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.
In this article, we report on the chemistry and the spectroscopic properties of well-defined imino-functionalized polyoctahedral oligomeric silsesquioxanes (imine-POSS) with various substitutions. ...Our efforts were mainly focused on side chains with sizable aryl groups possessing hydroxyl, nitro, and halide moieties. Such a choice enabled us to track their reduction abilities to secondary amine-POSS, tautomerization effects, and thermal properties. We also report for the first time the solid-state structures of five imino-functionalized cage-like octasilsesquioxanes. These structures provide unique examples of the complexities of three-dimensional packing motifs and their relationship with the assembly of tunable materials from nanobuilding blocks.
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 Li
(OSiPh
)
(THF)
(
), and sodium Na
(OSiPh
)
(
) species, which were later used in obtaining novel gadolinium Gd(OSiPh
)
(THF)
·THF (
), and erbium Er(OSiPh
)
(THF)
·THF (
) configuration, it can result in res were determined for all
-
compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for
and
lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of
and
were carried out in the temperature range 1.8-300 K. The
shows behavior characteristics for the paramagnetism of the Gd
ion. In contrast, the magnetic properties of
are dominated by the crystal field effect on the Er
ion, masking the magnetic interaction between magnetic centers of neighboring molecules.
An efficient synthesis strategy of a well-defined polylactide-dye conjugate in a controlled fashion is presented. The introduction of coloring species as end groups of polylactide (PLA) has been ...performed by using new homoleptic aminophenolate magnesium or zinc coordination compounds. The molecular structure of metal complexes has been determined in solution by NMR spectroscopy, and in the solid state by X-ray analysis. Lastingly colored polymers were obtained with 2-4-(Nitrophenylazo)-
-ethylphenylaminoethanol (Disperse Red 1) and 2-4-(2-Chloro-4-nitrophenylazo)-
-ethylphenylaminoethanol (Disperse Red 13) at very high lactide conversions, based on MALDI-ToF measurement, and the macromolecules were nearly fully chain end dye-functionalized. Based on
H NMR, the DP
of conjugates was in the range of 10-300, which was consistent with the reaction setup. Various methods of gel-permeation chromatography (GPC) analysis were applied, and they demonstrated that the number-average molar mass (
) values (polystyrene (PS) standards) were a bit higher than calculated, the molar mass distribution index (Ɖ
) values were moderate to high, the TDA (triple detection array) system was inappropriate for analysis, measurements with PDA (photo diode array) detection at 470 nm gave nearly the same molar mass distributions such as the refractometer, and the relative absorbance of conjugates at 470 nm increased linearly versus (DP
)
. The presented approach connects the gap between the current strategy of obtaining colored polymer fibers and the design of tailor-made initiators with eco polyesters designed for the targeted applications.
The development and integration of bio- and chemocatalytic processes to convert renewable or biomass feedstocks into polymers is a vibrant field of research with enormous potential for environmental ...protection and the mitigation of global warming. Here, we review the biotechnological and chemical synthetic strategies for producing platform monomers from bio-based sources and transforming them into eco-polymers. We also discuss their advanced bio-application using the example of polylactide (PLA), the most valuable green polymer on the market.
Alkyl-(S,S)-O-lactyllactate was prepared by chemoselective alcoholysis of lactide LA mediated by a magnesium catalyst. When ROH reacted with LA it yielded the ring-opened product ...R-(S,S)-O-lactyllactate exclusively, which remained intact as long as LA was present in the reaction mixture. Consumption of LA caused the reaction to proceed further giving R-(S)-lactate.
This work was aimed to obtain and characterize the well-defined biocomposites based on β-tricalcium diphosphate(V) (β-TCP) co-doped with Ce
and Pr
ions modified by poly(l-lactide) (PLLA) with precise ...tailored chain length and different phosphate to polymer ratio. The composites as well as β-tricalcium diphosphate(V) were spectroscopically characterized using emission spectroscopy and luminescence kinetics. Morphological and structural properties were studied using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The self-assembled poly(l-lactide) in a shape of rose flower has been successfully polymerized on the surface of the β-tricalcium diphosphate(V) nanocrystals. The studied materials were evaluated in vitro including cytotoxicity (MTT assay) and hemolysis tests. The obtained results suggested that the studied materials may find potential application in tissue engineering.
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.
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.
The quest for
ortho
,
meta
, and
para
isomers, as a part of the enigmatic synthesis of bifunctional POSS, from theoretical and experimental standpoints, is unraveling in our paper.
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.
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