Synthesis of nickel sulfide and nickel–iron sulfide nanoparticles from nickel dithiocarbamate complexes and their photocatalytic activities

[ Ni(dtc)₂] (dtc = N-(pyrrole-2-ylmethyl)-N-thiophenemethyldithiocarbamate ( 1 ), N-methylferrocenyl-N-(2-phenylethyl)dithiocarbamate ( 2 ), N-furfuryl-N-methylferrocenyldithiocarbamate ( 3 ), and (N-[pyrrole-2-ylmethyl]-N-thiophenemethyldithiocarbamato-S,S′)(thiocyanato-N)(triphenylphosphine)nickel(II) ( 4 ) complexes were prepared and characterized by elemental analysis, infrared, ultraviolet–visible, and nuclear magnetic resonance (¹H and ¹³C) spectroscopies. The data were consistent with the formation of square planar nickel(II) complexes, which was confirmed by single-crystal X-ray diffraction studies on 2 and 4 . Fe···Fe interactions exhibited by complex 2 led to supramolecular aggregation. The structure of 4 reveals intermolecular and intramolecular C-H···Ni anagostic interactions. The anion-sensing properties of 2 were studied with halide ions by cyclic voltammetry. It was observed that 2 acts as sensor for bromide. Complexes 1 , 2 , and 3 , were utilized to prepare nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2, respectively. The composition, structure, morphology, and optical properties of nickel sulfide and nickel–iron sulfides were examined using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible, fluorescence, and infrared spectroscopy. Powder X-ray diffraction patterns of nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2 indicate the formation of orthorhombic Ni₉S₈, cubic NiFeS₂, and cubic Ni₂FeS₄, respectively. The photocatalytic activities of as-prepared nickel sulfide and nickel–iron sulfide-1 nanoparticles were investigated for photodegradation of methylene blue and rhodamine-B under ultraviolet irradiation. Nickel–iron sulfide-1 nanoparticles show slightly higher photodegradation efficiency compared with the nickel sulfide nanoparticles.     

Synthesis and characterization of copper(II) dithiocarbamate complexes involving pyrrole and ferrocenyl moieties and their utility for sensing anions and preparation of copper sulfide and copper–iron sulfide nanoparticles

Bis(N‐(pyrrol‐2‐ylmethyl)‐N‐butyldithiocarbamato‐S,S′)copper(II) ( 1 ), bis(N‐(pyrrol‐2‐ylmethyl)‐N‐(2‐phenylethyl)dithiocarbamato‐S,S′)copper(II) ( 2 ), bis(N‐methylferrocenyl‐N‐(2‐phenylethyl)dithiocarbamato‐S,S′)copper(II) ( 3 ) and bis(N‐furfuryl‐N‐methylferrocenyldithiocarbamato‐S,S′)copper(II) ( 4 ) were prepared and characterized using elemental analysis and infrared and UV–visible spectroscopies. X‐ray diffraction (XRD) studies on 3 show that each copper centre adopts the square planar geometry by the coordination of four sulfur atoms of the metalloligand N‐methylferrocenyl‐N‐(2‐phenylethyl)dithiocarbamate. The Cu? S distances are symmetrical and are in the range 2.293–2.305 Å. The supramolecular architecture in complex 3 is sustained in the solid state by C? H???π, C? H???S, Fe???Fe and H???H interactions. Density functional theory calculations were carried out for 3 . Anion (F^?, Cl^?, Br^? and I^?) binding studies with complex 1 were performed using cyclic voltammetry. Copper sulfide, copper–iron sulfide‐ 1 and copper–iron sulfide‐ 2 nanoparticles were prepared from complexes 2 , 3 and 4 , respectively, and they were characterized using powder XRD, transmission electron microscopy (TEM) and energy‐dispersive X‐ray, UV–visible, photoluminescence and infrared spectroscopies. TEM images of copper–iron sulfide‐ 1 and copper–iron sulfide‐ 2 reveal that the particles are spherical and oval shaped, respectively. Photocatalytic activities of as‐prepared nanoparticles were studied by decolourization of methylene blue and rhodamine‐B under UV light. It was found that copper–iron sulfide degrades methylene blue and rhodamine‐B much better than does copper sulfide.     

Synthesis,spectra, crystal structures and anticancer studies of 26‐membered macrocyclic dibutyltin(IV) dithiocarbamate complexes: Single‐source precursors for tin sulfide nanoparticles

Four new macrocyclic dinuclear dibutyltin(IV) dithiocarbamate complexes of the type [Bu₂Sn(dtc)]₂, where dtc = hexane‐1,6‐diylbis(4‐fluorobenzyldithiocarbamate) anion ( 1 ), hexane‐1,6‐diylbis(4‐chlorobenzyldithiocarbamate) anion ( 2 ), hexane‐1,6‐diylbis(furfuryldithiocarbamate) anion ( 3 ) and hexane‐1,6‐diylbis(pyrrole‐2‐ylmethyldithiocarbamate) anion ( 4 ), have been prepared. The dithiocarbamate ligands efficiently self‐assemble with Bu₂Sn(IV) to form bimetallic 26‐membered macrocycles. All the complexes have been characterized using elemental analysis, infrared and NMR (¹H and ¹³C) spectroscopies and X‐ray crystallography. Single‐crystal X‐ray diffraction analysis of all the complexes confirms the formation of the dinuclear metallomacrocycles in which dithiocarbamate ligands are asymmetrically bound to the tin atoms. The coordination sphere around the tin atom in 1 – 4 can be described as a skew trapezoidal bipyramid. The dimensions of the cavity of the macrocycles of 1 – 4 are ca 8.0 × 9.0 Å². Complexes 1 – 4 were evaluated for their in vitro anticancer activity against MCF‐7 and HL‐60 cells. Complexes 1 and 2 are more active against MCF‐7 and HL‐60. Thermal decomposition of 1 and 4 yielded tin sulfides. They were characterized using powder X‐ray diffraction (PXRD), high‐resolution transmission electron microscopy and UV diffuse reflectance and energy‐dispersive X‐ray spectroscopies. PXRD studies reveal that the as‐prepared tin sulfides are composed of orthorhombic phase of SnS.     

Crystal Structure and Non-Hydrostatic Stress-Induced Phase Transition of Urotropine Under High Pressure

High-pressure behavior of hexamethylenetetramine (urotropine) was studied in situ using angle-dispersive single-crystal synchrotron X-ray diffraction (XRD) and Fourier-transform infrared absorption (FTIR) spectroscopy. Experiments were conducted in various pressure-transmitting media to study the effect of deviatoric stress on phase transformations. Up to 4 GPa significant damping of molecular librations and atomic thermal motion was observed. A first-order phase transition to a tetragonal structure was observed with an onset at approximately 12.5 GPa and characterized by sluggish kinetics and considerable hysteresis upon decompression. However, it occurs only in non-hydrostatic conditions, induced by deviatoric or uniaxial stress in the sample. This behavior finds analogies in similar cubic crystals built of highly symmetric cage-like molecules and may be considered a common feature of such systems. DFT computations were performed to model urotropine equation of state and pressure dependence of vibrational modes. The first successful Hirshfeld atom refinements carried out for high-pressure diffraction data are reported. The refinements yielded more realistic C−H bond lengths than the independent atom model even though the high-pressure diffraction data are incomplete.     

A Click-Chemistry Linked 2′3′-cGAMP Analogue

2′3′-cGAMP is an uncanonical cyclic dinucleotide where one A and one G base are connected via a 3′-5′ and a unique 2′-5′ linkage. The molecule is produced by the cyclase cGAS in response to cytosolic DNA binding. cGAMP activates STING and hence one of the most powerful pathways of innate immunity. cGAMP analogues with uncharged linkages that feature better cellular penetrability are currently highly desired. Here, the synthesis of a cGAMP analogue with one amide and one triazole linkage is reported. The molecule is best prepared via a first Cu^I-catalyzed click reaction, which establishes the triazole, while the cyclization is achieved by macrolactamization.     

Synthesis,structure, spectral and coordination properties of a crown ether derivative of 1,3-indandione. A new structural evidence for the versatile reactivity of 2-acetyl-1,3-indandione

The current study describes the synthesis of a new 1,3-indandione derivative with conjugated N-phenylaza-15-crown-5 moiety (4). The crystal structure of compound 4 was solved and its optical properties were studied in various solvents and in presence of alkaline and alkaline-earth metal ions. Quantum chemical (DFT) methods were employed to describe the structure and the optical properties of the studied compound and its complexes. The obtained results indicated that the synthesis of compound 4 using acid-catalyzed aldol reaction between 2-acetyl-1,3-indandione and the corresponding aldehyde is accompanied with an unexpected deacetylation step. In this way, the N-phenylaza-15-crown-5 moiety is directly conjugated with the 1,3-indandione fragment, known as a very strong electron acceptor. Therefore, the absorption spectra of 4 are only slightly influenced by complexation with Ba²⁺ and Sr²⁺ ions.     

Synthesis and spectral studies on NiS<Subscript>4</Subscript>, NiS<Subscript>2</Subscript>PN,NiS<Subscript>2</Subscript>P<Subscript>2</Subscript> chromophores: Single-crystal X-ray structure of [Ni(dbpdtc)<Subscript>2</Subscript>] (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate)

Three complexes of a dithiocarbamate ligand (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate), namely [Ni(dbpdtc)₂] (1), [Ni(dbpdtc)(NCS)(PPh₃)] (2) and [Ni(dbpdtc)(PPh₃)₂]ClO₄ (3) have been prepared. The complexes were characterized by IR, electronic spectroscopy and cyclic voltammetry. A single-crystal X-ray structural analysis was carried out for complex 1 and showed that the nickel is in a distorted square planar environment with a NiS₄ chromophore. For the two mixed ligand complexes, the thioureide ν _C–N values were shifted to higher wavenumbers compared to [Ni(dbpdtc)₂], suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. Electronic spectral studies suggest square planar geometries for the complexes. Cyclic voltammetry showed easier reduction of nickel(II) to nickel(I) in the mixed ligand complexes compared to [Ni(dbpdtc)₂].     

Biomimetic surface modifications based on the cyanobacterial iron chelator anachelin

Siderophores are natural iron chelators that have been evolutionarily selected to bind to Fe ions with very high binding constants. We utilize these unique properties to bind to metal oxide surfaces using a fragment of the cyanobacterial siderophore anachelin. The resulting poly(ethylene glycol) conjugate forms stable adlayers on TiO2 as has been shown by variable angle spectroscopic ellipsometry and X-ray photoelectron spectroscopy. Moreover, these coated surfaces are highly protein-resistant against the adsorption of full human serum.     

Conformationally restricted analogues of both (S)-β-homoserine and (S)-aspartic acid from chiral 3-acylamino pyrrolidin-2-ones

Starting from chiral 3,4-trans-disubstituted pyrrolidin-2-ones 11a and 11b, obtained from a Baylis-Hillman adduct, conformationally restricted analogues of both (S)-β-homoserine, 17, and (S)-aspartic acid, 21, were synthesized, respectively, and these compounds are suitable either for introduction in peptidomimetics or for synthesis of novel β-foldamers.     

Retention of stereochemistry in the microwave assisted synthesis of 1H-tetrazole bioisosteric moiety from chiral phenyl-acetic acid derivatives

Chiral substituted phenylethyl-1H-tetrazoles were built-up from the corresponding carboxylic acid derivatives by a useful three-step synthesis. The procedure, that preserves the chiral center from racemization, was successfully applied to a selection of several hit compounds by conversion of the carboxylic acid moiety to the nitrile derivatives and subsequent reaction with trimethylstannyl azide, under microwave conditions. A useful application to the corresponding tetrazole analogue has been found also in the conversion of the aminoacidic moiety like (R)-N-Cbz-phenylglycine showing a wide potential synthetic application.