This work introduces a novel class of hybrid antimicrobial agents by integrating sulfone and sulfonamide functionalities with polyhedral oligomeric silsesquioxanes (POSSs). By employing efficient synthetic protocols, we have successfully prepared both sulfone (ethylvinylsulfone-POSS and phenylethylsulfone-POSS) and sulfonamide (benzenesulfonamide-POSS, p-toluenesulfonamide-POSS, 3-fluorobenzenesulfonamide-POSS, and 2-naphthalenesulfonamide-POSS) derivatives with high yields (73-90%). All derivatives were examined using Fourier transform infrared spectroscopy, multinuclear (1H, 13C, 19F, and 29Si) NMR spectroscopy, MALDI-ToF MS spectrometry, and elemental analysis. Additionally, the crystal structure of the p-toluenesulfonamide-POSS hybrid was revealed. The unique cage-like POSS structure not only imparts enhanced thermal and chemical stability, a common feature of silsesquioxane-based hybrids, but also boosts the lipophilic character of these compounds, thereby facilitating their interaction with microbial membranes. This interaction, likely resulting in membrane disruption and cell lysis, translates into potent antimicrobial activity (against Escherichia coli, Pseudomonas aeruginosa, Enterococcus hirae, Staphylococcus aureus, and Candida albicans)─especially against Gram-positive bacteria─at remarkably low minimum inhibitory concentrations in the range from 125 to 3000 μM. In turn, E. hirae and S. aureus were more susceptible compared to Gram-negative bacteria and C. albicans. The strategic incorporation of POSSs into these sulfur-based moieties represents a significant breakthrough, opening new avenues for the development of advanced antimicrobial coatings and therapeutic agents in the fight against antibiotic resistance.

Vulvovaginal candidiasis, primarily caused by Candida albicans, presents a significant therapeutic challenge due to fungal biofilm formation and the poor aqueous solubility of azole antifungals like clotrimazole, CLT. Films are increasingly favored as antimicrobial drug carriers due to their capacity to provide prolonged vaginal retention, extended shelf life, and simplified storage compared to traditional drug forms. Current film formulations, however, often suffer from nonuniform drug distribution, uncontrolled drug release, and compromised structural integrity. To overcome these limitations, we developed novel, water-swellable polymeric networks designed for enhanced clotrimazole bioavailability and potent anti-Candida biofilm activity. Our strategy involved the reversible cross-linking of unique asymmetric open-Polyhedral Oligomeric Silsesquioxane (POSS) cages, functionalized with both hydrophobic, i.e., phenyl (IC-POSSPh) or isobutyl (IC-POSSiBu) groups and bearing hydrophilic 1,2-diol moieties, with poly(dimethylacrylamide-2-acrylamidephenylboronic acid) (P(DMAM-2-AAPBA)) copolymers. We tailored the copolymer composition to achieve precise control over the network cross-linking density. Comprehensive characterization, including 11B NMR spectroscopy, differential scanning calorimetry, rheology, and SEM-EDS (scanning electron microscopy-energy dispersive X-ray spectroscopy), elucidated the structure-property relationships. We demonstrated that IC-POSSPh cages intrinsically prevent CLT crystallization, likely via π-π-stacking interactions, facilitating homogeneous drug distribution. Conversely, while IC-POSSiBu cages showed less inherent drug compatibility, the P(DMAM-2-AAPBA) copolymers were crucial for achieving uniform CLT dispersion within these networks. Our studies revealed that higher 2-AAPBA content in the copolymer increased network cross-linking density, leading to slower drug release. Moreover, π-π interactions between IC-POSSPh cages in the networks contributed to a reduced swelling capacity and evidently slower drug release. Crucially, biological evaluations confirmed that these CLT-loaded polymeric films significantly enhanced antifungal efficacy against both planktonic C. albicans strains (ATCC 10231 and SC5314) and mature Candida biofilms, outperforming free CLT. This superior performance is attributed to the networks' ability to maintain CLT in the molecular state and enable its controlled release, thereby improving its bioavailability at the target site. The elaborated films also exhibited good cytocompatibility. This work highlights how subtle structural modifications in network components are crucial to achieving desired biological functions, representing a promising advance for antifungal drug delivery and, in general, hydrophobic drug carriers in various biomedical applications.

A monofunctional benzoxazine with an ortho-positioned hydroxy group was designed in an attempt to obtain low-curing monomers impelled by intra- and intermolecular hydrogen bonds. A set of hydroxybenzoxazines ((OH)Bx (R)) was synthesized with different substituents (R) on the nitrogen atom of the heterocyclic ring. The structure in the solid state indicates dimeric compounds in which benzoxazine molecules are bonded together by intermolecular hydrogen bonds between the hydroxyl functional and nitrogen atoms. All hydroxybenzoxazines showed lower curing temperatures in comparison with adequate benzoxazine monomers without hydroxy functionalization ((OH)Bx (R) < (tBu)Bx (R)). The ring-opening polymerization for hydroxybenzoxazines proceeds via different pathways stimulated by hydrogen bonds, giving rise to a new, unknown hydroxy-acetal type of polybenzoxazine. The crucial new stage in the modified structure of the polymer chain involves proton transfer from the hydroxy group to the activated oxygen atom from the open oxazine ring.

This study investigates the formation mechanisms of oligomeric phenyl silanols, focusing on polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) derivatives. Combining literature reports and crystal structures of solvated derivatives obtained in our laboratory, we show that the solvent choice significantly influences their structures. POSS-based silanols prefer aprotic solvents like THF, preserving dimerization, while double-deckers form stable architectures in protic solvents like isopropanol. This discrepancy arises from different stabilization mechanisms. Our findings enhance our understanding of hydrolytic condensation involving trimethoxyphenylsilane and suggest aprotic solvents for efficient reactions with POSS-based silanols.

This study explores the intricate coordination chemistry of sodium aminophenolate species and their significant role in the depolymerization of polylactide (PLA), offering novel insights into catalytic degradation processes. By examining sodium coordination entities, including dimers and larger aggregates such as tetramers, we reveal how structural modifications, particularly the manipulation of steric hindrances, influence the formation and stability of these complexes. The dimers, characterized by a unique four-center core (Na-O-Na-O), serve as a foundational motif, which is further elaborated to obtain complexes with varied coordination environments through strategic ligand design. Our research delves into the lability of the amino arm in these complexes, a critical factor that facilitates the coordination of PLA to the sodium center, thereby initiating the depolymerization process. Moreover, DFT studies have been pivotal in identifying the most energetically favorable structures for catalysis, highlighting a distinct preference for an eight-membered ring motif stabilized by intramolecular hydrogen bonds. This motif not only enhances the catalyst's efficiency but also introduces a novel structural paradigm for sodium-based catalysis in PLA degradation. Experimental validation of the theoretical models was achieved through NMR spectroscopy, which confirmed the formation of the active catalyst forms and monitored the progress of PLA degradation. The study presents a comprehensive analysis of the influence of ligand structure on the catalytic activity, underscoring the importance of the eight-membered ring motif. Furthermore, we demonstrate how varying the steric bulk of substituents on the amino arm affects the catalyst's performance, with benzyl-substituted ligands exhibiting superior activity. Our findings offer a profound understanding of the structural factors governing the catalytic efficiency of sodium aminophenolate complexes in PLA degradation. This research not only advances the field of coordination chemistry but also presents a promising avenue for the development of efficient and environmentally friendly catalysts for polymer degradation.

In this article, we explore theoretical validations of experimental findings pertaining to the classical corner-capping reactions of a commercially available heptaisobutyltrisilanol cage to mono-substituted phenylhepta(isobutyl)-POSS cages. Additionally, the process of opening a fully condensed cage is tracked to assess the possibility of isolating and separating the resulting isomers. The corner-capping reactions of potential silanotriols, both as monomers and dimers, and the impact of these structural motifs on their closing to bifunctional POSS cages are also investigated. Our studies highlight that analyzing experimental results alone, without incorporating complex theoretical investigations, does not offer a clear understanding of the reactions involving multiple simultaneously reacting substrates, which may also undergo further transformations, potentially complicating the conventional pathways of classic corner-opening/capping reactions.

Mono-substituted cage-like silsesquioxanes of the T8-type can play the role of potential ligands in the coordination chemistry. In this paper, we report on imine derivatives as ligands for samarium, terbium, and erbium cations and discuss their efficient synthesis, crystal structures, and magnetic and optical properties. X-ray analysis of the lanthanide coordination entities [MCl3(POSS)3]·2THF [M = Er3+ (3), Tb3+ (4), Sm3+ (5)] showed that all three compounds crystallize in the same space group with similar lattice parameters. All compounds contain an octahedrally coordinated metal atom, and additionally, 3 and 5 structures are strictly isomorphous. However, surprisingly, there are two different molecules in the crystal structure of the terbium coordination entity 4, monomer (sof 65%) and dimer (sof 35%), with one and two metal centers. Absorption measurements of the investigated materials recorded at 300 K showed that regardless of the lanthanide involved, their energy band gap equals 2.7 eV. Moreover, the analogues containing Tb3+ and Sm3+ exhibit luminescence typical of these rare earth ions in the visible and infrared spectral range, while the compound with Er3+ does not generate any emission. Direct current variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3-5 were performed between 1.8 and 300 K. The magnetic properties of 3 and 4 are dominated by the crystal field effect on the Er3+ and Tb3+ ions, respectively, hiding the magnetic influence between the magnetic cations of adjacent molecules. Complex 5 exhibits a nature typical for the paramagnetism of the samarium(III) cation.

We report unraveling the catalytic effect of N-activated benzoxazine monomers on the ring-opening polymerization of simple 1,3-benzoxazine. A novel series of ionic and neutral benzoxazine monomer couples were synthesized and thoroughly characterized using cutting-edge X-ray and spectroscopic techniques. Specially designed monomers act as latent catalyst systems that remain dormant at room temperature but become activated during heating. This two-stage process involves the detachment of chloroalkane and the opening of the oxazine ring, significantly reducing the ROP temperature. To shed new light on the catalytic performance of ionic monomers, simultaneous Fourier transform infrared and thermogravimetry measurements were conducted, providing a comprehensive understanding of the thermal transformation products and revealing the immense catalytic potential and effectiveness of ionic benzoxazines.

The use of diverse biomaterials for regenerative medicine is constantly evolving. Therefore, looking for easy-to-scale-up materials in terms of preparation, less complex composition, and featuring structural and chemical stability seems justified. In this work, we report the preparation of double-decker silsesquioxane-based (DDSQ-based) composites, which, according to our best knowledge, have never been used as biomaterials. A family of methacrylate-substituted DDSQs was obtained starting from the previously reported hydroxyalkyl double-decker silsesquioxanes. In the resulting hybrids, methacrylate groups are attached to each other's lateral silicon atoms of DDSQ in trans positions, providing an excellent geometry for forming thin layers. In contrast to pure organic methacrylates, the covalent bonding of methacrylate derivatives to inorganic silsesquioxane core improves mechanics, cell adhesion, and migration properties. Furthermore, to increase the hydrophilicity of the resulting DDSQ-based hybrids, polyvinyl alcohol (PVA) was added. The entire system forms an easy-to-obtain two-component (DDSQ-PVA) composite, which was subjected without any upgrading additives to biological tests later in the research. The resulting biomaterials fulfill the requirements for potential medical applications. Human fibroblasts growing on prepared hybrid composites are characterized by proper spindle-shaped morphology, proliferation, and activation status similar to control conditions (cells cultured on PVA), as well as increased adhesion and migration abilities. The obtained results suggest that the prepared biomaterials may be used in regenerative medicine in the future.

Rapid developments in materials engineering are accompanied by the equally rapid development of new technologies, which are now increasingly used in various branches of our life. The current research trend concerns the development of methods for obtaining new materials engineering systems and searching for relationships between the structure and physicochemical properties. A recent increase in the demand for well-defined and thermally stable systems has highlighted the importance of polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) architectures. This short review focuses on these two groups of silsesquioxane-based materials and their selected applications. This fascinating field of hybrid species has attracted considerable attention due to their daily applications with unique capabilities and their great potential, among others, in biomaterials as components of hydrogel networks, components in biofabrication techniques, and promising building blocks of DDSQ-based biohybrids. Moreover, they constitute attractive systems applied in materials engineering, including flame retardant nanocomposites and components of the heterogeneous Ziegler-Natta-type catalytic system.

Most biosurfactants are obtained using costly culture media, which limits their wider industrial use. In the present study, a low-cost culture medium, containing the agro-industrial residue black cumin cake, was devel-oped for amphisin production by Pseudomonas fluorescens DSS73. By using black cumin cake as the substrate, not only was the production cost reduced but also a higher production yield was achieved. A Box-Behnken experi-mental design was applied to maximize lipopeptide biosurfactant production. The optimal conditions for amphisin production, such as black cumin cake (6.6%) and NaCl (8.0 mM) concentration, and cultivation time (6.5 days), were determined. Yield of amphisin production, performed in optimal conditions, reached 16.51 +/- 0.49 g/L. Such high production has not been evidenced previously for Pseudomonas lipopeptide biosurfactants. Moreover, active utilization of the substrate, observed with the aid of scanning electron microscopy (SEM), documented by numerous holes and pitting on the black cumin cake surface, was confirmed. Finally, antifungal activity of amphisin against Aspergillus carbonarius was demonstrated. Hence, amphisin production by P. fluorescens was achieved with statistical optimization using an inexpensive agro-industrial by-product for the first time.

The CuAAC active-template approach was exploited to construct rotaxanes incorporating cage-like silsesquioxane stoppers, namely, POSSaxanes. The compounds were characterized in the solution and solid state, providing the unprecedented molecular structures of POSS-incorporating rotaxanes.

An easy, efficient, and scalable synthetic procedure is described to obtain novel amide-functionalized double-decker silsesquioxanes (DDSQs). The use of mild conditions of deprotection of the BOC group, which does not result to the cleavage of the cage-like silsesquioxane structure, is reported. This method leads to the so far undescribed hydrochloride salt of aminoalkyl-DDSQ. Interestingly, the cis/trans-isomerization of DDSQ molecules was observed during the reaction. The resulting compounds are characterized using multinuclear NMR (1H, 13C, and 29Si), MALDI-TOF, FT-IR, and elemental analysis. Moreover, crystal structures are reported for three trans DDSQs. The chloride salt of aminoalkyl derivative, obtained in one of the steps of the synthetic pathway, shows an intriguing structure of the crystal lattice in which large channels are present, caused by ionic interactions in the lattice. The described approach opens the way to synthesizing new DDSQ derivatives and materials using BOC-blocked amines. We believe our findings would advance investigations about new materials based on little known organic-inorganic DDSQ-based hybrids.

Properties of oligourethanes can be programmed by the monomer sequence, its composition, and stereocontrol.

A procedure to sequentially crystallize the two isomers of hydroxyalkyl-substituted double-decker silsesquioxanes from one another, which may result in the preparation of new materials and polymers with well-defined properties, is reported.

The functionalized cage-like silsesquioxanes (POSSs) have enticed scientific community's continuous interest. In this work, we try to supplement empirical expertises and answer questions concerning the coordination modes of copper(II) cation in the POSS-1 ligand neighborhood through the DFT calculations. It is postulated that ethanol solvent molecules take an active part in the coordination to the metallic center in the acidic environment. At the alkaline solution, the square planar shape of two POSS-1 ligands surrounded the copper(II) cation, including two oxygen and two nitrogen atoms in the first coordination sphere of copper, is recommended.

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li4(OSiPh3)4(THF)2] (1), and sodium [Na4(OSiPh3)4] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh3)3(THF)3]·THF (3), and erbium [Er(OSiPh3)3(THF)3]·THF (4) configuration, it can result in res were determined for all 1–4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8–300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd3+ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er3+ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.

The synthesis and structural characterization of two new potassium triphenylsiloxides, namely, aqua(propan-2-ol)hexakis(triphenylsilanolato)hexapotassium toluene disolvate, [K6(C18H15OSi)6(C3H8O)(H2O)]·2C7H8, and diaquahexakis(triphenylsilanolato)hexapotassium, [K6(C18H15OSi)6(H2O)2], are reported. Both compounds crystallize in the triclinic space group P-1. The structure in each case resembles an alkali metal polyoxometalate-like structure, in which electrostatic interactions are observed in the metal-oxygen core. Furthermore, both compounds also resemble a reverse micelles-like architecture, in which the hydrophilic core is enclosed in a hydrophobic shell. The cores of the complexes are flanked by hydrophobic aromatic rings derived from Ph3SiO- anions, where intramolecular π-interactions between the aromatic rings and potassium cations stabilize the cores of the crystals. Moreover, in both structures, the presence of hydrogen bonds is observed; until now, no crystal structures have been described containing K atoms and triphenylsiloxide molecules in which the presence of hydrogen bonds was confirmed. Thus, these coordination entities could be considered as attractive reagents for further synthetic protocols towards heterometallic complexes.

In this paper, we report on the synthesis of novel copper(ii) complexes containing a multi-donor N,O-type ligand based on mono-substituted cage-like silsesquioxanes bound by trifunctional acyl chloride.

The unexpected reaction between mono-functionalized amino-POSS and palladium acetate (different from the well-known pathway between a classical amine and a palladium salt) leads to novel coordination entities.