Coordination/Metal–Organic Cages Inside Out

Abstract

Cage-like molecules, assembled by the coordination of multiple metal ions and organic links, are pushing new frontiers in science due to their design flexibility and the resulting diverse and unique chemical properties. This field has been advanced by two close but distinct chemistry communities. Consequently, the family of molecules referred to as coordination cages (CCs) constituted of metal-pyridine coordination bonds or metal–organic cages (MOCs) based on dinuclear tetracarboxylates paddlewheel complexes in each community had not been reviewed cross-sectionally, even though they are conceptually similar. This review article extracted and compared experimental information on a total of 197 CCs and 78 MOCs from 182 reports to identify their synthetic and structural signatures. We did not merely enumerate the reports we collected; we meta-analyzed the data extracted from the reports and highlighted both the similarities and dissimilarities between CCs and MOCs. As a result, we clarified the key parameters governing the synthetic conditions. Furthermore, we identified a new research direction by visualizing unexplored features and properties of CCs and MOCs. This review article provides a good tutorial both for researchers attempting to cross the boundary between CCs and MOCs and those who are new to the field.

Rational design of metal-organic cages to increase the number of components via dihedral angle control

“…Metal-organic cages [11][12][13] are a well-established class of artificial self-assembled structures composed of multitopic ligands (L) and transition metal ions (M). The formation of M-L coordination bonds is the dominant enthalpic driving force of self-assembly.…”

“…The environments of two types of 4-pyridyl groups of the [Pd'242] 4+ ring parts (a 2 protons) in the square sheet might be magnetically identical. CSI FT-ICR mass measurement of the solution detected the signals for [Pd'1248] 24+square sheet as several ionic species of [Pd'1248(BF4)x(NO3)yF6] (18-xy)+ (x, y) = (1,13),(2,12),(3,11), (0,13),(1,12),(2,11), (10,2), (11,1), (12,0), (11,0) (FigureS26). The [Pd'1248] 24+ square sheet was further characterized by (H,H)-COSY, (H,H)-NOESY,13 C NMR, HSQC, and HMBC spectroscopy (FiguresS27-S31).…”