Cluster and Non-Cluster Based Open Framework Indium Chalcogenides

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Cluster and Non-Cluster Based Open Framework Indium Chalcogenides Pingyun Feng*, Cheng Wang, Xianhui Bu1, Nanfeng Zheng and Yuqi Li Department of Chemistry, University of California Riverside, California 92521, USA 1 Department of Chemistry, University of California Santa Barbara, California 93106, USA ABSTRACT Hydrothermal syntheses and structural characterizations of some new open framework chalcogenides are described here. Open framework sulfides are often formed with supertetrahedral clusters as the basic structural building units, but it is demonstrated here that non-cluster based open framework sulfides can also be prepared. Selenides and tellurides have a stronger tendency to form non-cluster based materials. In some cases, it is possible to make materials in which the inorganic framework consists of at least two chalcogen atoms. Such a compositional diversity makes it feasible to tune structural, electronic, and optical properties. INTRODUCTION Since their discovery in 1989 by Bedard et. al., chalcogenide open framework materials have generated a lot of interest [1]. These host-guest materials could have applications as porous solids similar to zeolites. In addition, because of their semiconducting properties, they may find applications in areas where their inorganic counterparts are currently being used (e.g., photo- or electro-luminescence, and photovoltaics). Thus far, a significant progress has been made in sulfides. The original motivation was to make zeolite-like microporous materials by replacing oxygen sites with sulfur atoms. The exploration of open framework sulfides started with the synthesis of Ge and Sn sulfides, in part because Ge and Sn are in the same group as Si that is a key element in zeolite frameworks. Subsequently, novel sulfides incorporating Sb or In were also synthesized [2, 3]. Some sulfides consist of large cages comparable to or even larger than those found in zeolites [4, 5]. We have two different objectives. One is to develop open framework chalcogenides with more complex chemical compositions such as those with more than one metallic element. Initially, we focus on ternary systems in which two metal cations with different oxidation numbers are incorporated into the same material. We expect that by controlling the local and overall charge distribution, we would be able to generate novel clusters and their covalent or non-covalent superlattices. We seek to develop an ability to control the cluster size and the interaction or linkage modes among clusters. Another objective is to extend open-framework materials from sulfides to heavy chalcogenides (i.e., selenides and tellurides). In comparison with sulfides, very few threedimensional open framework selenides are known [6]. To our knowledge, no three-dimensional tellurides directed by organic guest molecules are known prior to our work. The development of heavy chalcogenides such as selenides and tellurides is desirable because in addition to their possible use as unique porous materials, their compositional variations allow the el

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