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Based on excited state intramolecular proton transfer (ESIPT) and chelation enhanced fluorescence (CHEF) mechanisms, a new fluorescence ratiometric probe for Al3+ was designed and synthesized, and its structure was confirmed through single crystal X-ray study. This probe is capable of showing excited state intramolecular proton transfer through two different pathways. The introduction of Al3+ in a mixed aqueous solution with the probe results in an abrupt change in the photophysical properties of the probe. A ratiometric emission profile was observed in the presence of Al3+. Interestingly, the presence of other metal ions (especially trivalent ions, e.g. Fe3+, Cr3+, Ga3+ and In3+) do not perturb the fluorescence intensity of the probe (except Cu2+ and Pb2+, where slight changes were noticed). This indicates that the probe shows high affinity towards Al3+. The ratiometric sensing phenomenon may be explained by the presence of two different mechanisms, namely, excited state intramolecular proton transfer and chelation induced enhanced fluorescence, which are demonstrated by the probe in presence of Al3+ in the excited state. The complexation of the probe with Al3+ inhibits excited state intramolecular proton transfer while the chelation induced enhanced fluorescence mechanism becomes dominant. The probe efficiently detected the cellular uptake of Al3+, which is demonstrated here with human blood-cell imaging. Moreover, the detection limit was found to be 6.72 × 10−8 M. [ABSTRACT FROM AUTHOR]

Three series of isatin derivatives [3-hydrazino, 3-thiosemicarbazino, and 3-imino carboxylic acid derivatives] were synthesized employing microwave irradiation. The prepared compounds were characterized by FT-IR, NMR, elemental analysis, and X-ray crystallography for derivatives 5b. The synthesized compounds were screened for antimicrobial activity against selected bacteria and fungi. The results revealed that the N-alkyl isatin derivatives were biologically active with different spectrums activity. Most of the 3-hydrazino and 3-thiosemicarbazino isatin derivatives were biologically inactive and generally the active derivatives showed weak to moderate activity mainly against Gram-positive bacteria. The imino isatin carboxylic acid derivatives (2-[4-(1-benzyl-5-bromo-2-oxoindolin-3-ylideneamino) phenyl]acetic acid, 5d) showed promising activity against all tested Gram-positive bacteria and against fungal pathogens. [ABSTRACT FROM AUTHOR]

The phosphatase domain (PA3346PD) of the response regulator PA3346 modulates the downstream anti-anti-σ factor PA3347 to regulate swarming motility in Pseudomonas aeruginosa PAO1. PA3346PD, which comprises the protein phosphatase 2C domain (PP2C), is classified as a Ser/Thr phosphatase of the Mg2+- or Mn2+-dependent protein phosphatase (PPM) family. The recombinant PA3346PD, with molecular mass 26 kDa, was overexpressed in Escherichia coli, purified on an Ni2+-NTA agarose column and crystallized by the sitting-drop vapour-diffusion method. X-ray diffraction data were collected from PA3346PD crystals to a resolution of 2.58 Å and the crystals belonged to space group I4132 or I4332, with unit-cell parameter a = 157.61 Å. Preliminary analysis indicates the presence of a monomer of PA3346PD in the asymmetric unit with a solvent content of 58.4%. [ABSTRACT FROM AUTHOR]

Three derivatives of the novel (E)-2-cyano-N-(4-ethoxyphenyl)-3-methylthio-3-(substituted-amino)acrylamides3–5were selectively synthesized by the one-pot reaction of 2-cyano-N-(4-ethoxyphenyl)acetamide (2) with substituted isothiocyanates and methyl iodide in DMF containing potassium hydroxide as a basic catalyst. The stereochemistry and the structures of the synthesized compounds were confirmed by single crystal X-ray diffraction, IR,1H-NMR,13C-NMR, mass spectroscopy, and elemental analyses. [ABSTRACT FROM AUTHOR]

Two new cadmium(II) and lead(II)-thiocyanato coordination polymers with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dm-2,2′-bpy) as chelating ligands were synthesized and characterized by elemental analysis, IR and H NMR spectroscopy and by X-ray crystallography. Thermal and electrochemical properties were also studied as well. These complexes have formed formula [Cd(5,5′-dm-2,2′-bpy)(NCS)] ( 1) and [Pb(5,5′-dm-2,2′-bpy)(CHCOO)(NCS)] ( 2). The coordination numbers of Cd in 1 and Pb in 2 are six (CdNS) and seven (PbNOS), respectively. In 2, 'stereo-chemically active' electron lone pairs and the coordination spheres were hemidirected. Bridging properties of thiocyanato anions in 1 and 2 created one- and two-dimensional coordination polymers, respectively. The supramolecular features in these complexes were guided and controlled by weak directional intermolecular interactions. [ABSTRACT FROM AUTHOR]

Five new hydrazone derivatives, ( E)- N′-(4-fluorobenzylidene)-5-methyl-1-(4-nitrophenyl)-1 H-1,2,3-triazole-4-carbohydrazide, ( E)- N′-(4-chlorobenzylidene)-5-methyl-1-(4-nitrophenyl)-1 H-1,2,3-triazole-4-carbohydrazide, ( E)- N′-(4-bromobenzylidene)-5-methyl-1-(4-nitrophenyl)-1 H-1,2,3-triazole-4-carbohydrazide, ( E)- N′-(4-hydroxy-3-methoxybenzylidene)-5-methyl-1-(4-nitrophenyl)-1 H-1,2,3-triazole-4-carbohydrazide and ( E)- N′-(1-(4-bromophenyl)ethylidene)-5-methyl-1-(4-nitrophenyl)-1 H-1,2,3-triazole-4-carbohydrazide (denoted as A-E), were prepared and their molecular structures were characterized by single crystal X-ray diffraction. Compound A crystallizes in monoclinic P2/ c, a = 6.8057(1) Å, b = 12.7447(3) Å, c = 18.6936(3) Å, β = 105.356(1)°, B crystallizes in monoclinic P2/ c, a = 8.3815(2) Å, b = 20.8298(4) Å, c = 9.5932(2) Å, β = 99.612(1)°, C crystallizes in monoclinic P2/ c, a = 8.4213(8) Å, b = 21.077(2) Å, c = 9.5899(10) Å, β = 99.979(2)°, D crystallizes in monoclinic P2/ c, a = 11.1644(10) Å, b = 16.3508(15) Å, c = 9.7313(9) Å, β = 105.757(1)° and E crystallizes in triclinic $$P\bar{1}$$ , a = 8.7415(7) Å, b = 10.1032(8) Å, c = 11.6852(9) Å, α = 68.306(1)°, β = 84.894(1)°, γ = 68.289(1)°. All of the five compounds with close molecular conformations adopt a trans configuration with respect to the hydrazone C = N double bond and weak non-classical intermolecular C-H···O hydrogen bonds are observed in the crystal. Isomorphous substitution between compounds B and C with simple replacement of chlorine atom to bromine atom is giving rise to similar molecular geometries, unit cell parameters and intermolecular interaction pattern of three-dimensional network. Graphical Abstract: Five new hydrazone derivatives possessing 5-methyl-1-(4-nitrophenyl)-1,2,3-triazole moiety (denoted as A to E) are characterized by single crystal X-ray structure determination method. The intermolecular interaction pattern of D is strongly influenced by strong O-H···O hydrogen bond, whereas only non-classical C-H···O hydrogen bonds are observed in the rest. Compounds B and C with isomorphous chlorine-bromine substitution are crystallized under same space group and similar unit cell parameters.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Synthesis, spectroscopic characterization and X-ray crystal structure of a new (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]-N-phenylhydrazinecarboxamide (4) are reported. The stereochemistry of the title compound 4, C19H19N5O, about the imine bond [1.296 (4) Å] was assigned to have (E)-configuration. In the urea moiety, the N-H entities are trans to each other, and one of these forms is an intramolecular N-H ... H hydrogen bond. The compound crystallizes in the monoclinic space group P22/c with a = 5.8093 (2) Å, b = 20.5575 (6) Å, c = 14.0355 (5) Å, α = 90.00°, β = 97.365° (2), γ = 90.00°, V = 1662.36 (10) γ³, and Z = 4. The molecules are packed in crystal structure by weak intermolecular hydrogen interactions. [ABSTRACT FROM AUTHOR]

Abstract: The phase transition behaviour of three temperature polymorphs of hexamethylenetetraminium p-nitrobenzoate (HMTA–PNBA) crystal has been investigated by single crystal X-ray diffraction experiment at three different temperatures with the same crystal. The crystal undergoes multiple phase transitions from monoclinic Cm to Cc (first transition) and Cc to Cc (second transition). These transitions are reversible. Both of the phase transitions are of first order, involving the discontinuity and doubling of the c- and a-, b- axes at critical temperatures (TC ) 259.5 and 182.5K, respectively. The p-nitrobenzoate anions are disordered except for the low temperature phase (100K), displaying order–disorder phase transformation at transition temperature 182.5K. Hydrogen bonding plays a pivotal role in these phase transitions as shown by the decrease of hydrogen bonding as the temperature is raised. Both of the phase transitions are explained by Landau phenomenological theory. [Copyright &y& Elsevier]

Two substituted 2,2′-bipyridine lead(II) complexes, [Pb(5,5′-dm-2,2′-bpy)(tfac)2]n (1) (5,5′-dm-2,2′-bpy = 5,5′-dimethyl-2,2′-bipyridine and tfac = trifluoroacetate) and [Pb2(4,4′-dmo-2,2′-bpy)2(ftfa)4] (2) (4,4′-dmo-2,2′-bpy = 4,4′-dimethoxy-2,2′-bipyridine and ftfa = furoyltrifluoroacetonate), have been synthesized and characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopies, thermal behavior, and X-ray crystallography. Complexes 1 and 2 are 1D coordination polymer and dinuclear complex, respectively. The supramolecular features in these complexes are guided by weak directional intermolecular interactions. [ABSTRACT FROM AUTHOR]

Abstract: The crystal structure analyses on 2,4,4′-trimethoxybenzophenone (I) for data collected at 297(2)K show that there is only one intermolecular C–H···O hydrogen bond whereas there are four intermolecular C–H···O hydrogen bonds and an C–H···Π interaction for data collected at the temperature 100.0(1)K. All these hydrogen bonds are found to be weak. However these weak hydrogen bond interactions are attributable to the reversible temperature-dependent isomorphous phase transition found for (I). Compound (I) undergoes a reversible temperature-dependent isomorphous phase transition from monoclinic P21 at temperatures higher than the critical temperature (T C) of 154.5K to another monoclinic P21 at temperatures lower than T C. The phase transition is of first order, involving almost doubling of the c-axis at T C and is explained by Landau phenomenological theory. In the crystal structures at temperatures 297(2) and 100.0(1)K, the molecules are linked by the intermolecular C–H···O hydrogen bonds to form chains along the [100]-direction. At 100.0(1)K, another three intermolecular C–H···O hydrogen bonds and an C–H···Π interaction further interconnect these molecular chains into 2-dimensional sheets parallel to plane (001). [Copyright &y& Elsevier]

Abstract: The crystal of hexamethylenetetraminium-3,5-dinitrobenzoate hemihydrate (I) undergoes a reversible temperature-dependent phase transition from triclinic P-1 at the temperature higher than the critical temperature (T c ) 129K to another triclinic P-1 at temperature lower than T c . The phase transition is of first order, involving a discontinuity and a doubling of the c-axis at T c . The other unit cell parameters also undergo discontinuities during transition. The transition is explained by Landau phenomenological theory. The crystal structure analyses for data collected at 297(2) and 100.0(1)K show that there are two O–H…O hydrogen bonds between the 3,5-dinitrobenzoate and water molecule and two N–H…O hydrogen bonds between hexamethylenetetraminium and 3,5-dinitrobenzoate in the asymmetric unit of adduct I at 297(2)K whereas there are another two more N–H…O hydrogen bonds at 100.0(1)K. At 297(2)K, intermolecular N–H…O hydrogen bonds link the hexamethylenetetraminium and 3,5-dinitrobenzoate ions into layers stacked down the c-axis whereas at the 100.0(1)K the ions are linked into chains parallel to the b-axis. In the structures at both temperatures another C–H…O and C–H…N weak interactions interconnect the molecules into a three-dimensional network. The shorter donor–acceptor distances of the prevailing hydrogen bonds and the extra weak interactions interconnecting the hexamethylenetetraminium, 3,5-dinitrobenzoate and water molecule in the low temperature triclinic polymorph are attributable to the reversible temperature-dependent phase transition. [Copyright &y& Elsevier]

Abstract: The crystal of hexamethylenetetraminium-3,5-dinitrobenzote-3,5-dinitrobenzoic acid monohydrate undergoes a temperature-dependent phase transition from orthorhombic P bca at temperature higher than 220K to monoclinic P2 1 /c at temperature lower than 220K. The crystal structure analyses for data collected at 300 and 203K show that in both temperature structures, there are two conventional intermolecular hydrogen bonds between the hexamethylenetetraminium and water molecule and between 3,5-dinitrobenzote and 3,5-dinitrobenzoic acid in the asymmetric unit. Another conventional intermolecular O–H⋯N hydrogen bonds link the hexamethylenetetraminium and water molecules into chains parallel to the a-direction and stabilized by the 3,5-dinitrobenzoate-3,5-dinitrobenzoic acids. There are also another six weak intermolecular interactions interconnecting the molecules into a three dimensional network. The shorter donor-acceptor distances of the prevailing hydrogen bonds and the two extra weak intermolecular C–H⋯O interactions interconnecting the hexamethylenetetraminium and 3,5-dinitrobenzoate-3,5-dinitrobenzoic acids in the low temperature monoclinic structure are attributable to the reversible temperature-dependent phase transition. [Copyright &y& Elsevier]

Abstract: Two mononuclear [Cu(tren)(dca)]ClO4 (1) and [Zn(tren)(dca)]ClO4 (2) and one dinuclear [Cd2(tren)2(dca)](ClO4)3 (3) [tren=tris(2-aminoethyl)amine; dca=dicyanamide] compounds have been synthesized and characterized using spectroscopic, magnetic and X-ray crystallographic results. Complexes 1 and 2 adopt trigonal bipyramidal geometry with MN5 (M=Cu, Zn) chromophores coordinated through four N atoms of tren and one nitrile N atom of dca. In dinuclear 3, each pentacoordinated cadmium(II) center is in trigonal bipyramidal environment with a CdN5 chromophore coordinated once again by four N atoms of tren and the fifth position of each metal center is occupied by μ1,5 bridged dicyanamide. In the long-range form, complexed cations and counter anions in 1 are engaged in N–H···O, N–H···N and C–H···O hydrogen bondings resulting in a 2D sheet structure parallel to the ac-plane, and in 2 these hydrogen bonds are coupled with C–H···N hydrogen bond leading to a 3D network structure. In 3, cooperative N–H···O and C–H···O hydrogen bonds are seen affording a 3D continuum. [Copyright &y& Elsevier]

The Schiff base, 4-[3-(4-methoxy-phenyl)-allylideneamino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (TPMC/AAP) was synthesized by the condensation of 4-aminoantipyrine (4-amino-1,5-dimethyl-2-phenylpyrazole-3-one) and trans-para-methoxycinnamaldehyde (trans-3,4-methoxyphenyl-2-propenal) in dry methanol at 75 °C. The compound was characterized using elemental microanalysis, IR, NMR, UV spectroscopies and single-crystal X-ray crystallography. The X-ray structure determination shows that the Schiff base, (TPMC/AAP) is orthorhombic with the Pbca space group. The anti-microbial screening of the compound was carried out with Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudemonas aeruginosa, Candida albicans and Aspergillus niger using agar well diffusion method. The Schiff base possesses significant antimicrobial activity. The minimum inhibitory concentration (MIC) of the compound was also determined and the activity was compared with that of conventional drugs ciprofloxacin and ketoconazole. The compound (TPMC/AAP) showed varying activity against the cultured bacteria and fungi used. To complement the experimental data, density functional theory (DFT) was used to have deeper understanding into the molecular parameters and infrared spectra of the compound. [ABSTRACT FROM AUTHOR]

Novel series of 2-(4,6-dimethoxy,1,3,5-triazin-2-yl) amino acid ester derivatives were synthesized using simple one pot method in methanol. The products were obtained in high yields and purities as observed from their spectral data, elemental analyses, GC–MS and X-ray crystallographic analysis. The B3LYP/6-311G(d,p) calculated molecular structures are well correlated with the geometrical parameters obtained from the X-ray analyses. The spectroscopic properties such as IR vibrational modes, NMR chemical shifts and UV–Vis electronic transitions were discussed both experimentally and theoretically. The IR vibrational frequencies showed good correlations with the experimental data (R 2 = 0.9961–0.9995). The electronic spectra were assigned based on the TD-DFT results. Intense electronic transition band is calculated at 198.1 nm (f = 0.1389), 204.2 nm (f = 0.2053), 205.0 (f = 0.1704) and 205.7 (0.2971) for compounds 6a–i , respectively. The molecular orbital energy levels contributed in the longest wavelength transition band were explained. For all compounds, the experimental wavelengths showed red shifts compared to the calculations due to the solvent effect. The NMR chemical shifts were calculated using GIAO method. The NBO analyses were performed to predict the stabilization energies due to the electron delocalization processes occur in the studied systems. [ABSTRACT FROM AUTHOR]

Synthesis of (±)-1,3-dimethyl-5-(1-(3-nitrophenyl)-3-oxo-3-phenylpropyl)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione ( 3 ) is reported. The structure of compound 3 was deduced by using spectroscopic methods, X-ray crystallography, and DFT calculations. The calculated geometric parameters were found to be in good agreement with the experimental data obtained from the X-ray structure. The NBO calculations were performed to predict the natural atomic charges at the different atomic sites and to study the different intramolecular charge transfer (ICT) interactions. The high LP(3)O6 →z BD*(2)O5–N3 ICT interaction energy (165.36 kcal/mol) indicated very strong n → π* electron delocalization while the small LP(2)O → BD*(1)C–H ICT interaction energies indicated that the C–H … O intramolecular interactions are weak. The 1 H and 13 C NMR chemical shifts calculated using GIAO method showed good agreement with the experimental data. The calculated electronic spectra of the studied compound using TD-DFT method showed intense electronic transition band at 243.9 nm (f = 0.2319) and a shoulder at 260.2 nm (f = 0.1483) which were due to H-4/H-2/H-1/H → L+2 and H-5 → L electronic excitations, respectively. Compound 3 (IC 50 = 305 ± 3.8 μ M) was identified as a potent inhibitor of α -glucosidase in vitro and showed several fold more inhibition than the standard drug acarbose (IC 50 = 841 ± 1.73 μ M). Molecular docking of the synthesized compound was discussed. [ABSTRACT FROM AUTHOR]

The synthesis and spectral characterization of the 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione; 3 was reported. The solid state molecular structure of 3 was studied using X-ray crystallography. The relative stabilities of the seven possible isomers of 3 were calculated by DFT/B3LYP method using 6-311G(d,p) basis set. The calculated total energies and thermodynamic parameters were used to predict the relative stabilities of these isomers. The effect of solvent polarity on the relative stability of these isomers was studied at the same level of theory using PCM. It was found that the keto form, (T0), is the most stable isomer both in the gaseous state and solution. In solution, the calculated total energies of all isomers are decreased indicating that all isomers are stabilized by the solvent effect. The vibrational spectra of the most stable isomer, 3 (T0) are calculated using the same level of theory and the results are compared with the experimentally measured FTIR spectra. Good correlation was obtained between the experimental and calculated vibrational frequencies ( R 2 = 0.9992). The electronic spectra of 3 (T0) in gas phase as well as in solutions were calculated using the TD-DFT method. All the predicted electronic transitions showed very little spectral shifts and increase in the intensity of absorption due to solvent effect. Also the 1 H- and 13 C-NMR chemical shifts of the stable isomer were calculated and the results were correlated with the experimental data. Good correlations between the experimental and calculated chemical shifts were obtained. [ABSTRACT FROM AUTHOR]

Synthesis, characterization, and anti-Candida activity of ({(E)-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]amino}oxy)(4-nitrophenyl)methanone (4) are reported. Compound 4 showed anti-Candida albicans activity (MIC = 0.6862 µmol/mL) being nearly 5-fold more potent than the gold standard antifungal drug, fluconazole (MIC > 3.265 µmol/mL), on the clinical isolates of Candida albicans. Single crystal X-ray structure of the title compound 4 confirmed its assigned (E)-configuration. The compound crystallizes in the triclinic, P-1 (no. 2), a = 6.4633 (1) Å, b = 11.1063 (2) Å, c = 12.9872 (2) Å, α = 67.650 (1)°, β = 86.415 (1)°, γ = 86.776 (1)°, V = 860.01 (3)ų, Z = 2, R(F) = 0.046, wR(F²) = 0.139, T = 296 K. The crystal structure is stabilized by weak intermolecular C--H•••O hydrogen interactions. [ABSTRACT FROM AUTHOR]

Abstract: A new coumarin containing rhodamine architecture has been synthesized for selective and chromogenic detection of Cu2+ in aqueous media. Cu2+ induced spirocyclic ring opening of the rhodamine dye has been demonstrated by single crystal X-ray structures of the fluorescence probe as well as its bound Cu2+-complex. It is also promising as a Cu2+-selective sensor in the fluorescence imaging of living cells. [Copyright &y& Elsevier]

Abstract: Eleven new diterpenoids: pimaranes (1,2), rosanes (3) abietanes (4–7), icetexanes (8), and rearranged icetexanes (9–11), together with fifteen known diterpenes (12–26) and two known sesquiterpenes (27,28) have been isolated from the roots and twigs of Premna obtusifolia. The structures of these compounds were elucidated on the basis of spectroscopic analysis and X-ray crystallographic data of 8 and 9 were also determined. The antibacterial and anti-inflammatory activities of the isolates were evaluated. [Copyright &y& Elsevier]

Abstract: Five trinuclear substituted complexes of the type Ru3(CO)11L, Ru3(CO)10L2 and Ru3(CO)9L3 were synthesised by the reaction of Ru3(CO)12 with fluorine substituted phosphine ligands, {P(C6H4F-m)3 and P(C6H4F-p)3}, using the radical anion catalysed method. The structures of the resulting clusters were elucidated by means of elemental analyses and spectroscopic methods, which included IR, 1H, 13C and 31P NMR spectroscopy. X-ray crystallographic studies of four of the complexes were carried out. In all the complexes, the ligand occupies an equatorial position due to steric reasons, and coordination of the ligand is observed only at the phosphorus atom. In the two monosubstituted complexes, Ru3(CO)11P(C6H4F-m)3 and Ru3(CO)11P(C6H4F-p)3, the effect of substitution resulted in an increase in the Ru–Ru distances. Out of the three Ru–Ru bonds, the one which is cis to the ligand is noticeably longer than the other two. The asymmetric unit of the disubstituted complex Ru3(CO)10{P(C6H4F-p)3}2 is composed of two molecules, A and B. As expected, the two phosphorus ligands are equatorially bonded to two different ruthenium atoms. The asymmetric unit of the trisubstituted complex is composed of one molecule of Ru3(CO)9{P(C6H4F-m)3}3 and one disordered solvent molecule. The structure consists of one triangular ruthenium complex in which each of the phosphorus ligands is equatorially bonded to three different ruthenium atoms. In the structure, disorder of the fluorine atoms is observed. Bond parameters, especially bond lengths and bond angles, are correlated to the structure and also are compared with the literature data of similar compounds. [Copyright &y& Elsevier]

The title compound, C14H12OS, crystallizes with the two independent mol­ecules in the asymmetric unit. All bond lengths and angles in both mol­ecules show normal values. No inter­molecular hydrogen bonds or short contacts are found in the crystal structure. [ABSTRACT FROM AUTHOR]

Abstract: Four lead(II) complexes with substituted 2,2′-bipyridine adducts and β-diketonates ligands, [Pb(5,5′-dm-2,2′-bpy)(tfpb)2]2 1, [Pb(4,4′-dmo-2,2′-bpy)(tfpb)2]2 2, [Pb(4,4′-dm-2,2′-bpy)(tfnb)2]2 3 and [Pb(5,5′-dm-2,2′-bpy)(tfnb)2]2 4, (“4,4′-dm-2,2′-bpy”, “5,5′-dm-2,2′-bpy”, “4,4′-dmo-2,2′-bpy”, “Htfpb” and “Htfnb” are the abbreviations of 4,4′-dimethyl-2,2′-bipyridine, 5,5′-dimethyl-2,2′-bipyridine, 4,4′-dimethoxy-2,2′-bipyridine, 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, respectively) have been synthesized and characterized by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy and also studied by thermal and electrochemical as well as X-ray crystallography. The supramolecular features in these complexes are guided/controlled by weak directional intramolecular interactions. [ABSTRACT FROM AUTHOR]

Abstract: The syntheses, structures and spectroscopic properties of tricarbonylrhenium(I) complexes with N,N′-bis(2-bromo, 4-bromo, 4-chloro and 3-methoxybenzaldehyde)-1,2-diiminoethane Schiff base ligands have been investigated in this paper. Characterization of these complexes was carried out with FTIR, NMR, UV–Vis spectroscopy, elemental analysis and X-ray crystallography. The electrochemical behavior of the investigated complexes has been studied by cyclic voltammetry. The crystal structures of the 4-chloro, 4-bromo and 4-methoxy substituted complexes are stabilized by intermolecular C–H⋯Cl and C–H⋯O hydrogen bonds. The remarkable features of the 2-bromo, 4-bromo and 4-chloro substituted complexes are short intermolecular halogen–oxygen contacts. In the 4-bromo complex, short intermolecular Br⋯O and O⋯O contacts link neighboring molecules along the [100] direction, which are further stabilized by short intermolecular π⋯π interactions. In 2-bromo complex, intermolecular Br⋯O interactions link neighboring molecules into 1D extended chains along the [010] and [001] directions, forming a 2D network which is parallel to the bc-plane. [Copyright &y& Elsevier]

Abstract: A tetracoordinated [Hg2(L1)(SCN)4] (1) [L1 =N,N′-(bis-(pyridin-2-yl)benzylidene)-1,2-ethanediamine] and two pentacoordinated [Hg2(L2)(X)4] [L2 =N-((1-pyridin-2-yl)formylidene)-N′-[2-(4-{2-[((1-pyridin-2-yl)formylidene) amino]ethyl}piperazin-1-yl)ethyl]amine; X= , (2) and X=NCS−, (3)] dinuclear mercury(II) compounds have been prepared and characterized using microanalytical, spectroscopic, thermal and X-ray crystallographic results. Structural analyses reveal bis(bidentate) congregation behaviour of classical tetradentate L1 and bis(tridentate) character of L2 encapsulating two metal centers. Each mercury(II) center in 1 is in a distorted tetrahedral coordination environment with HgN2S2 chromophore. Hg(1) is attached with two N atoms of L1 and two S atoms of two terminal thiocyanates whereas neighbouring Hg(1) is ligated to the other two N donor set of the same Schiff base completing its bis(bidentate) mode and two S atoms of thiocyanates. In 2 and 3 each mercury(II) center adopts a distorted square pyramidal geometry with MN5 (in 2) and MN3S2 (in 3) chromophores and two metal(II) centers are encapsulated by bis(tridentate) congregation behaviour of L2 through donation of three N donor set to each metal and the fourth and fifth positions are occupied by two N atoms of terminal azides in 2 and two S atoms of terminal thiocyanates in 3. In solid-state, dinuclear units of 1 pack through cooperative C–H⋯N and C–H⋯S hydrogen bonds and C–H⋯π interactions giving rise to a 3D network. Individual dinuclear units of 2 and 3 self-assemble through cooperative C–H⋯N hydrogen bondings and C–H⋯π interactions affording 3D network structure and 2D continuum, respectively. In DMF solutions at room temperature all the complexes display high-energy intraligand 1(π–π∗) fluorescence. [Copyright &y& Elsevier]

Abstract: Reactions with NiII of a hexadentate Schiff base ligand, L, prepared from the reaction of 2-benzoylpyridine with N,N′-bis-(3-aminopropyl) ethylenediamine in the 2:1 molar ratio are reported. Mixing of this ligand with Ni(NO3)2 affords the mononuclear complex [NiL](NO3)2 (1), whereas the presence of NaN3 in the reaction system leads to the formation of the dinuclear complex [Ni2(L)(N3)4] (2). Both adducts have been characterized by X-ray crystallography revealing distorted octahedral NiN6 coordination environments around the NiII centers. The dinuclear complex contains terminal and end-on bridging azido ligands and displays Ni–N–Ni bridge angles of 101.1(2)° and 101.6(2)° and an intramolecular Ni⋯Ni separation of 3.330(1)Å. The bridges mediate ferromagnetic magnetic exchange interactions between the NiII centers of 2, leading to an S =2 ground state. Fitting of bulk magnetization data provided the coupling constant J =+20.96cm3 Kmol−1 (in the H =−2JS 1 · S 2 convention for the Heisenberg Spin Hamiltonian), as well as the parameters g =2.17, D =0.69cm−1 and TIP=622×10−6 cm3 mol−1. [Copyright &y& Elsevier]

In the title compound, C16H19NO3S, the dihedral angle between the benzene and phenyl rings is 54.17 (6)°. In the crystal structure, the mol­ecules are linked into a two-dimensional network parallel to the (001) plane by N—H⋯O and O—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]