STUDY OF THE MOLECULAR STRAIN OF POLYMERIZABLE CYCLIC OLIGOCARBONATES USING THE SPECTROSCOPIC TECHNIQUES
Keywords:
Cyclic oligocarbonates, spectroscopic techniques, molecular strainAbstract
Cyclic oligocarbonates, dimer, trimer and tetramer, were synthesized and purified into individual cyclic dimmer, trimer and tetramer, respectively. The UV/Vis, IR and Raman spectroscopic techniques were used to study the molecular strain of those cyclics. The UV/Vis data revealed that the λmax due to the phenyl group was shifted from 250 nm for the dimer to 280 nm for the trimer and tetramer. The λmax of the carbonyl group was also shifted from 305 to 316 nm. The extinction coefficient ratio at 254 and 280 nm, ε254/ε280, of the dimmer was also differed from the others. The results indicated the molecular ring-stained of the dimmer. IR and Raman spectroscopic data in the region of 3,700 - 2,400 cm-1, 2,200 - 1,000 cm-1, and 1,000 - 400 cm-1 of C-H stretching, carbonate linkage and =C-H bending of the cyclic dimmer that were obviously differed from the cyclic trimer and tetramer. The differences were believed to be arisen from the bond angle of the carbonate linkage and the intermolecular interaction of hydrogen on aromatic ring. The torsion angles of the aromatic ring on the isopropylidene group would be suspected as a prime contribution for the molecular strain of these cyclic species.
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