International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2572

Full Length Research Paper

Synthesis and phase transitions studies on Schiff base symmetrical dimers: α,ω-Bis(4-pyridine-3-methyleneaminoxy)alkanes

Sie-Tiong Ha1*, Lay-Khoon Ong2, Guan-Yeow Yeap3, Siew-Ling Lee4, S. Sreehari Sastry5 and Masato M. Ito6
  1Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jln Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia. 2Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jln Genting Klang, Setapak, 53300 Kuala Lumpur, Malaysia. 3Liquid Crystal Research Laboratory, School of Chemical Science, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia. 4Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia. 5Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar-522 510, India. 6Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan.
Email: [email protected] or [email protected]

  •  Accepted: 27 February 2012
  •  Published: 30 April 2012

Abstract

 

A series of symmetrical dimers bearing heterocyclic ring, α,ω-bis(4-pyridine-3-methylideneaminoxy)alkanes, were prepared and all the members are differed by the spacer length, CnH2n, where n = 6, 8, 10 and 12. Their transition temperatures and mesophase characteristics were studied by differential scanning calorimetry and optical polarizing microscopy techniques. DSC thermograms exhibited direct isotropization and recrystallization during heating and cooling cycles, respectively. The crystal phase texture changed to dark region isotropic without displaying any mesophase. The influence of molecular structure on the mesomorphic properties of symmetrical dimers was studied.

 

Key words: Schiff base, dimer, pyridine, phase transition, synthesis.