34692-88-1Relevant academic research and scientific papers
Hydrogen bonded helices: Synthesis, crystal structure and self-assembled microtubes
Mosae Selvakumar,Suresh,Subramanian
, p. 72 - 78 (2009)
Dicarboxylic bola-shaped compounds 1-3, possessing phthalyl head groups and diol spacers are synthesized and characterized. Keeping phthalyl head group common for all three diester-dicarboxylic acids, the spacer moiety is systematically altered by two and four carbon atoms in 1 and 2, 3, respectively. The flexible spacer moiety ethane-1,2-diol in compound 1 is replaced by cis-but-2-ene-1,4-diol and 1,4-butane diol in 2 and 3, respectively, to study the effect on the morphology of the microcrystal grown on them. Thus compound 2 and 3 though posses four carbon atoms in their respective spacer moiety, they differ by their rigidity. The single crystal X-ray structure obtained for 1, 2 and 3 indicates the formation of self-assembled single stranded helical structure mediated through O-H...O interaction of the end carboxylic acids. Interestingly compound 1 self-assembled into microtubes in ethanol:water solvent mixture. The solvent and the O-H...O; C-H...O interaction combinedly play crucial role in molecular self-assembly process and defines the morphology for 1 into "microtube" whereas 2 and 3 forming "bar" fails to produce such tubular texture though their respective crystal structure shows single stranded helices. The role of weak C-H...O interaction, incorporation of rigid spacer and various other factors such as polarity of the solvents are discussed in detail to explore the difference in the morphology.
