abstract
The first examples of chiral microporous rare-earth silico-germanates were obtained by isomorphous substitution of Si4+ by Ge4+ in small-pore Na-3[RESi3O9]center dot 3H(2)O (RE = Y3+, Eu3+), using hydrothermal synthesis. Single-crystal X-ray diffraction and Si-29 solid-state NMR clearly demonstrate the framework insertion of Ge4+, with preference for two of the three crystallographic T4+ sites. The isomorphous Ge4+ for Si4+ substitution originates a dispersion of the RE3+ environments, resulting in multiple and broader Eu3+ emission lines. Despite these, the main photoluminescence properties of pure Si- and Ge,Si-materials are very similar. A particularly intriguing feature is the detection, in both cases, of quasi-enantiomeric domains by selective excitation at 12 K. (C) 2012 Elsevier Inc. All rights reserved.
keywords
FRAMEWORK CERIUM SILICATE; ZEOLITE-TYPE MATERIALS; LANTHANIDE SILICATES; CRYSTAL-STRUCTURE; ABSOLUTE-CONFIGURATION; HYDROTHERMAL SYNTHESIS; HIGH-TEMPERATURE; ENERGY-TRANSFER; DIMENSIONALITY; RELAXIVITY
subject category
Chemistry; Science & Technology - Other Topics; Materials Science
authors
Ananias, D; Paz, FAA; Carlos, LD; Rocha, J
our authors
Duarte Ananias
Assistant Researcher
Filipe Alexandre Almeida Paz
Principal Researcher
João Rocha
Full Professor
Luís Carlos
Full professoracknowledgements
This work was financed by FEDER, via ‘‘Programa OperacionalFactores de Competitividade – COMPETE’’, and by FCT – ‘‘Fundaçãopara a Ciência e a Tecnologia’’, PEst-C/CTM/LA0011/2011. We aregrateful to FCT for specific financial support towards the purchase of the single-crystal diffractometer and to the Portuguese National NMR Network (RNRMN), also supported with FCT funds.