Synthesis of some selenacrown ethers and the thermodynamic origin of their complexation with C60

• Main Authors: Liu, Yu, Han, Jian Rong, Zhao, Yanli, Zhang, Heng Yi, Duan, Zhong Yu
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Biological sciences::Biochemistry
• Online Access: https://hdl.handle.net/10356/90776; http://hdl.handle.net/10220/7138
• Institution: Nanyang Technological University

Two new selenacrown ethers, i.e., N,N'-dimethyl-1,11-diaza-4,8,14,18,-tetraselenacycloicosane (1) and 7,11- diseleno-2,3,15,16,-dibenzo-1,4,14,17,20,23-hexaoxacyclopentacosane (2), have been synthesized and characterized by elemental analysis and UV, and 1H-NMR spectroscopy. An X-ray crystallographic structure was obtained for 1. UV-spectrophotometric titrations have been performed in CCl4 solution at 25–50 °C to obtain the complex stability constants (Ks) and the thermodynamic parameters (ΔH° and TΔS°) for the stoichiometric 1:1 complexation of [60]-fullerene (C60) with the crown ethers 1–4. The obtained Ks values together with that reported for dicyclohexano-24-crown-8 (5) reveal that, the more the heteroatom numbers in crown ether ring are, and the larger the cavity sizes of crown ethers are, the higher the Ks values for complexation with C60 are. Thermodynamically, the complexation of C60 with 1–5 is absolutely enthalpy-driven in CCl4, while the complex stability is governed by the entropy term.