Organoamine Templated Multifunctional Hybrid Metal Phosphonate Frameworks: Promising Candidates for Tailoring Electrochemical Behaviors and Size-Selective Efficient Heterogeneous Lewis Acid Catalysis

Abstract

The successful discovery of novel multifunctional metal phosphonate framework materials that incorporate newer organoamines and their utilization as a potential electroactive material for energy storage applications (supercapacitors) and as efficient heterogeneous catalysts are the most enduring challenges at present. From this perspective, herein, four new inorganic–organic hybrid zinc organodiphosphonate materials, namely, [C5H14N2]2[Zn6(hedp)4] (I), [C5H14N2]0.5[Zn3(Hhedp) (hedp)]·2H2O (II), [C6H16N2]­[Zn3(hedp)2] (III), and [C10H24N4]­[Zn6(Hhedp)2(hedp)2] (IV) (H4hedp = 1-hydroxyethane 1,1-diphosphonic acid), have been synthesized through the introduction of different organoamines and then structurally analyzed using various techniques. The compounds (I–IV) possess a three-dimensional network through alternate connectivity of zinc ions and diphosphonate ligands, as confirmed using single-crystal X-ray diffraction. The investigations of electrochemical charge storage behaviors of the present compounds indicate that compound III exhibits a high specific capacitance of 190 F g–1 (76 C g–1) at 1 A g–1, while compound II shows an excellent cycling stability of 90.11% even after 5000 cycles at 5 A g–1 in the 6 M KOH solution. Further, the present materials have also been utilized as active heterogeneous Lewis acid catalysts in the ketalization reaction. The screening of various substrate scopes during the catalytic process confirms the size-selective heterogeneous catalytic nature of the framework compounds. To our utmost knowledge, such a size-selective heterogeneous Lewis acid catalytic behavior has been observed for the first time in the amine templated inorganic–organic hybrid framework family. Moreover, the excellent size-selective catalytic efficiencies with the d10 metal system and recyclability performances make the compounds (I–IV) more efficient and promising Lewis acid heterogeneous catalysts.

Intrinsic Specific Activity Enhancement for Bifunctional Electrocatalytic Activity toward Oxygen and Hydrogen Evolution Reactions via Structural Modification of Nickel Organophosphonates

“…In accordance with the study performed using the BET technique, compound I displays a marginally higher surface area (6.150 m 2 /g) than compound II (2.498 m 2 /g) that may be attributed to the incorporation of auxiliary ligand in the structure of compound II and reduced surface area, similar to earlier reports (Figure 3). 17,31,55 Electrocatalytic Performances toward OER and HER. In order to investigate the electrocatalytic performance toward the OER and HER of the present materials (I and II), a threeelectrode setup was assessed in N 2 -saturated 1 M KOH and 0.5 M H 2 SO 4 electrolyte solutions.…”

“…In today’s scenario, dual-ligand approach has been taken into consideration for the synthesis of novel hybrid frameworks. − In general, metal phosphonates incorporated with different types of auxiliary ligands have given rise to distinct novel architectures of the hybrid frameworks. − Earlier, various N-containing aliphatic or aromatic ligands were utilized to form metal phosphonate hybrid structures. Such auxiliary ligands in hybrid framework structures can act as templates or structure-directing agents, and they can also coordinate with different metal centers to generate various molecular structures to 3D hybrid metal phosphonate frameworks. − ,− Among various N-containing auxiliary ligands, pyrazine-based metal phosphonate hybrid structures are very less explored until date. − The diverse alignment of the pyrazine ligand, which often binds with different metal centers, as well as the flexible coordination of phosphonate moieties not only provides new metal phosphonate architectures but also offers a versatile platform for designing active electrocatalysts to promote water-splitting reactions.…”

Bifunctional Role of Methyl Viologen in UV and X-ray Sensitive Switchable Organophosphonate Single Crystal

“…Despite the few X-ray-induced photochromic materials, recently viologen and their analogues, especially the methyl viologen (MV; N , N ′-dimethyl-4,4′-bipyridinium), holding an electron-deficient nature, have been considered to be ideal candidates to exhibit prominent UV and X-ray-induced photochromism with assistance of a suitable electron-rich moieties via efficient electron transfer pathway. ,− Generally, it can be seen that the methyl viologen based compounds can form different photogenerated intermediate species such as neutral MV 0 , radical cation MV •+ , or dication MV 2+ , depending upon the coordination behaviors of electron-rich units during photochromic redox process. − Moreover, incorporation of the MV into an organophosphonate compound can create more opportunity for isolating novel organic–inorganic hybrid structures as compared to earlier explored various traditional inorganic anions, holding fewer coordination opportunities. − Particularly, electron rich oxygen atoms of the organophosphonate moiety bind with different metal ions by diverse coordination linkages that often exhibit versatile architectures including interesting topologies. − MV regulated hybrid organophosphonate structure and X-ray induced photochromic behavior is still underdeveloped in the field of material chemistry.…”

Blue-Emitting Ligand-Mediated Assembly of Rare-Earth MOFs toward White-Light Emission, Sensing, Magnetic, and Catalytic Studies

“…ESI-MS for the products of the catalytic reaction is given in Figures S43–S50. The turnover number (TON) of the catalytic reaction has been calculated, and the values are given in Table . − The recyclability of the Tb-MOF catalyst was examined under the standardized conditions, which gave yields of 95, ∼89, and ∼87%, respectively (Figure ). For recyclability studies, the catalyst was separated by centrifugation and washed several times with fresh DMF, and dried at 70 °C in an oven for 2 h, which was utilized for the recyclability studies under similar reaction conditions.…”