Recent advances in the coordination and supramolecular chemistry of monopodal and bipodal acylthiourea-based ligands

Novel Thiourea Ligands-Synthesis, Characterization and Preliminary Study on Their Coordination Abilities

Two series of polydentate N,O,S-ligands containing thiourea fragments attached to a p-cresol scaffold, unsymmetrical mono-acylated bis-amines and symmetrical bis-thioureas, are obtained by common experiments. It is observed that the reaction output is strongly dependent on both bis-amine and thiocarbamic chloride substituents. The products are characterized by 1D and 2D NMR spectra in solution and by single crystal XRD. A preliminary study on the coordination abilities of selected products is performed by ITC at around neutral media.

Multifaceted exploration of acylthiourea compounds: In vitro cytotoxicity, DFT calculations, molecular docking and dynamics simulation studies

This study reports the synthesis and analysis of biologically active acylthiourea compounds (1 and 2) with a cyclohexyl moiety. The compounds were characterized using UV-Visible, FT-IR, 1H/13C NMR, and elemental analysis. The crystal structure of 2 was solved, revealing intra- and inter-molecular hydrogen bonds. Density functional theory (DFT) calculations provided insights into chemical reactivity and non-covalent interactions. Cytotoxicity assays showed the cyclohexyl group enhanced the activity of compound 2 compared to compound 1. Epoxide hydrolase 1 was predicted as the enzyme target for both compounds. We modeled the structure of epoxide hydrolase 1 and performed molecular dynamics simulation and docking studies. Additionally, in silico docking with SARS-CoV-2 main protease, human ACE2, and avian influenza H5N1 hemagglutinin indicated strong binding potential of the compounds. This integrated approach improves our understanding of the biological potential of acylthiourea derivatives.

Advancements in sustainable platinum and palladium recovery: unveiling superior adsorption efficiency and selectivity with a novel silica-anchored acylthiourea adsorbent

This study addresses the pressing issue of depleting natural resources of platinum group metals (PGMs), driven by their widespread use in modern applications and increasing demand for renewable energy technologies. With conventional sources dwindling, the search for economically viable recovery methods from alternative sources has become crucial. Our focus was on innovating efficient recovery strategies, leading to the development of two novel silica-anchored adsorbents: DTMSP-BT-SG, a highly efficient acylthiourea adsorbent, and BTMSPA-SG, a silica-anchored amine adsorbent. We conducted comprehensive experiments under PGM mining wastewater conditions, varying parameters such as adsorbent mass, pH, concentration, contact time, competing ions, and volume. DTMSP-BT-SG demonstrated exceptional performance, achieving maximum adsorption efficiencies of >98% for Pt and >99% for Pd at pH 2, 0.5 g L-1 dosage, and 5 mg L-1 concentration. In contrast, under the same conditions, BTMSPA-SG recovered <56% and <89% of Pt and Pd, respectively. The experimental data for both adsorbents were analysed using Langmuir and Freundlich isotherm models for concentration and pseudo-first and second-order models for contact time. The Langmuir model best described the adsorption data, indicating homogenous monolayer adsorption of Pt and Pd. The kinetic models suggested a pseudo-second-order process, implying chemisorption. Furthermore, in the presence of competing ions and other PGMs, DTMSP-BT-SG exhibited significantly higher recovery rates for Pt and Pd compared to BTMSPA-SG. Overall, DTMSP-BT-SG emerged as a more selective and efficient adsorbent across varied parameters. Its exceptional adsorption efficiency, coupled with cost-effectiveness, positions it as a promising and competitive recovery agent for extracting PGMs from mining wastewaters.

Ru(II)-p-Cymene Complexes of Furoylthiourea Ligands for Anticancer Applications against Breast Cancer Cells

Half-sandwich Ru(II) complexes containing nitro-substituted furoylthiourea ligands, bearing the general formula [(η⁶-p-cymene)RuCl₂(L)] (1-6) and [(η⁶-p-cymene)RuCl(L)(PPh₃)]⁺ (7--12), have been synthesized and characterized. In contrast to the spectroscopic data which revealed monodentate coordination of the ligands to the Ru(II) ion via a "S" atom, single crystal X-ray structures revealed an unusual bidentate N, S coordination with the metal center forming a four-membered ring. Interaction studies by absorption, emission, and viscosity measurements revealed intercalation of the Ru(II) complexes with calf thymus (CT) DNA. The complexes showed good interactions with bovine serum albumin (BSA) as well. Further, their cytotoxicity was explored exclusively against breast cancer cells, namely, MCF-7, T47-D, and MDA-MB-231, wherein all of the complexes were found to display more pronounced activity than their ligand counterparts. Complexes 7-12 bearing triphenylphosphine displayed significant cytotoxicity, among which complex 12 showed IC₅₀ values of 0.6 ± 0.9, 0.1 ± 0.8, and 0.1 ± 0.2 μM against MCF-7, T47-D, and MDA-MB-231 cell lines, respectively. The most active complexes were tested for their mode of cell death through staining assays, which confirmed apoptosis. The upregulation of apoptotic inducing and downregulation of apoptotic suppressing proteins as inferred from the western blot analysis also corroborated the apoptotic mode of cell death. The active complexes effectively generated reactive oxygen species (ROS) in MDA-MB-231 cells as analyzed from the 2',7'-dichlorofluorescein diacetate (DCFH-DA) staining. Finally, in vivo studies of the highly active complexes (6 and 12) were performed on the mice model. Histological analyses revealed that treatment with these complexes at high doses of up to 8 mg/kg did not induce any visible damage to the tested organs.

The Zinc-Binding Group Effect: Lessons from Non-Hydroxamic Acid Vorinostat Analogs

Histone deacetylases (HDACs) are enzymes pursued as drug targets in various cancers and several non-oncological conditions, such as inflammation and neurodegenerative disorders. In the past decade, HDAC inhibitors (HDACi) have emerged as relevant pharmaceuticals, with many efforts devoted to the development of new representatives. However, the growing safety concerns regarding the established hydroxamic acid-based HDAC inhibitors tend to drive current research more toward the design of inhibitors bearing alternative zinc-binding groups (ZBGs). This Perspective presents an overview of all non-hydroxamic acid ZBGs that have been incorporated into the clinically approved prototypical HDACi, suberoylanilide hydroxamic acid (vorinostat). This provides the unique opportunity to compare the inhibition potential and biological effects of different ZBGs in a direct way, as the compounds selected for this Perspective differ only in their ZBG. To that end, different strategies used to select a ZBG, its properties, activity, and liabilities are discussed.

Columnar Liquid Crystals of Copper(I) Complexes with Ionic Conductivity and Solid State Emission

Two neutral copper(I) halide complexes ([Cu(BTU)₂X], X = Cl, Br) were prepared by the reduction of the corresponding copper(II) halides (chloride or bromide) with a benzoylthiourea (BTU, N-(3,4-diheptyloxybenzoyl)-N'-(4-heptadecafluorooctylphenyl)thiourea) ligand in ethanol. The two copper(I) complexes show a very interesting combination of 2D supramolecular structures, liquid crystalline, emission, and 1D ionic conduction properties. Their chemical structure was ascribed based on ESI-MS, elemental analysis, IR, and NMR spectroscopies (¹H and ¹³C), while the mesomorphic behavior was analyzed through a combination of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and powder X-ray diffraction (XRD). These new copper(I) complexes have mesomorphic properties and exhibit a hexagonal columnar mesophase over a large temperature range, more than 100 K, as evidenced by DSC studies and POM observations. The thermogravimetric analysis (TG) indicated a very good thermal stability of these samples up to the isotropization temperatures and over the whole temperature range of the liquid crystalline phase existence. Both complexes displayed a solid-state emission with quantum yields up to 8% at ambient temperature. The electrical properties of the new metallomesogens were investigated by variable temperature dielectric spectroscopy over the entire temperature range of the liquid crystalline phase. It was found that the liquid crystal phases favoured anhydrous proton conduction provided by the hydrogen-bonding networks formed by the NH…X moieties (X = halide or oxygen) of the benzoylthiourea ligand in the copper(I) complexes. A proton conductivity of 2.97 × 10^-7 S·cm^-1 was achieved at 430 K for the chloro-complex and 1.37 × 10^-6 S·cm^-1 at 440K for the related bromo-complex.

Hinged Bipodal Furoylthiourea-Based Ru(II)-Arene Complexes: Effect of (ortho, meta, or para)-Substitution on Coordination and Anticancer Activity

We set out to design and synthesize bipodal ligands with the phenyl group as the spacer and varied the substitution on the spacer between ortho (L1), meta (L2), and para (L3). The respective ligands and complexes containing either p-cymene (PL1-PL3) or benzene (BL1-BL3) as the arene unit were synthesized and characterized successfully. The influence of the ligands due to substitution change on their coordination behavior was quite minimal; however, the differences were seen in the anticancer activity of the complexes. DFT studies revealed the structural variations between the three different substitutions, which was further confirmed by single-crystal X-ray diffraction studies. The anticancer activity of the complexes could be correlated with their rate of hydrolysis and their lipophilicity index as determined by UV-visible spectroscopy. The cell death mechanism of the active complexes was deduced to be apoptotic via staining assays, flow cytometry, and Western blot analysis.

NIR/MRI-Guided Oxygen-Independent Carrier-Free Anti-Tumor Nano-Theranostics

Imaging-guided photothermal therapy (PTT)/photodynamic therapy (PDT) for cancer treatment are beneficial for precise localization of the malignant lesions and combination of multiple cell killing mechanisms in eradicating stubborn thermal-resistant cancer cells. However, overcoming the adverse impact of tumor hypoxia on PDT efficacy remains a challenge. Here, carrier-free nano-theranostic agents are developed (AIBME@IR780-APM NPs) for magnetic resonance imaging (MRI)-guided synergistic PTT/thermodynamic therapy (TDT). Two IR780 derivatives are synthesized as the subject of nanomedicine to confer the advantages for the nanomedicine, which are by feat of amphiphilic IR780-PEG to enhance the sterical stability and reduce the risk from reticuloendothelial system uptake, and IR780-ATU to chelate Mn²⁺ for T₁ -weighted MRI. Dimethyl 2,2'-azobis(2-methylpropionate) (AIBME), acting as thermally decomposable radical initiators, are further introduced into nanosystems with the purpose of generating highly cytotoxic alkyl radicals upon PTT launched by IR780 under 808 nm laser irradiation. Therefore, the sequentially generated heat and alkyl radicals synergistically induce cell death via synergistic PTT/TDT, ignoring tumor hypoxia. Moreover, these carrier-free nano-theranostic agents present satisfactory biocompatibility, which could be employed as a powerful weapon to hit hypoxic tumors via MRI-guided oxygen-independent PTT and photonic TDT.

Syntheses, crystal structures and supramolecular assemblies of two Cu(ii) complexes based on a new heterocyclic ligand: insights into C–H⋯Cl and π⋯π interactions

A new heterocyclic ligand, N3L [4-(1-methylimidazole)-2,6-di(pyrazinyl)pyridine] and two Cu(ii) complexes have been synthesized and characterized by several spectroscopic and DFT methods.

Synthesis and characterization of novel acylthiourea compounds used in ions recognition and sensing in organic media

A series of novel N-acyl-N'-aryl thiourea derivatives were designed and prepared with the aim to develop dual responsive receptors for anions and cations. The structure of the new products was confirmed by NMR spectroscopy (¹³C and ¹H), elemental analysis, and IR spectroscopy. Their thermal stability was studied by thermogravimetric analysis (TG) and it was found that these acyl thiourea derivatives are stable up to 160 °C. The ion recognition and sensing properties of the acyl thiourea compounds were investigated by UV-VIS absorption spectroscopy in organic media upon the addition of various salts. The UV-VIS studies revealed that these acyl thiourea derivatives are able to sense biological important ions such as fluoride and copper (II) ions.

Structure, assembly mechanism and magnetic properties of heterometallic dodecanuclear nanoclusters DyIII4MII8 (M = Ni, Co)

Two isostructural heterometallic dodecanuclear nanoclusters [Dy4Co8(μ3-OH)8(L)8(OAc)4(H2O)4]·3EtOH·3CH3CN·H2O (1) and [Dy4Ni8(μ3-OH)8(L)8(OAc)4(H2O)4]·3.5EtOH·0.5CH3CN·5H2O (2) with different assembly mechanisms are presented here.

Photoactive PtII and PdII complexes of N,N-diethyl-N′-3,4,5-trimethoxybenzoylthiourea: synthesis, crystal structures, DFT and cytotoxicity studies

New trans-Pd^II/Pt^II acylthiourea complexes prepared by photo-induced isomerism are found to be more cytotoxic than cis-Pd^II/Pt^II against human prostate cancer and normal embryonic kidney cell lines.