2720-80-1

Alkali metal, copper, nickel and rhodium complexes of alkylated [S 2COC8H17] and fluoroalkylated xanthate ligands [S2COCmH2mCnF2n+1] (m = 2, n = 4, 6; m = 3, n = 1, 8) have been prepared in high yields and characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu(S2COC8H 17)(PPh3)2], [Cu(S2COC 3H6CF3)(PPh3)2], [Ni(S2COC3H6CF3)2], [Cp*RhCl(S2COC8H17)] and [Cp*RhCl(S2COC3H6CF3)] have been determined by single crystal X-ray diffraction.

This work investigates tuning of the molecular structure of a series of O-alkylxanthato zinc and cadmium precursor complexes to enhance production of ZnS and CdS materials. The structures of several bis(O-alkylxanthato) cadmium(II) complexes (8-13) and bis(O-alkyl xanthato)zinc(II) complexes (18 and 19) are reported based on single crystal X-ray diffraction data. CdS and ZnS films were produced by the spin-coating of these metal complexes followed by their thermal decomposition to the corresponding metal sulfides. Thin films of CdS were deposited by spin-coating the bis(O-alkylxanthato) cadmium(II) precursors (7-13) on glass substrates, followed by annealing at 300 °C for 60 min. Thin films of ZnS were deposited by spin-coating bis(O-alkylxanthato) zinc(II) (14-20), followed by annealing at 200 °C for 60 min. The molecular complexes and solid state materials are characterized using a range of techniques including single-crystal X-ray diffraction, pXRD, EDS and XPS, DSC and TGA, UV-vis and PL spectroscopies, and electron microscopy. These techniques provided information on the influence of alkyl chain length on the thermal conditions required to fabricate metal sulfide films as well as film properties such as film quality, and morphology. For example, the obtained crystallite size of metal sulfide films formed is correlated to the hydrocarbon chain length of xanthate ligands in the precursor. The behavior of the complexes under thermal stress was therefore studied in detail. DTA and TGA profiles explain the relationship between hydrocarbon chain length, decomposition temperatures, and the energies required for decomposition. A higher decomposition temperature for complexes with longer hydrocarbon chains is observed compared to complexes with shorter hydrocarbon chains. Band-gap energies calculated from the optical absorption spectra alongside steady state and time-resolved photoluminescence studies are reported for CdS films.

A series of N2S2-Cu(II) complexes based on N,N′-bis(alkylthiocarbamate)butane-2,3-diimine ligands have been synthesized and characterized by spectroscopic, electrochemical, and single crystal X-ray diffraction methods. This class of ligands contains a conjugated N2S2chelate framework with a non-coordinating, terminal alkoxy (–OR) group. Ligands and Cu(II) complexes were investigated for R = Me, Et,nPr,iPr, and octyl. Additionally, N,N′-bis(ethylthiocarbamate)hexane-3,4-diimine and its Cu(II) complex were analyzed. Single crystal X-ray diffraction studies on all six Cu(II) complexes confirm a square planar Cu(II) environment with no significant changes in the core structure as a function of R. Spectroscopic studies are consistent with a similar electronic environment in all complexes. However, electrochemical investigations reveal significant shifts in the CuII/Iand CuIII/IIreduction potentials throughout the series. The complexes are analogues of the well-known bis(thiosemicarbazone) Cu(II) which contain a similar donor core with terminal, non-coordinating amines. Substitution of the terminal amines of bis(thiosemicarbazones) with the alkoxy groups of N,N′-bis(alkylthiocarbamate)butane-2,3-diimines allows tuning of redox potentials with minimal changes in the physical and electronic structure.

Dithiocarbamates (DTCs) were recently discovered as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. A series of xanthates and a trithiocarbonate, structurally related to the DTCs, were prepared by reaction of alcohols/thiols with carbon disulfide in the presence of bases. These compounds were tested for the inhibition of four human (h) isoforms, hCA I, II, IX, and XII, involved in pathologies such as glaucoma (CA II and XII) or cancer (CA IX). Several low nanomolar xanthate/trithiocarbonate inhibitors targeting these CAs were detected. A docking study of some xanthates within the CA II active site showed that these compounds bind in a similar manner with the dithiocarbamates, coordinating monodentately to the Zn(II) ion from the enzyme active site. Several xanthates showed potent intraocular pressure lowering activity in two animal models of glaucoma via the topical administration. Xanthates and thioxanthates represent two novel, promising classes of CA inhibitors.