Search Results (4)

The interest in macromolecular alkoxysilyl-functionalized hybrids (self-assembling or nanostructured), which could be used as precursors in biomimetic silica precipitation and for the synthesis of hollow spherical silica particles, is growing. Nevertheless, reports on all-organosilicon systems for bioinspired silica precipitation are scarce. Therefore, a new kind of polyalkoxysilane macromonomer–linear polysilsesquioxane (LPSQ) of ladder-like backbone, functionalized in side chains with trimethoxysilyl groups (LPSQ-R-Si(OMe)₃), was designed following this approach. It was obtained by photoinitiated thiol-ene addition of 3-mercaptopropyltrimethoxysilane to the vinyl-functionalized polysilsesquioxane precursor, carried out in situ in tetraethoxysilane (TEOS). The mixture of LPSQ-R-Si(OMe)₃ and TEOS (co-monomers) was used in a sol–gel process conducted under acidic conditions (0.5 M HCl/NaCl) in the presence of Pluronic^® F-127 triblock copolymer as a template. LPSQ-R-Si(OMe)₃ played a key role for the formation of microparticles of a spherical shape that were formed under the applied conditions, while their size (as low as 3–4 µm) was controlled by the stirring rate. The hybrid materials were hydrophobic and showed good thermal and oxidative stability. Introduction of zinc acetate (Zn(OAc)₂) as an additive in the sol–gel process influenced the pH of the reaction medium, which resulted in structural reinforcement of the hybrid microparticles owing to more effective condensation of silanol groups and a relative increase of the content of SiO₂. The proposed method shows directions in designing the properties of hybrid materials and can be translated to other silicon–organic polymers and oligomers that could be used to produce hollow silica particles. The established role of various factors (macromonomer structure, pH, and stirring rate) allows for the modulation of particle morphology. Full article

This study presents a tentative synthesis of supported H-shaped and ladder-type compounds. If the ladders were not accessible, probably due to distance misfits between the reactive centers, a facile method for the synthesis of H-shaped N-alkylated aminomethyl oligobenzamides, i.e., arylopeptoids by on-resin homodimerization via the Copper(I)-Catalyzed-Alkyne-Azide-Cycloaddition (CuAAC) reaction is reported. While successful, a synthetic bottleneck was identified for further oligomer elongation due to congestion when the ligation occurs on solid support. However, this issue was effectively addressed using an elongated oligomer to conduct inter-strand cross-linking. Further CuAAC functionalization could be performed after elongation with additional alkyne groups to enhance diversity. Full article

Ladder oligomers containing calixarene skeletons in the main chain—calix[4]resorcinarene (CRA) ladder macromolecules with open chain and cyclic macromolecules with double ring-like (Noria-type) topologies—bring particular research attention as functional materials with various applications. However, there is still a remarkable lack of studies into the synthesis of fully water-soluble derivatives of these interesting macromolecules. Research on this topic would allow their bio-based research and application niche to be at least revealed. In the present study, a strategy for the synthesis of water-soluble polyglycidol-derivatized calix resorcinarene ladder oligomers with open chain and cyclic structures is introduced. A grafting from approach was used to build branched or linear polyglycidol chains from the ladder scaffolds. The novel structures were synthesized in quantitative yields and fully characterized by NMR, FTIR and UV–vis spectroscopy, gel permeation chromatography, MALDI-TOF mass spectrometry, analytical ultracentrifugation, and static light scattering to obtain the molar mass characteristics and composition. The biocompatibility and toxicity of the two polyglycidol-derivatized oligomers were investigated and the concentration dependence of the survival of three cell lines of human origin determined. The selective apoptosis effect at relatively low dissolve concentrations toward two kinds of cancerous cell lines was found. Full article

Poly-CPDTBT, as typical low-band gap copolymers, have potential applications in organic bulk heterojunction solar cells. To have a clear picture of its excited-state processes, the first task is to understand their excited states, in particular, electronic character and relevant optical absorption. Herein, the low-lying singlet excited states of Poly-CPDTBT oligomers were investigated via Algebraic Diagrammatic Construction Second Order (ADC(2)) and time-dependent density functional theory (TDDFT) method with several functionals. Six CPDTBT_N (N = 1–6) oligomers were taken as prototypes to study their excited states in detail. The results provide interesting clues to extrapolate the photophysical properties of such polymers with potential applications in photovoltaic materials. The result provided by ωB97XD functional gives good agreement with the experiment result. The vertical excitation energies of the four lowest excited states decrease almost linearly with increasing polymerization degree (N) for CPDTBT_N (N = 1–6). The transition density analysis indicates that the local excitations (LE) and the short-distance charge transfer (CT) excitations between two adjacent CPDT and BT units are dominant for low-lying excited states for short oligomers. For the long-chain oligomers (trimer to hexamer), the transition density shows a ladder (or zigzag) pattern along the diagonal blocks at the planar geometry. For long oligomers, the whole chain is involved in the transitions, and the CT excitations only exist between two adjacent CPDT and BT units. The present work provides a valuable basis for understanding the excited-state processes of Poly-CPDTBT and other conjugated polymers that conduct solar energy conversions, which has great significance for the development of new solar cells. Full article