Stimulus-responsive reversible thermochromism and exciplex emission of a Zn(ii) complex and selective sensing of NH3 gas

A Zn(ii) complex exhibits reversible thermochromism and emission switch, and the resulting free radical species responds fast and selectively toward NH₃.

Crystal structure of the BaII-based CoII-containing one-dimensional coordination polymer poly[[aqua{μ4-2,2'-[(4,10-dimethyl-1,4,7,10-tetra-aza-cyclo-dodecane-1,7-di-yl)bis(methylidene)]bis-(4-oxo-4H-pyran-3-olato)}-perchloratocobaltbarium] perchlorate]

The title compound, {[Ba{Co(H-2L1)}(ClO4)(H2O)]ClO4} n , L1 = 4,10-bis-[(3-hy-droxy-4-pyron-2-yl)meth-yl]-1,7-dimethyl-1,4,7,10-tetra-aza-cyclo-dodeca-ne, is a one-dimensional coordination polymer. The asymmetric unit consists of a {Ba[Co(H-2L1)](ClO4)(H2O)}+ cationic fragment and a non-coordinating ClO4- anion. In the neutral [Co(H-2L1)] moiety, the cobalt ion is hexa-coordinated in a trigonal-prismatic fashion by the surrounding N4O2 donor set. The Ba2+ ion is nine-coordinated and exhibits a distorted [BaO9] monocapped square-anti-prismatic geometry, the six oxygen atoms coming from three distinct [Co(H-2L1)] moieties, while the remaining three vertices are occupied by the oxygen atoms of a bidentate perchlorate anion and a water mol-ecule. A barium-μ2-oxygen motif develops along the a axis, connecting symmetry-related dinuclear BaII-CoII cationic fragments in a wave-like chain, forming a one-dimensional metal coordination polymer. Non-coordinating ClO4- anions are located in the space between the chains. Weak C-H⋯O hydrogen bonds involving both coordinating and non-coordinating perchlorate anions build the whole crystal architecture. To our knowledge, this is the first example of a macrocyclic ligand forming a BaII-based one-dimensional coordination polymer, containing CoII ions surrounded by a N4O2 donor set.

A novel three-dimensional SrII coordination polymer based on benzene-1,2,4,5-tetracarboxylate: hydrothermal synthesis, crystal structure and spectroscopic and thermal studies

Coordination of the anions of benzenecarboxylic acids with metal cations leads to coordination polymers with various structural features. Very few examples of strontium-based structures have been reported. A new three-dimensional coordination polymer, namely poly[aqua(μ12-benzene-1,2,4,5-tetracarboxylato)distrontium(II)], [Sr2(C10H2O8)(H2O)] n , has been synthesized under hydrothermal conditions and characterized by thermal analysis, vibrational spectroscopy (Raman and IR), single-crystal X-ray diffraction and powder X-ray diffraction. The coordination geometries around the two independent SrII ions can be described as a distorted dodecahedron and a distorted monocapped square antiprism. The compound features a three-dimensional structure containing inorganic motifs, with two-dimensional layers connected through organic linkers, and possesses a topologic structure of a binodal (6,12) connected alb net with the Schläfli symbol {415}2{448.618}. The final product of thermal decomposition is strontium oxide (SrO).

Copper pyromellitates: a complex story

Copper pyromellitate complexes range from unusual discrete molecular ions to 2- and 3-dimensional polymeric networks with considerable ligand structural versatility.

Poly[[hexa-aqua-sesqui(μ-benzene-1,2,4,5-tetra-carboxyl-ato)dicopper(II)disodium] monohydrate]

In the title compound, {[Cu₂Na₂(C₁₀H₂O₈)_1.5(H₂O)₆]·H₂O}_n, the Cu²⁺ ion is hexa­coordinated by five O atoms from benzene-1,2,4,5-tetra­carboxyl­ate (btec⁴⁻) ligands and one water mol­ecule. The Na⁺ ion is also hexa­coordinated, by four O atoms from btec⁴⁻ ligands and two water mol­ecules. One of the two btec⁴⁻ mol­ecules sits on a crystallographic inversion centre. CuO₆ and NaO₆ octa­hedra are connected, forming bi-dimensional layers. These layers, which extend parallel to the ac plane, are further inter­connected by μ₁₀- or μ₁₁-bridging btec⁴⁻ ligands and by O—H⋯O hydrogen bonds, involving both btec⁴⁻ ligands and water mol­ecules, forming a three-dimensional network.