Empirical conformational energy calculations were performed on helical poly(2,3-quinoxaline)s to predict stable conformations. Two energy minimum conformations were found by varying the dihedral angle ( ) between two adjacent quinoxaline units from 5 to 180®. Circular dichroism (CD) spectra were calculated for the two stable conformations ( = 45 and 135°) on the basis of exciton theory. The experimental CD spectrum of (+)-poly(2,3-quinoxaline) was in accord with the theoretical spectrum for a right-handed helical conformation with a dihedral angle of 135®.

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SUMMARY: Oligomerization of e-caprolactone and d-valerolactone was performed by use of SmMe-(C 5 Me 5 ) 2 (THF) 2 initiator, and the 26-mer, 28-mer and 30-mer of e-caprolactone were isolated in pure form by preparative SFC. The MALDI-TOF mass spectrum of the 28-mer indicates that the parent peak (3 256.1) emerges as 28-mer + 2Na -H (3 256.9). The ESI mass spectrum of the 28-mer indicates that the molecular weight (3 211.7) is consistent with the calculated value (3 211.9). In a similar manner, the 19-, 25-and 32-mers of d-valerolactone were isolated. The MALDI-TOF mass spectrum of the 19-mer indicates that the parent peaks (1 896.6 and 1 879.9) emerge as 19-mer + Na + K + MeOH -1-hexanol-5-one (1 896.3) and 19-mer + 2Na + MeOH -1-hexanol-5-one (1 880.2). Glass transition and melting temperatures (T g and T m ) of oligo-e-caprolactones and oligo-d-valerolactones increase with increasing degree of polymerization.

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