Syntheses, Characterization, and Luminescent Properties of Three 3D Lead−Organic Frameworks with 1D Channels

Three novel porous coordination polymers based on lead(II) and isonicotinic acid N-oxide, [Pb(INO)2]2·7H2O (1),
[Pb(INO)2]·nH2O (2), and [Pb4(OH)4(INO)4]·nH2O (3) (HINO = isonicotinic acid N-oxide), have been synthesized and characterized
through single-crystal X-ray diffraction. Compound 1 features a most remarkable and unique three-dimensional (3D) framework
with two distinct kinds of channels showing different sizes and shapes, which are occupied by two kinds of water clusters, according
to the size and shape of the channels. Compound 2 possesses a 3D framework built up from one-dimensional (1D) Pb−O chains and
INO ligands with 1D rectangular channels, in which lattice water molecules are located. The structure of 3 consists of [Pb4(OH)4]4+
cluster inorganic building blocks, which connect with μ4-INO ligands through oxygen atoms from N-oxide moieties and carboxylate
groups of INO to form 8.7 × 8.7 Å2 rhombic channels running along the c-axis. In addition, the photoluminescence properties of
coordination polymers 1−3 in the solid state have been reported. Gas adsorption properties of compound 3 have also been studied.