Multidimensional Open-Frameworks: Combinations of One-Dimensional Channels and Two-Dimensional Layers in Novel Bi/M Oxo-Chlorides

Here we discuss the synthesis and
characterization of three novel
bismuth oxo-chlorides ([Bi6Na0.5O7.5]­[Na0.5Cl3]channel[Cl]layer; [Bi17PbO22]­[Cl6]channel[Cl3]layer; [Bi9(Pb0.2Mn0.8)­O12]­[Cl3]channel [Cl2]layer) which all show an original multidimensional
crystal structure. It is formed of two-dimensional (2D)-layered blocks
separated by Cl– layers. The blocks are porous with
triangular one-dimensional (1D)-Cl– channels with
various section sizes. This multidimensional feature is unique in
the field of Bi and Pb oxo-halides, while so far only 1D or 2D halides
units have been reported. The stability of the framework is allowed
by Bi3+/Mn+ aliovalent substitution
to balance charge neutrality. The channel and tunnel walls are formed
by edge-sharing O­(Bi,M)4 oxocentered tetrahedra, while
the triangular tunnel junctions are achieved by O­(Bi,M)5 pyramids. The three compounds are rather stable, but only [Bi6Na0.5O7.5]­[Na0.5Cl3]tunnel[Cl]layer was obtain as a single-phase
material so that its photoluminecence properties have been investigated.
It shows an unusual red bright luminescence with a maximum at 14150
cm–1 at low temperatures due to Bi3+ transitions
that are well explained by the Bi-Cl bonding scheme.