A one-dimensional silver(I) coordination polymer with saccharin and pyrazine: synthesis,crystal structure,thermal analysis,FTIR spectra,and DFT studies

A silver(I) complex of saccharinate (sac) with pyrazine (pyz), [Ag(sac)(pyz)] _n , has been synthesized and characterized by elemental analysis, IR, thermal analysis, and single-crystal X-ray diffractometry. The complex crystallizes orthorhombic space group Pnma with unit cell parameters of a = 13.0073(9) Å, b = 6.4907(6) Å, c = 13.4007(9) Å, V = 1131.37(15) Å³, and Z = 4. [Ag(sac)(pyz)] _n is a one-dimensional coordination polymer, in which the sac ligand acts as a monodentate ligand through the N atom and the trigonal silver centers are linked by the bridging pyz ligands. The individual chains are connected into two-dimensional supramolemular network by aromatic π(sac)···π(pyz) stacking interactions. The FTIR spectrum of [Ag(sac)(pyz)] _n has been recorded in the region and 4,000–400 cm^?1. The optimized geometry, frequency, and intensity of the vibrational bands of [Ag(sac)(pyz)] _n were obtained by density functional theory (DFT) at the B3LYP level. The vibrational frequencies were calculated and the scaled values have been compared with the experimental FTIR data. The observed and calculated frequencies are found to be in good agreement.     

Biodegradation of Tetracycline Under Various Conditions and Effects on Microbial Community

Five hundred tons of antibiotics are consumed yearly in the world. In this study, the biodegradation characteristics of tetracycline (TET) under nitrate-reducing, sulfate-reducing, and methanogenic conditions were determined by batch tests. Also, effects of TET on mixed microbial cultures were revealed by microbiological analysis. In this scope, gas generation and composition, dissolved organic carbon, and electron acceptor concentrations were monitored during 120 days. Additionally, changes on quantities of specific microbial groups were determined by Q-PCR. TET showed non-biodegradable behavior under nitrate- and sulfate-reducing conditions, whereas slightly biodegradable behavior under methanogenic conditions approximately 46 % degradation. The effects of TET on the abundance of mixed culture varied according to taxonomic units. Sulfate-reducing bacteria were inhibited by TET, while archaeal, bacterial, and methanogenic populations were not affected significantly.     

Radioactivity measurements in epiphytic lichens of Uludağ Mountain in Western Anatolia

Activity concentrations of gross-β, naturally occurring ²²⁶Ra, ²³²Th, ²¹⁰Pb, ⁷Be and anthropogenic ¹³⁷Cs in epiphytic lichens collected from Uluda? Mountain are presented and discussed with the aim of evaluating potential usability of lichens as a biomonitor. The activity concentrations of gross-β, ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²³²Th, ²¹⁰Pb and ⁷Be in the lichen samples were found to be in the range of 177–707, 4.05–94.26, 86–211, below detection limit (BDL)—19.2, BDL—14.0, 229–872, and 72.1–220.7 Bq kg^?1 in dry weight, respectively. ¹³⁷Cs content in collected epiphytic lichens was in descending order: Parmelia sulcata > Lobaria pulmonaria > Pseudevernia furfuracea > Usnea filipendula. The best biomonitor for ¹³⁷Cs among the lichen species used in this study was determined as Parmelia sulcata. Pearson’s correlation coefficient was calculated between ¹³⁷Cs and ⁴⁰K activity concentrations using a statistical package program (SPSS ver. 17.0) and a negative correlation value (R = ?0,323, p = 0,222) was obtained. The highest ²²⁶Ra and ²³²Th activity concentrations were found in Bo?azova Yaylas? which has a geological structure including granitic rocks. It was found that ¹³⁷Cs and ⁷Be activity concentrations in species demonstrated an inverse behaviour. The effect of mean annual precipitation and temperature on ⁷Be activity concentration was determined using multi regression analysis. Also, correlations between the ¹³⁷Cs and ⁷Be, and ⁴⁰K and ⁷Be were investigated.     

Chelate structures of 5-(H/Br)-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazones (H2L): Synthesis and structural characterizations of [Ni(L)(PPh3)] and [Ru(HL)2(PPh3)2]

The reactions of 5-R-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazone {R: H (L¹); Br (L²)} with [M^II(PPh₃)nCl₂] (M = Ni, n = 2 and M = Ru, n = 3) in a 1:1 molar ratio have given stable solid complexes corresponding to the general formula [Ni(L)(PPh₃)] and [Ru(HL)₂(PPh₃)₂]. While the 1:1 nickel complexes are formed from an ONS donor set of the thiosemicarbazone and the P atom of triphenylphosphine in a square planar structure, the 1:2 ruthenium complexes consist of a couple from each of N, S and P donor atoms in a distorted octahedral geometry. These mixed-ligand complexes have been characterized by elemental analysis, IR, UV–Vis, APCI-MS, ¹H and ³¹P NMR spectroscopies. The structures of [Ni(L²)(PPh₃)] (II) and [Ru(L¹H)₂(PPh₃)₂] (III) were determined by single crystal X-ray diffraction.     

Baltimore PM2.5 Supersite: highly time-resolved organic compounds—sampling duration and phase distribution—implications for health effects studies

As part of the Baltimore PM2.5 Supersite study, intensive three-hourly continuous PM2.5 sampling was conducted for nearly 4 weeks in summer of 2002 and as well in winter of 2002/2003. Close to 120 individual organic compounds have been quantified separately in filter and polyurethane foam (PUF) plug pairs for 17 days for each sampling period. Here, the focus is on (1) describing briefly the new sampling system, (2) discussing filter/PUF plugs breakthrough experiments for semi-volatile compounds, (3) providing insight into phase distribution of semi-volatile organic species, and (4) discussing the impact of air pollution sampling time on human exposure with information on maximum 3- and 24-h averaged ambient concentrations of potentially adverse health effects causing organic pollutants. The newly developed sampling system consisted of five electronically controlled parallel sampling channels that are operated in a sequential mode. Semi-volatile breakthrough experiments were conducted in three separate experiments over 3, 4, and 5 h each using one filter and three PUF plugs. Valuable insight was obtained about the transfer of semi-volatile organic compounds through the sequence of PUF plugs and a cut-off could be defined for complete sampling of semi-volatile compounds on only one filter/PUF plug pair, i.e., the setup finally used during the seasonal PM2.5 sampling campaign. Accordingly, n-nonadecane (C19) with a vapor pressure (vp) of 3.25 × 10⁻⁴ Torr is collected with > 95% on the filter/PUF pair. Applied to phenanthrene, the most abundant the PAH sampled, phenanthrene (vp, 6.2 × 10⁻⁵ Torr) was collected completely in wintertime and correlates very well with three-hourly PM2.5 ambient concentrations. Valuable data on the fractional partitioning for semi-volatile organics as a function of season is provided here and can be used to differentiate the human uptake of an organic pollutant of interest via gas- and particle-phase exposure. Health effects studies often relay on PM2.5 exposure measurements taken over 24 h or longer. We found that maximum 3-h concentrations are frequently two to five times higher than that found for maximum 24-h concentrations, an important aspect when considering that short-term exposure to higher air pollution levels are more likely to overpower defense mechanisms in the human lung with subsequent adverse effects even at lower pollutant levels.     

Experimental and computational studies on (<Emphasis Type=Italic>Z</Emphasis>)-1-((4-phenylamino)phenylamino)-methylene)naphthalen-2(1<Emphasis Type=Italic>H</Emphasis>)-one

The Schiff base compound (Z)-1-((4-phenylamino)phenylamino)methylene)naphthalen-2(1H)-one has been synthesized and characterized by IR, UV–Vis, and X-ray single-crystal determination. Molecular geometry from X-ray experiment of the title compound in the ground state have been compared using the Hartree–Fock (HF) and density functional method (B3LYP) with 6−31G(d,p) basis set. Calculated results show that density functional theory DFT and HF can well reproduce the structure of the title compound. Using the time-dependent density functional theory (TD-DFT) and Hartree–Fock (TD-HF) methods, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and experimental ones is determined. The energetic behavior of the title compound in solvent media has been examined using B3LYP method with the 6−31G(d,p) basis set by applying the polarizable continuum model (PCM). The total energy of the title compound decreases with increasing polarity of the solvent. In addition, DFT calculations of the title compound, molecular electrostatic potential (MEP), natural bond orbital analysis (NBO), and non-linear optical (NLO) properties were performed at B3LYP/6−31G(d,p) level of theory.     

Preparation and thermal characterization of poly(2‐vinylpyridine) copolymers coordinated to Cr nanoparticles

In this study, polystyrene‐block‐poly(2‐vinylpyridine), PS‐b‐P2VP, polyisoprene‐block‐poly(2‐vinylpyridne), PI‐b‐P2VP and poly(methyl metacrylate)‐block‐poly(2‐vinylpyridine), PMMA‐b‐P2VP, coordinated to Cr metal were synthesized and characterized by Fourier transform infrared, transmission electron microscopy and direct pyrolysis mass spectrometry techniques. Both thermal degradation mechanism and thermal stability of P2VP blocks were affected by the coordination of Cr nanoparticles to nitrogen of pyridine rings. Thermal decomposition of P2VP blocks was started by loss of pyridine units leaving an unsaturated and/or crosslinked polymer backbone that degraded at relatively high temperatures. Incorporation of Cr metal did not noticeably influence thermal behavior of PS and PI blocks. However, increase in thermal stability of PMMA block was detected and associated with inhibition of the interactions between carbonyl groups of MMA chains with nitrogen atom of pyridine ring as a consequence of coordination to metal. Copyright © 2015 John Wiley & Sons, Ltd.