Bottom-Up De Novo Synthesis of Porous Organic Polymers with Enone Functionalities as Supports for Pd and Cu Nanoparticles for Catalytic Tandem Synthesis

Abstract

Two porous organic polymers (POPs), namely, ANT and NAP based on N,N,N′,N′-tetrakis(4-acetylphenyl)anthracene-9,10-diamine and N,N,N′,N′-tetrakis(4acetylphenyl)naphthalene-1,4-diamine, respectively, as core scaffolds and enone functionalities as the connecting backbones, were synthesized using an aldol condensation reaction. The enone backbones of the POPs mimic α,β-unsaturated ketone functionalities of dibenzylideneacetone (dba), which is frequently employed to stabilize Pd(0), e.g., Pd 2 (dba) 3 , for effective utilization in the catalysis of a myriad of organic transformations. We have thus leveraged the chalcone motifs inherent to ANT and NAP for stabilization of Pd(0) or Cu(0) nanoparticles (NPs) to provide access to POPs embedded with Pd(0) and Cu(0) nanoparticles, i.e., Pd@ANT, Pd@NAP, Cu@ANT, and Cu@NAP. Pd@POPs are shown to be applicable to facile synthesis of therapeutically useful N-arenesulfonylindoles and 2-arylbenzofurans by tandem Songashira coupling−cyclization reactions in a recyclable manner without any perceptible loss of their catalytic efficiency for up to 15 catalytic cycles. In a similar manner, Cu@POPs are shown to serve for expedient synthesis of (i) 1-aryl-1H-indazoles by tandem imine formation− Ullmann coupling, and (ii) unsymmetrical diaryl selenides by tandem activation of diphenyl diselenide−coupling with arylboronic acids in a recyclable fashion for up to eight catalytic cycles. The results thus attest to the fact that mechanisms that allow stabilization of nanoparticles can be built into the design of building blocks to develop, in a bottom-up fashion, robust POPs as supports, which obviate leaching issues and permit recyclability by precluding any loss in the catalytic efficacy of the catalysts. Furthermore, it is shown that POPs exhibit selective adsorption of clean and green fuel, namely, hydrogen gas over nitrogen, with a very high selectivity factor.

Metal‐Ion/Metal Nanoparticle‐Anchored Porous Organic Polymers as Efficient Catalysts for Organic Transformations – A Recent Overview

“…Tandem reaction catalyzed by Cu and Pd based POPs. [54] the heterogeneous catalyst development. This understanding not only helps in the improvement of catalyst performance but also indicates the role of other physical parameters such as porosity, surface area, surface wettability, etc.…”

“…Tandem reactions Yadav et al reported the use of enone functionalities in POP as support for metal nanoparticles (Pd, and Cu). [54] Two different porous organic polymers were synthesized via aldol condensation between an aromatic tetraketone and aromatic dialdehyde, as a result, α,β-unsaturated enone functionalities were produced. These enone functionalities were used to stabilize metal nanoparticles (Pd, and Cu) named Pd@ANT, Pd@NAP, Cu@ANT, and Cu@NAP.…”

Ionic Porous Organic Polymer as a Visible-Light Photocatalyst: Efficient Heterogeneous Oxidation of Arylmethylene Compounds and Alcohols Using Molecular Oxygen

“…In our ongoing research focused on the development of metal–organic frameworks (MOFs) , and POPs , by bottom-up de novo design of building blocks, we have demonstrated the development of POPs as heterogeneous recyclable catalysts for organic transformations. In our recent work, we showed that dialkyl bipyridine-based ionic POPs (IPOPs) can be exploited for Michael additions and condensation reactions; dialkyl salts of 4,4′-bipyridines are commonly known as viologens (paraquats) and serve as effective electron acceptors in photoinduced electron transfer reactions .…”

Porous Organic Polymer with Free Carboxylic Acids (Carboxy‐POP) for Heterogeneous Catalytic One‐Pot Synthesis of Xanthenes and Acridines

“…[23][24][25][26] In general, the performances of catalytic materials are controlled by the kind of support employed, the porous structure and physiochemical properties. In our continuing investigations on porous MOFs [27][28][29][30][31] and POPs, [32][33][34] we specifically sought to explore the catalytic performances of POPs endowed with carboxy functionalities. Herein, we report the synthesis of a carboxy-functionalized porous organic polymer, that is, Carboxy-POP, by Friedel-Crafts polyalkylation followed by hydrolysis, and its application for facile catalytic synthesis of biologically-active xanthenes and acridine derivatives.…”