NMR diffusion measurements on 10 different multicomponent hydrogen-bonded assemblies, viz. the three single rosettes SR1-SR3 (1 3 ؒ2a 3 , 1 3 ؒ2b 3 , 1 3 ؒ2c 3 ) the double rosettes DR1-DR5 (3a 3 ؒ2a 6 , 3b 3 ؒ2b 6 , 3c 3 ؒ2a 6 , 3d 3 ؒ2a 6 , 3e 3 ؒ2a 6 ), and DR6 (4a 3 ؒ1 6 ), and the tetrarosette TR (5 3 ؒ2a 12 ) are described. Some of the above rosettes have been previously identified as well-defined assemblies (viz. SR1, DR1-DR3, and TR) using established characterization techniques ( 1 H NMR spectroscopy, X-ray diffraction, and MALDI-TOF MS after Ag ϩ -labeling). The diffusion coefficients of these assemblies were studied and used as a reference for the identification of three new assemblies (DR4-DR6), the characterization of which could not be established unequivocally using other characterization tools. A good correlation was found between the experimental and calculated diffusion coefficients when DR1 was used as a reference. A relatively good correlation was obtained between the effective hydrolytic radii calculated from the diffusion data and those extracted from gas phase-minimized structures with SR1 and DR2 being exceptions. The diffusion measurements show that assembly DR4 is a thermodynamically stable species, while assemblies DR5 and DR6 are less stable and only present to a minor extent.

Herein we describe our results on the characterization of a wide variety of different hydrogen-bonded assemblies by means of a novel matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique with Ag+ labeling. The labeling technique with Ag+ ions is extremely mild and provides a nondestructive way to generate charged assemblies that can be detected by mass spectrometry. Up to now more than 25 different single (1(3).2(3)), double (3(3).2(6)), and tetrarosettes (4(3).2(12)) have been successfully characterized by the use of this method. The success of the method entirely depends on the presence of a suitable binding site for the Ag+ ion. A variety of functionalities has been identified that provide strong binding sites for Ag+, either acting in a cooperative way (pi-arene and pi-alkene donor functionalities) or individually (cyano and crown ether functionalities). The method works well for assemblies with molecular weights between 2,000 and 8,000 Da, and most likely far beyond this limit.

Covalent linkage of the three calix[4]arene units in hydrogen-bonded assemblies 1 3 •(DEB) 6 via a threefold ring closing metathesis (RCM) reaction quantitatively converts the dynamic assemblies into covalent systems (123-membered macrocycles) that can be easily characterized using MALDI-TOF MS and HPLC.