Synthesis and Hydrolysis–Condensation Study of Water-Soluble Self-Assembled Pentacoordinate Polysilylamides

Abstract

Polysilylamides (n = 1−8) with a Si−Cl functionality containing pentacoordinate silicon in the backbone were produced in high yield by transsilylation of bis(chloromethyl)methylchlorosilane and the trimethylsilyl derivative of diketopiperazine. Pentacoordinate polysilylamides were highly soluble in water as a result of silicon water coordination (Si←OH 2 ) from hydrolysis of the Si−Cl group in each repeat unit. Interestingly, the water silicon coordination in polysilanolamides was stable toward self-condensation and found to contain pentacoordinate silicon even in water, thus avoiding siloxane (Si−O−Si) bond formation. In the gas phase the polysilanolamides underwent intramolecular stepwise hydrolysis−condensation possibly as a result of CC double-bond formation at each monomer unit, as observed by MALDI-TOF MS. Low-intensity peaks of macrocyclic polysilanolamides (n = 2−5) were also observed that contain water molecules. For a better understanding of the hydrolysis−condensation process of the polysilylamide, new model compounds of pentacoordinated silicon derivatives of pyridones were synthesized, characterized, and compared with the polysilanolamides using NMR and X-ray crystallography. X-ray analysis of the model compounds revealed insight into the silicon water coordination in each repeat unit and the mode of packing within the polymers that contain these monomer units. It is found that the partial hydrolysis of the model pentacoordinate chlorosilanes gives water-coordinated pentacoordinate silicon species that resemble an intermediate in the aqueous hydrolysis of pentacoordinate polysilylamides.

Applications of Self‐Assembled Monolayers for Perovskite Solar Cells Interface Engineering to Address Efficiency and Stability

“…They interact to the adjacent silanol forming MOSi and SiOSi covalent bonds, respectively, providing a cross‐linked network, as shown in Figure 3 a. [ 51 ] Different from silane, the carboxyl acid anchoring groups possess two binding sites, a hydroxyl group (OH) and an oxygen atom that allows mono‐ or bidentate binding with metal oxides surfaces (Figure 3c). [ 52 ] The monodentate binding is formed by condensation of anchoring OH group with metal surface hydroxyl groups to form COM bond.…”

Apicophilicity versus Hydrogen Bonding. Intramolecular Coordination and Hydrogen Bonds in N-[(Hydroxydimethylsilyl)methyl]-N,N′-propyleneurea and Its Hydrochloride. DFT and FT-IR Study and QTAIM and NBO Analysis

“…The Si–Cl bond in these compounds is very labile, allowing synthesis of a wide variety of compounds with the coordination unit SiC 3 OX (X = Hal, OAlk, OAr, OTf, 0.5O(siloxanes)). One of the most interesting and least studied reactions of these compounds is hydrolysis (Scheme ), which easily occurs even by air moisture in the absence of HCl scavengers and leads to silanol hydrochloridesa new class of compounds of pentacoordinate silicon …”

Meta Selective C–H Borylation Directed by Secondary Silicon Oxygen Interaction

“…1B, a). Notably, while various reports of O-Si weak interactions have been shown in a number of intermediates (Fig 1B, b-e), 4,57,58 there was no report of utilization of these interactions in the catalysis research. Inspired from this background reports, 4,57,58 we have proposed a hypothesis where phenol is protected with an easily removable electropositive silane group and silane protected phenol meet all the necessary criteria (having electropositive silane with attached electronegative oxygen atom) for the O-Si weak interaction with 2-pyridone moiety having amide skeleton (4).…”