Effect of axial coordination environment on quantum tunnelling magnetization for dysprosium single ion magnet with theoretical insight

Herein, we report two mononuclear Dysprosium complexes [Dy(H4L){B(OMe)2(Ph)2}2](Cl)∙MeOH (1), and [Dy(H4L){MeOH)2(NCS)2](Cl) (2) (where H4L = 2,2′-(pyridine-2,6-diylbis(ethan-1-yl-1-ylidene))bis(N-phenylhydrazinecarboxamide) with different axial coordination environment. The structural analysis revealed that the pentadentate H4L ligand...

Ultra-Sensitive Detection of Pyridine in Water Using Zinc Porphyrin Incorporated in a Transparent Hydrophobic Film

In this study, we investigated the axial coordination reaction between pyridine and zinc meso-tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) incorporated in a transparent layered double hydroxide (LDH) film modified with 1-decanesulfonate (C10S) in an aqueous solution. The equilibrium constant (\({K}_{11}\)) of the axial coordination reaction between pyridine and ZnTPPS incorporated in the transparent ZnTPPS/C10S/LDH film was approximately 260 times that of the corresponding reaction in an aqueous solution. The hydrophobisation of the LDH interlayer space by C10S, which led to the elimination of water molecules surrounding ZnTPPS and enabled the accumulation of pyridine molecules, was responsible for such a significant increase in the \({K}_{11}\) value. The developed film can detect pyridine in aqueous solutions with ultra-high sensitivity in the order of 10−5 mol/L through changes in the colour tone, which is comparable to the molecular detection ability of insect antennae. The sensing response was also observed at pyridine concentrations as low as 10−9 mol/L.

Ultra-Sensitive Detection of Pyridine in Water Using Zinc Porphyrin Incorporated in a Transparent Hydrophobic Film

In this study, we investigated the axial coordination reaction between pyridine and zinc meso-tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) incorporated in a transparent layered double hydroxide (LDH) film modified with 1-decanesulfonate (C10S) in an aqueous solution. The equilibrium constant (K11) of the axial coordination reaction between pyridine and ZnTPPS incorporated in the transparent ZnTPPS/C10S/LDH film was approximately 260 times that of the corresponding reaction in an aqueous solution. The hydrophobisation of the LDH interlayer space by C10S, which led to the elimination of water molecules surrounding ZnTPPS and enabled the accumulation of pyridine molecules, was responsible for such a significant increase in the K11 value. The developed film can detect pyridine in aqueous solutions with ultra-high sensitivity in the order of 10−5 mol/L through changes in the colour tone, which is comparable to the molecular detection ability of insect antennae. The sensing response was also observed at pyridine concentrations as low as 10−9 mol/L.

Spin Crossover in Nickel(II) Tetraphenylporphyrinate via Forced Axial Coordination at the Air/Water Interface

Coordination-induced spin crossover (CISCO) in nickel(II) porphyrinates is an intriguing phenomenon that is interesting from both fundamental and practical standpoints. However, in most cases, realization of this effect requires extensive synthetic protocols or extreme concentrations of extra-ligands. Herein we show that CISCO effect can be prompted for the commonly available nickel(II) tetraphenylporphyrinate, NiTPP, upon deposition of this complex at the air/water interface together with a ruthenium(II) phthalocyaninate, CRPcRu(pyz)2, bearing two axial pyrazine ligands. The latter was used as a molecular guiderail to align Ni···Ru···Ni metal centers for pyrazine coordination upon lateral compression of the system, which helps bring the two macrocycles closer together and forces the formation of Ni–pyz bonds. The fact of Ni(II) porphyrinate switching from low- to high-spin state upon acquiring additional ligands can be conveniently observed in situ via reflection-absorption UV-vis spectroscopy. The reversible nature of this interaction allows for dissociation of Ni–pyz bonds, and thus, change of nickel cation spin state, upon expansion of the monolayer.

Increasing the CO2 Reduction Activity of Cobalt Phthalocyanine by Modulating the σ-donor Strength of Axially Coordinating Ligands

<p>Axial coordination of a pyridyl moieties to CoPc (either exogenous or within poly-4-vinylpyridine polymer) dramatically increases the complex’s activity for CO₂RR. It has been hypothesized that axial coordination to the Co active site leads to an increase in the Co dz² orbital energy, which increases the complex’s nucleophilicity and facilitates CO₂ coordination compared to the parent CoPc complex. The magnitude of the energy increase in the Co dz² orbital should depend on the σ-donor strength of the axial ligand—a stronger σ-donating ligand (L) will increase the overall CO₂RR activity of axially coordinated CoPc(L) and vice versa. To test this, we have studied a series of CoPc(L) complexes where the σ-donor strength of L is varied. We show that CoPc(L) reduces CO₂ with an increased activity as the σ-donor ability of L is increased. These observed electrochemical activity trends are correlated with computationally-derived CO₂ binding energy and charge transfer terms as a function of σ-donor strength. The findings of this study supports our hypothesis that the increased CO₂RR activity observed upon axial coordination to CoPc is due to the increased energy of the dz² orbital, and highlight an important design consideration for macrocyclic MN₄-based electrocatalysts.</p><p> </p><p> </p>

Increasing the CO2 Reduction Activity of Cobalt Phthalocyanine by Modulating the σ-donor Strength of Axially Coordinating Ligands

<p>Axial coordination of a pyridyl moieties to CoPc (either exogenous or within poly-4-vinylpyridine polymer) dramatically increases the complex’s activity for CO₂RR. It has been hypothesized that axial coordination to the Co active site leads to an increase in the Co dz² orbital energy, which increases the complex’s nucleophilicity and facilitates CO₂ coordination compared to the parent CoPc complex. The magnitude of the energy increase in the Co dz² orbital should depend on the σ-donor strength of the axial ligand—a stronger σ-donating ligand (L) will increase the overall CO₂RR activity of axially coordinated CoPc(L) and vice versa. To test this, we have studied a series of CoPc(L) complexes where the σ-donor strength of L is varied. We show that CoPc(L) reduces CO₂ with an increased activity as the σ-donor ability of L is increased. These observed electrochemical activity trends are correlated with computationally-derived CO₂ binding energy and charge transfer terms as a function of σ-donor strength. The findings of this study supports our hypothesis that the increased CO₂RR activity observed upon axial coordination to CoPc is due to the increased energy of the dz² orbital, and highlight an important design consideration for macrocyclic MN₄-based electrocatalysts.</p><p> </p><p> </p>