Porous zirconium and tin phosphonates incorporating 2,2?bipyridine as supports for palladium nanoparticles

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• 作者：Houston P. Perry^a ;   ; ^{hperry@mail.chem.tamu.edu} ; Justin Law^a ;   ; ^{walnitsuj@gmail.com} ; Jerzy Zon^b ;   ; ^{jerzy.zon@pwr.wroc.pl} ; Abraham Clearfield^a ;   ; ^{Clearfield@mail.chem.tamu.edu}
• 关键词：Zirconium phosphonate ; Tin phosphonate ; Layered materials ; Nanoparticles ; Pillaring
• 刊名：Microporous and Mesoporous Materials
• 出版年：2012
• 出版时间：1 February 2012
• 年：2012
• 卷：149
• 期：1
• 页码：172-180
• 全文大小：1952 K

文摘

We have utilized a 2,2?bipyridinediyl-5,5?bis(phosphonate) crosslinker and methylphosphonate as a ¡®spacer?unit to prepare a series of porous Zr^IV and Sn^IV phosphonates which possess covalently bound bipyridine moieties. The materials are agglomerates of 5?0 nm particles which show BET surface areas exceeding 500 m²/g. The surface area and size of the phosphonate nanoparticles have been shown to be strongly dependent on the amount of methylphosphonate spacer unit. These hybrid materials are stable to >450 ¡ãC in TGA under air. The compounds have been used to coordinate Pd^II from solution, which was then reduced to form nanoparticles within the phosphonate matrix. After reduction, the bipyridyl sites are no longer occupied by Pd^II, and are available for further coordination. The Pd⁰ nanoparticles can be made in two different size regimes: 10?5 nm by reduction in ethanol and 2? nm when reduced at elevated temperature under hydrogen. The nanoparticles are stable to 450 ¡ãC and are maintained without the use of surfactants or stabilizers. Increasing the reduction temperature has no evident effect on the final size of the nanoparticles, indicating that their growth is limited by the pore structure of the phosphonate matrix, which prevents aggregation, even at 450 ¡ãC. These materials have been explored by PXRD, TGA, TEM, SAXS, and UV¨CVis spectroscopy.