prov:value
| - The heterocyclic group represented by R11, R12, R13, R14, R21, R22, R23 and R24 is a monovalent group resulting from excluding one hydrogen atom from a substituted or unsubstituted 5- or 6-membered aromatic or nonaromatic heterocyclic compound having from 2 to 20, preferably from 2 to 10, more preferably from 3 to 8 carbon atoms and examples thereof include a 2-furyl group, a 2-thienyl group, a 2-
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