretical calculations and fully agree with the experimental findings. [Copyright &y& Elsevier]

Abstract: DNA binding, cleavage and cytotoxicity characteristics of a novel Schiff base ligand 3-(benzothiazol-2-yliminomethyl)-naphthalen-2-ol and ruthenium(II) complexes have been investigated. The DNA interaction properties of the complexes have been investigated using absorption spectra, as well as gel electrophoresis studies. Intrinsic binding constant (K b) has been estimated under similar set of experimental conditions. Absorption spectral study indicate that the ligand and ruthenium(II) complexes has intrinsic binding constant in the range of 1.4–7.2×104 M−1. Ruthenium(II) complexes show more binding ability than the ligand. Further, in vitro cytotoxicity study of the ligand and the complexes exhibited antitumor activity against HeLa and HEp2 tumor cells. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of three hexa-coordinated ruthenium(II) Schiff base complexes of the type [RuCl(CO)(B)L] (B=PPh3/AsPh3/py and L=monobasic tridentate Schiff base ligand derived by the condensation of salicylaldehyde with 4-aminoantipyrine) are reported. IR, electronic, NMR and mass spectral data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all the complexes. DNA binding properties of the ligand and its ruthenium(II) complexes have been investigated by electronic absorption spectroscopy. Two of the complexes were tested for DNA cleavage property. Finally, in vitro study of the cytotoxicity of the ligand and the complex [RuCl(CO)(PPh3)L] on HeLa were tested. The IC50 value for the ligand and the complex were 52.3 and 31.6μm respectively. [Copyright &y& Elsevier]

Elemental Te inserts across the C–I bond of in situ generated iodo derivatives of 1,3-dibromopropane, (trimethylsilyl)methyl iodide, benzyl chloride and m-nitro-benzyl bromide to give rise the , (Me3SiCH2)2TeI2, (C6H5CH2)2TeI2, and (m-NO2-C6H4CH2)2TeI2 molecules in good yield respectively. These molecules are characterised by 1H NMR and elemental analysis techniques. Among these (C6H5CH2)2TeI2 and (m-NO2-C6H4CH2)2TeI2 molecules are also characterized by single-crystal X-ray studies. In the packing diagram of (C6H5CH2)2TeI2, there are intermolecular Te⋯π-phenyl interaction (3.768 Å) between the tellurium atoms and phenyl rings of adjacent molecule. The crystal packing of (m-NO2–C6H4CH2)2TeI2, displays an interesting supramolecular synthon. This synthon is based on reciprocal several C–H⋯O, C–H⋯I Hydrogen bonding interactions along with Te⋯I Secondary bonding interactions. [ABSTRACT FROM AUTHOR]

The metathesis reaction of aryltellurium chloride, ppyTeCl [ppy=2‐(2'‐pyridyl)phenyl] (5) with AgClO4 afforded Intramolecular Chalcogen Bonding (IChB)‐stabilized organotellurenyl cation [ppyTe] ⋅ ClO4 ([6] ⋅ ClO4). The reaction of [6] ⋅ ClO4 with K2PtCl4 in acetic acid resulted in the formation of platinum(II)‐based carboxylate‐bridged heterobimetallic complex [Pt(ppyTe)(μ‐OOCMe)Cl2], 7 containing an organotellurenyl cation as ligand. This is the first time a Pt(II) complex of an organotellurenyl cation donor‐acceptor ligand has been reported. Complex 7 was characterized by multi‐nuclear NMR spectroscopy (1H, 13C, and 125Te), FT‐IR spectroscopy, CHN analysis, and single‐crystal X‐ray diffraction studies. The single‐crystal X‐ray diffraction studies and DFT analysis infer that the Te center in 7 behaves as an ambiphilic ligand, accepting electrons from the N‐atom of the ppy moiety and the O‐atom of the carboxylate groups while simultaneously donating electrons to the Pt(II) center. The 2D‐fingerprint plots derived from the Hirshfeld surface analysis reveal multiple intermolecular interactions in the packing diagrams of complex 7. The natural charges accumulated on the atoms in complex 7 were calculated by Natural Population Analysis (NPA). In addition, the HOMO‐LUMO energy gap in 7 was calculated. [ABSTRACT FROM AUTHOR]

Highly stable, environmentally benign ZnTiO3 nanopowder has been prepared via a sustainable sol–gel method. The nanopowder (90 nm) has been thoroughly characterized by SEM, XRD, EDS, Laser Raman, photoluminescence, UV and IR. The activity of the catalyst was probed through one-pot four-component reaction of aldehydes, ketones and two equivalent propanedinitriles in water without requiring any additives or anhydrous conditions. The reaction requires two different catalytic functions, i.e., an acidic one which is given by Ti(iv) ions and a basic one, given by the oxide ion incorporated within the ZnTiO3 metal oxide framework. The advantages of this method lie in its simplicity, cost effectiveness, environmental friendliness, and easier scaling up for large scale synthesis without using high pressure, temperature and toxic chemicals. As water was used as a reaction medium and since we are particularly interested in the isolation of a non-aromatic intermediate, the elimination of poisonous HCN was prevented by the Lewis acid character of Ti4+ up to a sufficiently high temperature. Thus, this process can be considered as a “green” process. Elimination of HCN at higher temperatures still maintains “green” attributes as HCN can be trapped by the basic catalyst under such conditions. Spontaneous generation of low molecular mass self-aggregated organic materials, their one-dimensional packing, and interesting photophysical properties are reported. [ABSTRACT FROM AUTHOR]

Abstract: The air-stable di-copper(I) complexes Cu2L(SCN)2 (1) and Cu2L(SCN)1.86I0.14 (2) of the N4 macrocyclic Schiff base ligand L have been synthesized and characterized by IR, elemental analysis, UV–Vis and crystal structure determination. X-ray analysis of the complexes shows an approximate distorted trigonal planar geometry around each copper(I) ion that is constructed from one N-bonded thiocyanate (or iodide in 2) group and two imine nitrogen atoms. DFT calculations were used to determine the structural features of the Cu2L(SCN)2 complex, and these were consistent with the experimental data for the complex. [Copyright &y& Elsevier]

Abstract: A new two-dimensional (2D) thiocyanato-bridged cobalt(II) network formulated as [LCo2(NCS)2] n (1), has been synthesized with the Schiff base ligand N,N′-bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H2L) and thiocyanate anions. This novel layered compound has been completely characterized by elemental analysis, FT-IR, UV–Vis spectroscopy and the structure has been established by single crystal X-ray diffraction studies. The structure of 1 consists of a doubly phenoxo-bridged dimer comprising two different cobalt(II) centers with different coordination geometries (octahedral and tetrahedral). The 2D network is accomplished by bridging thiocyanate ligands, connecting the dimeric motifs in an end-to-end fashion. Variable-temperature magnetic susceptibility and EPR measurements reveal predominant antiferromagnetic exchange interaction in the complex. [ABSTRACT FROM AUTHOR]

Abstract: Utilizing a new 20-membered macrocyclic Schiff base ligand with two coordination sites formed from the [2+2] condensation of 1,3-diaminopropane and benzene-1,3-dicarboxaldehyde in the presence of CuX (X=Cl−, Br−, I−) salts, air-stable dicopper(I) complexes were synthesized in acetonitrile, intramolecularly linked via two halide groups, and characterized by different physico-chemical techniques. The single crystal X-ray diffraction technique indicates these complexes consist of two N2X2 donor sets that have distorted tetrahedral coordination environments around the copper(I) ions. In these halogen-bridged binuclear Cu2LX2 systems the Cu⋯Cu separation can be controlled, as this distance is reduced on increasing the halide size and hence the X⋯X repulsion, with the rigidity of the macrocycle playing a significant role. [ABSTRACT FROM AUTHOR]

Abstract: The molecular structures of three new Schiff base compounds of the form R – hydrazinyl-8-(trifluoromethyl)-quinoline, and the fourth, a structurally related hydrate, have been examined by X-ray crystallography, B3LYP/6-3 G (d) and Hirshfeld surface and fingerprint calculations. Compound (I), C18H14F3N3, crystallizes in the tetragonal, I 41 /a space group (z =32) while compounds (II) – C18H13BrF3N3; P 21 /c, (III) – C18H14F3N3O·H2O; P 21 /c, and (IV) – C22H16F3N3; P 21/n, are monoclinic (z =4). In (I) there are two independent molecules in the asymmetric unit. In compounds (I), (II) and (IV) R=ethylidene 1-phenyl, ethylidene 3-bromophenyl and ethylidene naphthalen-2-yl while (III) consists of a 4-[(1E)-1-{2-[8-(trifluoromethyl)quinolin-4-yl]-hydrazinylidene}ethyl]-phenol hydrate. In all four compounds the trifluoromethyl group lies in the plane of the quinoline ring and the methyl group is in the plane of the hydrazine moiety. The mean plane of the quinoline ring is planar with hydrazine moiety in (II) and (IV) and twisted slightly in (I) and (III). In all four compounds weak π-stacking interactions are observed between ring centroids of the various naphthalene(benzene) and quinoline (benzene and pyridine) rings which contribute to the crystal packing. A comparison of the angles between mean planes of the benzene and quinoline rings in the crystal and with the DFT theoretical calculation as well as inclusion of strong and weak intermolecular hydrogen-bond interactions has been included for each molecule. Hirshfeld surface analysis for visually analyzing intermolecular interactions in crystal structures employing 3D molecular surface contours and 2D fingerprint plots have been used to examine molecular shapes. [Copyright &y& Elsevier]

Abstract: Two different sets of Schiff base ligands, set-1 (HL1 , HL2 ) and set-2 (H2L3 , H2L4 ) which have been prepared by mixing 1,3-diaminopropane and aldehydes (3-methoxy-2-hydroxybenzaldehyde or 3-ethoxy-2-hydroxybenzaldehyde) in 1:1 and 1:2 ratios, respectively, are employed for the synthesis of complexes with cobalt perchlorate. The octahedral cobalt(III) complexes of general formula [Co(L)2]ClO4 (L= L1 for complex 1, L2 for complex 1a) are obtained from the mono-condensed ligands, whereas the di-condensed ligand H2L4 results in the formation of a unique type of mixed-ligand complex [Co(L2)(L4)]ClO4 (2) where the respective di- and mono-condensed Schiff bases simultaneously coordinate to the metal center. The complexes are completely characterized by elemental analyses, IR, UV–vis spectroscopy and cyclic voltammetric studies. The structures of 1 and 2 are unequivocally established by single crystal X-ray diffraction analysis. The behavior of the Schiff base ligands during the reactions is directed by the template effect of CoIII ion modulated by the perchlorate anion present in the medium. [Copyright &y& Elsevier]

Abstract: Bis(4,4,6-trimethyl-1,3,2-dioxaphosphorinane-2-thione-2-thiolato)cobalt(II) complexes with nitrogen and phosphorus containing Lewis bases of the type, [Co(S2▪)*L n ] (where L=pyridine, n =2; L=2-picoline, 3-picoline, triphenylphosphine, 2,2′-bipyridine, 1,10-phenanthroline; n =1) were prepared by the addition of the Lewis base to an aqueous solution of CoCl2 ·6H2O followed by the addition of NH4S2▪ to yield a greenish-blue solution from which the adduct was extracted by addition of benzene These newly synthesized compounds were characterized by elemental analysis, IR and UV–Vis spectroscopy and magnetic measurements. The results for adducts with pyridine, 2,2′-bipyridine, 1,10-phenanthroline are consistent with distorted octahedral geometry around the central metal atom whereas those with 2-picoline, 3-picoline and triphenylphosphine are consistent with distorted trigonal bipyramidal geometry, as is confirmed by the single crystal X-ray crystal structures of [Co(S2▪)2(2-CH3-NC5H4)] and [Co(S2▪)2(3-CH3-NC5H4)]. [Copyright &y& Elsevier]

Abstract: Reaction of 1,3-diaryltriazenes (R–C6H4–N(NH)–C6H4–R, R=OCH3, CH3, H, Cl, NO2 at the para position) with [Rh(PPh3)3Cl] in ethanol in the presence of a base (NEt3) affords a family of yellow complexes (1-R) containing a PPh3, two de-protonated triazenes coordinated as bidentate N,N-donors, and an aryl (C6H4–R) fragment coordinated in the η1-fashion. A similar reaction in toluene yields a group of reddish-orange complexes (2-R) containing a PPh3, two N,N-coordinated triazenes, and a chloride. Structures of the 1-CH3 and 2-CH3 complexes have been determined by X-ray crystallography. All the 1-R and 2-R complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. The 1-R and 2-R complexes also fluoresce in the visible region under ambient condition while excited at around 400nm. Cyclic voltammetry on these complexes shows a Rh(III)–Rh(IV) oxidation (within 0.76–1.68 vs. SCE), followed by an oxidation of the coordinated triazene ligand (except the R=NO2 complexes). An irreversible reduction of the coordinated triazene is also observed for all the complexes below −0.96V vs. SCE. In the 1-R and 2-R complexes potential of the Rh(III)–Rh(IV) oxidation correlates linearly with the electron-withdrawing nature of the para-substituent (R). [Copyright &y& Elsevier]

In the title compound, C20H18N2O2S2, the dihedral angles between the 2-furoic acid group and the two benzyl groups are 72.4 (9) and 75.8 (8)°, while the angle between the mean planes of the two benzyl groups is 48.9 (2)°. The crystal packing is stabilized by intermolecular C—H⋯O interactions between the extended O atom of a 2-furoic acid group and H atoms from nearby benzyl and 2-furoic acid groups in the unit cell, linking the molecules into chains in a zigzag pattern, diagonally across the ac plane containing the 2-fuoric acid rings. Additional intermolecular interactions occur between the π orbitals of one benzyl ring and H atoms from a nearby benzyl ring at the opposite end of the molecule. Additional intramolecular interactions between the hydrazide H atom and both an O atom from a nearby furoic acid group and an S atom from a close sulfanyl group provide added stability to the molecule. [ABSTRACT FROM AUTHOR]

Two independent molecules (A and B) comprise the asymmetric unit in the crystal structure of the title compound, C11H15NO2. The cyclohexane ring adopts a boat configuration, as does the fused cyclohexene ring that bridges the cyclohexane ring. The crystal packing is stabilized by intermolecular O—H⋯O hydrogen bonding between the hydroxyl H atom of molecule A and the ketone O atom of molecule B and vice versa. These link the molecules into chains running diagonally along the bc face of the unit cell. [ABSTRACT FROM AUTHOR]

In the title molecule, C17H20N2O2, the angle between the mean planes of the 3-hydroxyphenyl and cyclohexa-2,4-dien-1-one rings is 10.7 (7)°. Intramolecular NH⋯O hydrogen bonding involving the amine H atom and the carbonyl O atom affects the conformation of the molecule. One of the ethyl arms is disordered over two conformations with occupancies of 0.766 (8) and 0.234 (8). Crystal packing is stabilized by intermolecular CH⋯O hydrogen bonding between the major component of the disordered ethyl C atom and a nearby carbonyl O atom, and by OH⋯O hydrogen bonding between the hydroxyl H atom and the carbonyl O atom. This links the molecules into chains in an alternate inverted pattern, parallel, oblique and diagonal to the bc face of the unit cell. [ABSTRACT FROM AUTHOR]

In the title molecule, C17H18Cl2N2O, the angle between the mean planes of the 2,5-dichlorophenylimino and phenol groups is 19.5 (5)°. The two ethyl groups adopt a synclinal conformation. The crystal structure is stabilized by intermolecular π-π stacking interactions between adjacent 2,5- dichlorophenyl rings, the distance between the centroids of interacting rings being 3.860 (8) Å. The molecules are stacked parallel to the a axis. In addition, an O—H⋯N intramolecular hydrogen-bonding interaction between the phenol H atom and imino N atom is observed. [ABSTRACT FROM AUTHOR]

In the title molecule, C15H11ClO, the angle between the mean planes of the two rings is 6.6 (8)°. The crystal packing is stabilized by van der Waals interactions, whereby the molecules are aligned in rows in a zigzag pattern. [ABSTRACT FROM AUTHOR]

In the title molecule, C21H22N2O, the angle between the mean planes of the 1-naphthylimino and 2-methylyphenyl groups is 63.3 (2)°. The two diethyl extensions from the 5-diethylamino group are twisted in a + and - antiperiplanar conformation. One of the ethyl arms is disordered over two conformations with occupancies of 0.644 (3) and 0.356 (3). The crystal packing is stabilized by intermolecular C—H⋯π interactions between π orbitals of the 1-naphthyl (I/II) rings and H atoms from a nearby benzene ring as well as from an ethyl C atom of an ethylamino group. The molecules are stacked along the b axis in alternate inverted chains with the 1-naphthyl rings obliquely parallel to the ab face of the unit cell. Intramolecular interactions between the hydroxyl H atom and the imino N atom provide additional conformational stability. [ABSTRACT FROM AUTHOR]

In the title compound, C23H17Cl3O2, the dihedral angles between the 2-chlorophenyl group and the two 4-chlorophenyl groups are 88.9 (3) and 12.9 (2)°, while the angle between the mean planes of the two 4-chlorophenyl groups is 77.9 (5)°. The crystal packing is stabilized by intermolecular C—H⋯O interactions between an H atom from each of the two 4-chlorophenyl groups and a ketone O atom in neighboring molecules, which link the molecules into chains diagonally along the ac plane of the unit cell. Additional intermolecular π-π stacking interactions occur between adjacent 2-chlorophenyl rings as well as between one of the 4-chlorophenyl rings and a 2-chlorophenyl ring, the distances between the centroids of interacting rings being 3.931 (6) and 3.9915 (4) Å, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of salicyldehyde thosemicarbazone (H2L1), 2-hydroxyacetophenone thiosemicarbazone (H2L2) and 2-hydroxynapthaldehyde thiosemicarbazone (H2L3) (general abbreviation H2L, where H2 stands for the two dissociable protons, one phenolic proton and one hydrazinic proton) with K2[PtCl4] afforded a family of polymeric complexes of type [{Pt(L)} n ]. Reaction of the polymeric species with two monodentate ligands (D), viz. triphenylphosphine (PPh3) and 4-picoline (pic), yielded complexes of the type [Pt(L)(D)]. These mixed-ligand complexes were also obtained from the reaction of the thiosemicarbazones with [Pt(PPh3)2Cl2] and [Pt(pic)2Cl2]. The crystal structure of [Pt(PPh3)(L2)] has been determined. The thiosemicarbazone ligands are coordinated, via dissociation of the two protons, as dianionic tridentate O,N,S-donors. The [Pt(L)(D)] complexes show characteristic 1H NMR spectra and intense absorptions in the visible and ultraviolet region. They also fluoresce in the visible region at ambient temperature. [Copyright &y& Elsevier]

Abstract: New nickel (II) complexes of 5-methyl-3-formylpyrazole-3-piperidinylthiosemicarbazone (HMP z 3Pi), [Ni(HMP z 3Pi)2]X2 ·2H2O (X=Cl, Br, ClO4, BF4 and NO3) have been synthesised and physico-chemically characterised by elemental analyses, magnetic susceptibility and conductivity measurements at RT, electronic and IR spectra. All the reported species are 1:2 electrolytic cationic complexes. Electronic spectra in the solid state and in MeOH solutions suggest a six-coordinate distorted octahedral geometry for all the reported complexes. IR spectral data (4000–200 cm−1) are indicative of a neutral NNS tridentate function of HMP z 3Pi coordinating to the central Ni(II) via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thio-keto sulfur. X-ray crystallography of [Ni(HMP z 3Pi)2]Cl2 ·2H2O (, triclinic) has authenticated a NiN4S2 octahedral coordination and the pair of coordinating ligands (HMP z 3Pi) are almost orthogonal. A close scrutiny of the X-ray data of HMP z 3Pi (Pbca, orthorhombic) and [Ni(HMP z 3Pi)2]Cl2 ·2H2O (, triclinic) indicates an unusual rotation about the azomethine (C bond during complexation with Ni(II). A possible mechanism for such a rotation has been proposed. [Copyright &y& Elsevier]

The title compound, [Cu2(bnpp)2(bpa)2](ClO4)2·0.5CH3CN [bpa is bis­(2-pyridylmeth­yl)amine (C12H13N3) and bnpp is bis­(4-nitro­phen­yl)phosphate (C12H8N2O8P)], contains two CuII ions, each coordinated in a distorted square-pyramidal geometry formed by the tridentate chelating ligand bpa and two O-atom donors from two bnpp ligands. Two bnpp anions bridge two CuII ions to form the dinuclear complex cation, one O-atom donor of each bnpp coordinating in a basal site and another coordinating in the apical position with a Jahn–Teller elongated bond of 2.189 (4) or 2.244 (3) Å. [ABSTRACT FROM AUTHOR]

The coordinating properties of the title ligand, 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex), synthesized and characterized (elemental analysis, MS, IR, 1H and 13C NMR and X-ray crystallography) for the first time, are reported by solid-state isolation of cobalt(III) complexes, [Co(MPz3Hex)2]X · nH2O (X=Cl, Br, NO3, ClO4 or BF4; n=1 to 2). The reported complex species have been spectroscopically characterized with X-ray structural identification of [Co(MPz3Hex)2]Br · H2O. IR and NMR data (1H and 13C) for the free ligand and its CoIII complexes confirm that the ligand, HMPz3Hex, behaves as a uninegative anion with NNS tridentate function via the pyrazolyl tert-nitrogen, azomethine nitrogen and thiol sulfur. Electronic spectral data recommend a distorted octahedral environment for the six-coordinate CoIII species. X-ray crystallography of [Co(MPz3Hex)2]Br · H2O (C2/c, monoclinic), has shown unambiguously that the crystallographic asymmetric unit consists of a [Co(MPz3Hex)2]+ cation and one Br− anion with one H2O molecule as solvent of crystallization. The two NNS ligands coordinate orthogonally to the central CoIII ion with mer-configuration. A critical scrutiny of the X-ray data of free HMPz3Hex (Pna21, orthorhombic) and [Co(MPz3Hex)2]Br · H2O indicates that an unusual rotation about the azomethine (C&z.dbnd6;N) double bond occurs during complexation with CoIII. A plausible reaction mechanism for the same has been proposed. Sulfur is involved in a C(7)–H(7)⋯S(1) intramolecular contact restricting the conformation of the ligand both in free and its complexed form. [Copyright &y& Elsevier]

Iron chelates such as ethylenediamine-N,N'-bis(2-hydroxyphenyl)acetic acid (EDDHA) and their analogues are the most efficient soil fertilizers to treat iron chlorosis in plants growing in calcareous soils. EDDHA, EDDH4MA (ethylenediamine-N,N'-bis(2-hydroxy-4-methylphenyl)acetic acid), and EDDCHA (ethylenediamine-N,N'-bis(2-hydroxy5-carboxyphenyl)acetic acid) are allowed by the European directive, but also EDDHSA (ethylenediamine-N,N'-bis(2-hydroxy-5-sulfonylphenyl)acetic acid) and EDDH5MA (ethylenediamine-N,N'-bis(2-hydroxy-5-methylphenyl)acetic acid) are present in several commercial iron chelates. In this study, these chelating agents as well as p,p-EDDHA (ethylenediamine-N,N'-bis(4-hydroxyphenyl)acetic acid) and EDDMtxA (ethylenediamine-N,N'-bis(2-metoxyphenyl)acetic acid) have been obtained following a new synthetic pathway. Their chemical behavior has been studied to predict the effect of the substituents in the benzene ring on their efficacy as iron fertilizers for soils above pH 7. The purity of the chelating agents has been determined using a novel methodology through spectrophotometric titration at 480 nm with Fe[sup 3+] as titrant to evaluate the inorganic impurities. The protonation constants were determined by both spectrophotometric and potentiometric methods, and Ca[sup 2+] and Mg[sup 2+] stability constants were determined from potentiometric titrations. To establish the Fe[sup 3+] and Cu[sup 2+] stability constants, a new spectrophotometric method has been developed, and the results were compared with those reported in the literature for EDDHA and EDDHMA and their meso- and rac-isomers, pM values have been also determined to provide a comparable basis to establish the relative chelating ability of these ligands. The purity obtained for the ligands is higher than 87% in all cases and is comparable with that obtained by ¹H NMR. No significant differences have been found among ligands when their protonation and stability constants were compared. As expected, no Fe[sup 3+] complexation was observed for p,pEDDHA and EDDMtxA. The presence of sulfonium groups in EDDHSA produces an increase in acidity that affects their protonation and stability constants, although the pFe values suggest that EDDHSA could be also effective to correct iron chlorosis in plants. [ABSTRACT FROM AUTHOR]

New cobalt(III) and nickel(II) complexes of 5-methyl-3-formylpyrazole-N(4)-dibutylthiosemicarbazone (HMPzNBu2), [Co(MPzNBu2)2]X·H2O and [Ni(HMPzNBu2)2]X2 (X=Cl, Br, ClO4, BF4 and NO3), respectively, have been synthesised and physico-chemically characterised by magnetic measurements (polycrystalline state), 1H NMR [for Co(III) complexes], electronic and IR spectra. The reported species are all cationic complexes, behaving as 1:1 [for Co(III) complexes] and 1:2 [for Ni(II) complexes] electrolytes in MeOH. Electronic spectral features of the diamagnetic Co(III) and paramagnetic Ni(II) species classify them as six-coordinate distorted octahedral ones. IR spectra (4000–200 cm−1) indicate a monoprotic tridentate (NNS) function of HMPzNBu2 coordinating to the central Co(III) via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atom; while for the Ni(II) complexes, HMPzNBu2 behaves as neutral NNS tridentate, bonding to Ni(II) through the pyrazolyl iminic nitrogen, azomethine nitrogen and thioketo sulfur. 1H NMR data (in DMSO-d6 at 300 MHz) for the uncomplexed ligand and those of its Co(III) complexes are commensurate with the propositions of bonding sites envisaged from IR data. X-ray crystallographic data of I (P1¯, triclinic) and of II (C2/c, monoclinic) have authenticated CoN4S2 and NiN4S2 octahedral coordination, respectively; in both I and II; the pair of coordinating ligands are nearly orthogonal to each other with the difference that while in I, the pair of ligands are monodeprotonated, in II, the same pair of ligands are neutral. [Copyright &y& Elsevier]

New iron(III) complexes of 5-methyl-3-formylpyrazole-3-piperidinylthiosemicarbazone (HMPz3Pi), [Fe(MPz3Pi)2]X·2H2O (X=Cl, ClO4 and NO3) have been synthesised and physico-chemically characterised by magnetic data (polycrystalline state), electronic, IR and EPR spectral studies. Each of the reported species is a cationic complex (1:1 electrolyte) containing two moles of monodeprotonated title ligand and an anionic counterpart. IR spectra (4000–200 cm−1) indicate coordination to the central iron(III) ion via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atoms of the primary ligand molecule. EPR data (RT and LNT) show the presence of a low spin iron(III) cation with d2 xz d2 yz d1 xy configuration. X-ray crystallographic data of [Fe(MPz3Pi)2]ClO4·2H2O (P1¯, triclinic) have authenticated a FeN4S2 octahedral coordination as envisaged from spectral data. In the complex species, the two azomethine nitrogen atoms are trans to each other, while the pyrazolyl ring nitrogens and the thiolato sulfurs are in cis positions. [Copyright &y& Elsevier]

Discusses the synthesis of mixed-ligand polypyridyl complexes of ruthenium using bipyridine and amino acids. Molecular species with potential for functioning as DNA intercalators; Properties for a complex to function as an intercalator; Role of metallointercalators in probing nucleic acid structure and function.

The co-ordination mode of the title ligand, HMPzNEt2 (synthesised for the first time and characterised by elemental analyses, mass, IR and 1H NMR spectral parameters), is reported by solid state isolation and physico-chemical identification of cobalt(III) complexes, [Co(MPzNEt2)2]X·2H2O (X=Cl, Br, ClO4, BF4 and NO3). Electronic spectral features of these diamagnetic Co(III) species classify them as six co-ordinate distorted octahedral ones. IR spectra (4000–200 cm−1) indicate that the Co(III) complexes have monoanionic tridentate NNS co-ordination of the title ligand through the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atoms. 1H NMR data (in CDCl3 at 300 MHz) for the uncomplexed ligand and those of its Co(III) complexes are commensurate with the NNS function of the monodeprotonated HMPzNEt2, as ascertained from downfield shift of the relevant protons adjacent to the bonding sites. X-ray crystallographic data of I and II (both P1¯, triclinic) have authenticated a CoN4S2 octahedral co-ordination in both the complex ions. [Copyright &y& Elsevier]