Ferroelectric liquid crystals with axially chiral 2,2′-spirobiindan-1,1′-dione cores

The axially chiral mesogens 5-alkoxy-5′-[(4-alkoxybenzoyl)oxy]-2,2′-spirobiindan-1,1′-dione (QL7-n) were synthesised as racemic mixtures and resolved as single enantiomers by preparative chiral phase HPLC. The shorter homologues (R)-QL7-8 and QL7-9 form enantiotropic N* and SmC* phases, whereas the longer homologues (R)-QL7-10 and QL7-12 form an enantiotropic SmC* phase only. Texture analysis showed that the helical pitch of the N* phase is below the wavelength range of visible light; a helical pitch of 187 nm was measured at T – T_NI = –5 K by selective reflection using enantiomerically enriched mixtures of (R)- and (S)-QL7-8 (0.35 ≤ ee ≤ 0.80). Spontaneous polarisations were measured as a function of temperature in the SmC* phase by the triangular wave method. P_S values at saturation range from 102 nC cm^–2 for (R)-QL7-8 to 120 nC cm^?2 for (R)-QL7-9, which are up to three times greater than the highest polarisation previously reported for an axially chiral SmC* mesogen. Optical tilt angles θ were measured as a function of temperature and showed a sharp rise consistent with first-order N*–SmC* or I–SmC* transitions, with values at saturation ranging from 42 to 44°.     

CRYSTAL STRUCTURE AND THERMAL ANALYSIS OF A 4,4′-BIPY-BRIDGED BINUCLEAR ZINC(II) COMPLEX, 2[R2NCS2]2 · Zn(4,4′-BIPY) (R=PIPERIDYL)

Abstract

The crystal structure of the title complex 2[R₂NCS₂]₂ · Zn(4,4′-bipy) (R = Piperidyl), 1, revealed that it consists of dimers made up from two crystallographically independent molecules. Each zinc atom in 1 forms a 5-coordinate pseudo-square-based pyramidal arrangement (with four Zn-S and one Zn-N interactions). Bondlengths to Zn with the coordinating atoms are comparable to those in other Zn(II) dithiocarbamate complexes. The piperidine ring has a chair conformation. To allow improved packing, the title complex molecules form an approximately linear arrangement extending along both a and b. TGA showed that 1 is decomposed in two close steps to produce ZnS as identified by residual weight. The complex 1 crystallizes in the monoclinic space group C2/c with cell parameters: a = 22.021(5), b = 22.215(3), c = 17.537(2) Å, β = 93.49(2)°, V = 8563(3) ų and Z = 8. The structure was refined by full-matrix least-squares methods to R = 0.067, R_w = 0.114.     

A new synthesis of 4′-trifluoromethyl-2,2′:6′,2″-terpyridine

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Two coordination polymers based on 2,2′-biimidazoles and d10 metal ions: syntheses,structures, and luminescence

Two d¹⁰ metal coordination polymers, [Zn(µ-Me₂biim)Cl₂] _n (1) and [Cd₃(MeHbiim)₂(1,4-BDC)₃] _n (2) (Me₂biim?=?N,N′-dimethyl-2,2′-biimidazole, MeHbiim?=?N-methyl-2,2′-biimidazole, 1,4-BDC?=?1,4-benzenedicarboxylate), were synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray crystallography. Complex 1 features an infinite neutral zigzag 1-D chain. Interchain hydrogen-bonding interactions further extend the 1-D arrangement to generate a 2-D supramolecular architecture. Complex 2 features a 3-D coordination polymer with α-Po net topology, based on linear trinuclear {Cd₃O₁₄N₄} clusters. Both complexes have high thermal stability and exhibit strong luminescence at room temperature.     

Spectral characterization and biocidal activity of organotin(IV) (E)-3-[(2′,6′-dichlorophenylamido)]propenoates

Biocidal and spectroscopic aspects of organotin(IV) complexes with (E)-3-[(2′,6′-dichlorophenylamido)]propenoic acid are described with support of elemental analysis. IR, ¹H, ¹³C, ¹¹⁹Sn NMR and mass spectral data suggest that the ligand is bidentate, coordinating through oxygen atoms and that diorganotin(IV) complexes are six-coordinate. Triorganotin(IV) carboxylates exist as pentacoordinated trigonal bipyramidal complexes in the solid state and tetrahedral ones in solution. The complexes have been screened against bacteria, fungi and brine-shrimp larvae to assess their biological activity.     

Lead(II) complexes of 2,2′-diamino-4,4′-bithiazole (DABTZ) including crystal structure of a novel 1D chain polymer, [PB(DABTZ)(μ-SCN)(μ-NO3)] n

Three new 2,2′-diamino-4,4′-bithiazole (DABTZ) lead(II) complexes were synthesized and characterized by elemental analyses, IR-, ¹H-NMR-, and ¹³C-NMR-spectroscopy. The single crystal X-ray structural analysis of [Pb(DABTZ)(μ-SCN)(μ-NO₃)] _n shows the complex to be a 1D chain polymer as a result of sequential thiocyanate and nitrate bridging. The Pb atoms are seven-coordinated by two nitrogen atoms of the 2,2′-diamino-4,4′-bithiazole, three nitrate and two thiocyanate ligands. The arrangement of the 2,2′-diamino-4,4′-bithiazole, nitrate and thiocyanate ligands does not suggest a gap in the coordination around the Pb^II ion, caused by a stereo-active lone pair of electrons on lead(II) where the coordination around the lead atoms is the less common holodirected.     

Application of a biological‐based nanomagnetic catalyst in the synthesis of bis‐pyrazols and pyrano[3,2‐c]pyrazoles

{Fe₃O₄@SiO₂@(CH₂)₃‐thiourea dioxide‐SO₃H/HCl}, a newly reported nanomagnetic core–shell supported solid acid catalyst, was successfully employed in the preparation of 4,4′‐(arylmethylene)bis(1H –pyrazol‐5‐ol) and pyrano[3,2‐c ]pyrazole derivatives. The presented methods are very efficient and high‐yielding. Also, the catalyst exhibited powerful potential for reusability in both types of reactions.     

Separation and Analysis of o.p'-DDD and its Lipophilic Metabolite,O.P'-DDE,in Tissue,Faeces and Plasma

Abstract

An analytical procedure based on electron capture gas chromatography for the determination of o,p′-DDD, a drug used for the treatment of Cushing′s syndrome, is presented. Detection of a metabolite, identified as o,p′-DDE, is also described.     

Pharmacological properties of dicyanidoaurate(I)-based complexes: characterization and single crystal X-ray analysis

The synthesis of three bimetallic cyanido complexes with edbea [2,2′-(ethylenedioxy)bis(ethylamine)] ligand is reported. [Ni^II(μ-edbea)₂{Au(μ-CN)₂}₂]_n (1), [{Cu^II(edbea)}₂{Au(μ-CN)₂}₄]_n (2) and [Cd^II(edbea)₂][Au(CN)₂]₂·H₂O (3) were fully characterized by elemental, infrared, XRD (3), ESI-MS and thermal analysis. The DNA/BSA binding properties of these complexes were evaluated by spectrophotometric titration, fluorometric ethidium bromide kinetics, and DNA electrophoresis studies and their partially minor groove binding mode between the base pairs of DNA and electrostatic interaction between the amino acid residues of BSA were explained. The complexes were tested for their pharmacological properties. These molecules had excellent in vitro antiproliferative activity and also exhibited a strong tumor inhibiting effect against HT29, HeLa, C6 and Vero cell lines. These complexes had metastatic features as they are able to reduce cell migration activity and suppress tumor growth in vitro. Analysis of the DNA topoisomerase I relaxing activity indicates that the complexes do not inhibit topoisomerase I which regulates the topological states of the DNA double helix during DNA processing reactions. The TUNEL and DNA laddering assay results indicated that these compounds may destroy cell maintenance by triggering apoptosis. Immunohistochemistry staining analysis demonstrated that these complexes significantly decreased the expression of Bcl-2 in HeLa and HT29 cells while increasing the expression of P53 levels. Overall, the potent antiproliferative activity, low cytotoxic effect, good solubility, and micro molar range dosage observed for these complexes emphasizes their potential as anticancer drug candidates.     

SYNTHESIS AND REACTVITY OF N-[N-PHOSPHORAMIDO-1H-BENZIMIDAZOL-2-YL] IMIDATES

N-(-1H-Benzimidazol-2-yl) imidates 1a–c react with chlorophosphoramide to give the N-[-1-N,N,N′,N′-tetramethylphosphoramidoyl-1H-benzimidazol-2-yl]-imidates 2a–c or with dichlorophosphoramide to yield the bis[(N-1-benzimidazol-2-yl)-imidate] phosphoramide derivatives 3a–b. The reaction of compounds 2a–c toward primary amines is studied. The obtained amidine derivatives 4a–b were unambiguously characterized by different spectroscopic techniques (IR, ¹H, ¹³C, and ³¹P NMR, and in some cases MS).