TY - JOUR

T1 - Post-synthetic modification of Zr-metal-organic frameworks through cycloaddition reactions

AU - Roy, Pascal

AU - Schaate, Andreas

AU - Behrens, Peter

AU - Godt, Adelheid

PY - 2012/4/16

Y1 - 2012/4/16

N2 - Cycloaddition reactions are highly attractive for post-synthetic modification of metal-organic frameworks (MOFs). We report herein on cycloaddition reactions with PIZOF(R 1,R 2)s, which are porous interpenetrated Zr-based MOFs with Zr 6O 4(OH) 4(CO 2) 12 as the nodes and the dicarboxylates -O 2C[PE-P(R 1,R 2)-EP]CO 2 - (P: phenylene, E: ethynylene; R 1, R 2: side chains at the central phenylene unit) as the linkers. 1,3-Dipolar cycloaddition between the pendant ethyne moieties of PIZOF(OMe,OCH 2C≡CH) and 4-methylbenzyl azide resulted in 98 % conversion of the ethyne groups. Reactions of PIZOF(OMe,O(CH 2) 3furan) with maleimide, N-methylmaleimide, and N-phenylmaleimide converted 98, 99, and 89 % of the furan moieties into the Diels-Alder adducts. However, no reaction occurred with maleic anhydride. High-resolution 1H NMR spectra were crucial in determining the conversion and identifying the reaction products. Of all the reagents (NaOD/D 2O, D 2SO 4, Bu 4NF, CsF, CsF/DCl, and KHF 2) tested for the disassembly of the PIZOFs in [D 6]DMSO, the combination of CsF and DCl was found to be the best. The disassembly at room temperature was fast (5-15 min), and after the addition of K 2CO 3 the 1H NMR data were identical to those of the diacids (=protonated linkers) dissolved in pure DMSO. This allowed for simple structure elucidation through data comparison. CsF/DCl dissolves not only PIZOFs but also the hydrolytically very stable UiO-66.

AB - Cycloaddition reactions are highly attractive for post-synthetic modification of metal-organic frameworks (MOFs). We report herein on cycloaddition reactions with PIZOF(R 1,R 2)s, which are porous interpenetrated Zr-based MOFs with Zr 6O 4(OH) 4(CO 2) 12 as the nodes and the dicarboxylates -O 2C[PE-P(R 1,R 2)-EP]CO 2 - (P: phenylene, E: ethynylene; R 1, R 2: side chains at the central phenylene unit) as the linkers. 1,3-Dipolar cycloaddition between the pendant ethyne moieties of PIZOF(OMe,OCH 2C≡CH) and 4-methylbenzyl azide resulted in 98 % conversion of the ethyne groups. Reactions of PIZOF(OMe,O(CH 2) 3furan) with maleimide, N-methylmaleimide, and N-phenylmaleimide converted 98, 99, and 89 % of the furan moieties into the Diels-Alder adducts. However, no reaction occurred with maleic anhydride. High-resolution 1H NMR spectra were crucial in determining the conversion and identifying the reaction products. Of all the reagents (NaOD/D 2O, D 2SO 4, Bu 4NF, CsF, CsF/DCl, and KHF 2) tested for the disassembly of the PIZOFs in [D 6]DMSO, the combination of CsF and DCl was found to be the best. The disassembly at room temperature was fast (5-15 min), and after the addition of K 2CO 3 the 1H NMR data were identical to those of the diacids (=protonated linkers) dissolved in pure DMSO. This allowed for simple structure elucidation through data comparison. CsF/DCl dissolves not only PIZOFs but also the hydrolytically very stable UiO-66.

KW - cycloaddition

KW - Diels-Alder reaction

KW - metal-organic frameworks

KW - post-synthetic modification

KW - zirconium

UR - http://www.scopus.com/inward/record.url?scp=84861549053&partnerID=8YFLogxK

U2 - 10.1002/chem.201103288

DO - 10.1002/chem.201103288

M3 - Article

AN - SCOPUS:84861549053

VL - 18

SP - 6979

EP - 6985

JO - Chemistry - a European journal

JF - Chemistry - a European journal

SN - 0947-6539

IS - 22

ER -