Synthesis and characterization of a cadmium(II)-organic supramolecular coordination compound based on the multifunctional 2-amino-5-sulfobenzoic acid ligand

Much attention has been paid by chemists to the construction of supramolecular coordination compounds based on the multifunctional ligand 5-sulfosalicylic acid (H₃SSA) due to the structural and biological interest of these compounds. However, no coordination compounds have been reported for the multifunctional amino-substituted sulfobenzoate ligand 2-amino-5-sulfobenzoic acid (H₂asba). We expected that H₂asba could be a suitable building block for the assembly of supramolecular networks due to its interesting structural characteristics. The reaction of cadmium(II) nitrate with H₂asba in the presence of the auxiliary flexible dipyridylamide ligand N,N'-bis[(pyridin-4-yl)methyl]oxamide (4bpme) under ambient conditions formed a new mixed-ligand coordination compound, namely bis(3-amino-4-carboxybenzenesulfonato-κO¹)diaquabis{N,N'-bis[(pyridin-4-yl)methyl]oxamide-κN}cadmium(II)-N,N'-bis[(pyridin-4-yl)methyl]oxamide-water (1/1/4), [Cd(C₇H₆NO₅S)₂(C₁₄H₁₄N₄O₂)₂(H₂O)₂]·C₁₄H₁₄N₄O₂·4H₂O, (1), which was characterized by single-crystal and powder X-ray diffraction analysis (PXRD), FT-IR spectroscopy, thermogravimetric analysis (TG), and UV-Vis and photoluminescence spectroscopic analyses in the solid state. The central Cd^II atom in (1) occupies a special position on a centre of inversion and exhibits a slightly distorted octahedral geometry, being coordinated by two N atoms from two monodentate 4bpme ligands, four O atoms from two monodentate 4-amino-3-carboxybenzenesulfonate (Hasba^-) ligands and two coordinated water molecules. Interestingly, complex (1) further extends into a threefold polycatenated 0D→2D (0D is zero-dimensional and 2D is two-dimensional) interpenetrated supramolecular two-dimensional (4,4) layer through intermolecular hydrogen bonding. The interlayer hydrogen bonding further links adjacent threefold polycatenated two-dimensional layers into a three-dimensional network. The optical properties of complex (1) indicate that it may be used as a potential indirect band gap semiconductor material. Complex (1) exhibits an irreversible dehydration-rehydration behaviour. The fluorescence properties have also been investigated in the solid state at room temperature.

Seven entangled coordination polymers assembled from triphenylamine-based bisimidazole and dicarboxylates: interpenetration, self-penetration and mixed entanglement

Seven entangled coordination polymers constructed from a triphenylamine-based bisimidazole and carboxylic acids have been synthesized and characterized.

I2-induced SC–SC transformation within two-dimensional Zn(ii)-triazole framework: an ideal detector of cyano-containing molecules

A SC–SC transformation process driven by I₂ has been shown to generate a 2D + 1D → 2D interpenetrated architecture from a 2D + 2D → 2D network. For the first time we demonstrate a selective sensor toward cyano-containing molecules.

Spontaneous chiral resolution of a rare 3D self-penetration coordination polymer for sensitive aqueous-phase detection of picric acid

A chiral, fluorescent and self-penetration coordination polymer was synthesized through spontaneous resolution, which showed sensitive detection of picric acid in the aqueous phase.

A rare (3,4,5)-connected metal–organic framework featuring an unprecedented 1D + 2D → 3D self-interpenetrated array and an O-atom lined pore surface: structure and controlled drug release

A rare (3,4,5)-connected metal–organic framework has been constructed, which features an unprecedented 1D + 2D → 3D self-interpenetrated array and an O-atom lined pore surface, and shows good controlled release of ibuprofen.