Despite the rich coordination chemistry, hydroxylamines are rarely used as ligands for transition metal coordination compounds. This is partially because of the instability of these complexes that undergo decomposition, disproportionation and oxidation processes involving the hydroxylamine motif. Here, we design macrocyclic poly-N-hydroxylamines (crown-hydroxylamines) that form complexes containing a d-metal ion (Cu(II), Ni(II), Mn(II), and Zn(II)) coordinated by multiple (up to six) hydroxylamine fragments. The stability of these complexes is likely to be due to a macrocycle effect and strong intramolecular H-bonding interactions between the N−OH groups. Crown-hydroxylamine complexes exhibit interesting pH-dependent behavior where the efficiency of metal binding increases upon deprotonation of the hydroxylamine groups. Copper complexes exhibit catalytic activity in aerobic oxidation reactions under ambient conditions, whereas the corresponding complexes with macrocyclic polyamines show poor or no activity. Our results show that crown-hydroxylamines display anomalous structural features and chemical behavior with respect to both organic hydroxylamines and polyaza-crowns.

Three pyrrolidine-derived phenanthroline diamides were studied as ligands for lutetium trinitrate. The structural features of the complexes have been studied using various spectral methods and X-ray. The presence of halogen atoms in the structure of phenanthroline ligands has a significant impact on both the coordination number of lutetium and the number of solvate water molecules in the internal coordination sphere. The stability constants of complexes with La(NO₃)₃, Nd(NO₃)₃, Eu(NO₃)₃, and Lu(NO₃)₃ were measured to demonstrate higher efficiency of fluorinated ligands. NMR titration was performed for this ligand, and it was found that complexation with lutetium leads to an approximately 13 ppm shift of the corresponding signal in the ¹⁹F NMR spectrum. The possibility of formation of a polymeric oxo-complex of this ligand with lutetium nitrate was demonstrated. Experiments on the liquid–liquid extraction of Am(III) and Ln(III) nitrates were carried out to demonstrate advantageous features of chlorinated and fluorinated pyrrolidine diamides.

Driven by the growing threat of cancer, many research efforts are directed at developing new chemotherapeutic agents, where the central role is played by transition metal complexes. The proper ligand design serves as a key factor to unlock the anticancer potential of a particular metal center. Following a recent trend, we have prepared unsymmetrical pincer ligands that combine benzothiazole and thiocarbamate donor groups. These compounds are shown to readily undergo direct cyclopalladation, affording the target S,C,N-type Pd(II) pincer complexes both in solution and in the absence of a solvent. The solid-phase strategy provided the complexes in an efficient and ecologically friendly manner. The resulting palladacycles are fully characterized using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy and, in one case, by single-crystal X-ray diffraction (XRD). The solvent-free reactions are additionally analyzed by powder XRD. The pincer complexes exhibit remarkable cytotoxicity against several solid and blood cancer cell lines, including human colorectal carcinoma (HCT116), breast cancer (MCF7), prostate adenocarcinoma (PC3), chronic myelogenous leukemia (K562), multiple plasmacytoma (AMO1), and acute lymphoblastic leukemia (H9), with the dimethylamino-substituted derivative being particularly effective. The latter also induced an appreciable level of apoptosis in both parental and doxorubicin-resistant cells K562 and K562/iS9, vindicating the high anticancer potential of this type of palladacycles.

Platinum-based drugs are commonly recognized as a keystone in modern cancer chemotherapy. However, intrinsic and acquired resistance as well as serious side effects often caused by the traditional Pt(II) anticancer agents prompt a continuous search for more selective and efficient alternatives. Today, significant attention is paid to the compounds of other transition metals, in particular those of palladium. Recently, our research group has suggested functionalized carboxamides as a useful platform for the creation of cytotoxic Pd(II) pincer complexes. In this work, a robust picolinyl- or quinoline-carboxamide core was combined with a phosphoryl ancillary donor group to achieve hemilabile coordination capable of providing the required level of thermodynamic stability and kinetic lability of the ensuing Pd(II) complexes. Several cyclopalladated derivatives featuring either a bi- or tridentate pincer-type coordination mode of the deprotonated phosphoryl-functionalized amides were selectively synthesized and fully characterized using IR and NMR spectroscopy as well as X-ray crystallography. The preliminary evaluation of the anticancer potential of the resulting palladocycles revealed a strong dependence of their cytotoxic properties on the binding mode of the deprotonated amide ligands and demonstrated certain advantages of the pincer-type ligation.

To develop efficient and structurally novel anticoagulants, a library of new hybrid molecules—(Z)-1-(2-(4-arylthiazol-2-yl)hydrazineylidene)-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-2-ones—was designed and synthesized through a two-step approach. The reaction of pyrrolo[3,2,1-ij]quinoline-1,2-diones with thiosemicarbazide produced thiosemicarbazones, which were subsequently reacted with α-bromoacetophenones. The structure of the resulting compounds was determined by HPLC-HRMS-ESI analysis, ¹H NMR spectroscopy, and ¹³C NMR spectroscopy. X-ray diffraction analysis unambiguously confirmed the structure of the resulting substances. The synthesized compounds were tested for their anticoagulant activity in vitro. Among the tested derivatives, two substances have a dual effect and exhibit 98–100% inhibitory ability against blood coagulation factors Xa and XIa at 30 μM. IC₅₀ values were also evaluated for these compounds. The results obtained show the high potential of the synthesized derivatives in the development of new multitarget anticoagulant drugs. The docking studies confirmed the experimental results.