Alkyne Activation by a Porous Silver Coordination Polymer for Heterogeneous Catalysis of Carbon Dioxide Cycloaddition

Abstract

The 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 CC 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 CC 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.

A mineralogically-inspired silver–bismuth hybrid material: an efficient heterogeneous catalyst for the direct synthesis of nitriles from terminal alkynes

“…Very recently, Duan and co-workers reported a pioneering methodology for the heterogeneous catalytic activation of internal alkynes by introducing a porous silver coordination polymer for the cyclization of propargylic alcohols with CO 2 . 19 Because of their incredible versatility, aromatic and aliphatic nitriles are of outstanding importance in fine chemical, pharmaceutical and natural product syntheses. Organic nitriles are essential precursors for amines, amides, aldehydes and various carboxylic acid derivatives, 20 and they are particularly important as intermediates for the production of valuable heterocycles.…”

Salts and Co-Crystalline Assemblies of Tetra(4-Pyridyl)Ethylene with Di-Carboxylic Acids

“…This general property of tetraarylethylenes coupled with a geometrically appealing molecular structure has resulted in studies examining the utility of tetraarylethylene derivatives in solution phase and solid state supramolecular assembly processes, often with the aim of capitalizing on enhanced luminescence to deliver new optical or sensing materials [19,20]. Indeed, several crystalline luminescent metal organic frameworks (MOFs) have been prepared using the symmetrical tetraphenylethylene carboxylic acid (2) as well as the extended biphenylethylene analogue (3) as rigid metal ligating components [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Additionally, we have investigated the electrooptical properties of crystalline organic assemblies constructed from phenoxyacetic acid (4) and bis(pyridine) derivatives [36].…”

Synthesis and crystal structure of a 6-chloronicotinate salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4′-bipyridine

“…Functional coordination polymers have attracted great interest in recent years, mostly due to their aesthetics and many interesting properties such as catalytic, magnetic and luminescent, potential for use in gas storage and separation, molecular sensing (Mueller et al, 2006;Bosch et al, 2017;Zhang et al, 2015;Zeng et al, 2014Zeng et al, , 2016Douvali et al, 2015;Xu et al, 2017;Zhou et al, 2017). The organic ligands, used as building blocks in the construction of coordination polymers, need to be multifunctional, which is evident from the position, coordination ability and steric hindrance of their donor atoms and/or groups.…”