A new supramolecular complex (Ru(Zn
2L
4)
3) was designed and synthesized as a luminescencesensor for inositol 1,4,5-triphosphate (IP
3), which is one of the important second messengers in intracellularsignal transduction, and its achiral model compound,
cis,
cis-1,3,5-cyclohexanetriol triphosphate (CTP
3),by a ruthenium(II)-templated assembly of three molecules of a bis(Zn
2+-cyclen) complex having a 2,2-bipyridyl linker (Zn
2L
4). Single-crystal X-ray diffraction analysis of a racemic mixture of Ru(Zn
2L
4)
3 showedthat three of the six Zn
2+-cyclen units are orientated to face the opposite side of the molecule with threeapical ligands (Zn
2+-bound HO
-) of each of the three Zn
2+ located on the same face.
1H NMR and UVtitrations of Ru(Zn
2L
4)
3 with CTP
3 indicated that Ru(Zn
2L
4)
3 forms a 1:2 complex with CTP
3, (Ru(Zn
2L
4)
3)-((CTP
3)
6-)
2, in aqueous solution at neutral pH. In the absence of guest molecules, Ru(Zn
2L
4)
3 (10
M) hasan emission maximum at 610 nm at pH 7.4 (10 mM HEPES with
I = 0.1 (NaNO
3)) and 25
C (excitationat 300 nm). An addition of 2 equiv of CTP
3 induced a 4.2-fold enhancement in the emission of Ru(Zn
2L
4)
3at 584 nm. In this article, we describe that Ru(Zn
2L
4)
3 is the first chemical sensor that directly responds toCTP
3 and IP
3 and discriminates these triphosphates from monophosphates and diphosphates. Thephotodecomposition of Ru(Zn
2L
4)
3, which is inhibited upon complexation with CTP
3, and the stereoselectivecomplexation of chiral IP
3 by Ru(Zn
2L
4)
3 are also described.