Akram Gholami

Steric and electronic control over the structural diversity of N-(n-pyridinyl) diphenylphosphinic amides (n = 2 and 4) as difunctional ligands in triphenyltin(IV) adducts

Two triphenyltin(IV) adducts of difunctional ligands, N-(n-pyridinyl) diphenylphosphinic amide (n = 2 and 4), have been synthesized and characterized by 1H, 31P, 119Sn NMR and IR spectroscopy. The spectroscopic properties of the complexes were compared with those of corresponding ligands. The crystal structures of the complexes were determined by X-ray crystallography, which reveals a trigonal bipyramidal geometry surrounding the tin(IV). Both of the ligands function in an ambidentate mode, ligating through either the O or N atom. The experimental and theoretical (DFT) studies show that the Sn(IV) interacts more strongly with the N-pyridine atom than the PO functional group. Furthermore, DFT calculations, at the B3LYP level, have been carried out to determine the deeper reasons for the adopted bonding mode in the complexes. The influence of the ligand structure on the coordination behaviour and the contribution of hydrogen bonding to the stability of the resulting complexes were elucidated. The results indicate that the intermolecular hydrogen bonds have an important role in the molecular structures and supramolecular associations of the organotin(IV) compounds.

Triphenyltin(IV) adducts of diphosphoryl ligands: structural, electronic and energy aspects from X-ray crystallography and theoretical calculations

Some triphenyltin(IV) adducts with a family of diphosphoryl ligands, RR′P(O)–X–P(O)RR′ (R = OPh, Ph, R′ = R, An (aniline)) and X = 1,4-OC6H4O, 1,4-OC6H4NH, 1,4-NHC6H4NH 1,4-(NHCH2)2C6H4, 1,3-(NHCH2)2C6H4 and piperazine have been synthesized and characterized by IR and NMR spectroscopy. X-Ray crystallography reveals that the structure of these complexes comprises a binuclear arrangement with two SnPh3Cl moieties linked via the bridging P(O)–X–P(O) ligands. The influence of the ligand structures on the organization of the crystal structures and the coordination interactions are discussed. Studies of the crystal packing reveal NH⋯Cl, CH⋯Cl or CH⋯O hydrogen bonding interactions, as a function of the X or R groups, to be the main factor controlling the supramolecular architecture in this series of complexes. Based on the results from quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses, Sn–ligand interactions are found to be mainly electrostatic (donor–acceptor-like with charge transfer from the phosphoryl donors to the tin atoms). The stronger coordination bonds are found in the complexes containing Ph substituents with aliphatic spacers, in agreement with the experimental evidence. Binuclear arrangements instead of polymeric or chelating systems may be attributed to the steric demands of SnPh3Cl, regardless of the ligand structures.

Highly sensitive voltammetric sensor based on immobilization of bisphosphoramidate-derivative and quantum dots onto multi-walled carbon nanotubes modified gold electrode for the electrocatalytic determination of olanzapine.

In the present paper, a new bisphosphoramidate derivative compound, 1, 4-bis(N-methyl)-benzene-bis(N-phenyl, N-benzoylphosphoramidate) (BMBPBP), was synthesized and used as a mediator for the electrocatalytic oxidation of olanzapine. The electro-oxidation of olanzapine at the surface of the BMBPBP/CdS-quantum dots/multi-walled carbon nanotubes (BMBPBP/CdS-QDs/MWCNTs) modified gold electrode was studied using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. This sensor showed an excellent electrocatalytic oxidation activity toward olanzapine at less positive potential, pronounced current response, and good sensitivity. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) were determined for olanzapine oxidation, using the electrochemical approaches. Surface morphology and electrochemical properties of the prepared modified electrode were investigated by scanning electron microscopy (SEM), cyclic voltammetry and electrochemical impedance spectroscopy techniques. The hydrodynamic amperometry at rotating modified electrode at constant potential versus reference electrode was used for detection of olanzapine. Under optimized conditions, the calibration plot was linear in the concentration range of 20 nM to 100 μM and detection limit was found to be 6 nM. The proposed method was successfully applied to the determination of olanzapine in pharmaceuticals and human serum samples.

Structural and photophysical characterization of mono- and binuclear Cu(I) complexes based on carbohydrazones: a combined experimental and computational study

Pyridinyl carbohydrazone ligands with different positions between functional groups of –NNHC(O)– and Npy (ortho-, meta- and para-) have been applied for the synthesis of cuprous halide complexes. X-ray crystallography reveals that the ortho analogous ligand, Lo, functions in a chelating mode, adopting a mononuclear structure in complex Co, [CuClLoPPh3], while the meta and para analogs, Lm and Lp, act as ambidentate ligands, coordinating through the Npy atom in halogen-bridged binuclear complexes [Cu(μ-X)LPPh3]2 (X = Cl, Br, I and L = Lm, Lp). The influence of non-covalent intermolecular interactions on the assembly of the final structures has been discussed by geometrical and Hirshfeld analyses. Moreover, the photophysical properties of the complexes have been explored, both experimentally and theoretically. The influence of ligand structure and halide variations on the structural and photophysical aspects of the complexes has been considered in this study.

Supramolecular assemblies of organotin(IV)-diphosphoryl adducts: insights from X-rays and DFT

Mono-, di- and tri-phenyltin(IV) adducts containing a neutral diphosphoryl ligand, Ph2P(O)OC6H4OP(O)Ph2, were synthesized and characterized. These 2 : 1 adducts of two trans-organotin(IV) moieties and the bridging ligand all crystallize around a centre of inversion. The influence of tin-substituents on the building up of multidimensional architectures, as well as, strength of the Sn–O interactions are discussed in terms of geometrical parameters, Hirshfeld surface analysis and theoretical calculations. The CH⋯Cl interactions make a substantial contribution to directing 1D self-assembly of the tin adducts. Replacement of Cl atoms with Ph groups on tin(IV) in these complexes has increased the probability of CH⋯π and H⋯H interactions and weakens the Sn–O bonds. QTAIM and NBO analyses reveal that the Sn–O interactions are principally electrostatic in nature (donor–acceptor like) with only a small amount of covalence increasing from the tri- to the mono-phenyltin adduct.