Novel cobalt bis(dicarbollide) based terminal alkynes with charge-compensated group in a spacer were synthesized by the nucleophilic ring-opening reactions of cyclic oxonium derivatives of cobalt bis(dicarbollide) with N,N-dimethylbut-3-yn-1-amine. A series of zwitterionic conjugates of cobalt bis(dicarbollide) with BODIPY were synthesized using the copper(I)-catalyzed azide-alkyne cycloaddition reaction. The absorption-emission spectra of the synthesized fluorescent conjugates of cobalt bis(dicarbollide) with BODIPY were obtained and it was shown that the conjugation with the metallacarborane moiety weakens the fluorescence of the BODIPY core, nevertheless the conjugates can be used to track boron in living systems. A spectroscopic study of the interaction of selected fluorescent conjugate with BSA in a stationary mode was carried out. Non-cytotoxic zwitterionic conjugate of cobalt bis(dicarbollide) with BODIPY retained fluorescence during cellular uptake, an effect attributable to its affinity for albumin. Laser confocal microscopy study demonstrated distributed perinuclear accumulation of the conjugate in cells and the absence of pronounced colocalization of the substance and early endosomes, which indicates a successful accumulation and distribution of conjugate inside the cell. This study creates prerequisites for further research in the development of methods for synthesizing fluorescent boron neutron capture therapy (BNCT) agents with the BODIPY moiety.

The preparation of 1-(ortho-carboran-1 '-yl)ethanol by the reaction of ortho-carborane and acetaldehyde in the presence of various bases, such as (Bu4N)F x 3H2O, Proton Sponge, DBU or Barton's base, was studied. The highest yield of 1-(ortho-carboran-1 '-yl)ethanol (60 %) was observed when using Barton's base. The treatment of 1-(ortho-carboran-1 '-yl)-ethanol with CrO3in acetic acid at room temperature leads to (1,2-dicarba-closo-dodecaboran-1-yl)-methyl ketone in nearly quantitative yield. The reaction of 1-phenyl-1,2-dicarba-closo-dodecaborane with acetaldehyde in the presence of (Bu4N)F in THF resulted in the tetrabutylammonium salt of 7-phenyl-7,8-dicarba-nido-undecaborate, which structure was determined by single-crystal X-ray diffraction study.

Malonate ligands demonstrate versatility for intercalating metal complexes into layered rare-earth hydroxides (LREHs), enabling controlled tuning of coordination geometry and composition. As a proof of concept, a series of copper(II) malonate complexes with various substituents was synthesized and successfully intercalated into layered yttrium, europium, or terbium hydroxide at room temperature via anion-exchange reactions. The copper content in these hybrid materials increased in the order: butylmalonate < benzylmalonate < cyclopropanedicarboxylate < dimethylmalonate. To further expand the range of accessible metal malonate complexes, dimethyl- and benzylmalonate anions were intercalated into layered yttrium hydroxide for the first time and subsequently metalated in situ, yielding well-defined Cu2+ species within the interlayer space without disrupting the host lattice. Density functional theory (DFT) calculations provided insight into the structural arrangements of the copper complexes in the interlayer galleries. Comprehensive characterization of the resulting materials by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), IR, UV-vis, and electron paramagnetic resonance (EPR) spectroscopy confirmed both the successful formation of hybrid structures and elucidated the coordination environment of the intercalated copper species.

Exploration of new possible molecular combinations for the preparation of energetic materials remains a challenging task. Herein, the construction of new azole assemblies incorporating the poorly studied 2,5-disubstituted tetrazole motif in combination with oxadiazole moieties is presented. A complete set of experimentally defined properties including thermal stability and mechanical sensitivity, as well as the calculated detonation performance, was evaluated. All target energetic substances have high densities (1.72-1.74 g cm-3) and high combined nitrogen-oxygen content (55-73%). Azo-bridged hexaheterocyclic entities showed high friction sensitivity (on the level of primary explosives), while the introduction of two amino groups improved the sensitivity up to a nitro ester's level, considered as the lowest acceptable level for manufacturing.

Intermolecular interactions play a pivotal role in chemical processes such as catalysis, crystal formation, and drug-protein complexation. The Quantum Theory of Atoms in Molecules (QTAIM) provides a robust framework for analyzing these interactions through topological descriptors of electron density. However, the computational cost of obtaining accurate electron density distributions for large systems remains a challenge. This study critically evaluates the promolecular approximation (Independent Atom Model, IAM) as a cost-effective alternative for QTAIM analysis, focusing on its ability to describe various non-covalent interactions, including hydrogen bonds, halogen bonds, π…π stacking, and dispersion interactions. By comparing promolecular and density functional theory (DFT) results across diverse molecular systems, we demonstrate that the IAM model reliably reproduces trends in QTAIM descriptors, particularly for weaker and medium-strength interactions. However, in the case of some types of non-directional interactions, the molecular graph is often incorrectly predicted. Furthermore, we propose a semi-quantitative model to estimate intermolecular binding energies using promolecular-derived descriptors, showcasing the potential of IAM for large-scale applications in supramolecular chemistry and materials science.

Weak noncovalent interactions are responsible for structure and properties of almost all supramolecular systems, such as nucleic acids, enzymes, and pharmaceutical crystals. However, the analysis of their significance and structural role is not straightforward and commonly requires model studies. Herein we describe an efficient and universal approach for the analysis of noncovalent interactions and determination of vdW radii using the Line-of-Sight (LoS) concept. The LoS allows to unambiguously identify and classify the “direct” interatomic contacts in complex molecular systems. This approach not only provides an improved theoretical base to molecular “sizes” but also enables the quantitative analysis of specificity, anisotropy and steric effects of intermolecular interactions.

The conformational mobility of the [8-EtO-8’-I-3,3’-Co(1,2-C2B9H10)2]− anion, which has been chosen as a model compound for many potential drugs based on cobalt bis(dicarbollide), was studied by 1H NMR spectroscopy, single crystal X-ray diffraction and quantum chemical calculations. According to the results of quantum chemical calculations, the most favourable conformation for [8-EtO-8’-I-3,3’-Co(1,2-C2B9H10)2]− is the transoid conformation, which is stabilized by one pair of CH···I and one pair of CH···O(Et) intramolecular hydrogen bonds between the dicarbollide ligands. However, the difference in energy between the transoid and gauche conformations is rather small, while the cisoid conformation is energetically extremely unfavorable. The transoid conformation of the anion was found in the crystal structure of (Bu4N)[8-EtO-8’-I-3,3’-Co(1,2-C2B9H10)2], while the 1H NMR spectroscopy data suggest the presence of an equilibrium between the transoid and gauche conformations in solution. Both the transoid and gauche conformations of the anion have a low dipole moment, which is characteristic of most low molecular weight drugs. This may explain the ease of penetration of molecules containing this fragment through biological membranes and their observed increased biological activity.

The design and synthesis of advanced energetic non-hydrogen 1,2,5-oxadiazole assemblies were realized. All target azo-1,2,5-oxadiazole assemblies have high densities (1.89-1.90 g cm-3), good thermal stabilities (180-181 °C), high enthalpies of formation (933-955 kJ mol-1), and positive oxygen balance with respect to CO (+7.5%). As a result, these compounds exhibit high detonation velocities (9.0 km s-1), high detonation pressures (38 GPa), and excellent heats of detonation (5.82-5.85 kJ g-1), unveiling new opportunities in the search for next-generation functional organic materials.

Background: Nitric oxide (NO) has been linked to the pathogenesis of asbestos-related pleural diseases, including an extremely aggressive cancer called malignant pleural mesothelioma (MPM). Given that MPM cells are characterized by a higher expression of NO synthases and elevated NO production relative to normal cells, the use of NO-donor compounds could potentially saturate the cancerous cells with NO, triggering their death. Methods: We developed a novel class of NO prodrugs by merging two NO-releasing components, 1,2,5-oxadiazole 2-oxides (furoxans) and 1,2,4-oxadiazoles, and studied their NO-releasing characteristics in a time-dependent manner using the Griess assay. The cytotoxicity against two human MPM cell lines and non-cancerous lung fibroblasts was evaluated using a colorimetric MTT assay. Results: All compounds exhibited excellent NO-donating properties, surpassing the capacity of two reference NO donor compounds, 3-carbamoyl-4-(hydroxymethyl)furoxan (CAS-1609) and 4-ethoxy-3-phenylsulphonylfuroxan (CHF-2363), by at least 1.5–3 times. All oxadiazole hybrids demonstrated high cytotoxicity against MPM cell lines in a low micromolar range, comparable or higher than the cytotoxicity of the standard-of-care drug cisplatin. Conclusions: Notably, the novel compounds displayed a markedly greater selectivity towards cancerous cells than cisplatin when compared with non-cancerous lung fibroblasts, aligning with the intended design.

Heterometallic d-4f coordination complexes are of paramount interest in modern coordination chemistry because of their potential applications in organic light-emitting devices and spintronic materials. Here we report the synthesis and thorough investigation of Ln and M=Ln (M = Zn, Cd; Ln = Sm, Eu, Gd, Tb) molecular complexes based on 2-furancarboxylic acid anion (Hfur): [Ln(2)(NO3)(2)(fur)(4)(DME)(2)] (Ln = Eu, Gd, Tb; DME is dimethoxyethane) and [M(2)Ln(2)(NO3)(2)(fur)(8)(bpy)(2)] (M = Zn, Cd; Ln = Eu, Gd, Tb, Sm; bpy is 2,2 '-bipyridyl). The structure and isostructural nature of compounds were determined based on the single-crystal and powder X-ray diffraction data. The photophysical properties of the obtained compounds were studied in detail: The energies of the triplet levels of the furoate anion and d-blocks {M(fur)(2)(bpy)} (M = Zn, Cd), the relaxation times of the excited states, and the quantum yields were determined. Critical step from Ln complexes to Zn=Ln and Cd=Ln (Ln = Eu, Tb) is accompanied by an increase in quantum yields, which correlates with a change in the energy of the triplet level of the aromatic part of the complexes and with the results of quantum chemical calculations indicating different schemes for the origination of triplet levels in M=Ln compounds.

Pyrazine 1,4-dioxide (PZDO) is a chemical frequently employed as a coformer in cocrystal design. It has two N-oxide fragments that signify potential hazards, but we found no information about it in prior literature. Therefore, we investigate the thermal behavior, thermochemical properties, and mechanical sensitivity of the title compound. We demonstrate that the material explodes in standard impact tests at a certain drop energy. By the level of its computed energetic potential, PZDO approaches benchmark trinitrotoluene. We screened ten energetic materials for cocrystal formation with PZDO using thermal analysis methods and predicted three novel cocrystals. However, we failed to grow the X-ray quality crystals by the conventional approach due to significantly differing solubility of PZDO and other components in common solvents. Two suitable coarse cocrystals of 3,4-dinitropyrazole/PZDO and 3,5-dinitropyrazole/PZDO were finally prepared by resublimation (vacuum recondensation of preformed comelt), and its X-ray structure is reported. Overall, we characterize PZDO as an energetic material and highlight the potential risks associated with the compound. The preparation of cocrystals via the gas phase route, although laborious, may be effective when the traditional (via solution) approach fails.

New promising energetic materials comprised of 1,2,4-triazole and furoxan rings and bearing explosophoric nitro group were rationally designed and synthesized. All newly prepared compounds were thoroughly characterized and their physicochemical properties were estimated. In the newly synthesized series, (1,2,4-triazolyl)furoxan 4 is completely insensitive to impact and friction and possesses good detonation performance (D = 8.4 km s-1; P = 33 GPa) enabling its further exploration as a promising high-energy material. New energetic (1,2,4-triazolyl)furoxans were synthesized and their physicochemical properties were estimated. The obtained results serve as an evidence that an alliance of 1,2,4-triazole and furoxan rings may constitute a suitable platform for the construction of promising energetic materials. image

Nitrogen heterocyclic scaffolds retain their leading position as valuable building blocks in material science, particularly for the design of small-molecule energetic materials. However, the search for more balanced combinations of directly linked heterocyclic cores is far from being exhausted and aims to reach ideally balanced high-energy substances. Herein, we present the synthetic route to novel pyrazole-furoxan framework enriched with nitro groups and demonstrate a promising set of properties, viz., good thermal stability, acceptable mechanical sensitivity, and high detonation performance. In-depth crystal analysis showed that the isomers having lower-impact sensitivity values in both types of regioisomeric pairs are those with the exocyclic furoxan oxygen atom being closer to the pyrazole ring. Owing to the favorable combination of high crystal densities (1.83-1.93 g cm(-3)), positive oxygen balance to CO (up to +13.9%), and high enthalpies of formation (322-435 kJ mol(-1)), the synthesized compounds show high calculated detonation velocities (8.4-9.1 km s(-1)) and excellent metal accelerating abilities. The incorporation of the 3-nitrofuroxan moiety increases the thermal stability (by ca. 20 degrees C) and decreases the mechanical sensitivity of target hybrid materials in both types of regioisomeric pairs. Simultaneously, the detonation performance of 3-nitrofuroxans is almost identical to that of 4-nitrofuroxans, highlighting the potential of the regioisomeric tunability in the future design of energetic materials.

The possibility to estimate the electron population of Bader’s interatomic surfaces using the electron density function values at the (3, −1) critical points is discussed taking the results of quantum chemical calculations of three model sets of isolated atomic aggregates as examples. A relevant method based on the approximation of normal distribution of the electron density over the interatomic surface is proposed and verified. The range of applicability of this approximation is considered using the results of calculations for a new model set.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A new approach to managing the extraction properties of eutectic solvents based on aliphatic alcohols is proposed. Aliphatic alcohols, when functioning as hydrogen bond donors within a eutectic solvent, significantly enhance the solvent’s efficiency in extracting metal ions. Conversely, when the alcohol acts as a hydrogen bond acceptor, its extraction properties diminish. Molecular modelling reveals that the extraction efficiency of these alcohols is directly proportional to the intermolecular interaction energy between the components of the eutectic solvent.

Based on the processing of supramolecular environments of nitro group from Cambridge Structural Database by means of the ‘Atoms in Molecules’ analysis of promolecular electron density function, it is demonstrated that the topological stability of intermolecular bonding within one associate reflects trends in prevalence of interactions with particular geometry in real crystals.

A new allyl derivative of curcumin containing three allyl groups (1E,6E)-4-allyl-1,7-bis(4′-allyloxy-3′-methoxyphenyl)hepta-1,6-diene-3,5-dione was synthesized by the reaction of curcumin with the excess of allyl bromide in the presence of K2CO3 in acetone under reflux. The triple-allylated curcumin was characterized by 1H and 13C-NMR spectroscopy and single-crystal X-ray diffraction analysis.

Design and synthesis of new energetic materials retains its urgency in chemistry and materials science. Herein, rational construction and regioselective synthesis of a series of energetic compounds comprising of a methylene-bridged combination of 1,2,5-oxadiazole and nitrogen-rich azoles (1,2,4-triazole and tetrazole) enriched with additional explosophoric functionalities (nitro and azo moieties) is presented. All target materials were thoroughly characterized using IR and multinuclear NMR (1H, 13C, 14N, 15N) NMR spectroscopy, high-resolution mass spectrometry, X-ray diffraction, and differential scanning calorimetry. All synthesized energetic substances showed good thermal stability (up to 239 °C) and low mechanical sensitivity, while their performance reached or exceeded the level of TNT.

The titled relationship is considered in this paper in terms of the (de)localization phenomenon and its emanation in the positional coordinate space. The similarity between the strength of bonding of a topological atom (in the sense of the population of the corresponding atomic surface) and the delocalization index is discussed. Based on the hypervirial theorem, a scalar one-particle field is suggested to visualize the consequences of (de)localization for the formation of bonding.