59Co NMR, a facile tool to demonstrate EEE, EEZ, EZZ and ZZZ configurational isomerism in fac-[Co(L-κS,O)3] complexes derived from asymmetrically substituted N,N-dialkyl-N′-aroylthioureas

Crystal structure of tris-{N,N-diethyl-N'-[(4-nitro-phen-yl)(oxo)meth-yl]carbamimido-thio-ato}cobalt(III)

The synthesis, crystal structure, and a Hirshfeld surface analysis of tris-{N,N-diethyl-N'-[(4-nitro-phen-yl)(oxo)meth-yl]carbamimido-thio-ato}cobalt(III) conducted at 180 K are presented. The complex consists of three N,N-diethyl-N'-[(4-nitro-benzene)(oxo)meth-yl]carbamimido-thio-ato ligands, threefold sym-metric-ally bonded about the CoIII ion, in approximately octa-hedral coordination, which generates a triple of individually near planar metallacyclic (Co-S-C-N-C-O) rings. The overall geometry of the complex is determined by the mutual orientation of each metallacycle about the crystallographically imposed threefold axis [dihedral angles = 81.70 (2)°] and by the dihedral angles between the various planar groups within each asymmetric unit [metallacycle to benzene ring = 13.83 (7)°; benzene ring to nitro group = 17.494 (8)°]. The complexes stack in anti-parallel columns about the axis of the space group (P), generating solvent-accessible channels along [001]. These channels contain ill-defined, multiply disordered, partial-occupancy solvent. Atom-atom contacts in the crystal packing predominantly (∼96%) involve hydrogen, the most abundant types being H⋯H (36.6%), H⋯O (31.0%), H⋯C (19.2%), H⋯N (4.8%), and H⋯S (4.4%).

Recent trends in chemistry, structure, and various applications of 1-acyl-3-substituted thioureas: a detailed review

The interest in acyl thioureas has continually been escalating owing to their extensive applications in diverse fields, such as synthetic precursors of new heterocycles, pharmacological and materials science, and technology. These scaffolds exhibit a wide variety of biological activities such as antitumor, enzyme inhibitory, anti-bacterial, anti-fungal, and anti-malarial activities and find utilization as chemosensors, adhesives, flame retardants, thermal stabilizers, antioxidants, polymers and organocatalysts. In addition, the synthesis, and applications of coordination complexes of these ligands have also been overviewed. The current review is a continuation of our previous efforts in this area, focusing on the recent advancements during the period 2017 to present.

This review encapsulates the recently designed acyl thioureas, and their crystal structures, metal complexes and various applications from 2017 to present, including pharmacological aspects, chemosensing and heterogenous catalysis.

Synthesis, characterization, DNA binding, topoisomerase inhibition, and apoptosis induction studies of a novel cobalt(III) complex with a thiosemicarbazone ligand

In this study, 9-anthraldehyde-N(4)-methylthiosemicarbazone (MeATSC) 1 and [Co(phen)2(O2CO)]Cl·6H2O 2 (where phen = 1,10-phenanthroline) were synthesized. [Co(phen)2(O2CO)]Cl·6H2O 2 was used to produce anhydrous [Co(phen)2(H2O)2](NO3)33. Subsequently, anhydrous [Co(phen)2(H2O)2](NO3)33 was reacted with MeATSC 1 to produce [Co(phen)2(MeATSC)](NO3)3·1.5H2O·C2H5OH 4. The ligand, MeATSC 1 and all complexes were characterized by elemental analysis, FT IR, UV-visible, and multinuclear NMR (1H, 13C, and 59Co) spectroscopy, along with HRMS, and conductivity measurements, where appropriate. Interactions of MeATSC 1 and complex 4 with calf thymus DNA (ctDNA) were investigated by carrying out UV-visible spectrophotometric studies. UV-visible spectrophotometric studies revealed weak interactions between ctDNA and the analytes, MeATSC 1 and complex 4 (Kb = 8.1 × 105 and 1.6 × 104 M-1, respectively). Topoisomerase inhibition assays and cleavage studies proved that complex 4 was an efficient catalytic inhibitor of human topoisomerases I and IIα. Based upon the results obtained from the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay on 4T1-luc metastatic mammary breast cancer cells (IC50 = 34.4 ± 5.2 μM when compared to IC50 = 13.75 ± 1.08 μM for the control, cisplatin), further investigations into the molecular events initiated by exposure to complex 4 were investigated. Studies have shown that complex 4 activated both the apoptotic and autophagic signaling pathways in addition to causing dissipation of the mitochondrial membrane potential (ΔΨm). Furthermore, activation of cysteine-aspartic proteases3 (caspase 3) in a time- and concentration-dependent manner coupled with the ΔΨm, studies implicated the intrinsic apoptotic pathway as the major regulator of cell death mechanism.

Cobalt(III) Metallacryptates and Their Guest Cation-Exchange in Solution Monitored by 59Co NMR

One-pot reactions of the catechol-scaffolding aroylbis(N,N-diethylthiourea) H₂L^cat with mixtures of CoCl₂ and MCl (M⁺ = Cs⁺, Rb⁺, K⁺, Tl⁺, or NH₄⁺) or with a Co(NO₃)₂/TlNO₃ mixture lead to the self-assembly of a series of cationic Co(III) metallacryptates of the general formula [M ⊂ {Co₂(L^cat)₃}]⁺ (M⁺ = Cs⁺, Rb⁺, K⁺, Tl⁺, or NH₄⁺). Crystalline PF₆^- salts were obtained after workup with (n-Bu₄N)(PF₆), and the single-crystal structures of all five metallacryptates have been determined. Depending on the nature of the guest cations, the directional interactions between guest cations and the metallacryptand {Co₂(L^cat)₃} are either weak coordination contacts or hydrogen bonds. The bonding mode and the size of the guest ions slightly influence the molecular skeleton of the host molecule. These small structural variations also exist in solution and could be detected by means of ⁵⁹Co NMR spectroscopy, which is shown to be a unique tool for an easy characterization of such compounds. ⁵⁹Co NMR chemical shifts are extraordinarily sensitive to the guest cation in the metallacryptates, and time-arrayed ⁵⁹Co NMR experiments show that cation-exchange processes in biphasic organic/aqueous systems can be studied in detail. This leads to insights into the relative rates of cation exchange, as well as the relative conditional distribution coefficients of such Co(III) metallacryptates between the aqueous and organic phases. Thus, the extent and the relative rate of the NH₄⁺ ion exchange in [NH₄ ⊂ {Co₂(L^cat)₃}](PF₆) by Cs⁺ and K⁺ ions across the organic/aqueous phase boundary at room temperature have been studied by in situ ⁵⁹Co NMR experiments. Preliminary ⁵⁹Co NMR experiments show that the K⁺ ion in [K ⊂ {Co₂(L^cat)₃}](PF₆) can be removed by its competitive complexation with the highly potassium-selective [2.2.2]cryptand, to give a transient ⁵⁹Co NMR signal of the relatively unstable "empty" {Co₂(L^cat)₃} complex, which slowly decomposes in solution.

Fluorescence studies and photocatalytic application for hydrogen production of ZnII and CdII complexes with isophthaloylbis(thioureas)

TiO₂-based semiconductor composites containing Zn^II and Cd^II complexes produced more hydrogen gas than pure TiO₂.