Anion-Directed Assembly of Nickel-Calixarene Complexes: Constructing Isolated {Ni<sub>8</sub>}, {Ni<sub>20</sub>}, {Ni<sub>24</sub>}, and {Ni<sub>32</sub>} Clusters
Kaiyue Li, Zhihua Zhuang, Wei Chen, Wuping Liao
Abstract
Four nickel-calixarene complexes, {Ni8(TC4A)4L}2– (CIAC-244), {Ni32(TC4A)8L8(CO3)4(HCOO)2Cl8}2– (CIAC-245), {Ni20(TC4A)5L5(SO4)5Cl5}5– (CIAC-246), and {Ni24(TC4A)6L5(CO3)5(SO4)(HCOO)Cl5}4– (CIAC-247) (H4TC4A = p-tert-butylthiacalix[4]arene, H2L = 2,5-dihydro-1,3,4-thiadiazole-2,5-dithiol), were synthesized by introducing different inorganic anions under the solvothermal conditions. CIAC-244 features a hinged double-dumbbell-like {Ni8} entity assembled by linking two sandwich-like Ni4-(TC4A)2 subunits with one L ligand. When a little DMF was introduced into the reaction system, CIAC-245 featuring a twisted double-bowl-shaped {Ni32} architecture was obtained with in situ generated CO32– anions. The attempt to replace the CO32– anions in CIAC-245 with the SO42– anions led to the formation of a {Ni20} coordination wheel (CIAC-246) constructed by five Ni4-TC4A SBUs, five L ligands, and five sulfate anions. When much nickel sulfate and a little DMF were added simultaneously, {Ni24} coordination bowl (CIAC-247) was obtained, which can be thought to form through substituting CO32– anions for the SO42– bridges and capping one end in CIAC-246. Different from CIAC-244 having sandwich-like Ni4-(TC4A)2 secondary building units (SBU), three others have some shuttlecock-like Ni4-TC4A SBUs. CIAC-246 exhibits efficient electrocatalytical activity for the oxidation of glucose.