POSS (Polyhedral Oligomeric Silsesquioxane)
Imine-POSS
Porous Silsesquioxane-Imine Frameworks (PSIF) was designed and synthesized by imine condensation approach starting from octa(3-aminopropyl)silsesquioxane cage compound (OAS-POSS) and selected multitopic aldehydes. The resulting PSIFs possess 3D micro-mesoporous structures with permanent porosity and high thermal stability. These aerogels were tested in sorption of I2 vapor. For PSIF-1a I2 uptake of 481%wt was obtained, which is the highest value reported to date. Preferential interaction of I2 with PSIFs can be attributed to the cooperative interactions of POSS cages and imine moieties in the porous framework.
Figure 1. Schematic representation of the synthesis of PSIF-1–5; bifunctional and trifunctional prolinkers used in the synthesis.
Crystal structure of imine-POSS show that the hierarchical self-organization steps of these units driven by a combination of noncovalent interactions lead to the formation of a 3D supramolecular network.
Figure 2. View of the 3D interpenetrated network in the crystal structure of 3 along the b axis. Chloroform molecules are trapped in the free space.
Figure 3. Crystal structure of 3D imine-POSS.
For more information see: ACS Appl. Mater. Interfaces 2018, 23, 19964-19973; Dalton Transactions 2016, 45, 12312-12321.
Amide-POSS
Abstract: Homosubstituted amido-functionalized polyocta-hedral oligomeric silsesquioxanes (POSS) have been synthe-sized by using acyl chlorides in high yields (ca. 95 %). The method proved to be superior over “conventional” syntheses applying carboxylic acids or acid anhydrides, which are much less efficient (ca. 60 % yield). A palette of aryl and alkyl groups has been used as side-chains. The structures of the resulting amide-POSS are supported by multinuclear 1H, 13C, 29Si NMR and FTIR spectroscopy and their full conversion into octasubstituted derivatives was confirmed using mass spectrometry. We also demonstrate that the functionalized silsesquioxanes with bulky organic side-chains attached to cubic siloxane core form spherical-like, well-separated nano-particles with a size of approximately 5 nm.
Scheme 1. Syntheses of homoocta-functionalized POSS-based hybrid materials. a) p-substituted benzoyl chloride, Et3N, DMF; b) hexanoyl chloride, Et3N, DMF.
Amide-POSS were extensively studied by TG and DTA techniques in flowing nitrogen and synthetic air atmospheres. Experiments were performed in the 30–1000 °C range and showed different behavior depending on the atmosphere. The residual masses obtained at different temperatures were analyzed using IR to get insight into the thermal degradation mechanism. Additionally, activation energies of the decomposition process using Kissinger method were calculated.
Figure 4. X-ray structure of amide-POSS. T8 type amido-POSS possess high thermal resistance.
For more information see: Journal of Organometallic Chemistry 2017, 847, 173-183. RSC Advances 2017, 7, 8394-8401. Chemistry - A European Journal 2014, 20, 15966-15974.
Amine-POSS
We present a simple approach for the synthesis of well-defined macromolecules based on precisely isolated amino-functionalized octa T8 and deca T10 silsesquioxanes (SQs). Here, we show that reorganization of the siloxane cage-like core (T8 / T10) can be easily performed, including isolation of intermediates, and cage rearrangement achieved by using Brønsted superacid, trifluoromethanesulfonic acid (CF3SO3H). Moreover, T10-like SQs can be obtained in a one-step reaction by alkoxysilane condensation in trifluoromethanesulfonic acid conditions. The resulting decamers of amine-SQ and an amido-functionalized derivative containing long alkyl chains are reported for the first time in the literature. The non-fluorinated amido derivatives due to their lamellar-like nature and specific packing can serve as transparent hydrophobic coatings in various industrial applications. The obtained compounds were fully characterized using FT-IR, UV-vis, multinuclear NMR (1H, 13C, 29Si), DOSY NMR, TG-DTA, DSC, HR-MS, TEM, EDS and elemental analysis.
Scheme 2. Synthesis of [OAS-POSS-NH3]X.
Scheme 3. Reaction of OAS-POSS-Cl with CF3SO3H in DMSO.
For more information see: RSC Advances 2016, 6, 66037-66047,RSC Advances 2015, 5, 72340-72351. Chemistry - A European Journal 2014, 20, 15966-15974.