Metal–Organic Frameworks
with Phosphotungstate
Incorporated for Hydrolytic Cleavage of a DNA-Model Phosphodiester
- Publication date
- Publisher
Abstract
Five phosphotungstate-incorporated metal–organic
frameworks
{[Eu<sub>4</sub>(dpdo)<sub>9</sub>(H<sub>2</sub>O)<sub>16</sub>PW<sub>12</sub>O<sub>40</sub>]}(PW<sub>12</sub>O<sub>40</sub>)<sub>2</sub>·(dpdo)<sub>3</sub>·Cl<sub>3</sub> (<b>1</b>); {ZnNa<sub>2</sub>(μ-OH)(dpdo)<sub>4</sub>(H<sub>2</sub>O)<sub>4</sub>[PW<sub>12</sub>O<sub>40</sub>]}·3H<sub>2</sub>O (<b>2</b>); {Zn<sub>3</sub>(dpdo)<sub>7</sub>}[PW<sub>12</sub>O<sub>40</sub>]<sub>2</sub>·3H<sub>2</sub>O (3); and [Ln<sub>2</sub>H(μ-O)<sub>2</sub>(dpdo)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>][PW<sub>12</sub>O<sub>40</sub>]·3H<sub>2</sub>O (Ln = Ho for <b>4</b> and
Yb for <b>5</b>) (dpdo = 4,4′-bipyridine-<i>N</i>,<i>N</i>′-dioxide) have been synthesized through
a one-step hydrothermal reaction and characterized by elemental analyses,
infrared (IR) spectroscopy, photoluminescence, and single-crystal
X-ray diffraction (XRD). The structural analyses indicate that <b>1</b>–<b>5</b> display diversity structure from one-dimensional
(1D) to three-dimensional (3D) series of hybrids. Kinetic experiments
for the hydrolytic cleavage of DNA-model phosphodiester BNPP (bis(<i>p</i>-nitrophenyl)phosphate) were followed spectrophotometrically
for the absorbance increase at 400 nm in EPPS (4-(2-hydroxyethyl)piperazine-1-propane
sulfonic acid) buffer solution, because of the formation of <i>p</i>-nitrophenoxide with <b>1</b>–<b>5</b> under conditions of pH 4.0 and 50 °C. Ultraviolet (UV) spectroscopy
indicate that the cleavage of the phosphodiester bond proceeds with
the pseudo-first-order rate constant in the range of 10<sup>–7</sup>–10<sup>–6</sup> s<sup>–1</sup>, giving an inorganic
phosphate and <i>p</i>-nitrophenol as the final products
of hydrolysis. The results demonstrate that <b>1</b>–<b>5</b> have good catalytic activity and reusability for hydrolytic
cleavage of BNPP
