18.5
Chalcogenides, Halides, Nitrides and Oxides
18.5.1
Sulfides and Selenides
The known classes of open-framework materials are overwhelmingly dominated by
oxide or mixed oxide/fluoride matrices. In 1989, however, Bedard and co-workers
of UOP [96] proposed to extend this class of materials to metal sulfide compounds.
Metals exhibiting tetrahedral coordination in sulfides were considered first in order
to imitate the crystal chemistry of the zeolites and nanoporous aluminophosphates. In the original paper, only germanium (IV) and tin (IV) sulfides were described, but the preparation of antimony (III) [97] and indium (III) [98] sulfides
was subsequently reported by Parise. These compounds are obtained under hydrothermal conditions in a similar way to zeolites and other derivatives. The reaction is carried out with a mixture of metal sulfide (or metal þ sulfur) and an amine
or quatenary alkylammonium species that is heated at temperatures from 25 to
18
C for several days. In some preparations, the organic template is used in the
carbonate or hydrogenosulfide (HS
À ) form, rather than the hydroxide; this appears
to give rise to a mineralizer effect. By changing the nature of the organic species,
new open-frameworks have been isolated and different configurations of building
units have been observed, depending on the elements.
The reaction of germanium sulfide with organic amines frequently leads to the
formation of amine germanium sulfides containing clusters of [Ge 4 S 10 ]
4À which
may be found isolated or in low-dimensional compounds such as DPA-GS-8 [99].
This kind of tetrameric unit is quite common in germanium sulfide chemistry and
is related to the structure of adamantane. The four germanium atoms are tetrahedrally coordinated by sulfur atoms and are connected by corner-sharing. This unit
can be viewed as a tetrahedron in which germanium occupies each corner and is
reminiscent of the tetrahedral units [SiO 4 ]
4À observed in silicates. The production
of three-dimensional networks is carried out by using an additional metal that furnishes the connection between the Ge 4 S 10 adamantine units. The utilization of
several metals, including Mn, Fe, Co, Ni, Cu, Zn, and Ga [96, 100], has been reported. Yaghi and co-workers [101] have proposed an alternative route for the synthesis of these sulfides. They can crystallize from the diffusion of an aqueous solution containing the 3d metal into a solution of a Ge 4 S 10 [amine] complex at room
temperature. In the case of copper(I), for example, the Ge 4 S 10 tetrahedral clusters
are bridged by the Cu(I) cations which can be in linear 2-fold coordination (CuS 2 )
or trigonal planar 3-fold coordination (CuS 3 ).
Little is known about the properties and potential applications of the openframework chalcogenides, though Jiang et al. [102, 103] have recently described the
adsorption and spectroscopic properties of some of the layered tin sulfides belonging to this family of materials.
18 Nanoporous Materials
606
Chalcogenides, Halides, Nitrides and Oxides
18.5.1
Sulfides and Selenides
The known classes of open-framework materials are overwhelmingly dominated by
oxide or mixed oxide/fluoride matrices. In 1989, however, Bedard and co-workers
of UOP [96] proposed to extend this class of materials to metal sulfide compounds.
Metals exhibiting tetrahedral coordination in sulfides were considered first in order
to imitate the crystal chemistry of the zeolites and nanoporous aluminophosphates. In the original paper, only germanium (IV) and tin (IV) sulfides were described, but the preparation of antimony (III) [97] and indium (III) [98] sulfides
was subsequently reported by Parise. These compounds are obtained under hydrothermal conditions in a similar way to zeolites and other derivatives. The reaction is carried out with a mixture of metal sulfide (or metal þ sulfur) and an amine
or quatenary alkylammonium species that is heated at temperatures from 25 to
18
C for several days. In some preparations, the organic template is used in the
carbonate or hydrogenosulfide (HS
À ) form, rather than the hydroxide; this appears
to give rise to a mineralizer effect. By changing the nature of the organic species,
new open-frameworks have been isolated and different configurations of building
units have been observed, depending on the elements.
The reaction of germanium sulfide with organic amines frequently leads to the
formation of amine germanium sulfides containing clusters of [Ge 4 S 10 ]
4À which
may be found isolated or in low-dimensional compounds such as DPA-GS-8 [99].
This kind of tetrameric unit is quite common in germanium sulfide chemistry and
is related to the structure of adamantane. The four germanium atoms are tetrahedrally coordinated by sulfur atoms and are connected by corner-sharing. This unit
can be viewed as a tetrahedron in which germanium occupies each corner and is
reminiscent of the tetrahedral units [SiO 4 ]
4À observed in silicates. The production
of three-dimensional networks is carried out by using an additional metal that furnishes the connection between the Ge 4 S 10 adamantine units. The utilization of
several metals, including Mn, Fe, Co, Ni, Cu, Zn, and Ga [96, 100], has been reported. Yaghi and co-workers [101] have proposed an alternative route for the synthesis of these sulfides. They can crystallize from the diffusion of an aqueous solution containing the 3d metal into a solution of a Ge 4 S 10 [amine] complex at room
temperature. In the case of copper(I), for example, the Ge 4 S 10 tetrahedral clusters
are bridged by the Cu(I) cations which can be in linear 2-fold coordination (CuS 2 )
or trigonal planar 3-fold coordination (CuS 3 ).
Little is known about the properties and potential applications of the openframework chalcogenides, though Jiang et al. [102, 103] have recently described the
adsorption and spectroscopic properties of some of the layered tin sulfides belonging to this family of materials.
18 Nanoporous Materials
606