Herein we report the synthesis and characterization of two asymmetric [NNO] tridentate imine ligands (H₂L¹ and H₂L²) functionalized with two hydroxyl groups and a bulky dansyl moieity. The existence of two hydroxyl substituents able to form bridges between metal ions make both molecules suitable as precursors of metallosupramolecular polynuclear species.

Hydrogen bonds are formed in the phenol-formaldehyde-ortho-naphthoquinondiazide-water system. In our work quantum-chemical calculations were made using the HF/3-21G ++ theory level and it was found out that phenol-formaldehyde forms three types of hydrogen bonds: between its hydroxyl group and carbonyl group of ortho-naphthoquinondiazide, between its hydroxyl group and water and between its hydroxyl groups intramolecularly forming a "circle-like" structure, and this type of bonds prevails.

In 2010, A. Suzuki was awarded the Nobel Prize in Chemistry together with R. Heck and E. Negishi for their study of C−C cross-coupling reactions [1] which are of great relevance in organic synthesis [2] and thus, in industrial processes and in pharmaceuticals. Palladium based compounds appear to be outstanding catalysts in the C−C cross-coupling reactions [3], and although there are commercially available catalysts such as [Pd(PPh₃)₄] or [Pd(OAc)₂], they fail to comply with air and thermal stability, so by tuning the ligands this problem can be overcome.

Given our vast experience in the synthesis and characterization of this type of compounds [4] with thiosemicarbazones as ligands, and their use as catalysts in the Suzuki-Miyaura reaction [5] within this communication we present the synthesis, characterisation and applicability of a family of palladium compounds to the Suzuki-Miyaura reaction.

References

[1] http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2010/

[2] J. Tsuji, Palladium Reagents and Catalysts: Innovations in Organic Synthesis, Wiley, New York, 1995

[3] I. P. Belestkaya, A. V. Cheprakov; J. Organomet. Chem. 2004, 689, 4055.

[4] B. Bermúdez Puente Compuestos Ciclometalados de Paladio y Platino. Reacciones de acoplamiento y catálisis. PhD Dissertation. Santiago de Compostela 2014.

 [5] N. Miyaura, K Yamada, A. Suzuki Tetrahedron, 1979, 36, 3437.

In our recent work we have made a conclusion that in the radical reaction between nitromethane and hydrogen sulphide the formation of the anion-radical does not happen. This conclusion was not expected due to oposite results that can be found in many experimental papers describing the similiar reactions with nitronaphtalene and amines. So, the additional research has been made using RT-TDDFT simulation at the PBE0/6-311++G** theory level. The simulation has shown no charge oscillations between reactants, that can be interpreted as an argument against the charge transfer mechanism. The study of correlation between solvent polarity and energetic parameters of reaction has been made using the SMD and COSMO above the DFT PBE0/6-311++G** calculation has shown non-polar nature of the reaction, that also might be used as an argument against the anion-radical formation mechanism.

The work reports ultrasound promoted facile synthesis of novel ten α-aminophosphonate derivatives coupled with indole-2,3-dione moiety, namely diethyl(substituted phenyl/heteryl)(2-(2-oxoindolin-3ylidene)hydrazinyl)methylphosphonates derivatives 4(a-j). The derivatives 4(a-j) were synthesized through one-pot three component Kabachnik-Fields reaction, by stirring at room temperature in presence of Cerric Ammonium Nitrate (CAN) as a catalyst, to give the final compounds in better yields and in shorter reaction time. Isatin, chemically known as 1-H-indole-2,3-dione, and its derivatives possess a broad range of biological and pharmacological properties. Isatin is widely used as starting material for the synthesis of a broad range of heterocyclic compounds and as substrates for drug synthesis. The α-amino phosphonate derivatives constitute an important class of organophosphorus compounds on account of their versatile biological activity. The general low mammalian toxicity of these compounds made them attractive for use in agriculture and medicine. Considering the importance of the two pharmacophores, promoted us to club both the pharmacophores in a single molecule using green synthetic protocol. The structures of the ultrasound synthesized compounds were confirmed by spectral analysis like IR, ¹H NMR, ¹³C NMR, ³¹P NMR and MS.

A simple, sensitive and easy high-performance liquid chromatographic [HPLC] method has been developed and validated for the simultaneous estimation of albendazole [ABZ] and praziquantel [PRQ] using diazepam as an internal standard in rat plasma. Extraction of ABZ, PRQ and Diazepam in rat plasma was carried out by a process which involves precipitation of proteins called protein precipitation. Protein precipitation method was done by using 8.25% v/v perchloric acid. Chromatographic separations were performed using an Enable C18 column [250 mm × 4.6 mm, 5 μm: Spinco Biotech Pvt. Ltd]. The mobile phase consisted of acetonitrile: water [60:40, v/v] at a flow rate of 1.0 mL min^-1 at an ambient temperature for plasma samples. The above method was developed and validated over the range from 50-8000 ng mL^-1 for both ABZ and PRQ in the rat plasma. The recovery of ABZ was found to be 97.81 to 105.28%, whereas PRQ recoveries ranged from 96.80 to 102.63% in the rat plasma. Acceptable Intra-day and inter-day assay precision [<15% R.S.D.] and accuracy [<15% R.S.D.] were observed over 50–8000 ng mL^-1 for ABZ and PRQ in rat plasma. This method can be effectively applied to the pharmacokinetic study of albendazole and praziquantel in rat plasma to determine all the pharmacokinetic parameters.

Photoreduction of ammonia, methylavine and phenylamine by the triplet nitromethane has been investigated. Using uB3LYP/6-311g* method the geometry of the transition states, pre- and post-complexes was established. The mechanism of photoreduction is quite simple: it is the hydrogen atom abstraction. The N-H-bond of amine breaks and H-atom passes to the nitrocompound. This reaction yields two radicals. Calculated activation energy of the reaction between nitromethane and ammonia is of 3.17 kcal∙mol^-1. This one is much lower comparing to the reported earlier by us. The EOM-CCSD/cc-pVDZ method predicts activation energy of 2.57 kcal∙mol^-1. The next examined reaction is the reaction between the triplet nitromethane and methylamine. The mechanism is the same. Calculated activation energy is of 1.17 kcal∙mol^-1. Due to the methyl group presence it is the energy drop relatively to the first reaction. Some pictures of the electron density are included in the article. Comparing the radicals the phenylamine with nitromethane has been implemented. Calculated activation energy is of 1.51 kcal∙mol^-1. Hence phenyl group enhances the activation threshold of the proton abstraction. The reaction mechanism is the same hydrogen atom abstraction.

A simple, sensitive, selective and reproducible method based on a reversed-phase chromatography was developed for the determination of Praziquantel in rat plasma using internal standard as Diazepam. Praziquantel & Diazepam was separated on a C18 column Enable (250 mm × 4.6 mm, 5 µm particle size: Spinco Biotech Pvt Ltd), with retention times of 6.4 & 8.5 min. Ultraviolet detection was set at 225 nm. The mobile phase consisted of acetonitrile and water (60:40, v/v), running through the column at a flow rate of 1.0 mL min^-1. The chromatographic analysis was operated at an ambient temperature. Sample preparation (200 µl plasma) was done by protein precipitation using perchloric acid. Calibration curve in plasma was plotted at different concentration level 5, 50, 100, 500, 1000, 2000, 3000 & 5000 ng mL^-1 were found to be linear with correlation coefficients (r) is 0.9989. The precision of the method based on within-day repeatability and reproducibility (day-to-day variation) was within 15% (relative standard deviation: R.S.D. should be less than 15 according to CDER guidance for Bio-analytical Method Validation). Good accuracy was observed for both the intra-day or inter-day assays, as indicated by the minimal deviation of mean values. Limit of quantitation (LOQ) was accepted as 5 ng mL^-1 using 200 µl samples. The mean recovery was found to be greater than 90% for praziquantel. The method appears to be robust and has been applied for pharmacokinetic study of praziquantel, in three different groups of rats following a single oral dose of 40 mg kg^-1 body weight of praziquantel.

In past years extensive work has been published on double cyclometallated complexes containing two independent metallated phenyl rings.[1-4] In spite of such a wide range of publications, relatively few studies deal with double metallation of the same phenyl ring. In order to make this possible, it is necessary for the ligand to contain two substituents with potentially donor atoms, such as nitrogen or sulfur, which allow the formation of two five− or six− membered chelate rings.

This paper describes the preparation, characterization and structural study of novel tridentate [C,N,S] biscyclopalladated complexes with ligands derived from the condensation of a primary amine −2-(methylthio)aniline− with the corresponding aromatic dialdehyde −terephthalaldehyde−. The compounds are also interesting due to their close-to-planarity arrangement and to the presence of seven fused rings in their structure.

Azoles are a large class of five-membered ring heterocyclic compounds containing at least one nitrogen atom. In particular, azoles and their derivatives have attracted increasing interest as versatile intermediates for the synthesis of biologically active compounds. In recent times the environmental impact has become very important in design of new synthetic methods in organic and medicinal chemistry. Therefore, the use of alternative activation factors like microwaves (MW), ultrasounds (US) or their cross-combination (SMUI - Simultaneous Microwave and Ultrasound Irradiation) became very promising and desirable synthetic methodologies in efficient and fast active structures formation. A comparative study between different activating factors for obtaining derivatives of pyrazole and isoxazole systems were described, including microwave irradiation, ultrasonic action and SMUI method and also classical reflux. Employing, the reactions of appropriate β-dicarbonyl compounds (e.g. 2,4-pentadione, ethyl l,3-oxobutanoate and their alkyl derivatives) respectively with hydrazine or hydroxylamine went to completion in 5-10 minutes and afforded the heterocyclic products in good yields. Based on good results of the above reactions, the next β-dicarbonyl structure modified in to heterocyclic derivatives under SMUI condition was curcumin, natural compound that is a candidate for therapeutic use. The pyrazole and isoxazole heterocyclic derivatives of curcumin were obtained in short time 10-20 minutes with good yield. SMUI was found to be the most efficient activating factor, followed by microwave and ultrasonic mode. Both microwave and ultrasonic factors promoted the heterocyclization reaction but the use of SMUI proved to be fundamental for reducing the reaction time.