In this research, manganese ferrite, MnFe₂O₄, nanoparticles with a pure cubic crystalline phase were synthesized by a fast solvent free auto-combustion method using microwave irradiation. Iron (III) nitrate nonahydrate and manganese nitrate hexahydrate as initial materials were mixed together with some organic agent as a fuel and oxidant. Then, the prepared mixture was transferred into a domestic microwave oven with the power of 900 W for 20 minutes.The experimental strong point of this strategy is the use of a simple, low-cost, fastmethod for synthesis of nanomaterialsand also placing in the category of green chemistry reactions.Microstructural studies were done using Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). Magnetic hysteresis measurements were performed on a vibrating sample magnetometer (VSM) showing the soft paramagnetic properties of the product.

The aim of this study was to prove the possibility of obtaining amphiphilic esters of β-cyclodextrin in the way of its enzymatic modification involving lipase from porcine pancreas and fungal (Candida Antarctica) lipases. The study was focused to direct esterification processes of carboxylic acids of varying chain lengths and degrees of unsaturation, and indirect esterification using vinyl ester of fatty acids. Also an attempt was done in order to perform transesterification of edible oils (rapeseed and olive oil). The study found that it is possible to obtain low-substituted ester cyclodextrin mainly in the direct esterification. Transesterification of vinyl esters and vegetable fats lead to saponification of the output esters mainly and the degree of cyclodextrin substitution is small. Construction of esters obtained was confirmed using infrared spectroscopy. It was also found that the main limiting factor for the esterification process is a cyclic structure, cyclodextrins, as well as the ability to substrates complexation (acyl donor).

The catalytic activities of two palladium complexes [Pd₄(dbbs)₄] (1) and [Pd(dpbs)Cl] (2) (where (dbbs)₂ = N,N'-(1,1'-dithio-bis(phenylene))-bis(salicylideneimine) and (dpbs)₂ = o,o’-(N,N’-dipicolinyldene)diazadiphenyl disulfide) were evaluated in the formation of C-C bond in Michael Addition, Heck and Suzuki reactions.  The formation of the coupling products were monitored using GC-MS.  The two palladium complexes were found to be ineffective catalyst towards Michael Addition reactions. However, both catalytic systems exhibited comparable activities in the Heck reaction with good to excellent yields of the desired products (> 99 %) even though complex 1 is tetranuclear and complex 2 is mononuclear.  The yields of the products were found to depend upon other parameters such as reaction time, catalyst loading, base, solvent and substrates. Preliminary investigations were also carried out in Suzuki reaction, where the cross-croupling product was obtained in the range of 60-99 %.  These two complexes are promising supramolecular skeleton for the construction of highly active catalysts.

With the aim of enhancing the comprehension of the cation-π interaction, a computational study of the interaction established between sumanene molecule and various cations was performed. Sumanene is a polycyclic aromatic hydrocarbon with a bowl-shaped structure. The curvature of the molecule causes an asymmetry in the distribution of its molecular electrostatic potential that is more negative in its outer (convex) side. This feature allows testing the role of the electrostatic contribution to cation-π interaction using the same molecule. Five cations with different sizes and shapes were selected for the study: sodium, potassium, ammonium, tetramethylammonium, guanidinium and imidazolium. These are monoatomic cations and models of cationic amino acids side-chains, all of which are known to participate in the formation of cation-π complexes in biological systems. The polyatomic cations were placed in different orientations with respect to the sumanene molecule including the “T-shaped” and “stacked” configurations of the flat cations. The study was accomplished at the RI‑MP2/aug-cc-pVTZ level of calculation, to ensure the correct retrieving of the correlation energy and also that the wavefunction size is appropriate for the modeling of effects more complicated than the electrostatic contribution. The interaction energy (Eint) was computed at different sumanene-cation distances following the C3v symmetry axe of sumanene and exploring it’s both sides: concave and convex. The rigid scans of the potential energy surface indicate that at sumanene-cation distances around the Eint minima, the complexes are more stable with the cation placed by the inner (concave) side of sumanene, with the only exception of the complexes with Na⁺, the smallest of the cations studied. This result is the opposite of that expected from the pure electrostatic interpretation of the cation-π interaction. As the cation moves away from the sumanene molecule the situation is reversed, and at long distances the outer complexes are more stable than its inner partners. These findings suggest that at long cation-molecule separations the electrostatic contribution dominates because its influence propagates to long distances but at short distances the cation-π interaction is controlled by other stabilizing contributions (induction and dispersion) defining the minimum of the Eint profile. The results obtained contribute to a better understanding the cation-π interaction and emphasize the importance of using the correct level of calculations in its theoretical modeling.

Ionic liquids (ILs) are largely used in biocatalysis, which is the use of biological systems (purified enzymes, cell free extracts or microorganisms) to perform chemical reactions.¹ ILs have been employed as greener solvents or cosolvents of the biocatalyzed reactions, to improve the solubility of reactants or even increase the activity and/or the selectivity of the processes. It is also remarkable the role of ILs as coating reagents in the immobilization of enzymes to generate heterogeneous biocatalysts.²

Baeyer-Villiger monooxygenases (BVMOs) are attractive enzymes in organic synthesis as they can perform several oxidative processes with high regio- and/or enantioselectivity while using mild and environmentally friendly conditions.³ Indeed, purified BVMOs have been applied in the synthesis of chiral sulfoxides, ketones and esters with high selectivities. However, the main drawback with these soluble enzymes is the lack of efficient catalyst recovery strategies. By this reason, we have developed a set of novel immobilized BVMOs preparations in presence of different ionic liquids. These immobilized biocatalysts have been tested in selective sulfoxidations with the aim of analyzing the activity and selectivity of the novel enzymatic preparations as well as their performance during different reaction cycles.

1. de G. thanks MINECO (Ramón y Cajal Program) for personal funding.
2. M.K. Potdar, G.F. Kelso, L. Schwarz, C. Zhang, M.T.W. Hearn, Molecules, 2015, 20, 16788-16816.
3. Y.F. Zhang, J. Ge, Z. Liu, ACS Catal. 2015, 8, 4503-4513.
4. G. de Gonzalo, W.J.H. van Berkel, M.W. Fraaije, in Science of Synthesis, Biocatalysis Vol. 3, K. Faber, N. J. Turner, W. D. Fessner, Eds.; Georg Thieme Verlag, 2015, Chapter 4, pp. 187-234. ISBN: 978-3-13-174661-0.

1,2,3- triazoles are 5-membered heterocyclic compounds that are used in many drugs, dyes, corrosion inhibitors and organic synthesis intermediates. Reach to straightforward procedure for synthesis of this important compounds is an attention grabbing issue among organic synthesis researchers. Applying of ball-mill prepared [Cu₂ (BDC)₂ (DABCO)] as a high stable, low leaching, clean and recyclable porous coordination polymer (PCP)  catalyst  for synthesis of triazole derivatives  proved to be a practical and facile procedure that was carrying out in water as a green solvent. Low reaction time, mild and non-toxic reaction media and high yield of desire product is other aspects of mentioned procedure.

Hydroxamic acids are functional groups with the ability to strongly chelate metal ions found in the reaction centers of biologically important proteins including that of Tumor Necrosis Factor alpha Converting Enzyme (TACE)/(ADAM-17).  These hydroxamic acids are able to inhibit the enzymatic activities that are necessary for the normal progression of diseases such as HIV and cancer. One example is hydroxamic acids (Vorinostat) ability to block the release of the TNFalpha into the bloodstream of cancer and HIV patients thereby decreasing the inflammation response and slowing disease progression. This work sought to understand what modification surrounding the hydroxamic acid would be able to increase the overall binding affinity for metal chelation.  Differences in the inductive effects that surround the acids will be explored using ab-initio energy (DFT-B3LYP-631++G, and DFT-B3LYP-321-G) changes between apo/metal chelated molecules. These differences will seek to determine the best structural modification for improved hydroxamic acid design.

The search for the optimal level of theory has been performed to achieve the best correspondence of calculated values and experimental results for further quantum-chemical modeling of systems compoused from sulphides and organic nitrocompounds in the triplet state. The reaction: HS + NO2 → HSO + NO was selected as the model reaction. The standard enthalpy of this reaction calculated theoretically was compared with its experimental value known from literature. Such theories as DFT, UHF and ROHF and the following basis sets: 6-31++G**, 6-311++G**, aug-cc-pVDZ, were used for computations. XC functionals for DFT calculations are the following: b3lyp, bhlyp, pbe0, xpbe96_cpbe96.

Metal Organic Frameworks(MOFs) are a compound of organic molecules and metal ions with regular structure and well-defined pores at the nano scale. They are crystalline materials with large internal surface areas and tunable chemical properties. Adsorption, separation and catalytic function of MOFs based on the size and shape of the pore and host-guest interactions are their functional application. In addition, MOFs have other applications such as bio/medicine, sensors and electronics which have attracted remarkable scientific interest in recent years. In this approach we have successfully encapsulated palladium nano particles in MOF and used it as catalyst in coupling reaction. This synthesis process could be achieved in one step through a simple temperature programming control without the addition of any external reducing agent.   

The Schiff base ligands and their corresponding metal complexes have expanded enormously and include a vast area of organometallic compounds and various aspects of bioinorganic chemistry [1]. On the other hand, azo compounds are very important molecules and have attracted much attention in both academic and applied research [2]. The azo compounds and their metal-azo complexes are extremely used in dyes and data storage [3]. In this paper, a new complex of Cu(II) and the title Schiff base as a ligand is reported. Elemental, and spectroscopic measurements are used to elucidate the structure of the prepared metal complex. The azo-dye Schiff base behaves as a di-negative N₂O₂ tetradentate ligand. The structure of metal complex is square planar. The azo-dye Schiff base and its complex is characterized by FTIR, DRS, EDAX and thermal analysis methods. 

References

[1] T.T. Tidwell, Angew Chem. Int. Ed. 47 (2008) 1016–1020. 

[2] H. Nishihara, Bull. Chem. Soc. Japan 77 (2004) 407–428. 

[3] R. Asgari-sabet, H. Khoshsima, Dyes Pigm. 87 (2010) 95–99.