Crystallographic study of self‐organization in the solid state including quasi‐aromatic pseudo‐ring stacking interactions in 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea

1‐Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen‐bond formation. Two novel 1‐benzoylthiourea derivatives, namely 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea, C₁₆H₁₆N₂O₃S, (I), and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea, C₁₁H₁₄N₂O₂S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P , while (II) crystallizes in the space group P 2₁/c . In both structures, intramolecular N—H…O hydrogen bonding is present. The resulting six‐membered pseudo‐rings are quasi‐aromatic and, in each case, interact with phenyl rings via stacking‐type interactions. C—H…O, C—H…S and C—H…π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N—H…S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry‐independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen‐bond donor and acceptor –OH groups participate in the formation of intermolecular N—H…O and O—H…S hydrogen bonds that join molecules into chains extending in the [001] direction.     

A novel alpha-helix-liked metallohelicate series and their structural adjustments for the isomorphous substitution

A novel metallohelical motif is well designed and synthesized by mimicking the alpha-helical fold structure of protein. The 1D helical structures of [Cd(CH2(COO)2)(SC(NH2)2)2]n (I) and [Zn(CH2(COO)2) (SC(NH2)2)2]n (II) are primarily induced and stabilized by the multiple long-range intrahelix hydrogen bonds. Malonate dianion acts as a bidentate ligand coordinated with metal ions to form the backbone of the helix, and thiourea molecules that bend into the helical turn are involved in the intrahelix hydrogen-bond system. The metal ion occupations in the helix of I and II can be freely substituted by simply controlling the initial ratio of those two metal ions. Single crystals of three mixed metal ion complexes of [Cd0.77Zn0.23(CH2(COO)2)(SC(NH2)2)2]n (III), [Cd0.50Zn0.50(CH2(COO)2)(SC(NH2)2)2]n (IV), and [Cd0.21Zn0.79(CH2(COO)2)(SC(NH2)2)2]n (V) were synthesized from systems with an initial Cd/Zn mole ratio of 1:1 for III, 1:2 for IV, and 1:8 for V. They are isomorphous as confirmed by X-ray characterization. When the metal ion is substituted, the multiple intrahelix hydrogen interaction motifs of the coordination polymer structure are self-adjusted to sustain their 1D helical motifs.     

Similarities and differences in the structures of 5‐bromo‐6‐hydroxy‐7,8‐dimethylchroman‐2‐one and 6‐hydroxy‐7,8‐dimethyl‐5‐nitrochroman‐2‐one

The title compounds, C₁₁H₁₁BrO₃, (I), and C₁₁H₁₁NO₅, (II), respectively, are derivatives of 6‐hydroxy‐5,7,8‐trimethylchroman‐2‐one substituted at the 5‐position by a Br atom in (I) and by a nitro group in (II). The pyranone rings in both molecules adopt half‐chair conformations, and intramolecular O—H...Br [in (I)] and O—H...O_nitro [in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O—H...O hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O—H...O hydrogen bonds form zigzag C(9) chains of molecules along the a axis. Because of the tetragonal symmetry, similar chains also form along b. In (II), however, similar contacts involving an O atom of the nitro group form inversion dimers and generate R₂²(12) rings. These also result in a close intermolecular O...O contact of 2.686 (4) Å. For (I), four additional C—H...O hydrogen bonds combine with π–π stacking interactions between the benzene rings to build an extensive three‐dimensional network with molecules stacked along the c axis. The packing in (II) is much simpler and centres on the inversion dimers formed through O—H...O contacts. These dimers are stacked through additional C—H...O hydrogen bonds, and further weak C—H...O interactions generate a three‐dimensional network of dimer stacks.     

Enhanced Anion Binding from Unusual Coordination Modes of Bis(thiourea) Ligands in Platinum Group Metal Complexes

Treatment of a range of bis(thiourea) ligands with inert organometallic transition‐metal ions gives a number of novel complexes that exhibit unusual ligand binding modes and significantly enhanced anion binding ability. The ruthenium(II) complex [Ru(η⁶‐p‐cymene)(κS,S′,N‐ L³ ?H)]⁺ ( 2 b ) possesses juxtaposed four‐ and seven‐membered chelate rings and binds anions as both 1:1 and 2:1 host guest complexes. The pyridyl bis(thiourea) complex [Ru(η⁶‐p‐cymeme)(κS,S′,N_py‐ L⁴ )]²⁺ ( 4 ) binds anions in both 1:1 and 1:2 species, whereas the free ligand is ineffective because of intramolecular NH???N hydrogen bonding. Novel palladium(II) complexes with nine‐ and ten‐membered chelate rings are also reported.     

Untersuchung von Kobalt(II)-Komplexen mit N-Arylthioharnstoffen

The complexes of cobalt(II) chloride with o, m, p-tolyl thiourea (I–III); m, p-nitrophenyl thiourea (IV, V); o, m, p-hydroxy phenyl thiourea (VI–VIII); m, p-bromophenyl thiourea (IX, X); p-iodophenyl thiourea (XI) and o-bromo-p-methyl phenyl thiourea (XII) have been synthesised. The elemental analysis reveals that ligands (I–V) form bis and the rest forms tris complexes with cobalt(II). Infrared and farinfrared spectral measurements prove that sulphur is taking part in co-ordination. All complexes are nonelectrolytes in acetone as revealed by conductivity measurements. The data obtained from magnetic susceptibility measurements, electronic spectra in solution are consistant with a practically tetrahedral symmetry.     

Molecular structures of (5656)macrotetracyclic chelates in M(II) ion–ethanedithioamide–methanimine–hydrogen cyanide quaternary systems by DFT calculations

The geometric parameters of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) (5656)macrotetracyclic complexes with the NNNN-coordination of the donor cites of the chelant, which can be formed upon template processes in M(II)–ethanedithioamide–methanimine–hydrogen cyanide quaternary systems, have been calculated using the density functional (DFT) hybrid method in the OPBE/TZVP approximation with the use of the Gaussian09 program package. It is shown that no one of the 5-membered chelate rings is planar, and these rings are not identical in the complexes studied. The 6-membered chelate rings are likewise not identical: one has a prominent noncoplanarity, and the other is almost planar. In all metal complexes, the nitrile nitrogen atom in one 6-membered ring noticeably departs from the plane of the ring, and in the other 6-membered ring, the respective nitrogen atom lies virtually in the plane of the ring.     

Photophysical and electrochemical properties of platinum(II) complexes bearing a chromophore-acceptor dyad and their photocatalytic hydrogen evolution

A series of platinum(II) complexes bearing a chromophore-acceptor dyad obtained by reacting 4-(p-bromomethylphenyl)-6-phenyl-2,2'-bipyridine or 4'-(p-bromomethylphenyl)-2,2':6',2'-terpyridine with pyridine, 4-phenylpyridine, 4,4'-bipyridine, 1-methyl-4-(pyridin-4'-yl)pyridinium hexafluorophosphate respectively, were synthesized. Their photophysical properties, emission quenching studies by Pt nanoparticles and methyl viologen, electrochemical properties and photoinduced electron-transfer reactions in a photocatalytic hydrogen-generating system containing triethanolamine and colloidal Pt without an extra electron relay, were investigated. A comparison of the rates of hydrogen production for the two photocatalytic systems, one containing a metal-organic dyad and the other comprising a 1:1 mixture of the parental platinum(II) complexes and the corresponding electron relay, showed that intramolecular electron transfer improves the photocatalytic efficiency. Compared with cyclometalated platinum(II) complexes, the related platinum(II) terpyridyl complexes exhibited poor performance for photocatalytic hydrogen evolution. An investigation into the amount of hydrogen generated by three platinum(II) complexes containing cyclometalated ligands with methyl groups located on different phenyl rings revealed that the efficiency of hydrogen evolution was affected by a subtle change of functional group on ligand, and the hydrogen-generating efficiency in the presence or absence of methyl viologen is comparable, indicating electron transfer from the excited [Pt(C^N^N)] chromophore to colloidal Pt. (1)H NMR spectroscopy of the metal-organic dyads in an aqueous solution in the presence of excess triethanolamine revealed that the dyad with a viologen unit was unstable, and a chemical reaction in the compound occurred prior to irradiation by visible light under basic conditions.     

Recognition of carboxylate and dicarboxylates by azophenol–thiourea derivatives: a theoretical host–guest investigation

Geometries of azophenol–thiourea derivative complexes with acetate, oxalate, malonate, succinate, glutarate, adipate, pimelate, suberate and azelate were carried out using the integrated MO:MO method. The binding and complexation energies of these complexes were derived from the ONIOM(B3LYP/6-31G(d):AM1) calculations. The relative stabilities of the complexes of azophenol–thiourea derivatives with carboxylate guests are reported. The binding interactions of the azophenol–thiourea receptor 1, 2 and carboxylate guests are described as multipoints hydrogen bonding, where the amine and phenolic hydrogen atoms of receptors act as hydrogen bond donors in complex with acetate and all amine-hydrogen and phenolic hydrogen atoms act as hydrogen bond donors in complex with dicarboxylate guests. Thermodynamic properties of binding interactions between receptors 1, 2 and their preorganizations and complexations are also reported.     

Coordination and hydrogen bonded network structures of Cu(II) with mixed ligands: a hybrid hydrogen bonded material, an infinite sandwich arrangement, and a 3-D net

Mixed-ligand Cu(II) complexes with deprotonated trimesic acid and phenanthroline-type ligands were synthesised by solvothermal methods to form 2-D infinite hexagonal hydrogen bonded structures with additional trimesic acid (H3tma) molecules. The complex [Cu(phendione)2(H2tma)2].2(H3tma).1.65(CF3CH2OH).2.5(H2O), where phendione = 1,10-phenanthroline-5,6-dione, has hydrogen bonded networks of [Cu(phendione)2(H2tma)2] complexes interspersed with layers of H3tma with a topologically identical hydrogen bonding network. Whereas in [Cu(1,10-phenanthroline)(H2tma)2]2.2(H3tma), a dimeric Cu(II) complex hydrogen bonds directly to additional H3tma molecules to form a three-layered 2-D network resembling an infinite sandwich. The synthesis and structures of simple Cu(II) complexes of the phendione ligand are also reported. One of these, [Cu(phendione)2Br2] shows a particularly polar packing arrangement.     

Synthesis and structural studies of some fluorescent group XII metal complexes with a terpyridine based ligand

Three 4′-(2-thienyl) substituted terpyridine (thioterpy) complexes of cadmium(II) and mercury(II) have been synthesized and fully characterized by spectroscopies. According to the crystallographic studies, the packing of these complexes was stabilized by several intermolecular interactions such as hydrogen bonding, C-H?π and π?π. Finally, the florescent properties of the prepared complexes have been investigated.     

Cu(II)- and Hg(II)-induced modulation of the fluorescence behavior of a redox-active sensor molecule

Here, we report on a fluorescent 1,2,4-thiadiazole derivative (oxidized form) and its reduced form, the corresponding iminoyl thiourea. The thiadiazole displays a strong modulation of its fluorescence behavior, selectively upon addition of Cu(II), while the iminoyl thiourea functions as a chemodosimeter for Hg(II). Additionally, the Cu(II)-thiadiazole complex is characterized by HRMS, and the Hg(II)-induced desulfurization of the iminoyl thiourea is monitored by mass spectrometry.     

Anion and cation binding by a pendant arm cyclam and its macrobicyclic derivatives

A series of transition-metal complexes of N,N',N',N'-tetra(3-hydroxypropyl)cyclam (L1) are reported. The X-ray structures of the compounds reveal pendant arm coordination of one of the alcohol groups to give square-pyramidal metal centres with simultaneous hydrogen bonding to the counter anions. Ligand L1 has been elaborated to form a series of macrotricyclic derivatives that form 1 ratio 1 complexes with Cu(II) and Ni(II). The X-ray structure of the tetrahydrate and protonated forms of L1 are also reported.     

Encapsulation of divalent tetrahedral oxyanions of sulfur within the rigidified dimeric capsular assembly of a tripodal receptor: first crystallographic evidence of thiosulfate encapsulation within neutral receptor capsule

A simple tris(2-aminoethyl)amine based meta-chloro substituted tripodal thiourea receptor L has been extensively studied with two divalent oxyanions of sulfur, such as sulfate and thiosulfate, with identical dimensionality. The solid state crystal structure of the anion complexes with L reveal that the anions are encapsulated within the dimeric rigid capsular assembly of the receptor via N-Hanion interactions. To the best of our knowledge this is the first report on the encapsulation of thiosulfate within dimeric capsular assembly of a neutral receptor. The tight capsular sizes for both anion complexes are quite comparable, whereas the coordination mode of the anions and the hydrogen bonding parameters are significantly varied. The three dimensional solid state structural orientations of the capsular complexes are mainly governed by the ClCl (for thiosulfate complex) and ClS (for sulfate complex) halogen bonding interactions. The solution-state binding and encapsulation of oxyanions by N-Hanion hydrogen bonding has also been confirmed by quantitative (1)H NMR titration and 2D NOESY NMR experiments. Both the experiments confirm that in contradiction of 2?:?1 solid state binding, in solution the studied anions are bound within the pseudocavity of the receptor with 1?:?1 binding stoichiometry. Moreover, the change in chemical shifts of thiourea -NH protons and the binding constant values suggest the receptor-sulfate interaction is more energetically favorable compared to the receptor thiosulfate interaction.     

Complexing properties of N-2-sulfoethyl chitosans

For a new sulfoethylated chitosan derivative with the degree of substitution of amino group hydrogen atoms of 0.5, the dissociation constant of functional groups has been determined by potentiometric titration. Complexing properties of sulfoethylated chitosan toward copper(II), cobalt(II), nickel(II), zinc(II), manganese(II), cadmium(II), silver(I), lead(II), magnesium(II), calcium(II), strontium(II), and barium(II) ions have been studied potentiometrically. Alkaline earth and magnesium ions do not form complexes with sulfoethylated chitosan. For the other ions, stability constants of the resulting complexes have been determined. The most stable N-2-sulfoethyl chitosan complexes are those with copper(II) and silver(I) ions.     

Synthesis, spectral and thermal studies of N,N − -pyridine-2,6-diyl bis[N −-phenyl(thiourea)] and its metal complexes

Four new metal complexes with the general formula, [ML·mH₂O]nH₂O (where, M = Cu(I), Co(II), Ni(II) or Zn(II); L = N,N ^?-pyridine–2,6-diyl bis[N ^?-phenyl (thiourea)] (PDPT); m = 1 or 3 and n = 0.5 or 4.0), have been synthesized and characterized by elemental analyses, spectral analyses (IR, UV–Vis., ¹H-NMR and MS), thermal analyses (TGA), conductivity and magnetic measurements. The results showed that the ligand (PDPT) acts in a mononegative tridentate manner towards Cu(I) ion coordinating via the two thiol sulfurs and pyridyl nitrogen groups with displacement of only one hydrogen atom from the thiol group, while the ligand behaves in a binegative tridentate manner towards the Co(II), Ni(II) and Zn(II) ions with displacement of two hydrogen atoms from the two thiol groups. The value of magnetic measurements showed a diamagnetic character of the copper complex indicating the reduction of Cu(II) to Cu(I). Semi-empirical calculations of the ligand and its metal complexes have been used to study the molecular geometry using ZINDO/1, PM3 and AM1. Also, the harmonic vibration spectra of the ligand and its metal complexes have been investigated with the purpose to assist the experimental assignment of metal complexes. The results of the optical absorption studies reveal that the optical transition is direct with band gaps energy (E_g) values 2.62, 1.98 and 1.85 eV for Cu, Co and Ni complexes, respectively, indicating that these complexes can behave as semi-conductors.     

Urease inhibition and anti-leishmanial assay of substituted benzoylguanidines and their copper(II) complexes

A series of N,N',N'-trisubstituted guanidines (1-6) and their copper(II) complexes, [κ(2)(O,N)-C(6)H(5)CONHC(NHC(6)H(4)Cl)NR](2)Cu(ii) (R = iso-propyl (1a), n-butyl (2a), sec-butyl (3a), tert-butyl (4a), benzyl (5a), and para-tolyl (6a)) were synthesized and characterized using elemental analysis, FTIR and NMR spectroscopy. DFT studies were used to assess the location of the protons in the free ligands. However, calculations have shown that, in all cases, hydrogen bonding from either N-H group gives conformations that are very similar in energy. Single crystal XRD studies were used to characterize ligands 1 and 4 and the related complexes 1a and 4a. The structures reveal that these complexes are mononuclear in the solid state and that copper adopts a regular square planar geometry. In both metallic species, the N, N', N'-trisubstituted guanidine ligands chelate the Cu(II) atom using the oxygen and one nitrogen. The synthesized compounds were investigated for urease inhibition using thiourea as a standard drug. Most complexes exhibit a better activity than the respective guanidines and compound 1a was found to be the most active with IC(50) = 9.83 ± 0.07 μM (the IC(50) for thiourea is 21.0 ± 0.1 μM). The species were also screened for their anti-leishmanial activity. However, all of the compounds were devoid of any significant activity.     

A nickel-substituted form of nanodiamonds and its catalytic activity in decomposition of hydrogen peroxide

Adsorption of nickel (II) ions with nanodiamonds obtained by the detonation synthesis was studied. A nickel-substituted form of nanodiamonds was obtained. The catalytic activity exhibited by nickel ions (II) in the form of the surface complexes with nanodiamond functional groups in decomposition of hydrogen peroxide was determined.     

Metal Complexes of Saccharin with the N-(2-hydroxyethyl)-ethylenediamine Ligand: Synthesis,Characterization and Spectroscopic Examination. Crystal Structures of trans- Bis(Saccharinato)Bis{N-(2-hydroxyethyl)-Ethylenediamine} copper(II) and Cadmium(II)

The novel transition metal saccharinato complexes of N-(2-hydroxyethyl)-ethylendiamine (HydEt-en) have been synthesized and characterized by elemental analyses, magnetic moments, UV-Vis and IR spectra. Coordination behaviour of HydEt-en has been studied. The Mn(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) form mononuclear complexes, while the Fe(II) and Co(II) complexes are dimeric. The crystal structures of the [Cu(sac)₂(HydEt-en)₂] and [Cd(sac)₂(HydEt-en)₂] complexes, where sac is the deprotonated form of saccharin, were determined by x-ray diffraction. The metal ions are octahedrally coordinated by these ligands. The amine ligand acts as a bidentate N-donor ligand and its ethanol group is not involved in coordination. The sac ions coordinate through the deprotonated N as a monodentate ligand. The NH and OH groups of the amine ligand are involved in intra- and intermolecular hydrogen bonding with the carbonyl and sulphonyl oxygens of the sac ions to form a three-dimensional infinite network.     

1,3‐Bis(ethylamino)‐2‐nitrobenzene, 1,3‐bis(n‐octylamino)‐2‐nitrobenzene and 4‐ethylamino‐2‐methyl‐1H‐benzimidazole

1,3‐Bis(ethylamino)‐2‐nitrobenzene, C₁₀H₁₅N₃O₂, (I), and 1,3‐bis(n‐octylamino)‐2‐nitrobenzene, C₂₂H₃₉N₃O₂, (II), are the first structurally characterized 1,3‐bis(n‐alkylamino)‐2‐nitrobenzenes. Both molecules are bisected though the nitro N atom and the 2‐C and 5‐C atoms of the ring by twofold rotation axes. Both display intramolecular N—H...O hydrogen bonds between the amine and nitro groups, but no intermolecular hydrogen bonding. The nearly planar molecules pack into flat layers ca 3.4 Å apart that interact by hydrophobic interactions involving the n‐alkyl groups rather than by π–π interactions between the rings. The intra‐ and intermolecular interactions in these molecules are of interest in understanding the physical properties of polymers made from them. Upon heating in the presence of anhydrous potassium carbonate in dimethylacetamide, (I) and (II) cyclize with formal loss of hydrogen peroxide to form substituted benzimidazoles. Thus, 4‐ethylamino‐2‐methyl‐1H‐benzimidazole, C₁₀H₁₃N₃, (III), was obtained from (I) under these reaction conditions. Compound (III) contains two independent molecules with no imposed internal symmetry. The molecules are linked into chains via N—H...N hydrogen bonds involving the imidazole rings, while the ethylamino groups do not participate in any hydrogen bonding. This is the first reported structure of a benzimidazole derivative with 4‐amino and 2‐alkyl substituents.     

Syntheses, structures and properties of dinickel(II) macrocyclic complexes with two 2-thiophenoethyl pendant arms

Three dinickel(II) macrocyclic complexes [Ni₂L(μ-OAc)]ClO₄•X (L = L¹, L² and L³) with two 2-thiophenoethyl pendant arms, have been synthesized by cyclocondensation between N,N-bis(3-aminopropyl)-2-thiophenoethylamine and 2,6-diformyl-4-R-phenol (where R = Me, Cl and F and X = MeOH, 2MeCN and H₂O, respectively), in the presence of nickel(II) ions. The complexes were characterized by elemental analysis, spectroscopic methods and X-ray diffraction techniques. The geometry around both of the Ni(II) ions in each molecule is a slightly distorted octahedral and the thiopheno groups do not coordinate to the Ni(II) ions, resulting that the complexes display contorted saddle-form configurations. The distances between the Ni?Ni centers for the complexes are 3.145, 3.171 and 3.155 Å, respectively. The influences of the substituted groups R in the benzene rings of the macrocyclic units on the structure, electrochemistry, magnetism, cleavage and antibacterial property to DNA have been investigated. The ES-MS results of the complexes confirm that [Ni₂L]²⁺ species in methanol solution are very stable because all the peaks in ES-MS spectra contain this kind of units. The reduction potentials of the complexes shift towards anode upon increasing the drawing electronic ability of substituted groups. Magnetic measurements in the 2-300 K range indicate weak antiferromagnetism for the dinuclear Ni(II) complexes and the magnetic exchange interactions enhance with the decrease of the Ni-Ni distances. These complexes exhibit cleavage activities towards plasmid pBR322 DNA and antibacterial activities.