Synthesis, structural elucidation and biological activities of organotin(IV) derivatives of 4-(2-thienyl)butyric acid

A series of tri- and diorganotin(IV) derivatives of 4-(2-thienyl)butyric acid have been synthesized by the reaction of ligand acid with tri- and diorganotin salts in 1:1 and 2:1 molar ratios, respectively. The synthesized compounds have been confirmed by CHNS elemental analyses, FTIR, multinuclear NMR (H-1 and C-13) spectroscopy and X-ray diffraction studies. NMR data reveal a 5-coordinate geometry for the triorganotin(IV) derivatives, while 6-coordinate for the diorganotin(IV) derivatives, respectively. The X-ray crystallographic analysis of the compound 2 showed polymeric 5-coordinate trigonal bipyramidal geometry. Antimicrobial studies were also evaluated against different strains of bacteria (Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis and Staphylococcus aureus) and fungi (Mucor species, Aspergillus solani, Helminthosporium oryzae, Aspergillus flavus, Aspergillus niger) to establish the biological significance of these compounds. The synthesized compounds probably work by interfering with the ability of bacteria to form cell walls by keeping unwanted substances from entering their cells and stop the contents of their cells from leaking out due which the bacteria get die. The antifungal activity of some of the tested compound is comparable to that of the standard drug, terbinafine. From their antimicrobial results, it was concluded that they might be used as potential candidate for the generation of new antimicrobial drugs.

alpha-Diimine homologues of cisplatin: synthesis, speciation in DMSO/water and cytotoxicity

Lucinda Kate Batchelor, Paul Joseph Dyson, Silvia Schoch

The Pt(ii) -diimine complexes [PtCl2{N-2-(HCNR)(2)}] (R = C6H11, 1; 4-C6H10OH, 2; 4-C6H4CH3, 3; 4-C6H4OH, 4) and [PtCl2{N-2-(CH3CNOH)(2)}] (5) were prepared in 60-81% yields from the 1:1 molar reactions of cis-[PtCl2(DMSO)(2)] with the appropriate -diimine, HCN(R) (R = C6H11, L1; 4-C6H10OH, L2; 4-C6H4Me, L3; 4-C6H4OH, L4), or dimethylglyoxime (dmgH(2)), in acetone at reflux. The reaction of cis-[PtCl2(DMSO)(2)] with two molar equivalents of dmgH(2) and NEt3 in methanol at reflux afforded the bis-dimethylglyoximato compound [Pt{N-2,N-(ON?C(CH3)C(CH3)?NOH)}(2)], [Pt(dmgH)(2)], as an insoluble material, in 97% yield. The oxalato derivative [Pt(O-2-C2O4){N-2-(HCN(C6H11))(2)}], 6, was obtained from the sequential treatment of 1 with AgNO3 and Na2C2O4, in 61% yield. Attempts to functionalize 4via esterification of the hydroxyl groups with aspirin (aspCO(2)H) led to [PtCl2{N-2-(HCN(4-C6H4OCO-asp))(2)}], 7, in an admixture with 4. All the products were characterized by elemental analysis, and IR and multinuclear NMR spectroscopy, and the molecular structures of 4THF and 5 were elucidated by single crystal X-ray diffraction. NMR spectroscopic studies in DMSO or DMSO/water/NaCl evidenced the substantial stability of 1-2 at 37 degrees C over 72 hours, whereas 3-5 released their N,N-ligand. The cytotoxic activity of 1, 2 and 6 was assessed on cisplatin sensitive and cisplatin resistant human ovarian carcinomas (A2780 and A2780cisR) and non-tumorigenic human embryonic kidney (HEK-293) cells. Compound 1 is moderately cytotoxic, whereas 2 and 6 did not display appreciable antiproliferative activity.

ROYAL SOC CHEMISTRY2018

Static and dynamic properties of non-collinear quantum antiferromagnets explored by neutron scattering

Luc Testa

This thesis is devoted to the investigation of static and dynamic properties of two different sets of quantum magnets with neutron scattering techniques and the help of linear spin wave theory. Both systems are copper-based with spin-1/2, which makes them ideal to study the interplay between purely quantum and semi-classical effects. I start with the analysis of the antiferromagnet SeCuO3, which has a canted spins structure. Through careful inelastic neutron scattering experiments on thermal and cold triple-axis spectrometers, I demonstrate that this compound exhibits three primary types of excitations that are intrinsically opposite : spin waves (magnons), singlet to triplet excitations (triplons), and fractional spins excitations (spinons). Such a strong coexistence and interdependence of these collective excitations has not been observed yet, thereby the quantification and description of the excitations in SeCuO3 leads the way to further theoretical work on multi-excitation spin systems, as well as the existence of quantum effects in high dimensional systems.\ My second project is on the extraction of the magnetic structure of three members of the A(BO)Cu4(PO4)4 chiral family, namely (A; B) = (Ba; Ti), (Sr; Ti) and (Pb; Ti), from spherical neutron polarimetry measurements. I prove that the first two compounds exhibit a highly non-collinear magnetic structure, with the Cu spins forming clusters of 'two-in--two-out' arrangements on each structural unit. This structure is stabilised by the presence of a strong Dzyaloshinskii-Moriya interaction, and explains the observation of magnetoelectric effects as emerging from quadrupole moments. The analysis of the latter compound did not lead to the confirmation of its magnetic structure due to strong nuclear-magnetic interference. I conclude this thesis by the investigation of the magnetic excitation spectrum of some members of the (A; B) family, probed by inelastic neutron scattering measurements. Indeed, its particular crystallographic structure makes it an ideal playground to study tetramerisation effects on the two dimensional square lattice. Additionally, the aforementioned Dzyaloshinskii-Moriya interaction ensures the presence of a structural gap, which competes with the quantum one emerging from tetramerisation effects. Using linear spin wave theory, I describe (Ba; Ti) as a chequerboard system with almost equal intra- and inter-plaquette couplings, with weak quantum effects. I also provide a qualitative description of (Pb; Ti), which exhibits similar physics, and conclude by presenting the first results on the highly symmetric compound (K; Nb), which shows hints of a strong quantum behaviour.

EPFL2021

Static and dynamic properties of non-collinear quantum antiferromagnets explored by neutron scattering

Luc Testa

EPFL2021