The slow diffusion method of CdCl
2 and MV[Pt(CN)
4] (MV
2+ =
N,
N'-dimethyl-4,4′-bipyridinium dication) in H
2O affords pale yellow block crystals of complex
1 (see experimental section in Supporting information). The purity of the polycrystalline sample of
1 was determined by Powder X-ray diffraction (PXRD) (Fig. S1 in Supporting information) and elemental analysis (EA). The single-crystal X-ray diffraction (SCXRD) of
1 at 293 K and 150 K revealed that complex
1 crystallizes in the monoclinic
C2/
m space group (Table S1 in Supporting information). Due to the same structure at both temperatures, the structure for
1 at 150 K is only discussed. In the structure of
1, only one crystallographically unique Cd(Ⅱ) atom (labeled as Cd1) is found (
Fig. 1a) and located at an inversion center. The Cd1 atom is coordinated by six N atoms which come from the square-planar [Pt(CN)
4]
2− anions, adopting a pseudo-octahedral [CdN
6] coordination sphere. Along the
bc plane of the structure, each [Pt1(CN)
4]
2− anion, which equatorially coordinates to the Cd1 atom, bridges four Cd1 atoms to give an extended wavelike layer. Then, the other [Pt2(CN)
4]
2− anions as pillars axially connected the Cd1 atoms, resulting in a three-dimensional (3D) negative framework [Cd
2{Pt(CN)
4}
3]
2− (Fig. S2a in Supporting information) showing two crossover one-dimensional (1D) channels of 6.5 × 7.3 Å and 6.3 × 10.1 Å along the respective
b and
c axis of the structure. A TOPOS analysis [
46] of the host framework defined a (4,4,6)-linked
fsy network (point symbol (4
4·6
2)
2(4
2·8
4)(4
8·6
2·8
5)
2) (Fig. S2b in Supporting information) once the Cd(Ⅱ) atoms and [Pt(CN)
4]
2− moieties are regarded as 6-connected nodes and 4-connected linkers, respectively. It should be noted the host framework for
1 shows the same structural topology with the reported complex [Fe
2{Pt(CN)
4}
3] [
47]. However, for the compound [Fe
2{Pt(CN)
4}
3], the selection of positive trivalent Fe(Ⅲ) atoms results in a neutral framework while the positive divalent Cd(Ⅱ) atoms in
1 give the negatively charged host framework. Therefore, for maintaining the charge balance, the MV
2+ counterions are encapsulated in the channels of the host framework for
1 (
Fig. 1c and Fig. S3 in Supporting information). Due to the confined effect of the channel, no structural disorder is observed for MV
2+ cations. Moreover, the two pyridinium rings of MV
2+ cation is coplanar and adopt the orientation almost parallel with the [Pt1(CN)
4]
2− moieties, resulting in the presence of host-guest stacks that contain the sequence MV
2+[Pt1(CN)
4]
2−MV
2+. The separation distance between MV
2+ and [Pt1(CN)
4]
2− moieties is around 3.4 Å (
Fig. 1b). Additionally, according to the elemental analysis, two H
2O molecules should exist in channels of the host framework. Actually, some void cavities, which can confine the solvent guests, are observed in the 1D channels along the
c axis of the host framework and are separated by the methyl groups of MV
2+ cations (Fig. S4 in Supporting information). However, the disorder of water molecules hinders further precise positioning through structural refinement. Further thermo-gravimetric (TG) measurement shows
1 starts to decompose at 435 ℃ (Fig. S5 in Supporting information), showing high thermal stability.