Herein,we report a newwet-synthesismethod to separate somewater-soluble chiral silver nanoclusterswith
high yield. The cluster materialwas obtained by the reduction of silver nitrate with NaBH4 in the presence of
three ligands L-penicillamine(L-pen), D-penicillamine (D-pen) and racemicmixture of penicillamine (rac-pen),
functioning as capping ligand. For characterizing all silver cluster samples, the particle size was assessed by
transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) and their average chemical
formula was determined from thermogravimetric analysis (TGA) and elemental analysis (EA). The particles
sizes of all three clusters are 2.1 ± 0.2 nm. The optical properties of the sampleswere studied by four different
methods: UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy
(PL) and circular dichroism (CD) spectroscopy. The spectra are dominated by the typical and intense
plasmonpeak at 486nmaccompanied by asmall shoulder at 540nm. Infraredspectroscopywasmeasured for
the free ligand and protected silver nanoclusters, where the disappearance of the S-H vibrational band (2535
e2570cm1) inthe silver nanoclusters confirmed anchoringof ligandto the cluster surface through the sulfur
atom.PL studies yieldedthefluorescentpropertiesof the samples.Themainfocus of thiswork,however, lies in
the chirality of theparticles. Forall silverclustersCDspectrawere recorded.While for clusters cappedwithone
of the two enantiomers (D- or L-form) typical CD spectrawere observed, no significant signalswere detected
for a racemic ligandmixture. Furthermore, silver clusters showquite large asymmetry factors (up to 3104)
in comparison tomost other ligand protected clusters. These large factors and bands in the visible range of the
spectrumsuggest a strong chiral induction fromthe ligand to themetal core. Textural features of the prepared
silver nanoclusters were investigated using nitrogen adsorption-desorption at 196 C. Specific surface area SBET, pore volume and average pore diameter were calculated.
ملخص البحث
قسم البحث
مجلة البحث
Materials Chemistry and Physics
المشارك في البحث
الناشر
Elsevier
تصنيف البحث
1
عدد البحث
180
موقع البحث
http://www.sciencedirect.com/science/article/pii/S025405841630431X
سنة البحث
2016
صفحات البحث
349-356