25 Click Chemistry to Metal-Organic …
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alkynes, for example, DMOF-NH 2 crystals, was easily dissolved by the treatment with
propiolic acid. According to the nitrogen adsorption measurement, the adsorption
surface area and pore volume are reduced in accordance with the conversion yields.
Therefore, the size of the nanopores can be finely controlled by the PSM. Inspired
by this method, Giambastiani and coworkers reported the unconventional double
derivatizations of the amine-tagged MOF (UMCM-1 and MIXMOF-5) by treatment
of single organic/organometallic acetylene derivatives for the first modification of
the click reaction [30]. The binary and ternary mixtures of the alkynes in variable
molar ratios were carried out for multi-modification by the single-step click reaction
for the MOF catalysts.
Finally, in recent years, the ring strain-promoting click reaction (SPAAC)has
been spotlighted [31, 32] because the cyclization takes place without the assistance
of the metal ion, then this reaction was used for the PSM of the MOF. Rosi and
coworkers prepared BioMOF (N 3 -bio-MOF-100) equipped with the azide group
(Scheme 25.2d). The click reaction of the azide groups in the MOF proceeded almost
quantitatively by the treatment of a 11,12-didehydrodibenzoazosine (DIBAC) derivative having a ring strain triple bond to the azide group [33]. It should be noted that one
equivalent was used for the azide groups in the MOF without any metal ions under
very mild conditions. The active ester with DIBAC was also quantitatively modified,
and further modification using the phenylalanine dimer could be achieved. In addition, Wöll and coworkers compared CuAAC and SPAAC for the PSM of MOF thin
films (SURMOF) on gold substrates and reported the usefulness of SPAAC [34].
This process should be of importance to overcome the intrinsic toxicity from conventional Cu catalyst for CuAAC and significantly broaden its utilization in biomedical
applications.
25.3 Post-synthetic Modification of MOF by Click Reaction
Other Than CuAAC
As mentioned in the previous section, with the progress of click chemistry, not only
the original CuAAC but also various reactions have come to be recognized as the
click reactions. We focus on them in this section. Cohen et al. reported a tandem postmodification method of the MOF using a reverse electron-requested Diels–Alder
reaction of vinyl compounds for 1,2,4,5-tetrazine (Scheme 25.3a) [35]. They first
synthesized UMCM-1-NH 2 from aminoterephthalic acid and zinc(II) ion followed
by the condensation reaction with 1-pentenic anhydride. For these MOF, it was
allowed to quantitatively react with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate to
generate a dihydropyridazine skeleton ring. By the tandem modification, a large pore
surface area derived from UMCM (4000 m
2 /g) decreased after the first amidation
(3600 m
2 /g) and the subsequent Diels–Alder reaction (2800 m
2 /g) according to the
nitrogen adsorption measurement. When a similar tandem modification of IRMOF3 with the smaller nanopores was attempted, the first step reaction quantitatively
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alkynes, for example, DMOF-NH 2 crystals, was easily dissolved by the treatment with
propiolic acid. According to the nitrogen adsorption measurement, the adsorption
surface area and pore volume are reduced in accordance with the conversion yields.
Therefore, the size of the nanopores can be finely controlled by the PSM. Inspired
by this method, Giambastiani and coworkers reported the unconventional double
derivatizations of the amine-tagged MOF (UMCM-1 and MIXMOF-5) by treatment
of single organic/organometallic acetylene derivatives for the first modification of
the click reaction [30]. The binary and ternary mixtures of the alkynes in variable
molar ratios were carried out for multi-modification by the single-step click reaction
for the MOF catalysts.
Finally, in recent years, the ring strain-promoting click reaction (SPAAC)has
been spotlighted [31, 32] because the cyclization takes place without the assistance
of the metal ion, then this reaction was used for the PSM of the MOF. Rosi and
coworkers prepared BioMOF (N 3 -bio-MOF-100) equipped with the azide group
(Scheme 25.2d). The click reaction of the azide groups in the MOF proceeded almost
quantitatively by the treatment of a 11,12-didehydrodibenzoazosine (DIBAC) derivative having a ring strain triple bond to the azide group [33]. It should be noted that one
equivalent was used for the azide groups in the MOF without any metal ions under
very mild conditions. The active ester with DIBAC was also quantitatively modified,
and further modification using the phenylalanine dimer could be achieved. In addition, Wöll and coworkers compared CuAAC and SPAAC for the PSM of MOF thin
films (SURMOF) on gold substrates and reported the usefulness of SPAAC [34].
This process should be of importance to overcome the intrinsic toxicity from conventional Cu catalyst for CuAAC and significantly broaden its utilization in biomedical
applications.
25.3 Post-synthetic Modification of MOF by Click Reaction
Other Than CuAAC
As mentioned in the previous section, with the progress of click chemistry, not only
the original CuAAC but also various reactions have come to be recognized as the
click reactions. We focus on them in this section. Cohen et al. reported a tandem postmodification method of the MOF using a reverse electron-requested Diels–Alder
reaction of vinyl compounds for 1,2,4,5-tetrazine (Scheme 25.3a) [35]. They first
synthesized UMCM-1-NH 2 from aminoterephthalic acid and zinc(II) ion followed
by the condensation reaction with 1-pentenic anhydride. For these MOF, it was
allowed to quantitatively react with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate to
generate a dihydropyridazine skeleton ring. By the tandem modification, a large pore
surface area derived from UMCM (4000 m
2 /g) decreased after the first amidation
(3600 m
2 /g) and the subsequent Diels–Alder reaction (2800 m
2 /g) according to the
nitrogen adsorption measurement. When a similar tandem modification of IRMOF3 with the smaller nanopores was attempted, the first step reaction quantitatively