The application of cooperative heterogeneous catalysts for the promotion of C-C bond formation is of great potential for making such chemical processes more sustainable. In the design of such materials, the main challenges are to form specific catalytic sites and to control the cooperative interactions. Because of the high complexity inherent to cooperative active site interactions, much of the research is focused on so called "enzyme inspired-materials." The current Progress Report identifies three material subgroups that are characterized by a rigid-ordered backbone (layered material), a flexible backbone (polymer based), or a constrained-flexibleordered backbone (metal organic frameworks). In each of these material types, examples that illustrate how key structural and chemical characteristics functions are associated with the efficient promotion of the cooperative mechanism are highlighted. The limitations and strengths of each of the systems are considered with the aim of providing an outlook with regard to the minimum requirements needed to construct an efficient cooperative catalytic material. Given the current accumulated common knowledge in this area, it is suggested that getting inspiration from the synthetic existing systems is perhaps more beneficial than from enzymes.

High surface area and highly crystalline tetragonal Ni-Si-doped ZrO 2 samples were prepared using a nonhydrolytic sol-gel method. The synthesis involved the condensation of zirconium chloride and isopropyl ether in the presence of a chitosan-based composites containing Ni and Si (Ni@Si-CS), followed by calcination to remove the CS. The interactions between the zirconium precursor and the Ni@Si-CS composites were studied and correlated with the effect on morphologies, crystalline structure, phase compositions, and surface area. These parameters were evaluated for different Ni@Si-CS to ZrO 2 mass ratios. It was found that increasing the concentration of Ni@Si-CS composite led to smaller grains of ZrO 2 nanocrystals and an overall material with a higher surface area. The stability of the tetragonal/cubic phases following calcination at 800°C was correlated with the presence of low amounts of Ni 2+ in the sublattice of ZrO 2 and the presence of the Si-chitosan, which acted as steric stabilizer.

Multifunctional hybrid polymer‐based materials are shown to self‐organize into a patterned solid microstructure, specific enough to induce cooperative catalytic interactions between primary amine sites and grafted titanium (Ti) sites. We demonstrate this by a new procedure for the grafting of titanium sites onto the backbone of polyhydroxylated‐amine‐containing polymer (chitosan). The Ti grafting is shown to form an amorphous hybrid (Ti@CS) high surface area material (up to 130 m2 g−1), despite the strong thermodynamic tendency of CS to collapse into a compact structure held by hydrogen bonds. We find that the surface area of Ti@CS materials is stable even at 110 °C under high vacuum. Tuning of the grafting conditions and the post treatment conditions provide control over the functionalities of both the Ti sites and the primary amine sites. These can be tuned such that the nitro‐aldol condensation (Henry), used as probe reaction, is either (i) not catalyzed, (ii) catalyzed by amines promoted by Ti presence or (iii) catalyzed cooperatively by the primary amines and the Ti sites. Critical parameters related to the microstructure and chemical interactions between the organic and inorganic components are discussed in detail and cross‐referenced with catalytic results.

The main focus of the present work is on identifying the critical parameters involved in inducing acid‐base cooperative catalytic interaction in hybrid metal‐polymer materials. To makes these hybrid materials Ti or Sn acid sites are grafted to the hydroxy groups of chitosan (CS). The cooperative catalytic interactions between the Ti/Sn and the primary amine sites on CS are tested for the nitro‐aldol condensation of nitromethane with 4‐nitro‐benzaldehyde. The observed results show that the synthesis conditions have a pronounce effect on the 3D arrangement of the hybrid materials, which in turn affect the reaction activity and selectivity. The catalysts are characterized using N2‐pysisorption, XRD, FTIR, XPS and HRTEM in conjunctions with reaction kinetic analysis. Using the combined results, a reaction mechanism is proposed, which emphasizes the effect of proximity and orientation of the Lewis acid (Ti or Sn) and base (NH2) active sites on cooperative catalysis in the Henry reaction.

The work here reports a new and versatile approach for distributing metal nanoparticles within an encapsulating nonhydrolytic sol–gel metal oxide framework. The method uses a metal–chitosan composite material as a sacrificial precursor, which allows for easy expansion to a range of encapsulating metal oxides as well as different active metal specie. To demonstrate this catalyst synthesis approach, we examined the distribution of Ni particles within an encapsulating SiO2–ZrO2 support. We show that the grafting of Si-sites on the chitosan backbone, the solvent used, and the drying rate can be controlled to obtain a high surface area composite of up to 178 m2/g. The effects of the initial composite surface area, the Si content, and Ni loading in the materials, obtained following encapsulation in the zirconia gel and calcination, are examined with respect to Ni distribution in the calcined material. Using methane dry reforming as a probe reaction, it is shown that the encapsulated Ni catalysts have higher activity (XCH4 = 33%; XCO2 = 41%) as compared to the impregnated catalyst (XCH4 = 26%; XCO2 = 32%). This result was obtained despite the higher NiO distribution on the impregnated supports and demonstrates the promoting effect of the encapsulation.