The N-alkyldithiocarbamato complexes [M(S2CNHR)2] (M = Cd(ii) Zn(ii); R = C2H5, C4H9, C6H13, C12H25); their synthesis, thermal decomposition and use to prepare of nanoparticles and nanorods of CdS

A chemically induced, room temperature, single source precursor to CuS (covellite) nanomaterials: synthesis and reactivity of [Cu(S2CNHBz)]n

Addition of two equivalents of NaS2CNHBz to CuSO4 affords the yellow diamagnetic coordination polymer [Cu(S2CNHBz)]n (1), resulting from intramolecular electron-transfer and concomitant formation of the thiourea, (BzNH)2CS. 1 reacts with PPh3 and 1,1'-bis(diphenylphosphino)ferrocene (dppf) in CH2Cl2 to give monomeric [Cu(κ2-S2CNHBz)(PPh3)2] (2) and [Cu(κ2-S2CNHBz)(κ2-dppf)] (3), respectively, both of which have been crystallographically characterised. While 1 is thermally stable in dimethylsulfoxide (DMSO) up to ca. 70 °C, addition of nBuNH2 to 1 leads to its rapid decomposition to afford CuS (covellite) nanomaterials; indeed in neat nBuNH2, covellite formation is rapid at room temperature. Thus, 1 serves as an effective low-temperature base-induced single source precursor to covellite nanomaterials.

Synthesis and Crystal Structures of Bis(diallydithiocarbamato)zinc(II) and Silver(I) Complexes: Precursors for Zinc Sulfide and Silver Sulfide Nanophotocatalysts

We report the preparation and crystal structures of bis(diallydithiocarbamato)zinc(II) and silver(I) complexes. The compounds were used as single-source precursors to prepare zinc sulfide and silver sulfide nanophotocatalysts. The molecular structure of bis(diallydithiocarbamato)zinc(II) consists of a dimeric complex in which each zinc(II) ion asymmetrically coordinates with two diallydithiocarbamato anions in a bidentate chelating mode, and the centrosymmetrically related molecule is bridged through the S-atom that is chelated to the adjacent zinc(II) ion to form a distorted trigonal bipyramidal geometry around the zinc(II) ions. The molecular structure of bis(diallydithiocarbamato)silver(I) formed a cluster complex consisting of a trimetric Ag₃S₃ molecule in which the diallydithiocarbamato ligand is coordinated to all the Ag(I) ions. The complexes were thermolyzed in dodecylamine, hexadecylamine, and octadecylamine (ODA) to prepare zinc sulfide and silver sulfide nanoparticles. The powder X-ray diffraction patterns of the zinc sulfide nanoparticles correspond to the hexagonal wurtzite while silver sulfide is in the acanthite crystalline phase. The high-resolution transmission electron microscopy images show that quantum dot zinc sulfide nanoparticles are obtained with particle sizes ranging between 1.98 and 5.49 nm, whereas slightly bigger silver sulfide nanoparticles are obtained with particle sizes of 2.70-13.69 nm. The surface morphologies of the ZnS and AgS nanoparticles capped with the same capping agent are very similar. Optical studies revealed that the absorption band edges of the as-prepared zinc sulfide and silver sulfide nanoparticles were blue-shifted with respect to their bulk materials with some surface defects. The zinc sulfide and silver sulfide nanoparticles were used as nanophotocatalysts for the degradation of bromothymol blue (BTB) and bromophenol blue (BPB). ODA-capped zinc sulfide is the most efficient photocatalyst and degraded 87% of BTB and 91% of BPB.

Cd(II) and Pd(II) Mixed Ligand Complexes of Dithiocarbamate and Tertiary Phosphine Ligands-Spectroscopic, Anti-Microbial, and Computational Studies

Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized via elemental analysis, molar conductance, NMR (1H and 31P), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes [Cd(PAC-dtc)2(dppe)] and [Cd(PAC-dtc)2(PPh3)2], the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {[Pd(PAC-dtc)2(dppe)](1), [Cd(PAC-dtc)2(dppe)](2), [Cd(PAC-dtc)2(PPh3)2](7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for [Cd(PAC-dtc)2(dppe)](2) compared to [Cd(PAC-dtc)2(PPh3)2](7) due to the ring constrain in the dppe ligand. Moreover, the [Pd(PAC-dtc)2(dppe)](1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex.

Dithiocarbamate Complexes as Single Source Precursors to Nanoscale Binary, Ternary and Quaternary Metal Sulfides

Nanodimensional metal sulfides are a developing class of low-cost materials with potential applications in areas as wide-ranging as energy storage, electrocatalysis, and imaging. An attractive synthetic strategy, which allows careful control over stoichiometry, is the single source precursor (SSP) approach in which well-defined molecular species containing preformed metal-sulfur bonds are heated to decomposition, either in the vapor or solution phase, resulting in facile loss of organics and formation of nanodimensional metal sulfides. By careful control of the precursor, the decomposition environment and addition of surfactants, this approach affords a range of nanocrystalline materials from a library of precursors. Dithiocarbamates (DTCs) are monoanionic chelating ligands that have been known for over a century and find applications in agriculture, medicine, and materials science. They are easily prepared from nontoxic secondary and primary amines and form stable complexes with all elements. Since pioneering work in the late 1980s, the use of DTC complexes as SSPs to a wide range of binary, ternary, and multinary sulfides has been extensively documented. This review maps these developments, from the formation of thin films, often comprised of embedded nanocrystals, to quantum dots coated with organic ligands or shelled by other metal sulfides that show high photoluminescence quantum yields, and a range of other nanomaterials in which both the phase and morphology of the nanocrystals can be engineered, allowing fine-tuning of technologically important physical properties, thus opening up a myriad of potential applications.

Understanding the role of zinc dithiocarbamate complexes as single source precursors to ZnS nanomaterials

Zinc sulfide is an important wide-band gap semi-conductor and dithiocarbamate complexes [Zn(S2CNR2)2] find widespread use as single-source precursors for the controlled synthesis of ZnS nanoparticulate modifications. Decomposition of [Zn(S2CNiBu2)2] in oleylamine gives high aspect ratio wurtzite nanowires, the average length of which was increased upon addition of thiuram disulfide to the decomposition mixture. To provide further insight into the decomposition process, X-ray absorption spectroscopy (XAS) of [Zn(S2CNMe2)2] was performed in the solid-state, in non-coordinating xylene and in oleylamine. In the solid-state, dimeric [Zn(S2CNMe2)2]2 was characterised in accord with the single crystal X-ray structure, while in xylene this breaks down into tetrahedral monomers. In situ XAS in oleylamine (RNH2) shows that the coordination sphere is further modified, amine binding to give five-coordinate [Zn(S2CNMe2)2(RNH2)]. This species is stable to ca. 70 °C, above which amine dissociates and at ca. 90 °C decomposition occurs to generate ZnS. The relatively low temperature onset of nanoparticle formation is associated with amine-exchange leading to the in situ formation of [Zn(S2CNMe2)(S2CNHR)] which has a low temperature decomposition pathway. Combining these observations with the previous work of others allows us to propose a detailed mechanistic scheme for the overall process.

The varied structures of cobalt(II)-pyridine (py)-sulfate: [Co(SO4)(py)4] n , [Co2(SO4)2(py)6] n , and [Co3(SO4)3(py)11] n

The solid-state structures of two cobalt-pyridine-sulfate compounds, namely catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O'], [Co(SO4)(C5H5N)4] n , (1), and catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O:O',O''-[bis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O,O':O''] n , [Co2(SO4)2(C5H5N)6] n , (2), are reported. Compound (1) displays a polymeric structure, with infinite chains of CoII cations adopting octa-hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ions. Compound (2) is also polymeric with infinite chains of CoII cations. The first Co center has an octa-hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The second Co center has an octa-hedral N2O4 coordination environment that involves two pyridine ligands and two bridging sulfate ions that chelate the Co atom. The structure of (2) was refined as a two-component inversion twin.

More crystal field theory in action: the metal-4-picoline (pic)-sulfate [M(pic)x]SO4 complexes (M = Fe, Co, Ni, Cu, Zn, and Cd)

Seven crystal structures of five first-row (Fe, Co, Ni, Cu, and Zn) and one second-row (Cd) transition metal-4-picoline (pic)-sulfate complexes of the form [M(pic)_x]SO₄ are reported. These complexes are catena-poly[[tetrakis(4-methylpyridine-κN)metal(II)]-μ-sulfato-κ²O:O'], [M(SO₄)(C₆H₇N)₄]_n, where the metal/M is iron, cobalt, nickel, and cadmium, di-μ-sulfato-κ⁴O:O-bis[tris(4-methylpyridine-κN)copper(II)], [Cu₂(SO₄)₂(C₆H₇N)₆], catena-poly[[bis(4-methylpyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'], [Zn(SO₄)(C₆H₇N)₂]_n, and catena-poly[[tris(4-methylpyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'], [Zn(SO₄)(C₆H₇N)₃]_n. The Fe, Co, Ni, and Cd compounds are isomorphous, displaying polymeric crystal structures with infinite chains of M^II ions adopting an octahedral N₄O₂ coordination environment that involves four picoline ligands and two bridging sulfate anions. The Cu compound features a dimeric crystal structure, with the Cu^II ions possessing square-pyramidal N₃O₂ coordination environments that contain three picoline ligands and two bridging sulfate anions. Zinc crystallizes in two forms, one exhibiting a polymeric crystal structure with infinite chains of Zn^II ions adopting a tetrahedral N₂O₂ coordination containing two picoline ligands and two bridging sulfate anions, and the other exhibiting a polymeric crystal structure with infinite chains of Zn^II ions adopting a trigonal bipyramidal N₃O₂ coordination containing three picoline ligands and two bridging sulfate anions. The structures are compared with the analogous pyridine complexes, and the observed coordination environments are examined in relation to crystal field theory.

Aerosol-Assisted Chemical Vapor Deposition of ZnS from Thioureide Single Source Precursors

A family of 12 zinc(II) thoureide complexes, of the general form [{L}ZnMe], [{L}Zn{N(SiMe₃)₂}], and [{L}₂Zn], have been synthesized by direct reaction of the thiourea pro-ligands ⁱPrN(H)CS(NMe₂) H[L¹], CyN(H)CS(NMe₂) H[L³], ^tBuN(H)CS(NMe₂) H[L²], and MesN(H)CS(NMe₂) H[L⁴] with either ZnMe₂ (1:1) or Zn{N(SiMe₃)₂}₂ (1:1 and 2:1) and characterized by elemental analysis, NMR spectroscopy, and thermogravimetric analysis (TGA). The molecular structures of complexes [{L¹}ZnMe]₂ (1), [{L²}ZnMe]₂] (2), [{L³}ZnMe]_∞ (3), [{L⁴}ZnMe]₂] (4), [{L¹}Zn{N(SiMe₃)₂}]₂ (5), [{L²}Zn{N(SiMe₃)₂}]₂ (6), [{L³}Zn{N(SiMe₃)₂}]₂] (7), [{L⁴}Zn{N(SiMe₃)₂}]₂] (8), [{L¹}₂Zn]₂ (9), and [{L⁴}₂Zn]₂ (12) have been unambiguously determined using single crystal X-ray diffraction studies. Thermogravimetric analysis has been used to assess the viability of complexes 1-12 as single source precursors for the formation of ZnS. On the basis of TGA data compound 9 was investigated for its utility as a single source precursor to deposit ZnS films on silica-coated glass and crystalline silicon substrates at 150, 200, 250, and 300 °C using an aerosol assisted chemical vapor deposition (AACVD) method. The resultant films were confirmed to be hexagonal-ZnS by Raman spectroscopy and PXRD, and the surface morphologies were examined by SEM and AFM analysis. Thin films deposited from (9) at 250 and 300 °C were found to be comprised of more densely packed and more highly crystalline ZnS than films deposited at lower temperatures. The electronic properties of the ZnS thin films were deduced by UV-Vis spectroscopy to be very similar and displayed absorption behavior and band gap (E_g = 3.711-3.772 eV) values between those expected for bulk cubic-ZnS (E_g = 3.54 eV) and hexagonal-ZnS (E_g = 3.91 eV).

The crystal structures of iron and cobalt pyridine (py)-sulfates, [Fe(SO4)(py)4] n and [Co3(SO4)3(py)11] n

The solid-state structures of two metal-pyridine-sulfate compounds, namely catena-poly[[tetra-kis-(pyridine-κN)iron(II)]-μ-sulfato-κ2O:O'], [Fe(SO4)(C5H5N)4] n , (1), and catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'-[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O,O':O''-[tris-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'], [Co3(SO4)3(C5H5N)11] n , (2), are reported. The iron compound (1) displays a polymeric structure, with infinite chains of FeII atoms adopting octa-hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ligands. The cobalt compound (2) displays a polymeric structure, with infinite chains of CoII atoms. Two of the three Co centers have an octa-hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The third Co center has an octa-hedral N3O3 coordination environment that involves three pyridine ligands, and two bridging sulfate ligands with one sulfate chelating the cobalt atom.

First-row transition metal-pyridine (py)-sulfate [(py)xM](SO4) complexes (M = Ni, Cu and Zn): crystal field theory in action

The crystal structures of three first-row transition metal-pyridine-sulfate complexes, namely catena-poly[[tetrakis(pyridine-κN)nickel(II)]-μ-sulfato-κ²O:O'], [Ni(SO₄)(C₅H₅N)₄]_n, (1), di-μ-sulfato-κ⁴O:O-bis[tris(pyridine-κN)copper(II)], [Cu₂(SO₄)₂(C₅H₅N)₆], (2), and catena-poly[[tetrakis(pyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'-[bis(pyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'], [Zn₂(SO₄)₂(C₅H₅N)₆]_n, (3), are reported. Ni compound (1) displays a polymeric crystal structure, with infinite chains of Ni^II atoms adopting an octahedral N₄O₂ coordination environment that involves four pyridine ligands and two bridging sulfate ligands. Cu compound (2) features a dimeric molecular structure, with the Cu^II atoms possessing square-pyramidal N₃O₂ coordination environments that contain three pyridine ligands and two bridging sulfate ligands. Zn compound (3) exhibits a polymeric crystal structure of infinite chains, with two alternating zinc coordination environments, i.e. octahedral N₄O₂ coordination involving four pyridine ligands and two bridging sulfate ligands, and tetrahedral N₂O₂ coordination containing two pyridine ligands and two bridging sulfate ligands. The observed coordination environments are consistent with those predicted by crystal field theory.

A, Singh VK. Synthesis and spectral characterization of bimetallic metallomacrocyclic structures [MII2-μ2-bis-{(κ2S,S-S2CN(R)C6H4)2O}] (M = Ni/Zn/Cd): density functional theory and host–guest reactivity studies

Compounds displayed the ability to form 1 : 1 host–guest inclusion complexes with bidentate guests and to form metal sulphides on thermal degradation.

Phase-pure fabrication and shape evolution studies of SnS nanosheets

SnS nanosheets were synthesized by the injection of n-bis(piperidinedithiocarbamato)tin(iv) into oleylamine at 230 °C.

AACVD of Cu2−xS, In2S3 and CuInS2 thin films from [Cu(iBu2PS2)(PPh3)2] and [In(iBu2PS2)3] as single source precursors

Environmentally benign metal–organic precursors have been synthesized and used for the deposition of Cu_2−xS, In₂S₃ and CuInS₂ thin films.

Effect of anions on the morphology of CdS nanoparticles prepared via thermal decomposition of different cadmium thiourea complexes in a solvent and in the solid state

Use of single-molecular precursors with different anions has been demonstrated to be an excellent method to synthesize CdS nanoparticles with different morphologies without using any external capping agent.

Understanding the role of single molecular ZnS precursors in the synthesis of In(Zn)P/ZnS nanocrystals

Environmentally friendly nanocrystals (NCs) such as InP are in demand for various applications, such as biomedical labeling, solar cells, sensors, and light-emitting diodes (LEDs). To fulfill their potential applications, the synthesis of such high-quality "green" InP NCs required further improvement so as to achieve better stability, higher brightness NCs, and also to have a more robust synthesis route. The present study addresses our efforts on the synthesis of high-quality In(Zn)P/ZnS core-shell NCs using an air- and moisture-stable ZnS single molecular precursor (SMP) and In(Zn)P cores. The SMP method has recently emerged as a promising route for the surface overcoating of NCs due to its simplicity, high reproducibility, low reaction temperature, and flexibility in controlling the reaction. The synthesis involved heating the In(Zn)P core solution and Zn(S2CNR2) (where R = methyl, ethyl, butyl, or benzyl and referred to as ZDMT, ZDET, ZDBT, or ZDBzT, respectively) in oleylamine (OLA) to 90-250 °C for 0.5-2.5 h. In this work, we systematically studied the influence of different SMP end groups, the complex formation and stability between the SMP and oleylamine (OLA), the reaction temperature, and the amount of SMP on the synthesis of high-quality In(Zn)P/ZnS NCs. We found that thiocarbamate end groups are an important factor contributing to the low-temperature growth of high-quality In(Zn)P/ZnS NCs, as the end groups affect the polarity of the molecules and result in a different steric arrangement. We found that use of SMP with bulky end groups (ZDBzT) results in nanocrystals with higher photoluminescence quantum yield (PL QY) and better dispersibility than those synthesized with SMPs with the shorter alkyl chain groups (ZDMT, ZDET, or ZDBT). At the optimal conditions, the PL QY of red emission In(Zn)P/ZnS NCs is 55 ± 4%, which is one of the highest values reported. On the basis of structural (XAS, XPS, XRD, TEM) and optical characterization, we propose a mechanism for the growth of a ZnS shell on an In(Zn)P core.

Bis(piperidinedithiocarbamato)pyridinecadmium(ii) as a single-source precursor for the synthesis of CdS nanoparticles and aerosol-assisted chemical vapour deposition (AACVD) of CdS thin films

The pyridine adduct of a cadmium piperidine dithiocarbamate complex was used to deposit CdS thin films and for the synthesis of CdS nanoparticles.

ZnS, CdS and HgS nanoparticles via alkyl-phenyl dithiocarbamate complexes as single source precursors

The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively.

Cadmium-free CuInS2/ZnS quantum dots for sentinel lymph node imaging with reduced toxicity

Semiconductor quantum dots (QDs) could significantly impact the performance of biomedical near-infrared (NIR) imaging by providing fluorescent probes that are brighter and more photostable than conventional organic dyes. However, the toxicity of the components of NIR emitting II-VI and IV-VI QDs that have been made so far (Cd, Hg, Te, Pb, etc.) has remained a major obstacle to the clinical use of QDs. Here, we present the synthesis of CuInS(2)/ZnS core/shell QDs emitting in the NIR ( approximately 800 nm) with good quantum yield and stability even after transfer into water. We demonstrate the potential of these QDs by imaging two regional lymph nodes (LNs) in vivo in mice. We then compare the inflammatory response of the axillary LN induced by different doses of CuInS(2)/ZnS and CdTeSe/CdZnS QDs and show a clear difference in acute local toxicity, the onset of inflammation only occurring at a 10 times more concentrated dose for CuInS(2)/ZnS QDs than for their Cd-containing counterparts.