The composite of hierarchical faujasite nanosheets and zeolitic imidazolate framework-8 (Hie-FAU-ZIF-8) has been successfully prepared via a stepwise deposition of ZIF-8 on modified zeolite surfaces. Compared to the direct deposition of metal organic frameworks (MOFs) on zeolite surfaces, ZIF-8 nanospheres were selectively attached to the external surfaces of the MOF ligand-grafted FAU crystals because of the enhancing interaction between the zeolite and MOF in the composite. In addition, the degree of surface functionalization can be greatly enhanced because of the presence of hierarchical structures. This behavior leads to an increase in the deposited MOF content, improving the hydrophobic properties of the zeolite surfaces. Interestingly, the designed hierarchical composite exhibits outstanding catalytic properties as an acid-base catalyst for the aldol condensation of 5-hydroxymethylfurfural with acetone. Compared to the isolated FAU and ZIF-8, a high yield of the product, 4-[5-(hydroxymethyl)furan-2-yl]but-3-en-2-one (67%), can be observed in the composite because of the synergistic effect between the Na-stabilized zeolite framework and the imidazolate linkers bearing basic nitrogen functions. This opens up interesting perspectives for the development of new organic and inorganic hybrid materials as heterogeneous acid-base catalysts.

Typical ring-opening copolymerization (ROCOP) of cyclic anhydrides (A) and epoxides (B) catalyzed by most metal complexes underwent strict alternating monomer insertions giving (AB) n polyesters. In this contribution, a novel polyester containing (ABB) n polymer sequences was prepared via the ROCOP of cyclic anhydrides and cyclohexene oxide (CHO) using a tin­(II) alkoxide complex. Quantum calculations revealed that the preference for the (ABB) n sequence was enhanced by the energetic preference of the second CHO insertion. The copolymer with (ABB) n content as high as 70% was obtained from the ROCOP of succinic anhydride and CHO with an enhanced T g of 65 °C (>20 °C higher than the (AB) n analogue). The ROCOP of maleic anhydride and CHO also gave a copolymer with high (ABB) n content at 48% and improved T g of 89 °C (38 °C higher). The improved thermal properties were a result of the more rigid (ABB) n polymer backbone compared with conventional alternating (AB) n copolymer analogues. In addition, terpolymerization with ε-caprolactone (ε-CL) was achieved by sequential addition of ε-CL affording the block copolymer with the (ABB) n backbone.

Tin(ii) complexes suported by guanidinate ligands have been synthesized and shown to polymerize lactide and ε-caprolactone to cyclic polyesters.

Triazole-based ligands, tris (triazolyl)methanol (Htbtm), bis (triazolyl)phenylmethanol (Hbtm), and phenyl (pyridin-2-yl)(triazolyl)methanol (Hpytm), with differences in ligand denticity (i.e., bidentate and tridentate) and type of N donors (i.e., triazole and pyridine) were functionalized onto a silica support to produce the corresponding SiO 2 -L (L = tbtm, btm, pytm). Subsequent reactions with Pd (CH 3 COO) 2 in CH 2 Cl 2 yielded Pd/SiO 2 -L. ICP-MS reveals that Pd loadings are higher with increased N loadings, resulting in the following trend: Pd/SiO 2 -tbtm (0.83 mmol Pd g −1 ) > Pd/SiO 2 -btm (0.65 mmol Pd g −1 )~Pd/SiO 2 -pytm (0.63 mmol Pd g −1 ). Meanwhile, TEM images of the used Pd/SiO 2 -L catalysts after the first catalytic cycle show that the mean size of Pd NPs is highest with Pd/SiO 2 -pytm (8.5 ± 1.5 nm), followed by Pd/SiO 2 -tbtm (6.4 ± 1.6 nm) and Pd/SiO 2 -btm (4.8 ± 1.3 nm). Based on TONs, catalytic studies toward aerobic oxidation of benzyl alcohol to benzaldehyde at 60°C in EtOH showed that Pd/SiO 2 -pytm possessed the most active surface Pd(0) atoms, most likely as a result of more labile properties of the pyridine-triazole ligand compared to tris-and bis (triazolyl) analogs. ICP-MS and TEM analysis of Pd/SiO 2 -btm indicate minimal Pd leaching and similar average Pd NPs sizes after 1 st and 5 th catalytic runs, respectively, confirming that SiO 2 -btm is an efficient Pd NPs stabilizer. The Pd/SiO 2 -btm catalyst was also active toward aerobic oxidation of various benzyl alcohol derivatives in EtOH and could be reused for at least 7 reaction cycles without a significant activity loss.

No abstract