A surface organic modification strategy is utilized to design and prepare a series of superhydrophobic SiO2-based nanocomposites with cobalt ions in the bulk phase and different organic groups on the surface. Physical properties such as BET surface area, surface hydrophilicity/hydrophobicity, and water adsorption amount changed significantly with the introduction of organic groups of various chain lengths, which was confirmed by TEM, SEM, FTIR, 29Si-NMR, N2 adsorption–desorption, sessile water contact angle, and TG-DTA measurements. Surface hydrophilicity/hydrophobicity altered from hydrophilic to superhydrophobic with an increase in carbon chain length, which showed an obvious effect on the catalytic performance in selective oxidation of hydrocarbons such as ethylbenzene. Superhydrophobicity was guaranteed for high catalytic activity, and the carbon chain length of the organic group was also an important factor. Superhydrophobic Pr–Co–SiO2 that contained the propyl group was the most efficient catalyst, and the conversion of ethylbenzene reached 70.4% with O2 as an oxidant under solvent-free conditions at 393 K for 7 h, which is nearly nine times that of the hydrophilic Co–SiO2 without surface organic modification.
Graphical Five single-side organically decorated Anderson-type molybdoaluminate compounds with R = CH 2 OH, NH 2 , CH 2 CH 3 , NHCH 2 COOH and CH 2 OCH 2 C(CH 2 OH) 3 have been synthesized through one-step and / or controlled reactions. The strategy utilized represents a common approach for the asymmetric modification of Anderson-type molybdoaluminates. Five single-side organic decorated Anderson-type molybdoaluminates have been synthesized from the reaction of the Na 3 (H 2 O) 6 [Al(OH) 6 Mo 6 O 18 ] · 2H 2 O cluster and RC(CH 2 OH) 3 ligands [R = CH 2 OH, NH 2 , CH 2 CH 3 , NHCH 2 COOH, CH 2 OCH 2 C(CH 2 OH) 3 ], followed by the addition of TBA · Br {TBA = [N(C 4 H 9 ) 4 ] + }. The prepared compounds possess an identical Anderson-type structural frame in each case, wherein three of the six hydroxy groups surrounding the Al III heteroatom are substituted by one RC(CH 2 OH) 3 group, forming asymmetric single-sided organically decorated clusters. The compounds demonstrate the simplest synthesis of covalent organic decoration for the single-sides of molybdoaluminates. All the prepared compounds in the present study were synthesized in aqueous solution and characterized by elemental and TG analysis, IR and 1 H NMR spectroscopy, and single-crystal X-ray diffraction analysis. In addition, the supramolecular structures of these compounds based on the hydrogen bonding have also been discussed. The method reported here provides a common approach for the asymmetric functionalization of Anderson-type molybdoaluminates.
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