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Tin sulfide nanoparticles were prepared from tin(ii) dithiocarbamate complexes: bis(benzylmethyl dithiocarbamate)tin(ii) (SnS1), bis(dibenzyl dithiocarbamato)tin(ii) (SnS2), and bis(imidazolyldithiocarbamato)tin(ii) (SnS3) single-source precursors. Powder X-ray diffraction patterns of the as-prepared tin sulfide nanoparticles confirmed orthorhombic crystalline phase irrespective of the tin(ii) dithiocarbamate precursors used to prepare the tin sulfide nanoparticles. Transmission electron microscopic images showed SnS nanoparticles with average particle size of 1.35 ± 0.04 nm for SnS1, 2.63 ± 0.65 nm for SnS2, and 1.55 ± 0.15 nm for SnS3. The energy bandgap of the SnS nanoparticles obtained from Tauc plots are in the range 3.80–4.37 eV. The as-prepared SnS nanoparticles were used as photocatalysts for the degradation of rhodamine B with efficiency of 90.97, 61.53, and 80.26% for SnS1, SnS2, and SnS3, respectively, while for phenol degradation efficiency was 96.45, 75.13, and 90.69% after 180 min. The results indicate that the as-prepared SnS nanoparticle are efficient photocatalyst for rhodamine B and phenol degradation. The photocatalytic degradation of rhodamine B and phenol follows pseudo-first-order reaction kinetics model from which the photodegradation rate could be obtained. Scavenger studies show that electrons (e−), hydroxy radicals (˙OH), and holes (h+) play significant role in the photodegradation of rhodamine B and phenol by the SnS nanoparticles. Recyclability studies show the SnS photocatalyst could be reused for four cycles without losing its photodegradation ability.

We report the synthesis and morphological studies of lead sulphide nanoparticles prepared from lead(II) complexes of morpholine dithiocarbamate (PbS1), thiomorpholine dithiocarbamate (PbS2), and N-(2-hydroxyethyl)phenyl dithiocarbamate (PbS3). Powder X-ray diffraction patterns (p-XRD) of the PbS nanoparticles are indexed to face-centered cubic phase of PbS. High-resolution transmission electron microscopy (HRTEM) micrograph revealed quasi-spherical PbS nanoparticles with particle size in the range 13.86–36.06 nm while scanning electron microscopy (SEM) revealed flaky/spherical/rough surface morphology. Photocatalytic degradation of methylene blue dye by the PbS nanoparticles showed degradation efficiency of 72.6 % for PbS1, 75.9 % for PbS2, and 47.4 % for PbS3. The photodegradation efficiency shows a correlation between efficiency and morphological properties. Total organic content removal by PbS2 is 69.5 % while that of PbS1 is 64.2 % and PbS3 is 40.1 %. The as-prepared PbS nanoparticles exhibited remarkable photostability in the recyclability studies.

Although pollutants pose environmental and human health risks, the majority are not routinely monitored and regulated. Organic pollutants emanate from a variety of sources, and can be classified depending on their chemistry and environmental fate. Classification of pollutants is important because it informs fate processes and apposite removal technologies. The occurrence of emerging contaminants (ECs) in water bodies is a source of environmental and human health concern globally. Despite being widely reported, data on the occurrence of ECs in South Africa are scarce. Specifically, ECS in wastewater in the Northern Cape in South Africa are understudied. In this study, various ECs were screened in water samples collected from three wastewater treatment plants (WWTPs) in the province. The ECs were detected using liquid chromatography coupled to high resolution Orbitrap mass spectrometry following Oasis HLB solid-phase extraction. The main findings were: (1) there is a wide variety of ECs in the WWTPs, (2) physico-chemical properties such as pH, total dissolved solids, conductivity, and dissolved organic content showed reduced values in the outlet compared to the inlet which confirms the presence of less contaminants in the treated wastewater, (3) specific ultraviolet absorbance of less than 2 was observed in the WWTPs samples, suggesting the presence of natural organic matter (NOM) that is predominantly non-humic in nature, (4) most of the ECs were recalcitrant to the treatment processes, (5) pesticides, recreational drugs, and analgesics constitute a significant proportion of pollutants in wastewater, and (6) NOM removal ranged between 35 and 90%. Consequently, a comprehensive database of ECs in wastewater in Sol Plaatje Municipality was created. Since the detected ECs pose ecotoxicological risks, there is a need to monitor and quantify ECs in WWTPs. These data are useful in selecting suitable monitoring and control strategies at WWTPs.

Bis(dibenzyldithiocarbamato)Zn(II), [Zn(dbzdtc)2], was synthesized and characterized by spectroscopic techniques, elemental analysis and single crystal X-ray crystallography. The compound is crysta...

Bis(morpholinyl-4-carbodithioato)-platinum(II) was synthesized and characterized using spectroscopic techniques and single-crystal X-ray crystallography. The Pt(II) complex crystallized in a monoclinic space group P21/n with a Pt(II) ion located on an inversion center coordinated two morpholinyl dithiocarbamate ligands that are coplanar to form a slightly distorted square planar geometry around the Pt(II) ion. The complex was thermolyzed at 120, 180, and 240 °C to prepare PtS2 nanoparticles. Powder X-ray diffraction patterns confirmed the hexagonal crystalline phase for the as-prepared PtS2 nanoparticles irrespective of thermolysis temperature. Bead-like shaped PtS2-120 nanoparticles with a particle size in the range of 12.46-64.97 nm were formed at 120 °C, while PtS2-180 prepared at 180 °C is quasi-spherical in shape with particles in the range of 24.30-46.87 nm. The PtS2-240 obtained at 240 °C is spherical with particles in the range of 11.45-46.85 nm. The broad emission maxima of the as-prepared PtS2 nanoparticles are ascribed to the particles' broad size distributions. The photocatalytic degradation of methylene blue by the PtS2 nanoparticles shows a maximum efficiency of 87% for PtS2-240 after 360 min. The effects of photocatalytic dosage, irradiation time, pH medium, and scavengers were also evaluated. Cyclic voltammetry of the PtS2 nanoparticles showed a reversible redox reaction, while the electrochemistry of the as-prepared PtS2 indicates that the electron transfer process is diffusion-controlled.

Hexadecylamine-capped PbS nanoparticles were prepared from lead(II) complexes of dibenzyl dithiocarbamate (Dibzydtc) [PbS 1], imidazolyl dithiocarbamate (Imdtc) [PbS 2], 2-oxo-pyrrolidine dithiocarbamate (Pydtc) [PbS 3], diallyl dithiocarbamate (Diallyldtc) [PbS 4], and dihexyl dithiocarbamate (Dihexdtc) [PbS 5], at 120 °C. Powder X-ray diffraction patterns of the PbS nanoparticles are indexed to the face-centered cubic phase. The average particle sizes obtained from the TEM images are 19.04 ± 5.85 nm for PbS 1, 6.94 ± 1.71 nm PbS 2, 18.77 ± 3.37 nm PbS 3, 2.93 ± 2.20 nm PbS 4 and 22.02 ± 6.68 nm for PbS 5. The PbS nanoparticles are spherical in shape except for PbS 1 and PbS 3 with cubic shapes. The bandgap energies range from 3.0 to 3.8 eV and PbS 1 has the lowest bandgap of 3.0 eV while PbS 3 has the highest bandgap of 3.8 eV. The bandgaps are blue-shifted in comparison to the absorption band edges due to quantum size effect. The photocatalytic degradation of bromothymol blue by the as-prepared PbS nanoparticles showed highest degradation efficiency of 66% for PbS 3.

Oleic acid (OA) and octadecylamine (ODA) capped lead sulphide (PbS) nanoparticles were prepared at 150, 190 and 230 °C. X-ray diffraction patterns indicates that the synthesized PbS nanoparticles were in the rock cubic salt crystalline phase. The particle sizes of the as-prepared PbS nanoparticles are in the range 2.91–10.05 nm for OA-PbS(150), 24.92–39.98 nm for ODA-PbS(150), 9.26 – 29.08 nm for OA-PbS(190), 34.54 – 48.04 nm for ODA-PbS(190), 17.96–88.07 nm for OA-PbS(230) and 53.60 – 94.42 nm for ODA-PbS(230). SEM images revealed flaky and agglomerated spherical like morphology for the nanoparticles. The energy bandgap of the PbS nanoparticles are in the range 4.14 – 4.25 eV, OA-PbS(230) have the lowest bandgap of 4.14 eV while ODA-PbS(150) have the highest bandgap of 4.25 eV. The PbS nanoparticles were used as photocatalyst for the degradation of Rhodamine B and OA-PbS(150) showed efficiency of 44.11% after 360 mins. Cyclic voltammetry of the PbS nanoparticles showed a reversible redox reaction and linear Randles-Sevcik plots indicates electron transfer process is diffusion controlled.

We report the effect of thermolysis time on the morphological and optical properties of CuS nanoparticles prepared from Cu(II) dithiocarbamate single-source precursor. The as-prepared copper sulfide nanoparticles were used as photocatalysts for the degradation of crystal violet (CV), methylene blue (MB), rhodamine B (RhB), and a ternary mixture of the three dyes (CV/MB/RhB). Powder XRD patterns confirmed the hexagonal covellite phase for the CuS nanoparticles. At the same time, HRTEM images revealed mixed shapes with a particle size of 31.47 nm for CuS1 prepared at 30 min while CuS2 prepared at 1 h consists of mixtures of hexagonal and nanorods shaped particles with an average size of 21.59 nm. Mixed hexagonal and spherically shaped particles with a size of 17.77 nm were obtained for CuS3 prepared at 2 h. The optical bandgaps of the nanoparticles are 3.00 eV for CuS1, 3.26 eV for CuS2 and 3.13 eV for CuS3. The photocatalytic degradation efficiency showed that CuS3 with the smallest particle size is the most efficient photocatalyst and degraded 85% of CV, 100% of MB, and 81% of RhB. The as-prepared CuS showed good stability and recyclability and also degraded ternary dyes mixture (CV/MB/RhB) effectively. The byproducts of the dye degradation were evaluated using ESI-mass spectrometry.

We report the effect of thermolysis temperature on the morphological and optical properties of cadmium sulphide quantum dots prepared from bis((2-morpholinoethyl) carbamodithioate)Cd(II) precursor at 120, 180 and 240 ℃. Powder XRD analysis revealed hexagonal crystalline phase for the CdS quantum dots. TEM images revealed almost spherical monodispersed particles, with size ranges of 3.2–4.9 nm for HDA-CdS1 prepared at 120 °C, while for HDA-CdS prepared at 180 °C particle sizes increased to 4.0-5.9 nm and 5.4–11.2 nm for HDA-CdS3 prepared at 240 °C. The results indicate thermolysis temperature influences the particle sizes and subsequently its use as photocatalyst. The band gaps were found to be 2.04 eV for HDA-CdS1, 2.01 eV for HDA-CdS2, and 2.07 eV for HDA-CdS3. The electrochemical properties of the HDA-CdS quantum dots were studied using cyclic voltammetry and calculated electrochemical band gaps were found to be 2.19 eV for HDA-CdS1, 2.15 eV for HDA-CdS2, and 2.06 eV for HDA-CdS3 which is close to the optical bandgap. The photocatalytic degradation of methylene blue by the CdS quantum dots showed degradation efficiency of 76 % for HDA-CdS1, 47 % for HDA-CdS2, and 61 % for HDA-CdS3.

Bis(dibenzyldithiocarbamato)Zn(II), [Zn(dbzdtc)2], was synthesized and characterized by spectroscopic techniques, elemental analysis and single crystal X-ray crystallography. The compound is crystallized in a monoclinic space group P21/n with Zn(II) located on crystallographic twofold symmetry and coordinated to two molecules of dibenzyl dithiocarbamato anions to form a rare four-coordinate mononuclear Zn(II) complex in a see-saw geometry. The cytotoxicity of the complex was evaluated by MTT assay against breast cancer cells (MCF-7) and human embryonic kidney cells (HEK293). The results showed that the complex is active against MCF-7 breast cancer cells with IC50 value of 6.41 and 4.423 μΜ against HEK293 cell line.

Tin sulfide (SnS) nanoparticles were prepared from tin(II) dithiocarbamate single source precursors. Powder X-ray diffraction patterns of the SnS nanoparticles confirmed orthorhombic herzenbergite phase of tin sulfide. High-resolution transmission electron microscope images show spherically shaped tin sulfide with particles size in the range 1.0���2.8 nm. The bandgap energy obtained from Tauc plots is in the range 2.95���3.32 eV. The as-prepared SnS nanoparticles were used as nano photocatalysts for the degradation of brilliant green (BG), crystal violet (CV), methylene blue (MB) and methyl red (MR) under visible light irradiation. The degradation efficiency of BG by the SnS nanoparticles after 180 min irradiation are 76%, 81% and 70% by SnS-1, SnS-2 and SnS-3. Degradation efficiency of 66%, 90% and 75% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against CV dye. While the efficiency of 79%, 97% and 93% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against MB dye. The results showed that the as-prepared SnS nanoparticles are efficient photocatalyst for the degradation of BG, CV, MB and MR dyes. Liquid chromatography-mass spectrometry was used to investigate the degradation pathway of the organic dyes. The effects of irradiation time, scavengers and photostability on the photocatalysis process were also evaluated.

Cobalt(II) and copper(II) complexes of a series (E)-N’-(5-X-salicylidene)isonicotinohydrazide Schiff bases derived from isonicotinic acid hydrazide and 5-substituted-salicylaldehydes have been synthesized and characterized by FTIR, AAS, UV-Visible spectroscopy and elemental analysis. Evaluation of the in-vitro antitubercular, antioxidant and cytotoxic activities of the compounds was carried out to establish their potential as antituberculosis agents. The FTIR spectra showed that the ligands behave as tridentate dibasic ligands towards the metal ions. The antioxidant activities of the compounds investigated through their scavenging effect on DPPH revealed that the IC50 for the nitro substituted Schiff base was highest, similarly, the LC50 value was much lower than the values for other compounds. The ligand complexes containing the nitro NO2 substituent exhibited enhanced in vitro Mycobacterium tuberculosis and antioxidant activities compared with the ligands and reference compounds (Isoniazid and vitamin C).

Mn(II), Co(II), Cu(II), Zn(II) and Pt(II) complexes of 2-(((4-methoxyphenyl)amino)methyl)phenolyl dithiocarbamato were synthesized and characterized by elemental analysis and spectroscopic techniques. Spectroscopic studies confirmed that two molecules of the dithiocarbamato anions coordinate the metal ions as bidentate chelating ligands. In vitro anticancer screening of the compounds was conducted in the human cervical adenocarcinoma cell (HeLa) and in the human foetal lung cancer cell (MRC5-SV2) and its normal (non-cancer) parental line (MRC5). All complexes except Cu(II) were cytotoxic to HeLa in the preliminary screen. When tested in the MRC5-SV2 cancer cell, Co(II) and Zn(II) were the most potent, with IC50 values (µM) of 12.9 ± 1.2 and 15.1 ± 2.4, respectively, while Mn(II) and Pt(II) had IC50 values of 31.5 ± 3.8 and 25.5 ± 4.4, respectively, compared to 8.6 ± 0.3 for the anti-cancer drug cisplatin. Zn(II) was the most cancer cell-selective, with a selectivity index (SI) of 2.0, followed by Co(II) with a SI of 1.4. Mn(II) was not cancer cell-selective, while Pt(II) was more cytotoxic against normal cells, with a SI of 0.2. The varied anticancer potencies of the metal complexes derived from the same ligand can provide direction for further research into the development of inorganic complexes as anti-cancer drugs.

We report the synthesis and crystal structures of bis(dibenzyl dithiocarbamato) copper(II) and silver(I) complexes and their use as precursors to prepare Cu1.8S and Ag2S nanoparticles. Single crystal analysis of bis(dibenzyl dithiocarbamato)Cu(II) complex consist of a monomeric entity where the two dibenzyl dithiocarbamate ligands form a distorted square planar geometry around the Cu(II) ion. The bis(dibenzyl dithiocarbamato)Ag(I) formed hexameric coordination complex consisting of two distorted hexagonal Ag3S3 rings. The complexes were thermolysed at 220 °C to prepare copper sulphide and silver sulphide nanoparticles. Powder X-ray diffraction (p-XRD) patterns of the copper sulphide nanoparticles were indexed to digenite Cu1.8S, while silver sulphide nanoparticles were confirmed to be acathinite Ag2S. High-resolution transmission electron microscopy (HRTEM) images showed Ag2S nanoparticles with particle size in the range 11.4–27.4 nm while Cu1.8S nanoparticles are semi-spherical in shape with slightly agglomerated particles in the range 6.9–24.0 nm. The as-prepared nanoparticles were used as nano-photocatalysts for the degradation of methylene blue dye (MB) under UV light irradiation with degradation efficiency of 42.52% and 48.39% for Cu1.8S and Ag2S nanoparticles respectively.

We report the synthesis, photocatalytic and cytotoxic studies of hexadecylamine capped zinc sulphide (ZnS) nanoparticles. XRD patterns confirmed hexagonal wurtzite phase of ZnS nanoparticles and HRTEM micrograph revealed spherically shaped particles with sizes in the range 2.81-4.48 nm. Energy band gaps of 4.67, 4.68 and 4.71 eV for ZnS1, ZnS2 and ZnS3 obtained at 30 min, 1 h and 2h. The photocatalytic degradation of methylene blue by the as-synthesized ZnS nanoparticles showed degradation efficiency of 55.16% for ZnS1, 53.58% for ZnS2 and 71.17% ZnS3 after 3 hours. Anticancer studies of the ZnS nanoparticles showed they exhibited very potent cytotoxicity activity against breast adenocarcinoma and human cervical carcinoma cancer cell lines.

Pb(II) complexes of N-ethyl-N-phenyl dithiocarbamate [Pb(EtPhdtc)2] and N-benzylmethyl dithiocarbamate [Pb(BzyMedtc)2] were synthesized and characterized by single crystal X-ray crystallography. The molecular structures of compounds reveal a distorted tetrahedral geometry around the Pb(II) ions. [Pb(EtPhdtc)2] crystalized as a dimeric structure with Pb … Pb and Pb … S interactions while [Pb(BzyMedtc)2] crystallized as monomeric complex with weak C–H interactions. Thermogravimetric analysis of the Pb(II) complexes shows they decomposed to give lead sulphide (PbS). The complexes were thermolysed in oleic acid (OA) at 120°C, 160°C and 200°C to study the influence of temperature on OA capped PbS nanoparticles. Powder X-ray diffraction patterns confirms that the as-prepared PbS are cubic rock salt crystalline phase of PbS. High resolution transmission electron microscopy (HRTEM) micrographs crystallite average size of 2.64 nm for particles prepared at 120°C, 4.12 nm for particles prepared at 160°C, and 1.93 nm for particles prepared at 200°C from [Pb(EtPhdtc)2]. The average crystallite sizes of PbS nanoparticles obtained from [Pb(BzyMedtc)2] are 6.61 nm at 120°C, 13.88 nm at 160°C, and 10.82 nm at 200°C. The as-prepared PbS nanocrystals were used as photocatalyst for the degradation of methylene blue with the highest degradation efficiency of 73.89% recorded for OAPbS1a.

SnS nanocrystals were synthesized using bis(phenylpiperazine dithiocarbamate)tin(II) in oleic acid (OA) and octadecylamine (ODA) at three different temperatures (150, 190, and 230°C). XRD diffraction pattern confirms that OASnS and ODASnS nanoparticles are in the orthorhombic phase and the type of capping agent used affects the crystallinity. Transmission electron microscopy (TEM) images shows spherically shaped nanocrystals for oleic acid capped SnS (OASnS) while octadecylamine (ODASnS) are cubic. Monodispersed SnS of size range 10.67–17.74 nm was obtained at 150°C for OASnS while the biggest-sized nanocrystals were obtained at 230°C for ODASnS. Temperature and capping agents tuned the crystallite sizes and shapes of the as-prepared nanocrystals. Electron dispersive X-ray spectroscopy indicates the formation of tin sulphide with the presence of Sn and S peaks in the nanocrystals. Flowery and agglomerated spherical-like morphology were observed for ODASnS and OASnS nanocrystals, respectively, using a SEM (scanning electron microscope). Direct electronic band gaps of the synthesized SnS nanocrystals are 1.71–1.95 eV and 1.93–2.81 eV for OASnS and ODASnS nanocrystals, respectively.

Lead(II) methyl xanthate [Pb(S2COMe)2] was synthesized and characterized by single crystal X-ray crystallography. The molecular structure showed a distorted tetrahedral geometry around Pb(II) with each monomeric unit linked with another through Pb···S interactions. The compound was used to prepare hexadecylamine capped PbS (HDA-PbS) and oleylamine capped PbS (OLA-PbS) nanoparticles. The PbS nanoparticles were indexed to the cubic PbS crystalline phase with particle sizes of 4.5 – 34.5 nm. The estimated optical bandgaps obtained from the tauc’s plots were 3.47 and 3.30 eV for HDA-PbS and OLA-PbS, respectively, which are blue shifted in comparison to bulk PbS. The photodegradation of methylene blue using PbS as photocatalyst shows that HDA-PbS have the best degradation efficiency of 77.70% after 240 min.