Renata Diniz

Nickel(II) complexes of dithiocarbimates from sulfonamides: syntheses and crystal structures

Abstract This work describes the syntheses of four compounds containing [Ni(RSO2NCS2)2]2− anions: (Bu4N)2[Ni(C6H5SO2NCS2)2] (1), (Bu4N)2[Ni(4-ClC6H4SO2NCS2)2] (2), (Bu4N)2[Ni(2-CH3C6H4SO2NCS2)2] (3) and (Bu4N)2[Ni(4-BrC6H4SO2NCS2)2] (4). They were obtained in the crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2NCS2K2) with nickel(II) chloride hexahydrate in methanol/water. Elemental analyses were consistent with the proposed formulae. UV–Vis and IR data are consistent with the formation of nickel–sulfur diamagnetic planar complexes. The 1H NMR and 13C NMR spectra showed the expected signals for the tetra-n-butylammonium cation and the dithiocarbimate moieties. Single crystal structure analyses showed that (Bu4N)2[Ni(2-CH3C6H4SO2NCS2)2] crystallizes in the triclinic space group P 1 , and (Bu4N)2[Ni(4-BrC6H4SO2NCS2)2] crystallizes in the monoclinic space group P21/c. In these compounds the Ni atom is coordinated to four S atoms in a distorted square plane geometry. The Ni and S atoms form a plane and NiS bonds are different from each other. In both compounds the Ni atoms are in the crystallographic center of symmetry.

Biological sulphide removal from anaerobically treated domestic sewage: reactor performance and microbial community dynamics

We developed a biological sulphide oxidation system and evaluated two reactors (shaped similar to the settler compartment of an up-flow anaerobic sludge blanket [UASB] reactor) with different support materials for biomass retention: polypropylene rings and polyurethane foam. The start-up reaction was achieved using microorganisms naturally occurring on the open surface of UASB reactors treating domestic wastewater. Sulphide removal efficiencies of 65% and 90% were achieved with hydraulic retention times (HRTs) of 24 and 12 h, respectively, in both reactors. However, a higher amount of elemental sulphur was formed and accumulated in the biomass from reactor 1 (20 mg S0 g−1 VTS) than in that from reactor 2 (2.9 mg S0 g−1 VTS) with an HRT of 24 h. Denaturing gradient gel electrophoresis (DGGE) results revealed that the the pink and green biomass that developed in both reactors comprised a diverse bacterial community and had sequences related to phototrophic green and purple-sulphur bacteria such as Chlorobium sp., Chloronema giganteum, and Chromatiaceae. DGGE band patterns also demonstrated that bacterial community was dynamic over time within the same reactor and that different support materials selected for distinct bacterial communities. Taken together, these results indicated that sulphide concentrations of 1–6 mg L−1 could be efficiently removed from the effluent of a pilot-scale UASB reactor in two sulphide biological oxidation reactors at HRTs of 12 and 24 h, showing the potential for sulphur recovery from anaerobically treated domestic wastewater.

1‐(7‐Chloro‐1,4‐dihydroquinolin‐4‐ylidene)thiosemicarbazide and its hydrochloride: evidence for the existence of a stable imine tautomer in the solid state of 4‐aminoquinoline free bases, an anomalous case in nitrogen heterocycles

In the solid state, crystals of both 1-(7-chloro-1,4-dihydroquinolin-4-ylidene)thiosemicarbazide-methanol-water (2/1/1), 2C10H9ClN4S·CH3OH·H2O, (I), and its hydrochloride salt {systematic name: [(7-chloro-1,4-dihydroquinolin-4-ylidene)azaniumyl]thiourea chloride}, C10H10ClN4S(+)·Cl(-), (II), assume the imine tautomeric form, contrary to other 4-amino-7-chloroquinolines. Of particular interest are the N-C bond lengths, which have appreciable double-bond character, and the C-N-C aromatic ring bond angle. Both of these parameters have been studied extensively in 4-amino-substituted quinolines. The crystal structures of (I) and (II) in this study provide interesting examples of the amino-imino tautomerism which exists in this class of compound and is, to the best of our knowledge, hitherto unreported.

Crystallization of Two 1-D Coordination Polymers Building by 5-Sulfoisophthalic Acid and Lanthanide Ions by Partial Hydrolysis of Collagen

This paper intends to show how to use collagen to assist in obtaining single crystals of small molecules of two one-dimensional coordination polymers built by 5-sulfoisophthalic acid and lanthanide ions. The crystals were grown at room temperature and crystalline forms appeared into viscous solution exhibiting well-shaped faces and large volumes with small amount of samples. The use of collagen in the system prevents the formation of precipitate, an advantage when compared to many crystals obtained in pure solution. The samples, Nd(5SIS)·(DMF)2·5H2O (1) and [La(5sis)·8H2O] (2), have been prepared and characterized by single-crystal X-ray diffraction and vibrational spectroscopic (Raman and FT-IR) analyses. The results have shown that the compounds belong to the monoclinic system and it is stabilized by a complex hydrogen bonds network. Coordination environment of metals tend to have more ionic character in their bonds. The advantages and limitations of the use of collagen in small molecule crystallization have also been discussed.

Synthesis and Crystalline Structure of Zinc Complexes with Antihypertensive Drug Lisinopril

The structural investigation of Zn2+ complexes with the ligand lisinopril (LIS), an inhibitor of angiotensin-converting enzyme (ACE), was performed. The main objective is to compare if Zn-LIS coordination in vitro is similar to that observed in vivo. Two zinc complexes were obtained from different synthetic routes. The synthesis of LISZn1 used stirring, while for LISZn2 involved solvothermal conditions, which favoured the full deprotonation of lisinopril ligand. In this sense, the different synthetic routes resulted in the formation of complexes with notorious chemical and structural differences. The crystal structure of LISZn2 showed that the ligand is coordinated to Zn2+ ion by oxygen and nitrogen atoms which is different from that observed in vivo. In vitro, the coordination of lisinopril occurs only by an oxygen atom of the central carboxylate group. LISZn2 forms a one-dimensional (1D) coordination polymer and presents disorder atoms in its unit cell.

Studies of filter media for zero-discharge systems collecting light greywater

ABSTRACT Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42−) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize sulfide to sulfate and elemental sulfur in all studied media. The results showed strong evidence supporting that the microbial community formed in the present study is more related to operational/environmental conditions than to the different tested filter media. Thus, this demonstrates that the control of interactive effects between pH, redox potential, and the COD/SO42− ratio can prevent the accumulation and/or release of sulfide in anoxic environments.