Synthesis, characterisation and structure determination of 3-[(1Z)-{2-[bis({[(2-methylphenyl)methyl]sulfanyl})methylidene]hydrazin-1-ylidene}methyl]benzene-1,2-diol

A light-yellow crystalline product (1), which was isolated after one week from the filtrate of the reaction between S-2-methylbenzyldithiocarbazate and 2,3-dihydroxybenzaldehyde, was characterised by single crystal X-ray diffraction, FTIR and NMR spectroscopic analyses. The experimental molecular structure of 1 has been established by X-ray crystallography and showed, to a first approximation, a planar C2N2S2 + dihydroxyphenyl region that has an almost orthogonal relationship to the rings of the pendant S-bound benzyl groups. This structure has been verified via density functional theory calculations using the B3LYP/6311G(d,p) level of theory. The molecular packing featured linear supramolecular chains along the b-axis sustained by tolyl-C–H…N(imine) and tolyl-C–H…π(tolyl) interactions; the importance of these contacts is indicated by a Hirshfeld surface analysis

Synthesis, characterisation and structure determination of 3-[(1Z)-{2- [bis({[(2-methylphenyl)methyl]sulfanyl})methylidene]hydrazin-1- ylidene}methyl]benzene-1,2-diol

A light-yellow crystalline product (1), which was isolated after one week from the filtrate of the reaction between S-2-methylbenzyldithiocarbazate and 2,3-dihydroxybenzaldehyde, was characterised by single crystal X-ray diffraction, FTIR and NMR spectroscopic analyses. The experimental molecular structure of 1 has been established by X-ray crystallography and showed, to a first approximation, a planar C2N2S2 + dihydroxyphenyl region that has an almost orthogonal relationship to the rings of the pendant S-bound benzyl groups. This structure has been verified via density functional theory calculations using the B3LYP/6311G(d,p) level of theory. The molecular packing featured linear supramolecular chains along the b-axis sustained by tolyl-CH…N(imine) and tolyl-CH … π(tolyl) interactions; the importance of these contacts is indicated by a Hirshfeld surface analysis

o-Vanillin derived Schiff Bases and their Organotin(IV) Compounds: Synthesis, structural characterisation, in-Silico studies and cytotoxicity

Six new organotin(IV) compounds of Schiff bases derived from S-R-dithiocarbazate [R = benzyl (B), 2- or 4-methylbenzyl (2M and 4M, respectively)] condensed with 2-hydroxy-3- methoxybenzaldehyde (oVa) were synthesised and characterised by elemental analysis, various spectroscopic techniques including infrared, UV-vis, multinuclear (1H, 13C, 119Sn) NMR and mass spectrometry, and single crystal X-ray diffraction. The organotin(IV) compounds were synthesised from the reaction of Ph2SnCl2 or Me2SnCl2 with the Schiff bases (S2MoVaH/S4MoVaH/SBoVaH) to form a total of six new organotin(IV) compounds that had a general formula of [R2Sn(L)] (where L = Schiff base; R = Ph or Me). The molecular geometries of Me2Sn(S2MoVa), Me2Sn(S4MoVa) and Me2Sn(SBoVa) were established by X-ray crystallography and verified using density functional theory calculations. Interestingly, each experimental structure contained two independent but chemically similar molecules in the crystallographic asymmetric unit. The coordination geometry for each molecule was defined by thiolate-sulphur, phenoxide-oxygen and imine-nitrogen atoms derived from a dinegative, tridentate dithiocarbazate ligand with the remaining positions occupied by the methyl-carbon atoms of the organo groups. In each case, the resulting five-coordinate C2NOS geometry was almost exactly intermediate between ideal trigonal-bipyramidal and squarepyramidal geometries. The cytotoxic activities of the Schiff bases and organotin(IV) compounds were investigated against EJ-28 and RT-112 (bladder), HT29 (colon), U87 and SJ-G2 (glioblastoma), MCF-7 (breast) A2780 (ovarian), H460 (lung), A431 (skin), DU145 (prostate), BE2-C (neuroblastoma) Int. J. Mol. Sci. 2019, 20, 854 2 of 34 and MIA (pancreatic) cancer cell lines and one normal breast cell line (MCF-10A). Diphenyltin(IV) compounds exhibited greater potency than either the Schiff bases or the respective dimethyltin(IV) compounds. Mechanistic studies on the action of these compounds against bladder cancer cells revealed that they induced the production of reactive oxygen species (ROS). The bladder cancer cells were apoptotic after 24 h post-treatment with the diphenyltin(IV) compounds. The interactions of the organotin(IV) compounds with calf thymus DNA (CT-DNA) were experimentally explored using UV-vis absorption spectroscopy. This study revealed that the organotin(IV) compounds have strong DNA binding affinity, verified via molecular docking simulations, which suggests that these organotin(IV) compounds interact with DNA via groove-binding interactions

Homoleptic tin(IV) compounds containing tridentate ONS dithiocarbazate Schiff bases: Synthesis, X-ray crystallography, DFT and cytotoxicity studies

Six new tin(IV) compounds derived from tridentate dinegatively charged ONS dithiocarbazate Schiff bases derived from 2-hydroxy-3-methoxybenzaldehyde (H2L1, H2L2 and H2L3) and 2,3-dihydroxybenzaldehyde (H2L4, H2L5 and H2L6) (where H2Ln = di-acids of Schiff base) are reported. The compounds were characterised by elemental analysis, FT-IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The crystal structures of tin(IV) [S-4-methybenzyl-β-N-(2-hydroxy-3-methoxybenzylmethylene)dithiocarbazate] (2) and tin(IV) [S-benzyl-β-N-(2-hydroxy-3-methoxy benzylmethylene)dithiocarbazate] (3) were determined by X-ray single crystal diffraction analysis. X-ray crystallography showed the molecular geometries in homoleptic 2 and 3 to be quite similar in which the dinegative tridentate ligand coordinated the tin atoms via thiolate-S, phenoxide-O and imine-N atoms. The coordination geometries are based on an octahedron with like-atoms mutually trans. The experimental findings were validated by density functional theory (DFT) calculations at the B3LYP/LanL2DZ/6-311G(d,p) level of theory. All the tin(IV) compounds, except the insoluble compound 2 were screened for their in vitro cytotoxicity against a panel ten of cancer cell lines and one normal breast cell line (MCF-10 A) by MTT assay. Interestingly, the cytotoxicity of five tin(IV) compounds against HT29, MCF7 and MIA was higher than the reference drug, cisplatin

Ab Initio investigation of the electronic structure and rovibrational spectroscopy of group-I and II metal hydrides and helides

Research Doctorate - Doctor of Philosophy (PhD)(**Note: this abstract is a plain text version of the author's abstract, the original of which contains characters and symbols which cannot be accurately represented in this format. The properly formatted abstract can be viewed in the Abstract and Thesis files above.**) The electronic structure and rovibrational spectroscopy of MH2, MHn+2, HMHen+ and MHen+2 (M = Li, Be, Na, Mg, K, Ca; n = 1, 2) have been investigated using correlated ab initio ansatz. In order to determine the efficacy of various electronic structure methods with respect to Group-I and II hydrides and helides, atomic properties of Li, Be,Na, Mg, K and Ca were calculated. Relativistically-corrected UCCSD(T) and ICMRCI(+Q) were deemed to be the most suitable ansatz with respect to both efficiency and accuracy. The lowest 2A1 and 2Σ- states of MH2 were found to be purely repulsive, in agreement with previous predictions. The main factor determining the structure and stability of the excited states of MH2 was the relative orientations and occupations of the valence p atomic orbital of M and the H2 1Ou orbital. The ground states of MHn+2 were found to be the result of the charge-quadrupole interaction between Mn+ and the H2 molecular subunit. The structures of the ground states of HMHe+ were extremely uxional with respect to the central bond angle co-ordinate. The ground state PESs of MHe+2 were also extremely sensitive to the ab initio ansatz by which they are modelled. The respective bonding of the H and He in both HMHe+ and HMHe2+ appeared to be charge-dependent in the case of Be, Mg and Ca. Despite the weak bonding observed for the Group-II hydrohelide and helide monocations, the corresponding dications each exhibit thermodynamically stable equilibria. The solution algorithm of von Nagy-Felsobuki and co-workers was employed in the calculation of vibrational and rovibrational spectra. This algorithm employed an Eckart-Watson Hamiltonian in conjunction with rectilinear normal co-ordinates. Vibrational and rovibrational Hamiltonian matrices were diagonalised using variational methods. This algorithm was extended so that the vibration transition moment integrals, and hence vibrational radiative properties, of linear triatomic molecules could be calculated. A method by which vibration-averaged structures are calculated was also developed and implemented. Analytical potential energy functions (PEFs) and dipole moment functions (DMFs) of (1A1)LiH+2, (1A1)NaH+2, (1A1)BeH2+2,(1A1)MgH2+2, (1Σ+g )BeHe2+2, (2Σ+)HBeHe2+, (1Σ+g )MgHe2+2 and (2Σ+)HMgHe2+ were developed using leastsquare regression techniques in conjunction with discrete ab initio grids. Vibrational structures and spectra of these species were subsequently calculated. In addition, the rovibrational spectra of (1A1)LiH+2, (1A1)NaH+2, (1A1)BeH2+2 and (1A1)MgH2+2 were calculated. For (1A1)LiH+2 and (1A1)LiD+2 , calculated rovibrational transition frequencies for J ≤ 10 and 0 ≤ K ≤ 3 were within ca. 0.1-0.2% of experimental values

Ab initio study of ground state MH₂, HMHe⁺ and MHe₂²⁺, M = Mg, Ca

The ground states of MH₂, HMHe⁺ and MHe₂²⁺ (M = Mg, Ca) have been investigated using relativistically-corrected CCSD(T), IC-MRCI and IC-MRCI+Q, in conjunction with ANO-RCC (Mg, Ca) and aug-cc-pVQZ (H, He) basis sets. The ground states of all magnesium species are predicted to be linear, in agreement with predicted trends. Conversely, HCaHe⁺ and CaHe₂²⁺ were determined to be quasi-linear species, with linear-inversion barriers of ca. 115 and 3 cm⁻¹, respectively. For CaH₂, a stationary point on the molecular potential energy surface corresponding to a non-linear equilibrium structure was not observed. Trends in bonding, dissociative potential well-depths and spectroscopic constants for these species have been considered with regards to isoelectronic and isovalent reasoning. These trends are consistent with helium and hydrogen forming electrostatic and covalent bonds with the metal ion, respectively

Structural and energetic trends in Group-I and II hydrohelide cations

The ground states of HMHe⁺ (M = Li, Na, K) and HMHe²⁺ (M = Be, Mg, Ca) have been investigated using relativistically-corrected CCSD(T) and IC-MRCI. The HLiHe⁺, HBeHe²⁺, HNaHe⁺ and HMgHe²⁺ ions were found to be linear in the ground state. Conversely, HKHe⁺ and HCaHe²⁺ were quasi-linear, with ²A'²Σ⁺ barrier heights of ca. 2 and 5 cm⁻¹, respectively. Structural and energetic trends are consistent with H and He sharing covalent and electrostatic bonds with the metal ion, respectively. These trends are also seen to be strictly dependent on the polarisability of the central metal ion

Ab initio electronic and rovibrational structure of MgH₂²⁺

The electronic structure of the ground state of MgH₂²⁺ has been investigated using relativistically-corrected CCSD(T) in conjunction with ANO-RCC (Mg) and aug-cc-pVQZ (H) basis sets. The MgH₂²⁺ molecular potential energy surface possessed minima corresponding to both ¹A₁ and ¹∑g⁺ equilibrium structures (with a 1∑⁺ transition state). The ¹A₁ structure possessed Re and θe values of 2.0297 Å and of 22.09°, respectively. The higher-energy ¹∑g⁺ structure exhibited an Re value of 2.1658 Å. Property surfaces were constructed to calculate rovibrational energies and spectral line intensities for the ground states of (¹A₁)MgH₂²⁺ , (¹A') MgHD²⁺ and (¹A₁)MgD₂²⁺. For the vibration ground state of (¹A₁) MgH₂²⁺, the vibration-averaged Re and θe values were calculated to be 2.0209 Å and 22.53°, respectively. The A, B and C rotational constants were calculated to be 58.0, 2.21 and 2.11 cm⁻¹, respectively

Ab initio vibrational spectrum of (²Σ⁺) He-MgH²⁺

The vibrational spectrum and structure of (²Σ⁺)He–MgH²⁺ has been investigated using relativistically-corrected UCCSD(T). Vibrational wave functions for low-lying l = 0 states were obtained numerically using a w co-ordinate Eckart–Watson vibrational Hamiltonian, in conjunction with an embedded analytical UCCSD(T) potential. For the ground vibrational state, vibration-averaged Mg–H and Mg–He bond lengths differ by −33 and 53 ma₀ from those corresponding to the ab initio potential surface minimum. Vibration transition moment integrals and associated radiative properties of (²Σ⁺)He-MgH²⁺ have been calculated using an adapted quadrature scheme, in conjunction with an embedded analytical UCCSD(T) dipole moment function