Synthesis and characterization of 3,3-dihydroxy-[1,1':4',1-terphenyl]-4,4- dicarboxylic acid derivatives as precursors for functionalized Co-MOF-74-III materials

[摘要] English: A series of new 4,4-di[methoxyethoxymethoxy]-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl]derivatives were synthesised as possible linkers for MOF-74-IIIderivatives. The following products were synthesised via Suzuki-Miyuara cross-coupling andcharacterized by a combination of FTIR and 1H NMR spectroscopy as well as MS spectrometry:4,4-di[methoxyethoxymethoxy]-2',5'-dimethyl-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl],(90 %); 4,4-di[methoxyethoxymethoxy]-2',5'-dihydroxy-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl], (90 %); 4,4-di[methoxyethoxymethoxy]-2',5'-bis-benzyloxy-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl],(60 %) and 4,4-di[methoxyethoxymethoxy]- 3'-[3-ferrocenylpropamide]-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl], (70 %). Novel methods were developed for thesyntheses of these linkers, with a different structural orientation than these found in literature. Ageneralized method, using methoxyethoxymethoxychloride (MEMCl), was developed for theprotection of the hydroxy- and carbonyl-functionalities on these ligands Two MOF-74-IIIderivatives, Co-MOF-74-III-Me, and Co-MOF-74-III-NHCOCH2CH2Fc were successfulsynthesised from the methylated and ferrocene-containing linkers respectively.Co-MOF-74-III-Me is mesoporous with a pore width of 32.6 Å. Co-MOF-74-III-Me andCo-MOF-74-III-NHCOCH2CH2Fc are both thermally stable up to 180°C.All the 4,4-di[methoxyethoxymethoxy]-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl]derivatives showed irreversible redox couples for the carbonyl functionalitiesof the MEM-groups (-1500 mV vs. FcH/FcH+). An additional redox couple (-2160 mV vs.FcH/FcH+) was found for the amide functionality of the 4,4-di[methoxyethoxymethoxy]- 3'-[3-ferrocenylpropamide]-[1,1':4',1-terphenyl]-3,3-di[methoxyethoxymethoxycarbonyl] ligand.Solid state cyclic voltammetry of Co-MOF-74-III-NHCOCH2CH2Fc, showed a redox couple (17mV vs. FcH/FcH+) for the ferrocenyl fragments on the linkers, detected because electron transferthrough the mesoporous material was fast enough.

[发布机构] University of the Free State