Quantum chemical investigation on complexation of palladium with iminopyridyl ligands: Structural,thermochemical, and electronic aspects

The main purpose of this research is to investigate computationally the structural, thermochemical and electronic properties in complexation process of dichloride {N-[(5-methylthiophen-2-yl)methylidene]?2-(pyridine-2-yl)ethanamine-κ²N,N′}palladium(II) complex. In the first step, we have concentrated on comparative survey of ability of density functional theory (DFT) and also semi-empirical approaches to reproduce the crystal structure of palladium(II) complex. Comparison of our calculated structural parameters of aforementioned complex with the available crystallographical data reveals that both functionals (B3LYP and M06) can well-reproduce x-ray structure of the complex with a near accuracy while PM6-D2 semi-empirical calculated values are not in a reliable agreement with the crystallographical data.

In the next step, we have shown the thermodynamical superiority in using THF as a polar solventin complexation reaction via polarized continuum model (PCM) computations which is in confirmation with experimental observations. Additionally, the bond orders of some selected key bonds in C₁₃H₁₄N₂Sligand andPdCl₂(C₁₃H₁₄N₂S) complex have been evaluated comparatively to analyze the electronic behavior of coordination.

Finally, we focused on topological analysis of electron density function via quantum theory of atoms in molecules (QTAIM) approach to explore the strength and nature of metal-ligand interactions on bond and ring critical points (BCPs).Strictly speaking, QTAIM calculations have been performed to determine the electronic density, its Laplacian and other electronic energy density indicators on some key BCPs to interpret the electronic features of complexation.     

Synthesis of KIT-5 decorated by Bi2S3-Fe3O4 photocatalyst for degradation of parathion pesticide in aqueous media: Offering a degradation model and optimization using response surface methodology (RSM)

In this research, a novel KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite was prepared. The structure and morphology properties of the nanocomposite were well characterized by XRD, FESEM-EDS-mapping, TEM, and N₂ adsorption–desorption. Benefiting from the visible light, the as-prepared KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite exhibit significantly improved photocatalytic performance for the degradation of parathion. The optimum photocatalytic efficiency of KIT-5/Bi₂S₃-Fe₃O₄ nanocomposite was investigated with the central composite design using Design Expert software. The four critical variables affecting parathion degradation such as the concentration of parathion, pH, irradiation time, and amount of KIT-5/Bi₂S₃-Fe₃O₄ nanocatalyst. A polynomial function corresponding to degradation percent was obtained for the experimental data. The results showed that this catalyst has a good performance for the degradation of parathion.     

Synthesis of 3-oxo-1,4-diazepine-5-carboxamides and 6-(4-oxo-chromen-3-yl)-pyrazinones via sequential Ugi 4CC/Staudinger/intramolecular nucleophilic cyclization and Ugi 4CC/Staudinger/aza-Wittig reactions

An efficient approach for the assembly of 1,4-diazepine-based and 6-(4-oxo-chromen-3-yl)-pyrazinone-based frameworks has been developed that involves the Ugi four-component reaction (U-4CR) followed by Staudinger/nucleophilic cyclization and Staudinger/Aza-Wittig reactions, respectively. This convergent approach exhibits a high bond-forming efficiency, involving the use of readily available commercial reagents and is an example of the reconciliation of structural complexity with operational simplicity in a time- and cost-effective manner.     

Preparation,characterization and utilization of a novel dicationic molten salt as catalyst for the synthesis of bis(6-amino-1,3-dimethyluracil-5-yl)methanes

Research on Chemical Intermediates - In this research, firstly, preparation and characterization of a novel dicationic molten salt, namely N,N,N′,N′-tetramethylethylenediaminium...     

Computational study on the structure and properties of ternary complexes of Ln3+ (Ln = La, Ce, Nd AND Sm) with 5,7-dichloroquinoline-8-ol and 4-vinyl pyridine

In the present research, we have mainly concentrated on the survey of interactions in Ln³⁺ (Ln = La, Ce, Nd, and Sm) ternary complexes of 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinyl pyridine (VP), [Ln(VP)₂(DCQ)₃]³⁺ by means of density functional theory, Hartree-Fock and Sparkle/PM3 semi-empirical computational methods. For VP and DCQ ligands, the cation binding energy sequence follows the order La³⁺ > Ce³⁺ > Nd³⁺ > Sm³⁺ as expected based on increasing in the hardness and decreasing in the ionic radius of this lanthanide cation series. A similar trend was observed in the calculated binding energy of the aforesaid ligands with the hydrated lanthanide cation series [Ln(H₂O)₉]³⁺, while the computed values of deformation energy of ligands upon complexation demonstrated an opposite order in the lanthanide cation series. Moreover, the solvent effects are considered via a polarized continuum model and provided a significant increase in the binding strength while the relative magnitude of binding energies is the same as that in the gas phase. Combining quantum and statistical mechanical calculations, we have also determined quantitatively a reliable estimate of the conformational distribution of the [Sm(VP)₂(DCQ)₃]³⁺ complex at various temperatures in the gas phase by computing the molecular partition functions and consequently the analysis of the conformational equilibrium constants.     

Adsorption behavior of Co and C2H2 on the graphite basal surface: A quantum chemistry study

The adsorption of CO and C₂H₂ molecules on the perfect basal surface of graphite is investigated by adopting cluster models in conjunction with quantum chemical calculations. The noncovalent interaction potential energy curves for three different orientations of CO and C₂H₂ molecules with respect to the inert basal plane of graphite are calculated via semi-empirical and Möller-Plesset ab initio methods. Then, we have considered the effects of interaction energies on the C≡O and C≡C bond lengths by performing the partial geometry optimization procedure on the CO-graphite and C₂H₂-graphite systems in various intermolecular distances. The computational analysis of all physical noncovalent potential energy curves reveals that the relative configurations in which CO and C₂H₂ molecules approach the graphite sheet from out of the plane have stronger interaction energy and so is more favorable from the energetic viewpoint. This means that the graphite layer prefers to increase its thickness via the chemical vapor deposition of CO and C₂H₂ on the graphite.     

Introducing a new triazoloquinoxaline‐based fluorene copolymer for organic photovoltaics: Synthesis,characterization, and photovoltaic properties

A new donor‐acceptor copolymer consisting of triazoloquinoxaline and 9,9‐dialkylfluorene units on the main chain has been synthesized, characterized and evaluated as donor material in bulk heterojunction solar cells using PC₆₁BM as an acceptor. The resulting polymer PTQF showed good thermal stability and solubility in common organic solvents. Cyclic Voltammetry measurements showed that the PTQF has HOMO–LUMO energy levels of ?5.13 and ?3.62 eV, respectively. DFT calculations revealed that the HOMO is delocalized all over the thiophene and fluorene units and the LUMO is localized mainly on the triazole and pyrazine units. PTQF absorbs broadly in the visible region and exhibits a bandgap of 1.4 eV. Photovoltaic devices exhibited 1.7% efficiency for 1:2 PTQF:PC₆₁BM blend ratio using Ca/Ag electrodes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013