Timisoara of Romanian Academy

Timişoara, Romania

Timisoara of Romanian Academy

Timişoara, Romania
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Popa A.,Timisoara of Romanian Academy | Avram E.,Petru Poni Institute of Macromolecular Chemistry | Lisa G.,Technical University Gheorghe Asachi | Visa A.,Timisoara of Romanian Academy | And 3 more authors.
Polymer Engineering and Science | Year: 2012

Phase transfer catalyzed reactions are often more easily and cheaply performed than conventional method and they are therefore of particular interest. A polysulfone functionalized with phosphonate (2-PSF) was prepared under phase transfer catalysis (PTC) conditions, and it was evaluated by spectrometric method (Fourier transform infrared spectroscopy, using potassium bromide (KBr) pellet). The phosphorus content of the modified polysulfone was determined, and it was used for the determination the fraction of repeating units functionalized with phosphonate groups. The modified polysulfone contains 1.40 mmol phosphonate/g polysulfone. Polysulfone functionalized with phosphonate groups and polysulfone functionalized with aldehyde groups (3-PSF) were used in Wittig-Horner reaction, to introduce double bonds on polymer and to obtain crosslinked polysulfone (4-PSF). The reactions were performed using PTC method, solid-liquid (potassium carbonate (K 2CO 3), tetrahydrofuran (THF), tetraethylammonium iodide (TEAI)) system. The structure of polysulfone functionalized with phosphonate groups and polysulfone functionalized with aldehyde group were confirmed by 1H-, 13C-, and 31P-nuclear magnetic resonance (NMR). The peak for phosphorus in PSF-phosphonate appears in 31P NMR spectrum as a singlet at 25.712 ppm. The thermal properties of aldehyde, phosphonate, and crosslinked polysulfone were studied by thermogravimetric analysis (TG) and differential thermogravimetric analysis (DTG). Scanning electron microscopy images for polysulfone functionalized with phosphonate and crosslinked polysulfone are in concordance with nitrogen (N 2) adsorption-desorption isotherms. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers.

Colodrero R.M.P.,University of Malaga | Cabeza A.,University of Malaga | Olivera-Pastor P.,University of Malaga | Choquesillo-Lazarte D.,Laboratorio Of Estudios Crystalograficos | And 8 more authors.
Inorganic Chemistry | Year: 2011

A family of M-VP (M = Ni, Co, Cd, Mn, Zn, Fe, Cu, Pb; VP = vinylphosphonate) and M-PVP (M = Co, Cd; PVP = phenylvinylphosphonate) materials have been synthesized by hydrothermal methods and characterized by FT-IR, elemental analysis, and thermogravimetric analysis (TGA). Their structures were determined either by single crystal X-ray crystallography or from laboratory X-ray powder diffraction data. The crystal structure of some M-VP and M-PVP materials is two-dimensional (2D) layered, with the organic groups (vinyl or phenylvinyl) protruding into the interlamellar space. However, the Pb-VP and Cu-VP materials show dramatically different structural features. The porous, three-dimensional (3D) structure of Pb-VP contains the Pb center in a pentagonal pyramid. A Cu-VP variant of the common 2D layered structure shows a very peculiar structure. The structure of the material is 2D with the layers based upon three crystallographically distinct Cu atoms; an octahedrally coordinated Cu2+ atom, a square planar Cu2+ atom and a Cu+ atom. The latter has an unusual co-ordination environment as it is 3-coordinated to two oxygen atoms with the third bond across the double bond of the vinyl group. Metal-coordinated water loss was studied by TGA and thermodiffractometry. The rehydration of the anhydrous phases to give the initial phase takes place rapidly for Cd-PVP but it takes several days for Co-PVP. The M-VP materials exhibit variable dehydration-rehydration behavior, with most of them losing crystallinity during the process. © 2011 American Chemical Society.

Fagadar-Cosma E.,Timisoara of Romanian Academy | Vlascici D.,Timisoara of Romanian Academy | Vlascici D.,West University of Timișoara | Fagadar-Cosma G.,Polytechnic University of Timişoara | And 7 more authors.
Molecules | Year: 2014

The present report deals with the tailoring, preparation and characterization of novel nanomaterials sensitive to CO2 for use in detection of this gas during space habitation missions. A new nanostructured material based on mixed substituted asymmetrical A3B porphyrin: 5-(4-pyridyl)-10,15,20-tris(3,4-dimethoxyphenyl)-porphyrin (PyTDMeOPP) was synthesized and characterized by1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC and AFM. Introducing one pyridyl substituent in the 5-meso-position of porphyrin macrocycle confers some degree of hydrophilicity, which may cause self-assembly properties and a better response to increased acidity. The influence of pH and nature of the solvent upon H and J aggregates of the porphyrin are discussed. Porphyrin aggregation at the air-THF interface gave a triangular type morphology, randomly distributed but uniformly oriented. When deposition was made by multiple drop-casting operations, a network of triangles of uniform size was created and a porous structure was obtained, being reorganized finally in rings. When the deposition was made from CHCl3, ring structures ranging in internal diameter from 300 nm to 1 μm, but with the same width of the corona circular of approx. 200 nm were obtained. This porphyrin-based material, capable of generating ring aggregates in both THF and CHCl3, has been proven to be sensitive to CO2 detection. The dependence between the intensity of porphyrin UV-vis absorption and the concentration of CO2 has a good correlation of 98.4%. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Bora A.,West University of Timișoara | Bora A.,Timisoara of Romanian Academy | Avram S.,Timisoara of Romanian Academy | Ciucanu I.,West University of Timișoara | And 2 more authors.
Journal of Chemical Information and Modeling | Year: 2016

In this study we developed two-dimensional pharmacophore-based random forest models for the effective profiling of kinase inhibitors. One hundred seven prediction models were developed to address distinct kinases spanning over all kinase groups. Rigorous external validation demonstrates excellent virtual screening and classification potential of the predictors and, more importantly, the capacity to prioritize novel chemical scaffolds in large chemical libraries. The models built upon more diverse and more potent compounds tend to exert the highest predictive power. The analysis of ColBioS-FlavRC (Collection of Bioselective Flavonoids and Related Compounds) highlighted several potentially promiscuous derivatives with undesirable selectivity against kinases. The prediction models can be downloaded from www.chembioinf.ro. © 2016 American Chemical Society.

Petric M.,Timisoara of Romanian Academy | Crisan L.,Timisoara of Romanian Academy | Crisan M.,Timisoara of Romanian Academy | Micle A.,Laboratory of Drug Analysis and Profiling | And 3 more authors.
Heteroatom Chemistry | Year: 2013

New phosphoramidic acid derivatives were synthesized by three different methods in the liquid-liquid and liquid-solid systems. The highest yields were obtained when the liquid-solid system was used. Moreover, for these compounds, the retention factor was predicted, using a robust model obtained for a set of phosphoramidic acid derivatives, which were previously synthesized in our laboratory. For these compounds, the retention factor (k″) was determined by means of the high performance liquid chromatography technique, using a Nucleosil C18 column as a stationary phase and methanol as a mobile phase. The stepwise multiple linear regression (MLR) and partial least square (PLS) methodology were used to investigate the correlation between the retention factor and a number of molecular descriptors for the mentioned compounds. In both procedures, a considerably large number of molecular descriptors have been used. The statistical qualities of MLR and PLS equations have been assessed on the basis of several parameters such as squares of the correlation coefficient (R2 = 0.985), standard error of estimate (SEE = 0.149), Fischer test (F = 257.528), and the cumulative sum of squares of the correlation coefficient R2 Y(CUM) = 0.984, the cumulative fraction of the total variation of the Y values that can be predicted for all the extracted principal components by cross-validation Q2 (CUM) = 0.971, respectively, and by the Y-randomization test. The MLR and PLS equations can be useful for the estimation and comparison of the retention factor, for new synthesized phosphoramidic acid derivatives, using the selected molecular descriptors. © 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:138-145, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21076 © 2013 Wiley Periodicals, Inc.

Muntean S.G.,Timisoara of Romanian Academy | Radulescu-Grad M.E.,Timisoara of Romanian Academy | Sfarloaga P.,Romanian National Institute for Research and Development in Electrochemistry and Condensed Matter
RSC Advances | Year: 2014

The efficiency of styrene-divinylbenzene functionalized with trimethylamonium groups as sorbent for the direct dye removal from aqueous solutions was investigated. The influence of process variables such as initial concentration, temperature and pH was developed. The amount of adsorbed dye was maximized at higher initial dye concentrations, while the removal percentage decreased. The increase of the temperature induced a positive effect on the adsorption indicating that the process is endothermic. The maximum removal percentage was obtained in acidic medium. The adsorption kinetics followed the pseudo-second-order equation, with regards to the intra-particle diffusion rate. The experimental data was well correlated by the Sips adsorption model, and the maximum theoretical adsorption capacity was determined to be 83.75 mg dye g-1 copolymer. The new obtained specific sorbent (dye-attached to copolymer) was investigated in the removal of heavy metals ions (Cu, Zn). Very high adsorption rates were observed at the beginning of the adsorption process and the equilibrium was achieved in about 5 minutes. © 2014 the Partner Organisations.

Macarie L.,Timisoara of Romanian Academy | Plesu N.,Timisoara of Romanian Academy | Iliescu S.,Timisoara of Romanian Academy | Ilia G.,Timisoara of Romanian Academy | Tara-Lunga-Mihali M.,Timisoara of Romanian Academy
Iranian Polymer Journal (English Edition) | Year: 2016

Dimethyl vinylphosphonate (DMVP), a very promising monomer, was copolymerized with acrylic monomer bisphenol A ethoxylate dimethacrylate (BEMA), in different molar ratios, by radical photoinitiated polymerization in the presence of photoinitiator Darocur 4265 (3 wt%) and in the absence of solvent. The UV light polymerization was an efficient method to obtain polymers in a green procedure. The molar ratio between DMVP and acrylic monomer BEMA varied between 1:1 and 5:1. The copolymers were characterized by FTIR, thermal analysis, water uptake and conductivity. From the ATR-FTIR spectra of DMVP-BEMA copolymers at the molar ratios of 1:1–5:1, it was observed that the intensity of P-O-C aliphatic band increased with increases in DMVP content. The synthesized copolymers showed good thermal stability in the range of 335–390 °C. DMVP:BEMA copolymer at 1:1 molar ratio displayed the highest stability, with decomposition temperature above 390 °C, the highest temperature in the series. The water uptake decreased with increases in DMVP content and this behavior was correlated with the ionic conductivity. Based on the Bode diagrams, the ionic conductivity of DMVP:BEMA of 1:1 molar ratio was 6.15 × 10−8 S cm−1 and that of DMVP:BEMA of 2:1 molar ratio was 3.69 × 10−8 S cm−1 which were considered promising as valuable conducting materials. © 2016, Iran Polymer and Petrochemical Institute.

Yen M.-H.,University of Sheffield | Chaiprapa J.,University of Sheffield | Zeng X.,University of Sheffield | Liu Y.,Zhejiang Sci-Tech University | And 5 more authors.
Journal of the American Chemical Society | Year: 2016

We report a columnar superlattice formed by blends of dendron-like Li 3,4,5-Tris(n-Alkoxy)benzoates with n-Alkanes. Without the alkane, the wedge-shaped molecules form liquid crystal columns with 3 dendrons in a supramolecular disk. The same structure exists in the blend, but on heating one dendron is expelled from the disks in every third column and is replaced by the alkane. This superlattice of unequal columns is confirmed by complementary X-ray and neutron diffraction studies. Lateral thermal expansion of dendrons normally leads to the expulsion of excess molecules from the column, reducing the column diameter. However, in the already narrow columns of pure Li salt, expulsion of one of only three dendrons in a disk is not viable. The added alkane facilitates the expulsion, as it replaces the missing dendron. Replacing the alkane with a functional compound can potentially lead to active nanoarrays with relatively large periodicity by using only small molecules. © 2016 American Chemical Society.

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