Design, Synthesis, Magnetic Properties, and Hydrogen Evolution Reaction of a Butterfly-like Heterometallic Trinuclear [CuII2MnII] Cluster

A novel heterometallic trinuclear cluster [CuII2MnII(cpdp)(NO3)2(Cl)] (1) has been designed and synthesized by employing a molecular library approach that uses CuCl2·2H2O and Mn(NO3)2·4H2O as inorganic metal salts and H3cpdp as a multifunctional organic scaffold (H3cpdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol). This heterometallic cluster has emerged as an unusual ferromagnetic material and promising electrocatalyst for hydrogen evolution reaction (HER) in the domain of inorganic and materials chemistry. Crystal structure analysis establishes the structural arrangement of 1, revealing a butterfly-like topology with an unusual seven-coordinated Mn(II) center. Formation of this cluster is accomplished by a self-assembly process through functionalization of 1 with one μ2:η1:η1-nitrate and two μ2:η2:η1-benzoate groups via the CuII(μ2-NO3)CuII} and {CuII(μ2-O2CC6H5)MnII} linkages, respectively. Variable-temperature SQUID magnetometry revealed the coexistence of ferromagnetic and antiferromagnetic interactions in 1. The observed magnetic behavior in 1 is unexpected because of a large Cu-O-Mn angle with a value of 132.05°, indicating that the correlation between coupling constants and the structural parameters is a multifactor problem. This cluster shows excellent electrocatalytic performance for the HER attaining a current density of 10 mA/cm2 with a Tafel slope of 183 mV dec-1 at a 310 mV overpotential value. Essentially, cluster 1 shows exceptional electrochemical stability at ambient temperature, accompanied by minimal degradation of the current density as examined by chronoamperometric studies. Density functional theory calculations establish the mechanistic insight into the HER process, indicating that the CuII-OCO-MnII site is the active site for formation of molecular hydrogen.

Achieving stable photoluminescence by double thiacalix[4]arene-capping: the lanthanide-oxo cluster core matters

Luminescence stability is a critical consideration for applying phosphors in practical devices. In this work, we report two categories of double p-tert-butylthiacalix[4]arene (H₄TC4A) capped clusters that exhibit characteristic lanthanide luminescence. Specifically, {[Ln₄(μ₄-OH)(TC4A)₂(DMF)₆(CH₃OH)₃(HCOO)Cl₂]}·xCH₃OH (Ln = Eu (1), Tb (2); x = 0–1) with square-planar [Ln₄(μ₄-OH)] cluster cores and {[Ln₉(μ₅-OH)₂(μ₃-OH)₈(OCH₃) (TC4A)₂ (H₂O)₂₄Cl₉]}·xDMF (Ln = Gd (3), Tb (4), Dy (5); x = 2–6) with hourglass-like [Ln₉(μ₅-OH)₂(μ₃-OH)₈] cluster cores are synthesized and characterized. By comparing 2 and 4, we find that several critical luminescence properties (such as quantum efficiency and luminescence stabilities) depend directly on the cluster core structure. With the square-planar [Ln₄(μ₄-OH)] cluster cores, 2 demonstrates high quantum yield (∼65%) and excellent luminescence stability against moisture, high temperature, and UV-radiation. A white light-emitting diode (LED) with ultrahigh color quality is successfully fabricated by mixing 2 with commercial phosphors. These results imply that high quality phosphors might be achieved by exploiting the double thiacalix[4]arene-capping strategy, with an emphasis on the cluster core structure.

{Ln₄} cores outperform {Ln₉} cores in achieving stable photoluminescence from double thiacalix[4]arene-capped lanthanide-oxo clusters.

Impact of flexible succinate connectors on the formation of tetrasulfonylcalix[4]arene based nano-sized polynuclear cages: structural diversity and induced chirality study

The formation of three types of supramolecular coordination cages is described. Tetrasulfonylcalixarene, combined with metallic salts (Ni, Co and Zn) and the flexible succinate ligand, led to cages. H bonded induced chirality was observed for both isomorphous cages.

Thiacalixarene-Supported Irregular Co26 and Ni28 High-Nuclearity Clusters with Pyridyl-Diphosphonates: Strategies to Create Active Metal Sites and Fabricate Multicomponent Materials

Two new irregularity high-nuclearity clusters [Co₂₆(TC4A)₆(HL)₄Cl₄(HCOO)₄(CH₃O)₂(OH)₂(DMF)₁₀(H₂O)₅] (+ solvent) (Co₂₆) and [Ni₂₈(TC4A)₆(HL)₆(PO₄)₂(μ₃-O)₂Cl₂(CH₃OH)₁₄(H₂O)₂(DMF)₈][(CH₃NH₂CH₃)₄] (+ solvent) (Ni₂₈) have been solvothermally synthesized by p- tert-butylthiacalix[4]arene (H₄TC4A), transition metals (CoCl₂·6H₂O/NiCl₂·6H₂O), and 1-hydroxy-2-(3-pyridinyl)ethylidene-1,1-diphosphonic acid (H₅L). The clusters were structurally characterized by single crystal X-ray diffraction, PXRD, TGA, and FT-IR spectrum and Raman spectrum. Co₂₆ features a rodlike Co₂₆ core constructed by six Co₄-TC4A secondary building units (SBUs) and four HL^4- with two extra cobalt ions. Ni₂₈ cluster represents a flowerlike Ni₂₈ core built from six Ni₄-TC4A SBUs, six HL^4-, and four additional nickel ions. The multidentate risedronic acid displaying various new coordination mode bonds with SBUs to assemble two nanoclusters that enable high density possible coordinatively unsaturated metal sites (PCUMSs). Co₂₆ and Ni₂₈ clusters can be directly dispersed on carbon paper (CP) and showed extraordinary oxygen evolution reaction (OER) activity due to the larger exposed liable coordination active metal sites. The thermodecomposition of both nanoclusters at different temperatures afforded serial multicomponent complexes.

A high-nuclearity complex containing a decanuclear iron(iii)/oxo cage in a football-like structure and rare (R-/S)-hemiacetalate ligands in a butterfly-like format

A challenge in the field of high nuclearity Fe(iii)/oxo cluster chemistry remains the development of new synthetic methods to such molecules. In this work, the employment of pyridine-2-carboxaldehyde (py-2-al) in high-nuclearity transition-metal cluster chemistry has provided access to an unprecedented decanuclear iron(iii) complex, [Fe₁₀(NO₃)₇(O)₆(OH_0.5)₂((S)-py-hemi)₄((R)-py-hemi)₄]·4H₂O (1) ((R-/S)-py-hemi = (R-/S)-pyridine-2-carboxaldehyde hemiacetalate). The synthesis, beautiful structure and the physical characterization (thermal gravimetric analysis, X-ray powder diffraction, proton nuclear magnetic resonance, magnetic susceptibility) of complex 1 are described in this contribution. Complex 1 provides a new route to obtain high nuclearity magnetic clusters with beautiful structures.

The employment of pyridine-2-carboxaldehyde in high-nuclearity cluster chemistry has provided access to a decanuclear iron(iii)/oxo cage in football-like structure and unusual (R-/S)-hemiacetalate ligands in butterfly-like format.

The remarkable influence of N,O-ligands in the assembly of a bis-calix[4]arene-supported [MnIV2MnIII10MnII8] cluster

Bis-calix[4]arene is a highly versatile ligand that is capable of forming a range of polymetallic clusters. Use of an N,O-chelating co-ligand affords a very high nuclearity mixed-valence Mn cluster (shown here) that displays coordination modes relative to each ligand type.

Syntheses, structures, luminescence and magnetic properties of three high-nuclearity neodymium compounds based on mixed sulfonylcalix[4]arene-phosphonate ligands

The solvothermal reactions of p-tert-butylsulfonylcalix[4]arene (H₄BSC4A), phosphonic acid and neodymium chloride have resulted in three novel high-nuclearity neodymium coordination compounds.

Construction of Fe6, Fe8 and Mn8 metallamacrocyclic complexes and magnetic properties

Hexanuclear-based 1 and octanuclear metallamacrocycle-based three-dimensional isostructural framework 2 and 3 have been obtained and characterised. Magnetic susceptibility measurements show that the three complexes display antiferromagnetic couplings.