Inorganic Janus nanosheets bearing two types of covalently bound organophosphonate groups via regioselective surface modification of K₄Nb₆O₁₇·3H₂O

Abstract

Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.

Preparation of water-dispersible Janus nanosheets from K4Nb6O17·3H2O and their behaviour as a two-dimensional surfactant on air–water and water-toluene interfaces

“…Here we report the preparation of K 4 Nb 6 O 17 •3H 2 O-based single-layered Janus nanosheets with one surface modified by phenylphosphonic acid and the other with phosphoric acid. These Janus nanosheets could be dispersed in water by increasing their hydrophilicity compared to the Janus nanosheets reported in our previous study, 25 which have octadecylphosphonate moiety and carboxypropylphosphonate moiety on the opposite surfaces of each nanosheet. In order to clarify their surfactant behaviour, the nanosheets' surface behaviour at the air-water interface was investigated by Scheme 1 Preparation and investigation of behaviour of PPA_PA_NS.…”

“…Furthermore, weak signals assignable to n-dodecyl chains in C 12 N + were observed at 16-41 ppm, a result indicating the presence of C 12 N + in PPA_PA_NbO. 25 Since PA has no organic moiety, sequential surface modifications can be monitored using solid-state 31 P MAS NMR. Fig.…”

“…28 It is therefore concluded that Nb-O-P bonds were additionally formed between the PA moiety and niobate layer. Based on our previous study using the same set of alkylammonium ions for preparing intermediates, 25 it can be concluded that PPA and 26 Then, the amounts of PPA and PA moieties as well as of 2C 18 2MeN + and C 12 N + alkylammonium ions at interlayers I and II in the products were estimated based on the ICP and CHN results (Table 1). It should be noted that the amounts of PPA and PA in PPA_PA_NbO are the important pieces of information for determining whether PPA_PA_NbO can be converted into "Janus" nanosheets by exfoliation.…”

“…It should be noted that stable Nb-O-P bonds are present between the niobite nanosheet surface and surface functional groups, which is very advantageous for their use as a two-dimensional surfactant. These K 4 Nb 6 O 17 •3H 2 O-based Janus nanosheets furthermore exhibit versatility in the selection of surface functional groups achieved by changing the surface modifiers, 25 O-based Janus nanosheets with appropriate hydrophilicity and hydrophobicity on opposite sides of the individual nanosheets for their stable dispersion in water can be prepared by proper selection of surface modifiers and behaves as a two-dimensional surfactant.…”

Adsorchromism: Molecular Nanoarchitectonics at 2D Nanosheets—Old Chemistry for Advanced Chromism

“…[ 5 , 6 , 7 ] Fully exfoliated and dispersed nanosheets provide adsorption sites on both sides of nanosheets a few nm apart. [ 8 ] Restacking of these hybrid complexes allows the intercalation of adsorbates in the layers, and the flexibility of these layered materials might allow the fabrication of highly designed and controlled reaction fields. Thus, the 2D interlayer area is a unique, extendable adsorption space, allowing the adsorbed molecules to change their conformation.…”