Hydrophobicity‐Driven Self‐Assembly of an Eighteen‐Membered Honeycomb Lattice with Almost Classical Spins

The design and synthesis of model compounds that do not exist naturally is one of the important targets in modern coordination chemistry. Herein, an eighteen‐membered honeycomb structure with equal numbers of Mn^II (s=5/2) and Gd^III (s=7/2) metal centers has been prepared, for the first time, by using a hydrophobic force‐directed self‐assembling process. Due to the weakly coupled Gd^III pairs, the magnetic properties are mainly determined by eight‐membered chains in the experimentally considered temperature range. These [Mn₄Gd₄] ”finite‐size“ chains, albeit with large Hilbert space, can be fully resolved by the high‐temperature series expansion and the powerful finite‐temperature Lanczos method, which reveal that the exchange‐couplings between the metal centers are antiferromagnetic and consistent with the magnetization measurement. Interestingly, from the surface‐engineering point of view, the [Mn₄Gd₄] chains are ”precisely“ assembled into a 2D honeycomb pattern, which is potentially desirable in the design of weakly coupled qubits.