Varied pore organization in mesostructured semiconductors based on the [SnSe4]4- anion

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Abstract
Open framework metal chalcogenide solids, with pore sizes in the nano- and mesoscale, are of potentially broad technological and fundamental interest in research areas ranging from optoelectronics to the physics of quantum confinement. Although there have been significant advances in the design and synthesis of mesostructured silicas, the construction of their non-oxidic analogues still remains a challenge. Here we describe a synthetic strategy that allows the preparation of a large class of mesoporous materials based on supramolecular assembly of tetrahedral Zintl anions [SnSe4]4- with transition metals in the presence of cetylpyridinium (CP) surfactant molecules. These mesostructured semiconducting selenide materials are of the general formulae (CP)4-2xMxSnSe4 (where 1.0 < x < 1.3; M=Mn, Fe, Co, Zn, Cd, Hg). The resulting materials are open framework chalcogenides and form mesophases with uniform pore size (with spacings between 35 and 40 A). The pore arrangement depends on the synthetic conditions and metal used, and include disordered wormhole, hexagonal and even cubic phases. All compounds are medium bandgap semiconductors (varying between 1.4 and 2.5 eV). We expect that such semiconducting porous networks could be used for optoelectronic, photosynthetic and photocatalytic applications.