Patent ID: 8648194

Claim:
A compound having a phenanthroline structure of formula (I) or a salt thereof: wherein, R 3 and R 4 are each independently a hydrogen atom, a C 1-6 alkyl group, a C 3-8 cycloalkyl group, a C 2-6 alkenyl group, a C 2-6 alkynyl group, a C 6-14 aryl group, or a C 7-20 aralkyl group; and X 1 and X 2 are each independently the following structure: wherein, m is an integer of from 1 to 6; and R 5 is a hydrogen atom, a C 1-6 alkyl group, a C 3-8 cycloalkyl group, a C 2-6 alkenyl group, a C 2-6 alkynyl group, a C 6-14 aryl group, or a C 7-20 aralkyl group.