cs6b03404_si_002.cif (13 kB)
Alkyne Activation by a Porous Silver Coordination Polymer for Heterogeneous Catalysis of Carbon Dioxide Cycloaddition
dataset
posted on 2017-02-22, 21:15 authored by Zhen Zhou, Cheng He, Lu Yang, Yefei Wang, Tao Liu, Chunying DuanThe widely studied porous coordination
polymers, possessing large pores to adsorb waste carbon dioxide gas
and further transform it into valuable chemical products, have been
attracting research interest, both industrially and academically.
The active silver(I) ions endow the specific alkynophilicity to activate
CC bonds of alkyne-containing molecules via π activation.
Incorporating catalytic Ag metal sites into the porous frameworks
represents a promising approach to construct heterogeneous catalysts
that cyclize propargylic alcohols with CO2, which is highly
desirable for the environmentally benign conversion of carbon dioxide
to fine chemicals. We report the preparation of porous coordination
polymers (PCPs) with active silver sites and efficient silver–silver
bond formation by carefully modifying the coordination geometries
of the silver sites. The decentralized silver(I) chains in the porous
frameworks enable the efficient conversion of CO2 and derivatives
of acetylene to α-alkylidene cyclic carbonates in a heterogeneous
manner. X-ray structure analysis reveals two kinds of substrate molecules
positioned within the pores of the framework, which correspond to
trapping and activated modes through the multiple interactions with
the functional Ag chains. The example of tandem conversion of simple
alkynes and carbon dioxide to α-alkylidene cyclic carbonates
is also presented. The well-positioned catalytic silver(I) sites and
the crystalline properties of the frameworks facilitated the structural
analyses of the intermediates of each catalytic step, providing knowledge
of the synergistic nature of the σ and π activation of
CC bonds. The successful catalysis of azide–alkyne
cycloaddition and synthesis of propargylic alcohols via terminal alkynes
could also give another indicator for the activation properties of
Ag sites.