Two 3D-hybrid monolithic
catalysts containing immobilized copper
and palladium species on a silica support were synthesized by 3D printing
and a subsequent surface functionalization protocol. The resulting
3D monoliths provided a structure with pore sizes around 300 μm,
high mechanical strength, and easy catalyst recyclability. The devices
were designed to perform heterogeneous multicatalytic multicomponent
reactions (MMCRs) based on a copper alkyne–azide cycloaddition
(CuAAC) + palladium catalyzed cross-coupling (PCCC) strategy, which
allowed the rapid assembly of variously substituted 1,2,3-triazoles
using a mixture of tBuOH/H2O as solvent. The reusable multicatalytic
system developed in this work is an example of a practical miniaturized
and compartmental heterogeneous 3D-printed metal catalyst to perform
MMCRs for solution chemistry.
For this work, an integrated system composed of a polypropylene reactor and a palladium on silica monolithic catalyst was designed and manufactured by 3D‐printing. These devices are able to perform solution phase chemistry in a robotic orbital shaker. The capped reactor was obtained in its entirety by 3D‐printing, using polypropylene and fused deposition modeling. The monolithic catalyst was also obtained by 3D‐printing ‐robocasting‐ of a silica support, sintering and subsequent palladium deposition through the wet impregnation method. The catalytic efficiency in Sonogashira or Suzuki reactions as well as the recyclability of the entire system – catalyst+reactor – were studied. The strong electrostatic adsorption (SEA) of the palladium on sintered silica and the reduced mechanical stress produced by the convenient adjustment of the catalyst into the polypropylene reactor makes the catalytic system reusable without significant loss of catalytic activity.
A tricatalytic compartmentalized system that immobilizes metallic species to perform one-pot sequential functionalization is described: a three-dimensional (3D)-printed palladium monolith, ferritic copper(I) magnetic nanoparticles, and a 3D-printed polypropylene capsule-containing copper(II) loaded onto polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene (PS-TBD) allowed the rapid synthesis of diverse substituted 1-([1,1′-biphenyl]-4-yl)-1H-1,2,3-triazoles. The procedure is based on the Chan−Lam azidation/copper alkyne−azide cycloaddition/Suzuki reaction strategy in the solution phase. This catalytic system enabled the efficient assembly of the final compounds in high yields without the need for special additives or intermediate isolation. The monolithic catalyst-containing immobilized palladium species was synthesized by surface chemical modification of a 3D-printed silica monolith using a soluble polyimide resin as a key reagent, thus creating an extremely robust composite. All three immobilized catalysts described here were easily recovered and reused in numerous cycles. This work exemplifies the role of 3D printing in the design and manufacture of devices for compartmented multicatalytic systems to carry out complex one-pot transformations.
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