End-to-end thiocyanato-bridged helical chain polymer and dichlorido-bridged copper(II) complexes with a hydrazone ligand: synthesis, characterisation by electron paramagnetic resonance and variable- temperature magnetic studies, and inhibitory effects on human colorectal carcinoma cells

The reactions of the tridentate hydrazone ligand, N’-[1-(pyridin-2-yl)ethylidene]acetohydrazide (HL), obtained by condensation of 2-acetylpyridine with acetic hyadrazide, with copper nitrate trihydrate in the presence of thiocyanate, or with CuCl2 produce two distinct coordination compounds, namely a one-dimensional helical coordination chain of [CuL(NCS)]n (1) units, and a doubly chlorido-bridged dinuclear complex [Cu2L2Cl2] (2) (where L=CH3C(O)=N − N=CCH3C5H4N). Single-crystal X-ray structural determination studies reveal that in complex 1, a deprotonated hydrazone ligand L- coordinates a copper(II) ion that is bridged to two neighbouring metal centres by SCN- anions, generating a one-dimensional helical coordination chain. In complex 2, two symmetry-related, adjacent copper(II) coordination entities are doubly chlorido-bridged, producing a dicopper entity with a Cu···Cu distance of 3.402 (1). The two coordination compounds have been fully characterised by elemental analysis, spectroscopic techniques including IR, UV– vis and electron paramagnetic resonance, and variable-temperature magnetic studies. The biological effects of 1 and 2 on the viability of human colorectal carcinoma cells (COLO-205 and HT-29) were evaluated using an MTT assay, and the results indicate that these complexes induce a decrease in cell-population growth of human colorectal carcinoma cells with apoptosis

A mixed valent heterometallic Cu-II/Na-I coordination polymer with sodium-phenyl bonds

A mixed valent heterometallic Cu/Na coordination polymer (1) is generated by the reaction of a Schiff base ligand, (6,6′-(1E,1′E)-(2-hydroxypropane-1,3-diyl)bis(azan-1-yl-1-ylidene) bis(methan-1-yl-1-ylidene)bis(2-methoxyphenol)) with copper(ii) acetate and sodium perchlorate. In addition to the presence of alcohol oxygen-sodium coordination bonds, the single crystal X-ray structure reveals that the 1D coordination polymer is stabilised by the formation of phenyl-sodium η-bonds, face-to-face π-π contacts and Cu-π interactions. This journal i

Dichlorido{N′-[1-(2-pyridin-2-yl)ethyl­idene]acetohydrazide-κ2 N′,O}copper(II)

In the title compound, [CuCl2(C9H11N3O)], the CuII atom is in a distorted square-pyramidal CuCl2N2O coordination geometry. The tridentate acetohydrazide ligand chelates in a meridional fashion. The chloride ligand in the axial position forms a long Cu—Cl distance of 2.4892 (9) Å. In contrast, the Cu—Cl distance from the equatorial chloride ligand is much shorter [2.2110 (7) Å]. Inter­molecular N—H⋯Cl and C—H⋯Cl hydrogen bonds link the complexes into a three-dimensional network

Di-μ-azido-bis­({N′-[1-(2-pyrid­yl-κN)ethyl­idene]acetohydrazidato-κ2 N′,O}dicopper(II))

The dimeric title compound, [Cu2(C9H10N3O)2(N3)2], is located on a crystallographic inversion center. The Cu atom is coordinated by a tridentate anionic hydrazone ligand and two bridging azide ligands in a distorted square-pyramidal coordination geometry. The non-bonding Cu⋯Cu distance is 3.238 (1) Å. Non-classical inter­molecular C—H⋯N hydrogen bonds link the dimers into chains along the c axis

An enolato-bridged dinuclear Cu(II) complex with a coumarin-assisted precursor: a spectral, magnetic and biological study

Coumarin assisted dinuclear [Cu2(L)2(DMF)2] (1) shows weak ferromagnetic interaction and a geometric distortion occurs while lowering the temperature in EPR

A Ni(II) dinuclear complex bridged by end-on azide-N and phenolate-O atoms: spectral interpretation, magnetism and biological study

A new dinuclear complex, [Ni(L)(μ1,1-N3)Ni(L)(OH2)2]·ClO4(1), has been synthesized. It shows the presence of ferromagnetic interactions and is endowed with both anti-mycobacterial and anticancer properties

Structural diversity, topology and luminescent properties of a two-dimensional Cd(II) coordination polymer incorporating 4,4′-dipyridyl and 4,4′-sulfonyldibenzoic acid

A new Cd(II) derivative, [Cd2(H2O)4(bipy)(sdba)2]∙10H2O (1), is synthesized hydro(solvo)thermally by the combination of divalent cadmium nitrate tetrahydrate as metal salt, an N-donor ancillary ligand 4,4′-bipyridine (bipy), and the flexible aromatic carboxylate, 4,4′-sulfonyldibenzoic acid (sdba), as organic linker. Single crystal X-ray diffraction analysis reveals that the Cd(II) atoms show a distorted trigonal bipyramidal environment. In the asymmetric unit, both the carboxylate and the N-donor connectors bridge pairs of cadmium ions; this ultimately leads to the formation of a set of undulated sheets formed by fused rings comprising six cadmium centers, two bipy and four sdba ligands. Considering the cadmium ions as nodes and the ligands as connectors, the structure can be described as a stack of 3-c uninodal nets of the type hcb, with point symbol {44.62} and vertex symbol [6.6.6]. The encapsulation of the Cd(II) derivative displays a moderate luminescent property

<span style="font-size:15.0pt;mso-bidi-font-size:12.0pt;mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:HI" lang="EN-GB">Pyrene-appended Schiff base as a turn-on fluorescence sensor for Al³⁺ detection and interaction with DNA</span>

1446-1450Pyrene appended Schiff base, 1,3-bis-((E)-pyrene-1-ylmethyleneamino)propan-2-ol (HL) fluoresces at 419 nm and 508 nm in DMF solution upon excitation at 344 nm. The addition of Al3+ results in a significant 100 fold increase of its fluorescent intensity with the emission maximum red shifted from 421 nm to 508 nm with intense green emission. This phenomenon may be attributed to the formation of a 1:2 stoichiometric [Al2Cl5(L)] complex, which has been supported by Jobs, NMR titration and mass spectral data. The complexation inhibits the photo-induced electron transfer process and the cheletropic enhancement of fluorescence mechanism is responsible for the turn-on fluorescence sensitivity. The limit of detection of Al3+ (7.42×10-8 M) is the second lowest in the series of pyrene functionalized chemosensor. Both HL and its Al3+ complex, [Al2Cl5(L)], show DNA stacking interaction (binding constant Kb 9.8×104 M-1 (of HL) and 3.8×104 M-1 (of [Al2Cl5(L)]).</span

Effect of electrostatic potential of transition state on the stereoselectivity in ene cyclisation: A theoretical study

45-50Investigation on the transition structure of the ene reaction between propyne and forma ldehyde reveals that negative electrostatic potential is generated around the carbonyl oxygen and acetylenic group. The generated electrostatic potential controls the orientation of the oxygenated substituent present on the forming cyclohexane ring in ene cyclisation. Data from the study of mono substituted transition structures have been used to rationalize the stereoselectivity of an ene cyclisation with poly oxygenated substituents

Structural elucidation, EPR and photoluminescent property of a Ce(III) two dimensional coordination polymer with 4,4′-bipyridine and 2-sulfoterephthalate

A new Ce(III) coordination polymer, {[Ce(stp)(bipy)(H2O)]·H2O}n (1) is afforded via the reaction of trivalent cerium nitrate [Ce(NO3)3·6H2O], 2-sulfoterephthalic acid monosodium salt Na(H2stp), and 4,4′-bipyridine (bipy). Based upon the versatile coordination modes of the stp ligand as linker and bipy as connector, the aforementioned compound is arranged in a 2-D network, as evidenced by single-crystal X-ray diffraction technique. In 1, the central Ce atom possesses on a distorted tricapped trigonal-prismatic coordination environment. The EPR measurement reveals that there exhibits a weak antiferromagnetic coupling between paramagnetic Ce3+ ions. The encapsulation of the Ce(III) CP disposes a moderate luminescent activity. Thermal analysis is also carried out to check the water loss of the molecule which is in accordance with the structural evidence