Highly Selective Recognition and Fluorescence Imaging of Adenosine Polyphosphates in Aqueous Solution

The
design and synthesis of chemosensors for the recognition of
a certain nucleoside polyphosphate among various structurally similar
nucleoside polyphosphates remain a fundamental challenge. Herein,
we report the new fluorescent chemosensor [Zn2L]­(ClO4)4 (1; L = (3,6,10,13,17,20,24,27-octaaza-1,15­(2,6)-dipyridina-8,22­(9,10)-dianthracenacyclooctacosaphane),
which can selectively recognize adenosine polyphosphates (ATP and
ADP) among various nucleoside polyphosphates, with a large fluorescence
enhancement (Fmax/F0 = 70 and 80 for ATP and ADP, respectively) and strong binding
affinity (K = 3.1 × 1011 M–1 for [Zn2HL­(H–1ATP)2]−, 2.8 × 1011 M–1 for
[Zn2L­(H–1ATP)2]2–, and 1.5 × 1013 M–1 for [Zn2L­(H–1ADP)2]2–) in aqueous solution at physiological pH 7.40. The structure of
[Zn2L]­(P2O7) (2) was
investigated, which shows that μ2-pyrophosphate anions
alternately link [Zn2L]4+ cations to generate
a 1D coordination polymer. The results of 31P NMR studies
and DFT calculations reveal that the two Zn­(II) ions in 1 can interact with ATP/ADP anions through coordination interactions
between Zn­(II) and the polyphosphate groups, and two anthracene moieties
in 1 can interact with adenine groups from two ATP or
ADP anions through stacking interactions to form a sandwichlike structure.
These multiple recognition interactions between 1 and
ATP/ADP enhance the affinity and selectivity of 1 toward
ATP/ADP. Due to its highly selective and sensitive ability to detect
adenosine polyphosphates, 1 was successfully applied
to fluorescence imaging for ATP and ADP in living cells, demonstrating
the potential utility of 1 as a fluorescent chemosensor
for detecting ATP and ADP.