Structural Tweaking of Zwitterionic Metallosupramolecular Assemblies for Intense NIR Emission and High Charge Carrier Mobility

Metal organic materials (MOMs) with intense NIR emission and charge transport are essential for biomedical and bioelectronic applications, particularly in devices for medical diagnostics. Metallosupramolecular assemblies guided by directional metal-ligand coordination is a viable option for creating MOMs with strong electronic communication required for targeted optical and electronic properties. Herein, we demonstrate that the zwitterionic metallosupramolecular assemblies of squaraine dyes can be structurally tweaked to exhibit exceptionally intense NIR emission on the one hand and charge carrier mobility on the other hand. We have designed a monotopic squaraine dye (MSq) and a ditopic squaraine dye (DSq) and their corresponding metallosupramolecular assemblies. Among these, the Zn²⁺ coordinated metallosupramolecular assemblies of DSq showed strong near infrared luminescence with a maximum at 666 nm whereas the one generated with MSq exhibited a high charge carrier mobility 2.5 cm²V^-1s^-1 when compared to the parent squaraine dye. This value is the highest measured for a metallosupramolecular system known till date.