Two different macrocyclic hosts are amplified and expressed by metal guests from the same dynamic combinatorial library (DCL) of oligoimines. We studied the thermodynamic template effect and the structure of the final compounds by a combination of ESI-MS, UV and NMR spectroscopy, and Xray crystallography techniques. The use of Ba II or Cd II metal salts allows the selective synthesis of dimeric [2+2] or trimeric [3+3] cyclic structures, respectively. We observed a cooperative molding effect for the Cd ion-templated process. A study of the DCL behavior in situ demonstrated a second level of molecular diversity, based on the imine/α-methoxy-

Cadmium promoted diastereoselective amplification of a single member from a dynamic combinatorial library of stereoisomeric oligoimines of different sizes allows the efficient preparation of a new macrocyclic polyamine.

An encapsulated Cu3(OH)2 ensemble is formed within a macrocyclic ligand consisting of three (R,R)‐1,2‐cyclohexanediamine residues linked through 2,6‐dimethylpyridine spacers (see picture; Cu orange, O red, N blue). Its crystal structure, magnetic behavior, and characterization in solution by potentiometric measurements and paramagnetic 1H NMR spectroscopy are reported.

The interaction of a synthetic enantiopure azamacrocyclic receptor (L) with biologically important chiral dicarboxylates (A, 1-7) has been studied by means of potentiometric titrations in 0.15 M NaCl aqueous solution in a wide pH range. This macrocycle forms strong complexes of the type [HnLA](n-2) (with n = 0-5). As a general trend, the binding is much tighter at basic or neutral pH than in acidic medium. Interestingly, nonprotected excitatory amino acids (Asp and Glu) are strongly bound even at acidic pH. Regarding selectivity, the receptor showed stereoselective binding toward those substrates bearing an H-bonding donor at Calpha, being S-selective in most of the cases, except for glutamic acid. Thus, L displayed an excellent enantioselectivity for (S)-malate dianion (KS/KR = 11.50 at pH 10.0 and KS/KR = 6.86 at pH 7.0) and exhibited moderate enantiopreference for (S,S)-tartrate (KSS/KRR = 3.01 at pH 10 and KSS/KRR = 1.70 at pH 7.0). For this last anion, a very good diastereopreference was also observed (KSS/KRS = 8.46 at pH 10 and KSS/KRS = 4.99 at pH 7.0). On the contrary, L is smoothly R-selective toward (R)-Glu (KR/KS = 3.22 at pH 10 and KR/KS = 2.05 at pH 7.0) due to its longer and more flexible molecular structure. The stereoselectivity of the corresponding complexes decreased when decreasing pH values. For the hydroxy derivatives, mass spectrometry also reflected the trends observed by potentiometry and confirmed the receptor:dicarboxylate 1:1 stoichiometry of the supramolecular complexes. Additional experimental techniques were used to study the most stereoselective example. Solution studies by NMR suggested a good geometrical complementarity between the malate dianion and the receptor, which showed a predominant helical conformation in solution. Besides, self-diffusion rates (PGSE) of the diastereomeric complexes with malate also agree with binding data. Circular dichroism was also used in this case at different pH values, showing a very good correlation between the helical content of the receptor and the stereoselectivity of the molecular recognition process.