Solvothermal reactions of Zn(NO
3)
2·6H
2O, HPB, and
R/
S-DCH in a mixed solvent (DMF/EtOH) gave flaky crystals of
R/S-1 (for details, see Supporting information). Single-crystal X-ray diffraction revealed that both
R-1 and
S-1 crystallize in a chiral orthorhombic space group
P2
12
12
1. Hence the structural description is restricted to the
R-1. As shown in
Fig. 1a, the asymmetric unit of
R-1 contains four Zn
2+ ions, two
R-L, and six terminal water molecules. There are three kinds of Zn
2+ ions with different coordination environments. Zn1 and Zn2 atoms have pentacoordinate environments and adopt two different distorted square pyramidal geometries. Zn1 coordinates with two nitrogen atoms (N1 and N2) and two oxygen atoms (O1 and O2) from one
R-L and one nitrogen atom N3 from another ligand. The bond distances of Zn–O and Zn–N are in the range of 2.010(6)–2.053(6) Å and 2.021(7)–2.071(8) Å, respectively. The formed metallosalen ligands (denoted as
R-ZnL) bridge each other to construct an infinite right-handed 2
1 helical chain (
Fig. 1b and Fig. S1a in Supporting information). The helical chains extend to form a two-dimensional (2D) layer substructure in the
bc plane with Zn3 as connecting atoms (Fig. S1b in Supporting information). The Zn3 has a distorted octahedral geometry by coordinating with four oxygen atoms of two adjacent
R-ZnL and two oxygen atoms of terminal water molecules. The bond distances of Zn3–O are in the range of 2.086(5)–2.090(5) Å. In addition, the Zn4 atom adopts a similar octahedral geometry surrounded by four water-oxygen atoms (Zn4–O distances are 1.97(2)–2.058(17) Å) and two nitrogen atoms (Zn–N bonds are 2.124(10)–2.131(7) Å) from two
R-L ligands. Finally, the 2D substructures are connected to each other through Zn4 atoms, forming a chiral 3D framework structure (
Fig. 1c and Fig. S1c in Supporting information). It is worth noting that four adjacent Zn4 atoms form a parallelogram-shaped cavity with lengths of
ca. 11.0 and 14.4 Å, offering anchorable sites and chiral pockets (
Fig. 1d). The
S-1 shows the enantiomeric structure features to
R-1 (Fig. S2 in Supporting information). There are two types of channels along the
b and
c axes, which are filled with solvent molecules and NO
3− anions (Fig. S3 in Supporting information). PLATON calculations revealed the accessible voids of
R-1 and
S-1 are 4515 Å
3 (51.1%) and 4329 Å
3 (47.6%) per unit cell, respectively. From the perspective of topological analysis, simplifying the dimer substructure containing two
R-L ligands as a 6-connected node (Fig. S4 in Supporting information), the underlying topology of
R-1 and
S-1 can be obtained as the
acs net with minimal transitivity [
11] and a point symbol of {4
9.6
6} (
Fig. 1d) [
45,
46].