naphthalene moieties are responsible for the gelation [117]. Addition of Zn
2+
produces Zn
2+ -coordinated metallogel 89-Zn and the fluorescence intensity of 89
gel decreases with red shift from 410 to 430 nm. In the gelation strong coordination
between Zn
2+ and both of N-atoms and O-atoms of the hydrazide groups is
involved. Both 89 and 89-Zn gels show efficient and different sensing behaviours
towards F
− ion without a gel–sol transition because of the variation in
self-assembling nature. During the process, 89 forms fluoride-containing organogel
89-F with variation in colour from blue to greenish yellow via strong
aggregation-induced emission (AIE) phenomenon and 89-Zn produces fluoridecontaining metallogel 89-Zn–F with modulation in colour from blue to blue green.
The binding constant and the detection limit of 89-Zn towards F
− are about
4.0 Â 10
6 L mol
−1 and 1.3 Â 10
−6 mol L
−1 .
3.3.3 Metal–Organic Gels for Sorption
Metal-carboxylate gels show hierarchical porosity with micro- and mesoporosity.
The microporosity has been applied in gas uptake [118]. Thallapally and co-workers
reported that Fe-BTC aerogel selectively uptakes 33 wt% (7.5 mmol g
−1 ) of CO 2 at
high pressure (30 bar), while only ca. 3.5 wt% of CH 4 is taken up under similar
conditions. What’s more, Zhang, Su and co-workers reported that Al-BTC/Al-BDC
aerogels uptakes H 2 up to 1.52 wt% (the total uptake is 2.52%) without saturation
at 1 bar and 77 K. The aerogels display CO 2 uptakes up to 61 wt% (308 cm
3 g
−1 )
without saturation at 1 bar and 195 K. The aerogels also adsorb benzene up to 86%
(247 cm
3 g
−1 ), n-hexane up to 47 wt% (122 cm
3 g
−1 ) and methanol up to 96 wt%
(672 cm
3 g
−1 ) [49].
The mesoporosity of metal-carboxylate gels can be applied in uptake of bulky
molecules. Cr-BTC aerogel is highly efficient in the absorption of several dyes,
including methyl orange, dimethyl phthalate, and methylene blue [48]. Al-BDC
aerogels show high adsorbing capacities of up to 633.4 and 621.3 mg g
−1 for congo
red (CR) and brilliant blue R-250 (BBR-250), respectively [49]. Zou and
co-workers developed heterometallic MOGs based on Fe
3+ and Al
3+ . Fe
3+ and Al
3+
at the Fe/Al radio of 1:1 react with H 3 BTC to form metal–organic gels (Fig. 3.35)
[119]. The corresponding aerogel shows high surface area (1861 m
2 g
−1 ) and pore
volume (9.737 cm
3 g
−1 ). This material shows the large uptakes of dye molecules
(290 mg g
−1 rhodamine B and 265 mg g
−1 methyl orange) with fast sorption
kinetics. So, the hierarchical gels can be used to absorb dye molecules with high
efficiency. Zou and co-workers shows that Al-BTC gel with sufficient metal sites
and carboxyl groups has strong affinity for the toxic pollutant microcystin-LR
[120]. The Al-BTC xerogel effectively removes microcystin-LR in water and its
adsorption capacity is as high as 6861 lg g
−1 at an initial MC-LR concentration of
10,000 ppb. Al-BTC aerogel shows more adsorption capacity 9007 mg g
−1 to
MC-LR at the same conditions. It indicates that it is a good material to remove
microcystin-LR from the environment.
3.3 Applications
105
2+
produces Zn
2+ -coordinated metallogel 89-Zn and the fluorescence intensity of 89
gel decreases with red shift from 410 to 430 nm. In the gelation strong coordination
between Zn
2+ and both of N-atoms and O-atoms of the hydrazide groups is
involved. Both 89 and 89-Zn gels show efficient and different sensing behaviours
towards F
− ion without a gel–sol transition because of the variation in
self-assembling nature. During the process, 89 forms fluoride-containing organogel
89-F with variation in colour from blue to greenish yellow via strong
aggregation-induced emission (AIE) phenomenon and 89-Zn produces fluoridecontaining metallogel 89-Zn–F with modulation in colour from blue to blue green.
The binding constant and the detection limit of 89-Zn towards F
− are about
4.0 Â 10
6 L mol
−1 and 1.3 Â 10
−6 mol L
−1 .
3.3.3 Metal–Organic Gels for Sorption
Metal-carboxylate gels show hierarchical porosity with micro- and mesoporosity.
The microporosity has been applied in gas uptake [118]. Thallapally and co-workers
reported that Fe-BTC aerogel selectively uptakes 33 wt% (7.5 mmol g
−1 ) of CO 2 at
high pressure (30 bar), while only ca. 3.5 wt% of CH 4 is taken up under similar
conditions. What’s more, Zhang, Su and co-workers reported that Al-BTC/Al-BDC
aerogels uptakes H 2 up to 1.52 wt% (the total uptake is 2.52%) without saturation
at 1 bar and 77 K. The aerogels display CO 2 uptakes up to 61 wt% (308 cm
3 g
−1 )
without saturation at 1 bar and 195 K. The aerogels also adsorb benzene up to 86%
(247 cm
3 g
−1 ), n-hexane up to 47 wt% (122 cm
3 g
−1 ) and methanol up to 96 wt%
(672 cm
3 g
−1 ) [49].
The mesoporosity of metal-carboxylate gels can be applied in uptake of bulky
molecules. Cr-BTC aerogel is highly efficient in the absorption of several dyes,
including methyl orange, dimethyl phthalate, and methylene blue [48]. Al-BDC
aerogels show high adsorbing capacities of up to 633.4 and 621.3 mg g
−1 for congo
red (CR) and brilliant blue R-250 (BBR-250), respectively [49]. Zou and
co-workers developed heterometallic MOGs based on Fe
3+ and Al
3+ . Fe
3+ and Al
3+
at the Fe/Al radio of 1:1 react with H 3 BTC to form metal–organic gels (Fig. 3.35)
[119]. The corresponding aerogel shows high surface area (1861 m
2 g
−1 ) and pore
volume (9.737 cm
3 g
−1 ). This material shows the large uptakes of dye molecules
(290 mg g
−1 rhodamine B and 265 mg g
−1 methyl orange) with fast sorption
kinetics. So, the hierarchical gels can be used to absorb dye molecules with high
efficiency. Zou and co-workers shows that Al-BTC gel with sufficient metal sites
and carboxyl groups has strong affinity for the toxic pollutant microcystin-LR
[120]. The Al-BTC xerogel effectively removes microcystin-LR in water and its
adsorption capacity is as high as 6861 lg g
−1 at an initial MC-LR concentration of
10,000 ppb. Al-BTC aerogel shows more adsorption capacity 9007 mg g
−1 to
MC-LR at the same conditions. It indicates that it is a good material to remove
microcystin-LR from the environment.
3.3 Applications
105