posted on 2017-10-30, 00:00authored byYan-Ping He, Lv-Bing Yuan, Guang-Hui Chen, Qi-Pu Lin, Fei Wang, Lei Zhang, Jian Zhang
We
have successfully constructed a tetrahedral Ti4L6 cage with calixarene-like coordination-active vertices. It
further features high solubility and stability in H2O and
DMF/H2O solution, affording an interesting stepwise assembly
function with other metal ions. Through trapping of different amounts
of Co or Ln ions, the Ti4L6 tetrahedra can be
organized into various dimensional architectures, including a Ti4L6-Co3 cage, a Ti4L6-Ln2 cage, a Ti4L6-Ln2 chain, and a three-dimensional Ti4L6-Ln framework.
An unusual mixed-valence phenomenon was observed in the Ti4L6 cage, whose Ti3+/4+ compositions were adequately
identified by electron spin resonance and X-ray photoelectron spectroscopy
analyses. More remarkably, the calixarene-like oxygen vertices of
the Ti4L6 cage can also be used for the recognition
of C3-symmetric dye molecules through
N–H···O hydrogen bonding. Accordingly, driven
by visible light, selective and efficient homogeneous photodecomposition
of acid blue 93 and alkali blue 4B were successfully achieved. Therefore,
this work not only represents a milestone in constructing symmetric
Ti-based cages with interesting coordination assembly function but
also provides a new method for preparing technologically important
soluble photoactive cages.