Nucleic acid detection method, compound and fluorescent probe

A compound having a structure represented by general formula (1A) or general formula (1B),

• where
• RA, RB, and RC each independently have a structure selected from the group consisting of formula (1C), formula (1D), formula (1E), and formula (1F) below (* representing a binding site),
• X is selected from the group consisting of O, S, and Se,
• R1, R3, R5, and R7 are each independently selected from the group consisting of —(CH2)n-, and —(CH2CH2O)n-, n being a natural number of 1 to 100, and
• R2, R4, R6, and R5 are each independently selected from the group consisting of H, —OH, methyl, an amine, a terminal alkyne, an alkene, an alkyl acid, an amine acid, sulfonate (SO3−), an aryl group, and a heterocyclic compound.

A compound comprising:

• a donor;
• and
• three acceptors bound to the donor so as to perform rotary motion with respect to the donor, wherein
• a fluorescence property of the compound changes in accordance with change in the rotary motion of each acceptor.