Synthesis, structure and properties of [Zn(l-Tyr)2(bpy)]2⋅ 3H2O·CH3OH complex: Theoretical, spectroscopic and microbiological studies

High pressure studies on bis(l-histidinate)nickel(II) monohydrate

Raman spectra of bis(l-histidinate)nickel(II) monohydrate crystal were obtained for pressures up to 9.5GPa. Our results show the disappearance of some of the Raman modes and the appearance of other modes. These modifications evidence that the sample undergoes phase transitions at around 0.8 and 3.2GPa. The role played by the Ni ions and hydrogen bonds in the dynamics of the phase transitions is discussed. Under decompression, down to atmospheric pressure, the original Raman spectra are recovered, showing that both phase transitions are fully reversible.

Co, Zn and Ag-MOFs evaluation as biocidal materials towards photosynthetic organisms

In the present study, the biocidal activity of three different metal organic frameworks (MOFs) based on Co (Co-SIM1), Zn (Zn-SIM1) and Ag (Ag-TAZ) has been evaluated towards one green alga and two cyanobacteria. These organisms are present in fresh- and seawater and take part in the early stages of the biofouling process. The biocidal activity of these materials was evaluated by measuring chlorophyll a concentration and by inhibition zone testing. After 24h of exposure the three different MOFs caused >50% of chlorophyll a concentration inhibition towards both cyanobacteria, however, although the green alga presented a great sensitivity for Ag-TAZ (reaching 90% of chlorophyll a concentration inhibition), it was much more resistant to the rest of MOFs. Bioavailability of these metals was studied using ICP-MS, the chemical speciation program Visual MINTEQ, and a heavy metal bioreporter bioanalytical tool. We have elucidated that the biocidal activity presented by these MOFs was due to the dissolved metals released from them and more exactly, it depended on the bioavailability presented by these metal ions, which was closely related with the free ion concentration. This article highlights the potential use of different MOFs as biocidal material towards photosynthetic organisms and reveals important differences in the sensitivity between these organisms that should be taken into account in order to increase the biocidal spectrum of these materials.

Structural, spectroscopic, magnetic behavior and DFT investigations ofl-tyrosinato nickel(ii) coordination polymer

The 4,4′-bpy molecules are weakly bonded with nickel(ii) ions in 1Dl-tyrosinato coordination polymer.

μ3-Methoxido-κ(3) O:O:O-tris-(μ-l-p-tyrosinato-κ(3) N,O:O)tris-(l-p-tyrosinato-κ(2) N,O)trinickel(II,III) methanol tetra-solvate

A trinuclear nickel complex, [Ni₃(C₉H₁₀NO₃)₆(CH₃O)]·4CH₄O, was synthesized and characterized as a neutral cluster containing the incomplete cubane {Ni₃(μ₁-O)(μ₂-O)₂(μ₃-O)} core of 2M3–1 topology. The three nickel cations show similar octa­hedral coordination, {Ni(μ₁-O)(μ₂-O)₂(μ₃-O)(μ₁-N)₂}; the positive charge is balanced by six tyrosinate ligands and one methoxide ion. The mean oxidation state of each Ni^II ion is therefore +2.33. The common coordination modes, chelating (via the amino N and the carboxyl­ate O atoms) and bridging (via the carboxyl­ate O atom), are exhibited by the tyrosinates. Three inter­ligand (intra­cluster) N—H⋯O hydrogen-bonding inter­actions stabilize the incomplete cubane-type moiety. Additional N—H⋯O, O—H⋯O and C—H⋯O inter­actions are formed between clusters, and between the clusters and methanol mol­ecules to regulate the spatial orientation of the tyrosinate and the assembly of the clusters in the crystal. The approximate equilateral triangular arrangement of the three nickel cations in the incomplete cubane-type moiety suggests the possible magnetic frustration, and the proximity of these metal cations indicates weak metallic bonds. The structure contains approximately 39% solvent-accessible volume between the clusters. This is filled with 17 mol­ecules of disordered methanol and was modelled with SQUEEZE [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the reported unit-cell characteristics do not take these mol­ecules into account. The H atoms of the solvent mol­ecules have not been included in the crystal data.