Molecular Dumbbell, Sandwich, and Paddle-Wheel Assembled with Methylresorcin[4]arene Cavitands and Organooxotin Clusters

Assemblies of two methylresorcin[4]arene cavitands with Bu2SnO and n-BuSn(O)OH afforded four organooxotin-cluster-based compounds, namely, [(Bu2Sn)2(μ3-O)(L1)(EtO)]2·2EtOH (1), [(Bu2Sn)2(μ3-O)(L2)(EtO)]2·2EtOH (2), [(BuSn)12(μ3-O)14(μ2-OH)6](L1)2·2EtOH (3), and [(BuSn)(μ3-O)(L2)]6·6(toluene) (4) (HL1 = methylresorcin[4]arene cavitand-C1-COOH-in and HL2 = methylresorcin[4]arene cavitand-C1-COOH-out). It is the first time that the methylresorcin[4]arene cavitands were successfully incorporated into the organooxotin clusters. Both 1 and 2 exhibit similar dumbbell-like structures, where the skeletons of methylresorcin[4]arene cavitands stretch in different directions on account of the different configurations of the carboxylate groups of L1 and L2 anions. As a result, the C–H···π interactions lead to slightly distinct 1D supramolecular architectures of 1 and 2. 3 displays a sandwich-like structure based on one [(BuSn)12(μ3-O)14(μ2-OH)6]2+ macrocation and two L1 anions, where the macrocation is trapped in the dimeric L1 anions through O–H···O hydrogen-bonding interactions. The sandwiches further stack through π–π interactions to afford a supramolecular dimer. 4 exhibits an unusual giant paddle-wheel motif composed of a typical Sn6O6 drum and six L2 anions. Further, the paddle-wheel motifs are extended by π–π interactions to give a supramolecular layer. Moreover, the luminescent properties of 2 and 4 and the preliminary anticancer activity of 4 were also investigated.