Provided is a ligand capable of stably bonding together interfaces composed of different types of nanoparticles, different bulk interfaces, or an interface composed of nanoparticles and a bulk interface. A tetraphenylporphyrin derivative represented by the following formula (I):; wherein in formula (I), R1, R2, R3, and R4 are each independently one substituent selected from the group consisting of the following formulas (II) to (VII); and X and Y are any substituents that are different from each other:;
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