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Article Dans Une Revue Journal of Cluster Science Année : 2014

Beyond the Icosahedron: The Quest for High-Nuclearity Supraicosahedral Metallaboranes

Dipak Kumar Roy
  • Fonction : Auteur
Sundargopal Ghosh

Résumé

A novel spiroborate-​based double-​stranded helicate bearing photoresponsive cis-​stilbene units in the middle (cis-​3) was successfully synthesized from the corresponding cis-​stilbene-​bound tetraphenol strand in the presence of NaBH4, whereas the tetraphenol strands with a trans-​stilbene or trans-​azobenzene unit did not form such a double-​stranded helicate. The 1H NMR and NOESY expts. revealed that cis-​3 adopted contracted (cis-​3C) and extended (cis-​3E) forms under equil. in CD3CN at 25 °C. The contracted cis-​3C that accommodated a Na+ ion in the center showed an almost reversible extension and contraction motion by removal and addn. of a Na+ ion. The cis-​to-​trans photoisomerisation of the extended cis-​3E with UV light (295 nm) further induced an extension of the helicate, producing a mixt. of cis,​trans-​3E and trans-​3E helicates at the photostationary state. However, trans-​to-​cis photoisomerisation of the trans-​mixts. using UV light (360 nm) was irreversible in this system and produced the photooxidated aldehyde species (trans-​4)​, resulting from the photo-​cleavage of the trans-​stilbene moieties of the trans-​3E.
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Dates et versions

hal-01088747 , version 1 (28-11-2014)

Identifiants

Citer

Dipak Kumar Roy, Sundargopal Ghosh, Jean-François Halet. Beyond the Icosahedron: The Quest for High-Nuclearity Supraicosahedral Metallaboranes. Journal of Cluster Science, 2014, 25 (1), pp.225-237. ⟨10.1007/s10876-013-0682-0⟩. ⟨hal-01088747⟩
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