Stereoselective Solid‐State Synthesis of Substituted Cyclobutanes Assisted by Pseudorotaxane‐like MOFs

Abstract

Regioselective photodimerization of trans-4-styrylpyridine (4-spy) derivatives is performed using pseudorotaxane-like Zn-based metal organic frameworks MOFs as templates. The formation of rctt-HT (head-to-tail) dimers is achieved by confining pairs of coordinated 4-spy derivative ligands within hexagonal windows and then irradiating them with UV light. It is also possible to achieve a photodimerization reaction where two different substituted 4-spy ligands are included in such a MOF material. The ether bond formation is employed to protect the sensitive -OH group of HO-spy and the methyl group of CH O-spy is subsequently removed after the formation of cyclobutane derivative in the CH O-spy-based MOF. Introducing substituents at the 2- or 3-position of the phenyl group of 4-spy does not significantly affect the rate of the dimerization process except in the case of the strongly electron-withdrawing nitro group where the rate is significantly decreased. These results are in striking contrast to the mixtures of photoproducts and low yields obtained by untemplated photodimerization in organic solvents.

Co (II) Boron Imidazolate Framework with Rigid Auxiliary Linkers for Stable Electrocatalytic Oxygen Evolution Reaction

“…[1][2][3][4][5][6][7][8] However, a loss of these functionalities in aqueous electrolytes (strong acid or alkali) severely limits application of MOFs in energy-related electrocatalysis. [1][2][3][4][5][6][7][8] However, a loss of these functionalities in aqueous electrolytes (strong acid or alkali) severely limits application of MOFs in energy-related electrocatalysis.…”

“…Single-crystal X-ray diffraction analysis showed that BIF-91 crystallized in P21/c space group in which each Co 2+ center adopts a CoN 4 O 2 distorted octahedral coordination geometry and is bonded by four (4) nitrogen atoms in B(im) 4 − ligands and two O atoms in ndc 2− linker (Figure 1a, and Table S1, Supporting Information). In the BIF-91 framework, the six-coordinated and five-connected center is linked with ndc 2− and B(im) 4 − ligands into a 3D porous framework ( Figure 1b). Importantly, as demonstrated in Figure 1c, there are obvious CH···π interactions between the ndc 2− linker and B(im) 4 − ligands in the channel.…”

“…In the BIF-91 framework, the six-coordinated and five-connected center is linked with ndc 2− and B(im) 4 − ligands into a 3D porous framework ( Figure 1b). Importantly, as demonstrated in Figure 1c, there are obvious CH···π interactions between the ndc 2− linker and B(im) 4 − ligands in the channel. These act to strengthen the stability of whole framework.…”

“…[13][14][15] This is because transition-metal-based MOFs readily collapse in these relative harsh environments. [1][2][3][4][5][6][7][8] However, a loss of these functionalities in aqueous electrolytes (strong acid or alkali) severely limits application of MOFs in energy-related electrocatalysis. Therefore, designing new MOFs with intrinsic stability is important for their applications in electrocatalysis field.…”

“…We report a new Co-based red-block crystal of CoB(im) 4 (ndc) 0.5 (BIF-91, im = imidazolate, ndc = 2, 6-naphthalenedicarboxylate) that was successfully synthesized by reaction of H 4 ndc with cobalt (II) acetate tetrahydrate and presynthesized KB (im) 4 ligand. Notably, the presence of bridging ndc acid ligands in the BIF-91 molecular channels decreased its porosity and increased the density of coordination bonds.…”