Job/Unit: O50124 /KAP1 Date: 20-04-15 15:13:00 Pages: 8 FULL PAPER DOI: 10.1002/ejoc.201500124 Synthesis of Functionalized Organoselenium Materials: Selenides and Diselenides Containing Cholesterol Tiago E. Frizon, [a,b] Jamal Rafique, [a] Sumbal Saba, [a] Ivan H. Bechtold, [c] Hugo Gallardo, [a] and Antonio L. Braga* [a] Keywords: Liquid crystals / Mesophases / Selenium / Steroids A simple and efficient procedure for the synthesis of three new series of chalcogen liquid crystals, based on selenides and diselenides, containing cholesterol in their structure, is described. Thermal and liquid crystalline properties were in- vestigated by POM, DSC, TGA and XRD scattering. Six of the nine molecules synthesized showed liquid crystal proper- ties, with smectic mesomorphism. All the compounds pre- Introduction In recent years, interest in organochalcogen compounds has been driven by their potential applications in modern organic synthesis of materials and in catalysis. [1,2] Addition- ally, diorganodiselenides, the selenium counterpart of or- ganic peroxides, play an important role in organochalcogen chemistry, because they are stable, easy to handle, and suffi- ciently reactive to produce electrophilic, nucleophilic, and radical species. [3,4] The design of new organoselenium com- pounds, along with other developments, is attracting con- siderable attention, particularly because of their ability to mimic natural compounds with important biological prop- erties, such as antioxidant, antitumor, antimicrobial, and antiviral activity. [5–8] In addition, it has been shown that the presence of different chalcogen atoms in organic com- pounds can induce changes in their photophysical proper- ties. [9,10] Moreover, the photophysical properties allied with their liquid crystalline character mean that such materials are promising for optical device applications, such as emis- sive LC displays, polarized organic lasers, and anisotropic OLEDs. However, examples of the use of selenium com- pounds as liquid crystalline materials are rare. [9] Organo [a] Department of Chemistry LabSelen, Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, Brazil E-mail: braga.antonio@ufsc.br http://ppgqmc.posgrad.ufsc.br/braga/ [b] Department of Materials Science and Engineering, Universidade do Extremo Sul Catarinense, 88806-000 Criciúma, SC, Brazil [c] Department of Physics, Federal University of Santa Catarina (UFSC), 88040-900 Florianópolis, Brazil Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/ejoc.201500124. Eur. J. Org. Chem. 0000, 0–0 © 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1 sented good thermal stability. The smectic mesomorphism was confirmed through XRD analysis. The morphology of the surface of the films was investigated by using atomic force microscopy (AFM). All prepared diselenides showed good glutathione peroxidase like activity and one of the diselen- ides was 3.3 times more active than the standard Ebselen. selenium derivatives have been studied in relation to the architecture of organic materials of technological interest; such compounds exhibit behavior that may be suitable for use in electroconductive polymers, organic semiconductors, and liquid crystals. [9–15] Despite the potentially beneficial properties of applying diorganodiselenide compounds as constituent units in organic functionalized materials, to our knowledge, only the disulfide structures have been investi- gated. [16,17] In this context, the aim of this study was to associate the remarkable properties of selenium with the structure of cholesterol, to generate an important class of biological and synthetic materials in which the molecules are macroscopi- cally arranged in a periodic helicoidal structure. [18,19] Cholesterol is a well-known natural product that appears as a building block in molecular associations. Its versatility comes from its unique structural features, which are not found in other compounds. Cholesterol is extensively incor- porated in molecular systems for a number of reasons: (i) it is commercial availability; (ii) it has a rigid structure with eight chiral centers; and (iii) the structure can be easily deri- vatized. [18–20] Derivatives of cholesterol are present in sev- eral unique aggregates, including liquid crystals, organic gels, and monolayers, making it a versatile building block in organic synthesis. [21,22] The self-assembly of cholesterol- derived compounds into thermotropic liquid crystalline (LC) phases is well known. In fact, the first observation of LC phases was reported for cholesteryl benzoates and cholesteryl acetates. [23] According to their chemical nature, cholesteric liquid crystals can be divided into: (a) steroidal, mainly cholesterol esters; (b) nonsteroidal, better known as chiral nematics; and (c) induced cholesteric systems, comprised of a nematic matrix and an optically active