Porphyrin-Based Conjugated Microporous Polymers for Highly Efficient Adsorption of Metal Ions.

The capture and elimination of anions and cations from water have attracted a great deal of attention and are quite vital for clean production and environmental remediation. In this work, we present the synthesis of four porphyrin (Por)-based conjugated microporous polymers (CMPs, namely, Por-CMP-1-4), which were produced through a Sonogashira-Hagihara linked response using porphyrin and acetylene aromatic compounds as building blocks and used as absorbents to eliminate metal ions from water. The as-synthesized Por-CMP-1-4 exhibit an amorphous porous structure and outstanding caloric and physicochemical properties. Taking advantage of their larger specific surface areas, i.e., 541.47, 614.58, 382.38, and 677.90 m2 g-1 for Por-CMP-1-4, respectively, and their chelating active site that originated from the porphyrin ring, Por-CMP-1-4 show better Zn2+, Cu2+, and Pb2+ adsorption ability. Among them, Por-CMP-3 has the greatest adsorbability of 640 mg g-1 for Zn2+, with an adsorption efficiency of 80%, whereas its adsorption capacities for Cu2+ and Pb2+ ions were both 334 mg g-1, with an adsorption efficiency of 42% for Cu2+ and Pb2+. Employing Por-CMP-3 as a representative example, its adsorption kinetics has been systematically investigated. The adsorption behavior of Por-CMP-3 with respect to the Zn2+ ion is shown to exhibit pseudo-first-order kinetics and Langmuir isotherm modes. Meanwhile, the adsorption mechanism is discussed in detail, and it was thought it might be chelation, in which the nitrogen atoms with a single pair of electrons on the porphyrin ring interacted with metal ions to form stable chelation coordination bonds, thus removing metal ions selectively and effectively. Furthermore, Por-CMP-3 exhibited good reusability, retaining 60% of its Zn2+ removal rate after four continuous adsorptions.

2-{[2-(Pyridin-4-yl)-1H-benzimidazol-1-yl]meth-yl}phenol.

In the title compound, C19H15N3O, the benzimidazole ring system makes dihedral angles of 44.36 (7) and 75.67 (7)° with the pyridine and benzene rings, respectively. In the crystal, phenolic O-H⋯N hydrogen bonds to benzimidazole N-atom acceptors give rise to a chain extending along [011].

A one-dimensional silver(I) coordination polymer based on the 2-[2-(pyridin-4-yl)-1H-benzimidazol-1-ylmethyl]phenol ligand exhibiting photoluminescence.

A one-dimensional Ag(I) coordination complex, catena-poly[[silver(I)-µ-{2-[2-(pyridin-4-yl)-1H-benzimidazol-1-ylmethyl]phenol-κ(2)N(2):N(3)}] perchlorate monohydrate], {[Ag(C19H15N3O)]ClO4·H2O}n, was synthesized by the reaction of 2-[2-(pyridin-4-yl)-1H-benzimidazol-1-ylmethyl]phenol (L) with silver perchlorate. In the complex, the L ligands are arranged alternately and link Ag(I) cations through one benzimidazole N atom and the N atom of the pyridine ring, leading to an extended zigzag chain structure. In addition, the one-dimensional chains are extended into a three-dimensional supramolecular architecture via O-H···O hydrogen-bond interactions and π-π stacking interactions. The complex exhibits photoluminescence in acetonitrile solution, with an emission maximum at 390 nm, and investigation of the thermal stability reveals that the network structure is stable up to 650 K.

Dimethyl 2,2'-[2,2'-bi(1H-1,3-benzimidazole)-1,1'-di-yl]diacetate.

The whole mol-ecule of the title compound, C(20)H(18)N(4)O(4), is generated by an inversion center. The benzimidazole ring mean plane make a dihedral angle of 89.4 (8)° with the plane passing through the acetate group (COO). In the crystal, mol-ecules are linked via weak C-H⋯O hydrogen bonds and π-π inter-actions [centroid-centroid distance = 3.743 (3) Å] involving inversion-related benzimidazole groups.

Aqua-[1-(pyrazin-2-yl)ethanone oximato-κ²N,N'][1-(pyrazin-2-yl)ethanone oxime-κ²N,N'](thio-cyanato-κN)nickel(II).

In the title complex, [Ni(C6H6N3O)(NCS)(C6H7N3O)(H2O)] or [Ni(mpko)(SCN)(mpkoH)(H2O)] [where mpkoH = 1-(pyrazin-2-yl)ethanone oxime], the Ni(II) cation is in a slightly distorted octa-hedral geometry, being coordinated in the equatorial plane by four N atoms from two different mpkoH ligands, one of which is deprotonated, and by one N atom from a thio-cyanate anion and one O atom from a water mol-ecule in the axial positions. There is an intra-molecular O-H⋯O hydrogen bond involving the oxime units of the two ligands. In the crystal, a three-dimensional supra-molecular architecture is formed by O-H⋯O and O-H⋯N hydrogen bonds.

Bis{2-[bis-(3,5-dimethyl-1H-pyrazol-1-yl-κN(2))meth-yl]pyridine-κN}cobalt(II) dinitrate.

The central Co(II) ion in the title complex, [Co(C(16)H(19)N(5))(2)](NO(3))(2), is located on a twofold rotation axis and has a slightly distorted octa-hedral coordination sphere. It is bonded to six N atoms from two 2-[bis-(3,5-dimethyl-1H-pyrazol-1-yl)meth-yl]pyridine ligands. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions.

Bis{2-[bis-(3,5-dimethyl-1H-pyrazol-1-yl-κN)meth-yl]pyridine-κN}copper(II) dinitrate.

In the mononuclear title complex, [Cu(C(16)H(19)N(5))(2)](NO(3))(2), the Cu(II) ion is located on a twofold rotation axis and is six-coordinated by six N atoms from two 2-[bis-(3,5-dimethyl-1H-pyrazol-1-yl)meth-yl]pyridine ligands, forming a distorted octa-hedral geometry. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions.