Carboxylic Acid Functionalized Clathrochelate Complexes: Large, Robust, and Easy-to-Access Metalloligands

Abstract

Polycarboxylate ligands are among the most important building blocks for the synthesis of metal-organic frameworks (MOFs). The ability to access these ligands in an efficient way is of key importance for future applications of MOFs. Here, we demonstrate that mono- and dinuclear clathrochelate complexes are versatile scaffolds for the preparation of polytopic carboxylate ligands. The largely inert clathrochelate complexes have a trigonal-bipyramidal shape. The synthesis of functionalized clathrochelates with two, three, four, or five carboxylic acid groups in the ligand periphery can be achieved in a few steps from simple starting materials. Apart from being easily accessible, the metalloligands display interesting characteristics for applications in metallasupramolecular chemistry and materials science: they are rigid, large (up to 2.2 nm), and robust and they can show additional functions (e.g., fluorescence or extra charge) depending on the metal ion that is present in the clathrochelate core. The utility of these new metalloligands in MOF chemistry is demonstrated by the synthesis of zinc- and zirconium-based coordination polymers. The combination of Zn(NO3)2 with clathrochelates having two or three carboxylic acid groups gives MOFs in which the clathrochelate ligands are connected by Zn4O clusters or zinc paddlewheel links. The structures of the resulting two- and three-dimensional networks could be established by single-crystal X-ray crystallography. The reaction of carboxylic acid functionalized clathrochelates with ZrCl4 gives amorphous powders that display permanent porosity after solvent removal.

Dinuclear clathrochelate complexes with pendent cyano groups as metalloligands

“…So far, efforts have focused on clathrochelates with pendent pyridyl 9 or carboxylic acid groups. 10 Below, we show that clathrochelates can also be decorated with cyano groups. Following two distinct synthetic strategies, we were able to prepare clathrochelates containing two, three, four, or five cyano groups which are oriented in a divergent fashion.…”

Template Synthesis and X-Ray Structure of the First Cobalt(II) Glyoximate Clathrochelate with Terminal Formyl Groups

“…Very recently, the corresponding mononuclear tris-glyoximate iron(II) clathrochelates [7] and their aliphatic tris-dioximate analogs, [8] as well as the homobinuclear manganese(II) and cobalt(II) 4-formylphenylboron-capped clathrochelates [8] have been prepared and X-ray structurally characterized. Among them, the binuclear cage complexes are reported in [4] to be prospective for production of magnetic materials: for example, the binuclear cobalt(II) clathrochelates with pendant carboxylic acid groups showed high-spin state of their encapsulated cobalt(II) ions. In this work we report the synthesis and X-ray structure of the first mononuclear macrobicyclic cobalt(II) trisglyoximate with terminal formyl groups.…”

“…Among them, the binuclear cage complexes are reported in [4] to be prospective for production of magnetic materials: for example, the binuclear cobalt(II) clathrochelates with pendant carboxylic acid groups showed high-spin state of their encapsulated cobalt(II) ions. In this work we report the synthesis and X-ray structure of the first mononuclear macrobicyclic cobalt(II) trisglyoximate with terminal formyl groups.…”

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Cobalt(II) tris-glyoximate clathrochelate CoGm 3 (B4-CКлючевые слова: Макроциклические соединения, клатрохелаты, темплатная конденсация.Mono-and binuclear clathrochelate complexes with functionalizing apical and ribbed substituents containing terminal donor groups such as pyridine, carboxylic or cyano groups as prospective rigid and robust macrobicyclic ligands towards transition and main groups metal ions are reported in [1][2][3][4][5][6] allowing to obtain a wide range of nanosized heterometallic clathrochelate-based metallomacrocycles, coordination polymers and cages. On the other hand, the formyl-terminated clathrochelates seems to be suitable ligand synthones or monomers for the design and synthesis of the imine coordination cages and coordination polymers and their amine derivatives as well.

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Synthesis and characterisation of two Cu(I) metalloligands based on tetradentate tripodal ligands

“…Recently, the design and synthesis of metalloligands for use as building blocks in supramolecular chemistry has been of increasing interest [1][2][3] due to their usefulness for precisely controlling the construction of larger homo or hetero metallo-supramolecular entities. Despite considerable effort devoted to the development of different metalloligand types, their synthesis for use in producing new supramolecular architectures with designed properties remains a significant challenge [4][5][6][7][8][9][10].…”