Design and Applications of Water-Soluble Coordination Cages

Abstract

Compartmentalization of the aqueous space within a cell is necessary for life. In similar fashion to the nanometer-scale compartments in living systems, synthetic water-soluble coordination cages (WSCCs) can isolate guest molecules and host chemical transformations. Such cages thus show promise in biological, medical, environmental, and industrial domains. This review highlights examples of three-dimensional synthetic WSCCs, offering perspectives so as to enhance their design and applications. Strategies are presented that address key challenges for the preparation of coordination cages that are soluble and stable in water. The peculiarities of guest binding in aqueous media are examined, highlighting amplified binding in water, changing guest properties, and the recognition of specific molecular targets. The properties of WSCC hosts associated with biomedical applications, and their use as vessels to carry out chemical reactions in water, are also presented. These examples sketch a blueprint for the preparation of new metal–organic containers for use in aqueous solution, as well as guidelines for the engineering of new applications in water.

Increasing structural and functional complexity in self-assembled coordination cages

“…A similar approach was developed by Fujita and co-workers to synthesize a heteroleptic [ rhombicuboctahedron, 32 up to a [Pd 30 L 60 ] icosidodecahedron, 75 by tuning the ligands' binding angles, lengths and exibility. In order to further develop this principle to achieve heteroleptic assembly, two bis-pyridine ligands (18,19) bearing the same binding angle of 120 , but different length, were employed. Combining each of these ligands alone with Pd II cations leads to the formation of homoleptic [Pd 12 L 24 ] spheres.…”

“…[1][2][3][4] Routes to assemble such compounds can be primarily subclassied into hydrogen-bonded, 5,6 dynamic-covalent [7][8][9][10][11][12] and metal-mediated approaches. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In the latter category, most systems are built up from a combination of two major components: metal centres acting as nodes, and organic ligands serving as bridges to join the nodes into a regularly shaped, 3-dimensional object with an accessible cavity. Metal nodes are mostly from the transition elements, but systems based on main group metals have been reported as well.…”

Supramolecular Interaction of Molecular Cage and β‐Galactosidase: Application in Enzymatic Inhibition, Drug Delivery and Antimicrobial Activity

“…In biological systems, barrel‐shaped molecules such as β‐ barrel proteins are known for diffusing the small molecules and ions across cell membranes [19] . In this regard, various barrel‐shaped molecules having large intrinsic cavities have been reported in literature with potential applications in biology [20] …”

Electrochemical Recognition of Aromatic Species with Ferrocenylated 1,3,5‐Triazine‐ or 1,3,5‐Triphenylbenzene‐Containing Highly Organized Molecules

“…[7][8][9] Cage or cage-like compounds, which are commonly synthesized by utilizing dynamic covalent chemistry concepts starting from various building blocks, act as the prominent class of highly organized organic compounds for various applications. [10][11][12][13][14][15] Importantly, the introduction of redox-active species to the above-discussed molecules is an interesting approach toward tuning their properties and functions and opening new areas of applications. [16][17][18][19] Ferrocene (Fc), a redox-active metallocene, is commonly a first-or best-choice molecule for such purpose, because of its stability in air, good solubility in many organic solvents, as well as its electrochemical and thermal stability.…”