| Abstract
| - A supramolecular dimeric rhomboid and its trimeric counterpart, a hexagon, are generated bydesign via the directional bonding methodology of self-assembly. The different-sized supramolecularmacrocycles formed by Pt-coordination undergo a concentration- and temperature-dependent dynamicequilibrium. The two structures are characterized by multinuclear NMR and ESI-MS. Extensive study ofthe dynamic equilibrium of the two species in solution is performed to obtain its thermodynamic properties.By varying the ionic strength, μ, of the solutions, the true thermodynamic equilibrium constant, K, isdetermined at each experimental temperature (K253 = 36 ± 7, K273 = 18 ± 6, K293 = 10 ± 3, K313 = 9 ±2, K333 = 5 ± 2, and K353 = 3.0 ± 0.2). By applying these values of trueK at the respective temperaturesto the van't Hoff equation extended with the entropy term, the standard enthalpy and entropy changes aredetermined for the equilibrium: with ΔH° = −18 ± 1 kJ mol-1 and ΔS° = −43 ± 4 J mol-1 K-1, respectively,for the forward reaction (rhomboid to hexagon) of the equilibrium. The rhomboid is selectively crystallized,and its crystal structure is determined by X-ray diffraction. The structure reveals a significant amount ofporosity as well as distortion of the rhomboid from planarity, leading to channels that can be observedfrom two viewing positions of the packing.
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