Synthesis and anticancer activities of 1,4-phenylene-bis-<Emphasis Type="Italic">N</Emphasis>-acetyl- and <Emphasis Type="Italic">N</Emphasis>-phenylpyrazoline derivatives

Novel 1,4-phenylene-bis-N-acetyl- (3a–h) and bis-N-phenylpyrazoline derivatives (4a–h) were obtained by addition of hydrazine hydrate and phenylhydrazine to bis-chalcone derivatives (1a–h) in acetic acid and acetic acid/ethanol for 4 and 8 h in reflux conditions, respectively. The structures of the obtained bis-N-acetylpyrazoline and bis-N-phenylpyrazoline derivatives were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic methods and elemental analysis. Compounds 3a–h and 4a–h were investigated to evaluate their anticancer activities against C6 (rat brain tumor cells) and HeLa (human uterus carcinoma) in vitro using a dose-dependent assay from 5 to 100 μM with 5-fluorouracil (5-FU) as standard anticancer drug. Compound 3a showed higher cell-selective activity compared with 5-FU against HeLa cells. Compounds 3a–h (except 3d) were shown to have better activities than 5-FU against both cells, particularly at high concentration. Compound 4c showed higher cell-selective activity compared with 5-FU against C6 cells. Compound 3a may be particularly promising as an anticancer drug against HeLa cells.     

Synthesis and in vitro anticancer,antibacterial, and antioxidant studies of unsymmetrical Schiff base derivatives of 4-[(1<Emphasis Type="Italic">E</Emphasis>)-<Emphasis Type="Italic">N</Emphasis>-(2-aminoethyl)ethanimidoyl]benzene-1,3-diol

Schiff bases such as 2-hydroxy-1-(4-hydroxyphenyl)ethanone (DHAP) and its derivatives have attracted attention because they are useful in design and development of novel organic compounds for potential pharmaceutical applications. In this work, a series of 4-[(1E)-N-(2-aminoethyl)ethanimidoyl]benzene-1,3-diol (4a–h) Schiff bases were synthesized by reaction of ethylenediamine, DHAP, and appropriate aldehyde moieties. The compositions of the prepared compounds were established using elemental analysis and Fourier-transform infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopies. The compounds were screened against three Gram-positive and three Gram-negative bacteria, and the results compared with standard drugs ciprofloxacin and amoxicillin. Compounds 4g, 4h were found to have higher activity against Staphylococcus aureus with minimum inhibitory concentration (MIC) value of 2.5 mg/mL, while compounds 4f and 4h inhibited Escherichia coli with MIC values of 2.5 and 5 mg/mL, respectively. The IC₅₀ values of compounds 4a–h for scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical ranged from 2.63 ± 0.79 to 3.85 ± 0.83 µM with good correlation coefficient of R ² = 0.957–0.994. In vitro anticancer screening of the compounds showed that compounds 4f, 4h, and parthenolide efficiently affected cell viability of cancer cell line MCF-7 with IC₅₀ values of 4.10 ± 1.32, 4.01 ± 2.26, and 0.44 ± 2.02 µM, respectively.     

Synthesis and characterization of half-sandwich ruthenium(II) complexes with N-alkyl pyridyl-imine ligands and their application in transfer hydrogenation of ketones

A series of new arene ruthenium(II) complexes were prepared by reaction of ruthenium(II) precursors of the general formula [(η⁶-arene)Ru(μ-Cl)Cl]₂ with N,N′-bidentate pyridyl-imine ligands to form complexes of the type [(η⁶-arene)RuCl(C₅H₄N-2-CH=N-R)]PF₆, with arene = C₆H₆, R = iso-propyl (1a), tert-butyl (1b), cyclohexyl (1c), cyclopentyl (1d) and n-butyl (1e); arene = p-cymene, R = iso-propyl (2a), tert-butyl (2b). The complexes were fully characterized by ¹H NMR and ¹³C NMR, UV–Vis and IR spectroscopies, elemental analyses, and the single-crystal X-ray structures of 2a and 2b have been determined. The single-crystal molecular structure revealed both compounds with a pseudo-octahedral geometry around the Ru(II) center, normally referred to as a piano stool conformation, with the pyridyl-imine as a bidentate N,N ligand. The activity of all complexes in the transfer hydrogenation of cyclohexanone in the presence of NaOH and iso-propanol is reported, the compounds showing turnover numbers of close to 1990 and high conversions. Complex 2b was also shown to be very effective for a range of aliphatic and cyclic ketones, giving conversions of up to 100 %.     

Structural systematics and conformational analyses of an isomer grid of nine tolyl-<Emphasis Type="Italic">N</Emphasis>-pyridinylcarbamates

A 3 × 3 isomer grid of nine Methylphenyl-N-pyridinylcarbamates (CxxM) is reported with seven CxxM crystal structures at 294 K (xx = pp, pm, po, mp, op, om, oo; x = para-, meta-, ortho), where Cx = pyridinyl ring (as C₅NH₄NH-) and xM is representative of –C(=O)OC₆H₄CH₃. All seven carbamate crystal structures aggregate via N–H…N intermolecular interactions with the three CpxM carbamates having C(6) zigzag chains, CmpM with C(5) zigzag chains and three ortho-pyridine CoxM structures as hydrogen-bonded dimers with graph set \(R_{2}^{2}\) (8) and augmented by flanking C–H…O contacts. The CpoM crystal structure crystallises with 0.25 CHCl₃ per carbamate molecule and solvent channels aligning along the a-axis direction. Conformational analyses of the nine minimised CxxM structures in gas phase are detailed for comparisons with the solid-state structures and demonstrate similarities between both structural methods. The modelling results also demonstrate the problems associated with pendant ortho-groups sterically clashing in the CmoM and CooM structures and methods to find a reasonable estimate of the CxxM conformational landscape.     

The role of substituents in a bidentate <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-chelating ligand on the substitution of aqua ligands from mononuclear Pt(II) complexes

The rate of substitution of aqua ligands from three mononuclear platinum(II) complexes, namely [Pt{2-(pyrazol-1-ylmethyl)pyridine}(H₂O)₂](ClO₄)₂, [Pt(H ₂ Py)]; [Pt{2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine}(H₂O)₂](ClO₄)₂, [Pt(dCH ₃ Py)] and [Pt{2-[(3,5-bis(trifluoromethyl)pyrazoly-1-ylmethyl]pyridine}(H₂O)₂](ClO₄)₂, [Pt(dCF ₃ Py)] by thiourea, N,N-dimethylthiourea and N,N,N′,N′-tetramethylthiourea, was studied in aqueous perchloric acid medium of constant ionic strength. The substitution reactions were investigated under pseudo-first-order conditions as a function of nucleophile concentration and temperature using UV/Visible and stopped-flow spectrophotometries. The observed pseudo-first-order rate constants, \( k_{{{\text{obs }}\left( {1/2} \right)}} \), for the stepwise substitution of the first and second aqua ligands obeyed the rate law: \( k_{{{\text{obs}}\left( {1/2} \right)}} = k_{{2 \left( { 1 {\text{st/2nd}}} \right)}} \left[ {\text{Nu}} \right] \). The first substitution reaction takes place trans to the pyrazole ligand, while the second entering nucleophile is stabilised at the reaction site trans to the pyridine ligand. The rate of substitution of the first aqua ligand from the complexes followed the order: Pt(dCF ₃ Py) > Pt(H ₂ Py) > Pt(dCH ₃ Py), while that of the second was Pt(H ₂ Py) ≈ Pt(dCF ₃ Py) > Pt(dCH ₃ Py). Lower pK _a values were found for the deprotonation of the aqua ligand cis to the pyrazole ring. Density functional theory calculations were performed to support the interpretation of the experimental results.     

Syntheses,structures, and solid-state phosphorescence characteristics of <Emphasis Type="Italic">trans</Emphasis>-bis(salicylaldiminato)Pt(II) complexes bearing perpendicular <Emphasis Type="Italic">N</Emphasis>-aryl functionalities

The syntheses, structures, and solid-state emission characteristics of trans-bis(salicylaldiminato)Pt(II) complexes bearing N-aromatic functionalities are described herein. A series of Pt complexes bearing various N-phenyl (1) and N-(1-naphthyl) (2) groups on the salicylaldiminato ligands were prepared by reacting PtCl₂(CH₃CN)₂ with the corresponding N-salicylidene aromatic amines, and the trans-coordination and crystal packing of these complexes were unequivocally established based on X-ray diffraction (XRD). Complexes with 2,6-dimethylphenyl (1c), 2,6-diisopropylphenyl (1d), 1-naphthyl (2a), and 1-(2-methylnaphthyl) (2b) groups on the N atoms exhibited intense phosphorescent emission at ambient temperature in the crystalline state, while those with phenyl (1a), 2,6-dibromophenyl (1b), and 2,6-bis(N,N-dimethylamino)phenyl (1e) functionalities were either less emissive or non-emissive under the same conditions. XRD analyses identified significant intramolecular interactions between Pt and H atoms of the N-aryl functionalities in the emissive crystals of 1c, 1d, and 2a. These interactions were evidently an important factor associated with intense emission at ambient temperature.     

Molecular and crystal structure of 15-acetylsongorine and songoramine isolated from <Emphasis Type="Italic">Aconitum szechenyianum</Emphasis> Gay

Two napelline skeletal diterpenoid alkaloids 15-acetylsongorine, C₂₄H₃₃NO₄ I, and songoramine, C₂₂H₂₉NO₃ II, were first isolated from the roots of Aconitum Szechenyianum Gay. The crystal structures were determined by X-ray single-crystal diffraction analysis. The crystal I is the triclinic system with space group P1 having unit cell parameters of a = 9.360(8) Å, b = 11.593(9) Å, c = 11.830(16) Å, α = 113.223(15)°, β = 105.950(16)°, γ = 101.296(12)°, and Z = 2. Hydrogen bonds O–H···O and O–H···N joint the molecules into dimer. The crystal II belongs to the orthorhombic system with space group P2₁2₁2₁ having unit cell parameters of a = 8.950(2) Å, b = 13.272(3) Å, c = 15.454(4) Å and Z = 4. The O–H···O hydrogen bonding interaction links the molecule into linear chains. The distortion of rings of compound I and II were evaluated by calculation of the Cremer and Pople puckering parameters. The presence of the C–O–C bond in the compound II results in the changes of ring conformations compared with that of the compound I.     

Synthesis,crystal and molecular structures of 1D and 2D supramers of copper(II) with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-{bis(pyridin-2-yl) benzylidene}butane-1,4-diamine

Reaction of copper(II) perchlorate with N,N′-{bis(pyridin-2-yl)benzylidene}butane-1,4-diamine (bpbd) yielded monoclinic crystals of bluish green [Cu(bpbd)(ClO₄)]ClO₄ (1), and a similar reaction in presence of azide anion, N₃ ^? formed monoclinic crystals of dark green [Cu(bpbd)(N₃)]₂ClO₄ (2). Crystal data for 1: space group P21/c, Z=4, a=17.3968(4) Å, b=9.3182(2) Å, c=17.6794(4) Å, β=102.149(1)°. The geometry around Cu(II) centre is distorted square pyramidal with axial site occupied by O atom of perchlorate and in plane Cu is bonded to four N atoms of the organic ligand. The intermolecular C–H...π stacking in 1 forms a zigzag chain (1D) supramer. Crystal data for 2: space group C2/c, Z=4, a=22.3109(4) Å, b=17.7832(3) Å, c=14.3389(2) Å, β=92.553(1)°. In dinuclear 2, Cu(II) has tetragonally distorted octahedral geometry coordinated by four N atoms of bpbd, with the fifth and sixth positions occupied by N atoms of two end-on bridging azides. The π...π interaction leads to a two dimensional (2D) sheet within which the counter anions are embedded. Both the compounds 1 and 2 show simple paramagnetism. Cyclic voltammetry and fluorescence spectra are also reported.     

Phosphorus–nitrogen compounds part 33: in vitro cytotoxic and antimicrobial activities,DNA interactions,syntheses, and structural investigations of new mono(4-nitrobenzyl)spirocyclotriphosphazenes

The condensation reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with N-alkyl-N′-mono(4-nitrobenzyl)diamines (1–3), NO₂PhCH₂NH(CH₂) _n NHR₁ (R₁ = CH₃ or C₂H₅), led to the formation of the mono(4-nitrobenzyl)spirocyclotriphosphazenes (4–6). The tetra-pyrrolidino (4a–6a), piperidino (4b–6b), and 1,4-dioxa-8-azaspiro[4,5]decaphosphazenes (4c–6c) were prepared from(for) the reactions of partly substituted compounds (4, 5, and 6) with excess pyrrolidine, piperidine, and 1,4-dioxa-8-azaspiro[4,5]decane (DASD), respectively. The partly substituted geminal (4d and 5d) and cis-morpholino (6d) phosphazenes were isolated from the reactions of excess morpholine in boiling THF and o-xylene, but the expected fully substituted compounds were not obtained. The structures of all the phosphazene derivatives were determined by elemental analyses, MS, FTIR, ¹H, ¹³C{¹H}, ³¹P{¹H} NMR, HSQC, and HMBC techniques. The crystal structures of 4, 6, 4a, and 5a were verified by X-ray diffraction analysis. In addition, in vitro cytotoxic activities of fully substituted phosphazenes (4a–6c) against HeLa cervical cancer cell lines (ATCC CCL-2) and the compounds 4a and 4c against breast cancer cell lines (MDA-MB-231) and L929 fibroblast cells were evaluated, respectively. Apoptosis effect was determined by MDA-MB-231 cancer cell lines and fibroblast cells. The MIC values of the compounds were in the ranges of 9.8–19.5 µM. The compounds 6, 5a, 6a, 5b, and 6d have greater MIC activity against bacterial and yeast strain. The investigation of DNA binding with the phosphazenes was studied using plasmid DNA. The phosphazene derivatives inhibit the restriction endonuclease cleavage of plasmid DNA by BamHI and HindIII enzymes. BamHI and HindIII digestion results demonstrate that the compounds bind with G/G and A/A nucleotides.     

<Emphasis Type="Italic">cis</Emphasis>-Dioxomolybdenum(VI) complexes of sterically encumbered phenol-based tetradentate N<Subscript>2</Subscript>O<Subscript>2</Subscript> ligands: Structural,spectroscopic, and electrochemical studies

Two cis-dioxomolybdenum(VI) complexes [MoO₂L] (L: L ¹, 2 and L: L ², 3) in a phenol-based sterically encumbered N₂O₂ ligand environment have been synthesized, and their crystallographic characterizations are reported. The orange crystals of 2 are monoclinic, space group P2₁/a with unit cell dimensions as a=16.2407(17) Å, b=7.2857(8) Å, c=18.400(2) Å, β=98.002(9)°, Z=4, and d _cal=1.486 g cm^?3. The light orange crystals of 3, however, are orthorhombic, space group, Pbcn, with unit cell dimensions a=8.3110(12) Å, b=12.637(3) Å, c=34.673(5) Å, Z=4, and d _cal=1.187 g cm^?3. The structures were refined by a full-matrix least-squares procedure on F ² to a final R=0.046 (0.055 for 3) using 4944 (3677) all independent data. In both the cases, the Mo atom exists in a distorted octahedral geometry defined by a N₂O₄ donor set, which features a cis-Mo(–O)₂ and a trans-Mo(OPh)₂ arrangement. Compound 2 undergoes a quasireversible one-electron reduction at ?1.3 V vs Ag/AgCl reference due to Mo^VIO₂/Mo^VO₂ electron transfer and thus providing a rare example of steric solution to the comproportionation–dimerization problem encountered frequently in the development of valid biomimetic models for the active sites of oxomolybdenum enzymes.     

Effective reduction of <Emphasis Type="Italic">p</Emphasis>-nitrophenol catalyzed by nickel(II) adamantane complexes

Two Ni(II) adamantane complexes, [Ni(bqad)Cl₂] (1) and [Ni(bpad)(dmbp)(H₂O)](ClO₄)₂·CH₃OH H₂O (2) (bqad = N,N′-bis(2-quinolinylmethyl) amantadine, bpad = N,N′-bis(2-pyridylmethyl)amantadine, dmbp = 5,5′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, infrared spectroscopy and single crystal X-ray diffraction. The nickel centers in complex 1 have a distorted tetragonal pyramidal geometry, while the coordination polyhedron of 2 can be described as a distorted octahedron. The reaction kinetics for reduction of p-nitrophenol to p-aminophenol catalyzed by these complexes has been investigated by UV–visible spectrophotometry. Complex 1 exhibits a higher turnover frequency of 1.4 min^?1 for the reduction of p-nitrophenol.     

Amberlyst-15 catalyzed synthesis of novel thiophene–pyrazoline derivatives: spectral and crystallographic characterization and anti-inflammatory and antimicrobial evaluation

Increasing instances of antimicrobial drug resistance and Inflammation-mediated disorders requires the design and synthesis of new small-molecules with higher affinity and specificity for their potential targets to serve as antibiotics or anti-inflammatory drugs, respectively. The current study presents the synthesis of a series of chalcones, 3(a–h) by the reaction of 3-methylthiophene-2-carbaldehyde, 1 and acetophenones, 2(a–h) by Claisen–Schmidt approach. The chalcones were efficiently transformed into thienyl-pyrazolines, 5(a–h) by their reaction with thiosemicarbazide hydrochloride, 4 in the presence of Amberlyst-15 as a catalyst in acetonitrile at room temperature. Alternatively, the compounds 5(a–h) were prepared by conventional method using acetic acid (40%) medium. Structures were characterized by spectral and single crystal X-ray diffraction studies. Preliminary assessment of the anti-inflammatory properties of the compounds showed that, amongst the series, compounds 5b and 5c have excellent anti-inflammatory activities. Further, compound 5c showed excellent activity against Escherichia coli (MIC, 15 µg/mL), Bacillus subtilis (MIC, 20 µg/mL), Aspergillus niger (MIC, 20 µg/mL), and Aspergillus flavus (MIC 15 µg/mL), respectively. Compounds 5a and 5b were also found to be active against the tested microorganisms.     

Synthesis of novel 2-phenoxybenzo[<Emphasis Type="Italic">g</Emphasis>][1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazoline and its derivatives starting with diphenyl-<Emphasis Type="Italic">N</Emphasis>-cyanoimidocarbonate

Cyclocondensation reaction of 3-hydrazinyl-2-naphthoic acid with diphenyl-N-cyanoimidocarbonate furnished the target 2-phenoxy-benzo[g][1,2,4]triazolo[1,5-a]quinazolin-5(4H)-one (1) in high yield. Alkylation, thionation and chlorination of the lactam group in the compound 1 produced a variety of derivatives 2–17. Their structures were characterized by NMR and HREI-MS analyses.     

Structure of methyl-7-methoxy-7-phenyl-6-<Emphasis Type="Italic">endo</Emphasis>-halobicyclo[3.1.1]heptane-6-<Emphasis Type="Italic">exo</Emphasis>-carboxylate diastereomers in single crystals

The structure of diastereomeric methyl-7-anti-methoxy-7-syn-phenyl-and methyl-7-syn-methoxy-7-anti-phenyl-6-endo-bromobicyclo[3.1.1]heptane-6-exo-carboxylates 2a and 3a and their chlorine-and iodine-substituted analogs 2b and 3c was studied by XRD. The diastereomers differ in the geometrical parameters of the carbon framework of the molecules. The C(1)-C(2)-C(3)-C(4)-C(5)-C(6) six-membered ring is in the intermediate conformation between envelope and chair in structures 2 and envelope in structures 3. In compound 2a, the cyclobutane fragment has a higher degree of folding than in 3a; one of the possible reasons for that is the donor-acceptor interaction between the 6-methoxycarboxylic and 7-methoxy groups in molecule 2a.     

Synthesis and crystal structures of tetraacetylethylenediamine and <Emphasis Type="Italic">N</Emphasis>-(2-ammoniumethyl)carbamate

Two ethylenediamine derivatives—N-(2-ammoniumethyl)carbamate HN(COO^?)CH₂CH₂N⁺H₃ (I) and tetraacetylethylenediamine (H₃CC(O))₂NCH₂CH₂N(C(O)CH₃)₂ (II) (synthesized for the first time)—have been synthesized and characterized by X-ray crystallography. Compounds I and II are isolated as minor admixtures upon an attempt to synthesize ethylenediamine complexes of lanthanum and neodymium nitrates, respectively. The crystals of I and II are monoclinic: a = 7.778 Å, b = 8.060 Å, c = 7.568 Å, β = 95.73°, Z = 4, space group P2₁/c (I); a = 5.946, b = 10.255, c = 9.343 Å, β = 95.72°, Z = 2, space group P2₁/c (II). The bond lengths and bond angles lie within the corresponding standard values. Compounds I and II have different conformations of the N-C-C-N ethylenediamine moiety: gauche in I and trans in II, and the corresponding torsion angles are equal to 66.6° and 180°, respectively.     

Palladium clusters Pd<Subscript>4</Subscript>(SR)<Subscript>4</Subscript>(OAc)<Subscript>4</Subscript> and Pd<Subscript>6</Subscript>(SR)<Subscript>12</Subscript> (R = Bu,Ph): Structure and properties

The structures of the Pd₄(SBu)₄(OAc)₄ (I) and Pd₆ (SBu)₁₂ (II) palladium clusters are determined by the X-ray diffraction method. For cluster I: a = 8.650(2), b = 12.314(2), c = 17.659(4) Å, α = 78.03(3)°, β = 86.71(2)°, γ = 78.13(3)°, V = 1800.8(7) ų, ρcalcd = 1.878 g/cm³, space group P \(\bar 1\), Z = 4, N = 3403, R = 0.0468; for structure II: a = 10.748(2), b = 12.840(3), c = 15.233(3) Å, α = 65.31(3)°, β = 70.10(3)°, γ = 72.91(3)°, V = 1767.4(6) ų, ρ calcd = 1.605 g/cm³, space group P \(\bar 1\), Z = 1, N = 3498, R = 0.0729. In cluster I, four Pd atoms form a planar cycle. The neighboring Pd atoms are bound by two acetate or two mercaptide bridges (Pd…Pd 2.95–3.23 Å, Pd…Pd angles 87.15°–92.85°). In cluster II, the Pd atoms form a planar six-membered cycle with Pd···Pd distances of 3.09–3.14 Å, the PdPdPd angles being 118.95°–120.80°. The Pd atoms are linked in pairs by two mercaptide bridges. The formation of clusters I and II in solution is proved by IR spectroscopy and calorimetry. Analogous clusters are formed in solution upon the reaction of palladium(II) diacetate with thiophenol.     

Synthesis,spectroscopic characterization,crystal structures,and theoretical studies of (<Emphasis Type="Italic">E</Emphasis>)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone and (<Emphasis Type="Italic">E</Emphasis>)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone

Two thiosemicarbazones, (E)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone (24-MBTSC (1)) and (E)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone (25-MBTSC (2)), derived from 2,4-dimethoxybenzaldehyde and 2,5-dimethoxybenzaldehyde, respectively, with thiosemicarbazide have been synthesized and their structures were characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, and X-ray single-crystal diffraction analysis. Molecular orbital calculations have been carried out for 1 and 2 by using an ab initio method (HF) and also density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the monoclinic system, space group P2₁/c, with a = 8.1342(5) Å, b = 18.1406(10) Å, c = 8.2847(6) Å, β = 109.7258(17)°, V = 1150.75(12) Å³, and Z = 4, whereas compound 2 crystallizes in the orthorhombic system, space group Pbca, with a = 11.0868(6) Å, b = 13.1332(6) Å, c = 15.9006(8) Å, V = 2315.2(2) Å³, and Z = 8. The compounds 1 and 2 displays a trans-configuration about the C=N double bond.     

Aggregation in isomeric imides: analysis of the weak interactions in six <Emphasis Type="Italic">N</Emphasis>-(benzoyl)-<Emphasis Type="Italic">N</Emphasis>-(2-pyridyl)benzamides

Crystal structures of 4-chloro-N-(4-chlorobenzoyl)-N-(2-pyridyl)benzamide (I) Clpod, 3-chloro-N-(3-chlorobenzoyl)-N-(2-pyridyl)benzamide (II) Clmod and 2-chloro-N-(2-chlorobenzoyl)-N-(2-pyridyl)benzamide (III) Clood together with three methylated analogues, Mpod, Mmod and Mood, are presented herein. The Clxod acyclic imides are produced from reacting the 4-/3-/2-chlorobenzoyl chlorides (Clx) with 2-aminopyridine (o), respectively, together with their benzamide analogues Clxo; the Mxod/Mxo triad are produced similarly and in good yield. The five Clxod, Mpod and Mmod structures adopt the open transoid conformations as expected, but Mood crystallises with cisoid oriented benzoyl groups, and this conformation was unexpected, though not unknown. Halogen bonding contacts and weak hydrogen bonding C-H···N/O/π contacts are noted in the structures lacking strong hydrogen bonding donor atoms/groups but possessing a variety of strong and weaker acceptor atoms/groups. For Clxod, contact studies show that both hydrogen and carbon account for a high percentage of elements (70–75%) on the molecular surface and being the most abundant have C···H forming 26–30% of the contacts. Contact enrichment ratios are an indicator of the likelihood of chemical species to form intermolecular interactions with themselves and other species. The C-H···N and C-H···O are the most enriched (with E_HN?>?2.15), indicating that these weak hydrogen bonds are the driving force in the Clxod crystal packing formation. For Mxod, the C···H contact type at 40–52% is the most abundant contact type and C-H···O and C-H···N weak hydrogen bonds dominate with enrichment values in the 1.48–1.78 range. In Mxod, N/O···N/O contacts are effectively absent, except for Mpod (0.2%, N···N contacts) and both H···H and C···C non-polar contacts are moderately impoverished while the C···H interactions are slightly enriched (E?=?1.1–1.21).     

Lanthanide contraction effect on the crystal structures of 2D lanthanide coordination polymers based on 2-(trifluoromethyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazole-4,5-dicarboxylic acid

A series of new two-dimensional (2D) lanthanide(III) coordination polymers, namely {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₄] · 2H₂O} _n [Ln = Pr (1); Nd (2); Sm (3); Eu (4); H₃TFMIDC = 2-(trifluoromethyl)-1H-imidazole-4,5-dicarboxylic acid, DMA = N,N′-dimethylacetamide] for type I and {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₂(H₂O)₂] · DMA} _n [Ln = Eu (5); Gd (6)] for type II, have been successfully prepared under solvothermal conditions and structurally characterized for the first time. Both two types of structures exhibit similar 2D honeycomb-like networks, which are constructed by the linkages of μ ₂-HTFMIDC^2? bis-(bidentate) bridging ligands and Ln(III) metal centers. However, slightly different ABAB stacking fashions of the 2D layers and distinctly different hydrogen bonding interactions between the neighboring 2D layers are observed in crystal structures of type I and type II, which may be attributed to the lanthanide contraction effect. Meanwhile, the solid-state luminescent properties of 4 and 5 have been also investigated.     

Co(II) and Ni(II) complexes incorporating <Emphasis Type="Italic">N</Emphasis>-acetimidoylacetamidine ligand: Synthesis and structures

Two new square planar complexes with the formula Co(L)₂ · CH₃OH (1) and Ni(L)₂ · CH₃OH (2) (HL = HN{C(Me)=NH}₂ = N-acetimidoylacetamidine) have been synthesized by solvothermal reactions in methanol/acetonitrile. N-acetimidoylacetamidine ligand was derived from the self-condensation reaction of acetonitrile, and the reaction was promoted by the cooperation of M(II) (M = Co in 1 and M = Ni in 2) with diphenylcarbazide. 1 and 2 are characterized by single crystal X-ray diffraction, elemental analysis and infrared spectrum. Both complexes crystallize in the monoclinic space group P2₁/c with a = 9.329(6) Å, b = 11.494(7) Å, c = 13.040(8) Å, β = 92.945(11)°, V = 1396.3(16) ų and Z = 4 for 1, and a = 9.323(4)Å, b = 11.512(5) Å, c = 13.020(6)Å, β = 92.819(7)°, V = 1395.7(10)ų and Z = 4 for 2.