The nanoporous coordination polymer [Cu(pyrimidin-2-olate-N1,N3)(2)](n) (1(C)) of the sodalite zeotype sorbs a variety of metal nitrates [M(NO3)(m), M = Na+, K+, Rb+, Tl+, Ca2+, Sr2+, Ba2+, Pb2+, La3+, Nd3+, Gd3+, Er3+] from H2O/MeOH solutions, with a concomitant structural change to a layered [Cu(pyrimidin-2-olate-N1,N3)(2)](n)center dot[M(NO3)(m)](n/2) (MNO3@1(L)) coordination framework. Single-crystal X-ray diffraction analyses revealed that the layers are based on Cu-4(pyrimidin-2-olate-N1,N3)(4) square grids of copper(II) ions bridged by N1,N3 exobidentate ligands, displaying a structural motif of the metallacalix[4]arene type in pinched cone conformation. The interlayer space is occupied by the guest metal nitrates, each metal being coordinated by (at least) the four oxygen atoms of a metallacalix[4]arene. Magnetic measurements on the MNO3@1(L) series denoted a weak ferromagnetic ordering taking place below the Neel temperatures (typically close to 35 K), arising from spin-canting phenomena of the antiferromagnetically coupled copper centers. When M = Nd3+, Gd3+, or Er3+, additional magnetic ordering is observed at lower temperatures, which, on the basis of static and dynamic magnetic susceptibility measurements, can be attributed to copper- lanthanide interactions.