Engineering Supramolecular {HAT(CN)6;Oligoresorcinol;Anion} Synthons and Knots via Cooperating Multimodal Noncovalent Interactions.

Abstract

The interplay of multiple noncovalent interactions offers a powerful strategy for the design of functional supramolecular architectures. Here, we developed a unique series of ternary cocrystal salt-like {coformer1;coformer2;salt} systems in the solid state and in solution to approach the problem of collective binding of halide (Cl-, Br-) or pseudohalide (SCN-) anion pairs. Exploiting HAT(CN)6 π-acid (coformer1) and oligoresorcinol hydrogen-bond donors (coformer2), we identify five new ternary {coformer1;coformer2;[anion]n} (n = 1-2) supramolecular synthons that integrate anion-π interactions, π-π stacking, and hydrogen bonding, reflecting the intrinsic preferences of components. SC XRD and solution 1H/13C NMR studies demonstrate transferability of the synthons among the relevant binary and ternary crystal phases, as well as between the solid state and solution. DFT+D computational analysis confirms the contribution of all three types of supramolecular interactions to the formation and stability of observed motifs, showing a variable hierarchy of these forces modulated by the structural and electronic features of building blocks. Our results demonstrate that while crystal packing influences solid-state arrangements, system's integrity arises from a balance of cooperation and competition among noncovalent interactions. This establishes a new library of complex supramolecular synthons for further consideration in overall supramolecular design.