Magnetically recoverable nanoparticles (MNPs) represent an economical, practical and environmentally benign means for catalyst recovery, providing catalytic properties intermediate between homogeneous and bulk heterogeneous materials. In recent years, nano Fe3O4 (magnetite) has attracted a great attention as heterogeneous catalyst due to its simple handling, ease of recovery with an external magnetic field, oxidative stability, biological compatibility, and high catalytic activities in various organic transformations. The construction of carbon–sulfur bond, especially under a green and safe condition, is an important transformation in organic synthesis. Sulfur containing compounds are found in many products of biological and medical relevance as well as in commercial drugs. Among them, thioethers (sulfides) and thiol esters are two important classes of organosulfur compounds. In continuation of our interest in applications of Fe3O4 MNPs for organic transformations, herein, we report a robust and magnetically reusable Fe3O4 nanoparticle catalyzed reaction of thiols with alkenes, alkynes, alkyl- and acyl halides. A diverse range of thioethers, vinyl thioethers, and thiol esters were obtained in moderate to excellent yields under neat and aerial conditions at room temperature. The catalyst was recycled and reused eight times with minor decrease in its catalytic activity.

Sequential 5-alkenyl hydantoin and pyrrolidine ring-forming reactions have been applied in the synthesis of conformationally constrained fused bicyclic scaffold. These novel compounds share the structural complexity characteristic of certain alcaloid natural products and represent a source of chemical diversity that complements more traditional classes of heterocyclic compounds of interest as potential pharmaceutical agents. They are assembled in only three-step reaction sequence from two variable building blocks (readily available β-ketoesters and alkenyl halides) by combining Bucherer-Bergs reaction with a final selenium-promoted intramolecular cyclization as a key step. Chemoselectivity of bicyclic hydantoin formation is strongly influenced by experimental factors such as the solvent and the use of additives. The reaction is regiospecific giving only five-membered fused bicyclic hydantoins in good to excellent yields stemming from the nucleophilic attack of the nitrogen atom to cyclic selenuranium ion intermediate during the cyclization step. Formation of this sole regioisomer proceed via favorable 5-exo-trig ring closure process. The separable diastereomeric mixture are obtained. The products with bridgehead substituents and phenylseleno groups in cis relationships were formed predominantly. The reaction tolerates a variety of substitution on double bond. Furthermore, the presence of substituents in C-5 and N-3 position open up capability of generating a broad structural diversity. This methodology would be extended to access six-membered ring systems.

An efficient procedure for the synthesis of functionalized chiral ammonium, imidazolium and pyridinium-based ionic liquids derived from (1R, 2S)-ephedrine using solvent-free microwave activation has been described. Good yields were obtained in very short reaction time. These chiral ionic liquids were used as chiral reaction media for the asymmetric Michael addition, giving good yields and moderate enantioselectivities.

Recently we observe the growing interest in the field of nitroso oxides being isomers of nitrocompounds. They are strong oxidizers, can eliminate singlet oxygen and generate atomic oxygen. On the base of our quantum chemical calculations we have assumed that there exists a possibility of in situ formation of nitroso oxide-like fragments in the course of photochemical oxidation reactions of nitrosocompounds, olefins and SO2 by nitrocompounds. We used DFT/6-31G(d) and DFT/6-311+G(d) methods from the Gaussian-03 program package. Identification of the nitroso oxide moieties we have performed on the comparison of the calculated geometries and spectra of the reagents in the transition states with corresponding values known from experiment and/or previously made quantum chemistry calculations.

Chitosan is a polysaccharide of β(1-4) linked D-glucosamine with a number of advantages such as non-toxicity, biocompatibility, and biodegradability. The control of their chemical and physical properties allows Chitosan derivatives to be used for different biomedical and industrial applications. Degree of deacetylation (DD) and polymer chain length (molecular weight, Mw) can be considered the most important features to determine the physico-chemical properties of these systems and consequently decisive factors to give desired results in formulations and applications.  Fluorescent probes have a broad range of applications in biotechnology, biology, and health research and their use is continually increasing due to their versatility, sensitivity and quantitative capabilities. In particular, fluorescent polymers have application as fotoconductive resins, photosensitive materials, electroluminescent materials, getters photon, and as biological markers. On the other hand, trimethylated chitosan derivatives have emerged in recent years for gene delivery and engineering applications. In this field, our specific interest is to develop pH probes for aberrant physiological changes. We report here the reductive amination of coumarin aldehydes with Chitosan as well as the N-acylation of Chitosan owning different DD and Mw by a coumarin derived carboxylic acid. Moreover, quaternization of the amino groups of the new chitosan derivatives that should provide water-soluble compounds has been also explored. The new solvent- and pH-dependent fluorescent polymers are characterized by HPLC-SEC, IR and NMR.

The aim of this work is the synthesis of some BINOL derivatives due to their catalytic, biological and medicinal activity. The rigid structure, thermal stability and the C₂ symmetry of the binaphthyl molecules play an important rol in asymmetric induction. We report here a study on the radical addition of different triorganotin hydrides, R3SnH (R= n-Bu, Ph), to four (S)-BINOL unsaturated diesters (1,1'-binaphthyl-2-2´-diyl diacrylate; 1,1´-binaphthyl-2-2´-diyl dimethacrylate; 1,1´-binaphthyl-2-2´-diyl-(Z)-2-methyl-3-phenyl-2- propenoate and 1,1´-binaphthyl-2-2´-diyl di-(Z)-2,3-diphenyl-2-propenoate). The expected cyclohydrostannation products were not obtained in spite of the different conditions used for the reaction: sonication, irradiation and refluxing in toluene, with AIBN as radical initiator. This probably occurred due to the restricted conformational structure of the BINOL diesters. Rather than cyclization products, the corresponding mono- and diorganotin adducts were the mainly products obtained under radical addition of the tin hydrides. These organotin adducts can be easily derived in halotrialkyltin or halodialkylaryltin compounds, some of them with probable catalytic activity. For example, organotin halides are Lewis acids so they can be used as catalysts in different reactions, such as asymmetric Diels-Alder cycloaddition and alcohol acylations among others, where the metal catalytic centre is near the chiral binaphthyl moiety. Some authors have demonstrated that diorganotindihalides has higher catalytic effect compared to triorganotin halides and similar to geminal bis(haloorganostannanes). We studied the relation between mono and distannilated products and the diasteroselectivity in appropiate cases. These compounds were characterized with 1H, 13C and 119Sn-NMR.

The solar cells of third generation, which can be classified in hybrids and organics, are the target of uncountable studies and developments along the last few years. These cells present low fabrication cost, flexibility, lightness, and stability. After considerable time in which DSCs based on Ru(II) polypyridyl sensitizers were clearly the most efficient, DSCs based on fully organic sensitizers have recently made huge strides forward in development.   Porphyrins offer several distinct advantages over Ru(II)polypyridyl sensitizers due to their high molar extinction coefficients, sharp absorption bands and high photostability and recent examples of DSC devices based on D-π-A porphyrins show >10% efficiency. However, their properties in DSCs still need to be fully investigated and molecular structure-device function rules need to be outlined to fully understand device performance for devices based on these dyes. In this work we will describe two new Zinc–porphyrin sensitizers, bearing triphenylamine. The synthesis, characterizatoion and the application in dye sensitized solar cells employing iodide/tri-iodide and cobalt based electrolytes will be presented.

Dialkyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylates have been prepared in a batch mode under conventional heating as well as under continuous flow conditions in the Miniflow 200 S, Sairem's microwave-assisted batch and continuous flow equipment. Real-time monitoring of the reactions by Raman spectroscopy enabled to compare both heating modes and to determine (optimized) reaction times.

Utilizing diphenylphosporyl azide (DPPA) to promote the Curtius reaction, we report a divergent synthesis of several dendrimers. The synthetic scheme involves several diol and triol core molecules. Each generation is propagated through reaction with 3,5-bis(3-acetoxypropyloxy)benzoic acid and DPPA. The generations for each core are characterized by HNMR, CNMR and MALDI-TOF MS.We had previously reported a convergent synthesis of structurally different polyurethane dendrimers and discuss the modification made to facilitate the preparation of these dendrimers.We had previously reported a convergent synthesis of structurally different polyurethane dendrimers.  We discuss the modification made to facilitate the preparation of these dendrimers.

Juglone [=5-hydroxy-1,4-naphthalenedione] is a natural product obtained from plants belonging to Juglandaceae  genus (e.g. walnut). Past folk medicine used extract of walnut  for antimicrobial, anti-inflammatory and antioxidant treatments. Recently juglone has shown  a cytotoxic activity on (HL-60, HL-60R, A549 and SCG-7901) human tumor cells  by  inducing apoptosis, and its complexes with transition metal ions were proved antibacterial activity.² From here our interest in the structural analysis of Cu(II) and Ni(II) complexes of juglone.    Over the last decades, infrared spectroscopy (IR) has experienced a renewed role in the molecular structure elucidation of organic compounds, due to the availability of simulated spectra by density functional theory (DFT) calculations able to assign the frequencies associated to vibrational modes obtained by experimental spectra. The juglone metal complexes, whose stoichiometry was supported by ESI-MS/MS experiments were analyzed by FT-IR spectroscopy equipped with the attenuated total reflectance (ATR) technique and the frequencies assigned by DFT calculated spectra using a B3LYP/6-311G(d) basis set. The changes induced by metal chelation are discussed also in comparison with the ion-dipole interactions observed for Na and Cs salts of juglone.