198 Topics in Current Chemistry Editorial Board: A. de Meijere KN ...

144 Y. Aoyama
In the presence of a strong but weakly coordinating base such as triethylamine,
fully deprotonated trimesic acid (43) (Fig. 12) acts as a hexamonodentate unit.
It is assembled with the 6-coordinate Zn II ion (Zn(NO 3) 2) formally in a 2D
fashon 44 and then into a rigid metal-coordinated 3D network 45 [58]. The basic
unit in adduct 43 ◊ 2Zn◊ (NO 3)◊ (H 2O)◊ 5(CH 3CH 2OH) is a 10-membered macrocyclic
ring motif 46. Highly mobile ethanol and water molecules reside in the
extended channel having a 14 Å cross-section. Coordination networks can often
be further cross-linked via hydrogen bonding between metal ligands [59, 60].
A chiral bicyclic diol 47 and its analogues such as 50 and 52 form spiral hydrogen-bonded
spines ◊◊◊O-H◊◊◊O-H◊◊◊O-H◊◊◊O-H◊◊◊ (48) around a threefold screw
axis (Fig. 13) [61]. The molecules are assembled in a helical manner to give welldefined
intrahelix canals 49, 51,and 53 of different cross-sections) supported by
six such spines. The cross-sectional area is ~ 20 Å 2 in the case of 49 and a variety
of guest molecules are included therein to form a class of helical tubulate in-
43 44
45
Fig. 12. 3D net formed by 43◊2Zn◊(NO 3). The counteranion is not shown for clarity
46