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Title:	Synthesis, crystal structures and biological activities of some new calix[4]resorcinarenes
Authors:	Hamza Milad Ahmed Abosadiya (P59487)
Supervisor:	Bohari M. Yamin, Prof. Dr.
Keywords:	Calix[4]resorcinarenes Synthesis Crystal Spectroscopic techniques Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	28-Dec-2015
Description:	Twenty new calix[4]resorcinarenes have been synthesized and characterized by CHNS microelemental analysis, FT-IR and Nuclear Magnetic Resonances (NMR) spectroscopic techniques. FT-IR spectra of all synthesized compounds are quite similar showing the stretching frequencies of ν(O-H) as broad peaks in the range of 3306-3480 cm-1, while the stretching frequencies of aromatic functional group C=C were observed in the range of 1421-1479 cm-1. 1H-NMR spectra of the synthesized calix[4]resorcinarenes show a clean two sets of phenolic protons belong to the resorcinarene rings in the range of 7.19-9.04 ppm indicating nonequivalent due to the orientation of the two adjacent phenolic rings and lead to the adoption of chair conformation. In addition, the methine linkage protons also appeared at two different chemical shifts in the range of 4.53-6.44 ppm. Similarly, the 13C-NMR spectra of the synthesized compounds showed two sets of phenolic carbon chemical shifts in the range of 139.5-156.9 ppm, while the four tertiary methine carbons appeared as a singlet peak in the range of 36.0-44.1 ppm. X-ray crystallographic study indicate all the calix molecules adopted the chair X-ray crystallographic studies indicate all the calix molecules adopt chair conformation (C2h) except C-3,4,5-trimethoxyphenyl calix[4]-2-methylresorcinarene dimethylformamide solvate and C-2-sulfophenyl calix[4]resorcinarene which preferred diamond-Cs and boat-C2v symmetrical conformation, respectively. The host-guest interactions are clearly existing in the crystal structures by O–H…..O and C–H…..O supramolecular interaction involving the oxygen and hydrogen atoms of the phenolic host molecules with the solvent guests. The flexibility of the conformers, formation and number of hydrogen bonds between the calix and solvent molecules are strongly influence the stability of the calix molecules. On the other hand the presence of many solvent molecules could pose a problem in locating the hydrogen atoms and disordered behavior in chemical crystallography studies even with data collected at low temperatures. The strong interaction between the solvent and the host calix is also shown by thermogram (TGA) where the solvent molecule is released at about 400 °C. The antioxidant screening by DPPH method showed the calix[4]resorcinarenes have good antioxidant property with radical scavenging ability of about 67-85%. The calix[4]resorcinarenes exhibit weak antibacterial against gram-positive bacteria only but possess strong antiviral against HSV-1. The cytotoxicity testing on vero cells showed that the compounds are non-toxic with a CC50 of more than 0.4 mg/mL.,Certification of Master's/Doctoral Thesis" is not available
Pages:	239
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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