Monolayer Formation of Luminescent Germanium Nanoparticles on Silica Surface in Aqueous Buffer Solution

Abstract

The present paper reports monolayer formation of germanium nanoparticles (Ge NPs) on silica substrate. The NPs were prepared by hydride reduction of GeCl4, which is encapsulated with an inverse micelle of dimethyldioctylammonium bromide, with lithium aluminum hydride, and subsequent hydrogermylation of allylamine in the presence of platinum catalyst. The resultant NPs showed the blue photoluminescence property. Due to the terminal amine, the NPs were soluble highly in aqueous buffer solution. To fabricate a monolayer of Ge NPs, the chemical reactivity of the NPs was studied using a multi-functional microarray in which different kinds of siloxane monolayers were periodically aligned on a silica substrate. We observed using fluorescence microscope whether the terminal amines of the NPs recognize the specific monolayers in the microarray. In terms of fluorescence observation, the entire surface of the monolayer-covered microsize-domains emits uniformly the blue light. This suggests a high degree of coverage of the luminescent NPs covering over the monolayer regions in the microarray, and implies the non-occurrence of quenching through energy transfer between adjacent NPs.

Advances in Transition‐Metal‐Catalyzed Hydrogermylation of Alkenes and Alkynes†

“…Shirahata reported the hydrogermylation of germanium nanoparticles (Ge NPs) with allylamine (Scheme 3). [ 59 ] In the presence of H 2 PtCl 6 , the hydrogermylation of allylamine with hydrogen‐ terminated Ge NPs, formed from the hydride reduction of GeCl 4 with lithium aluminum hydride, gives aminoalkyl‐functionalized Ge NPs. The resulting germanium nanoparticles exhibit blue photoluminescence property and are soluble highly in aqueous buffer solution because of the existence of terminal amine.…”

“…The catalytic hydrogermylation reactions mainly include the following categories: free radical hydrogermylation initiated by photo‐ [ 32‐33 ] or thermal‐excitation, [ 34‐37 ] peroxides, [ 38‐40 ] organic boron reagents [ 41‐48 ] or others [ 49‐51 ] and transition‐metal‐catalyzed hydrogermylation. [ 9,52‐101 ] Transition‐metal‐catalyzed hydrogermylation has the potential advantages of selectivity control upon catalyst tuning.…”

“…The exploration on transition‐metal‐catalyzed hydrogermylation started quite early. Similar to the hydrosilylation reactions, the precious metals, such as Pt, [ 55‐59,82,84‐86,102‐103 ] Pd, [ 52‐54,74‐81 ] Rh, [ 61‐62,90‐94 ] Ru, [ 62,95‐98,104 ] have been found capacity of catalyzing the hydrogermylation of unsaturated carbon‐carbon bonds with good to high regio‐ and stereoselectivity. From an economic and green sustainable perspective, it is more desirable to develop new catalytic systems based on cheap and earth‐abundant metals to promote the hydrogermylation of unsaturated carbon‐carbon bonds.…”