Controlled Supramolecular Polymerization of d⁸ Metal Complexes through Pathway Complexity and Seeded Growth

Abstract

In recent years, pathway complexity has been studied in detail for a large variety of organic and π-conjugated molecules. However, such investigations on their metal-containing analogues have received only little attention to date, despite the well-known potential of metal complexes in various fields. In this Minireview, we have collected recent examples of d 8 metal complexes (Pt(II), Pd(II) and Au(III) complexes) exhibiting controlled supramolecular polymerization through pathway complexity and seeded-growth approaches. Controlling the competing thermodynamic vs. kinetic pathways in these systems should help develop advanced metallosupramolecular functional materials with excellent photophysical, electronic, magnetic, catalytic, and biomedical applications.

Externally Regulated Specific Molecular Recognition Driven Pathway Selectivity in Supramolecular Polymerization

“…Supramolecular polymers of π‐systems [1–5] have emerged as an intense research field in the past decade for fundamental studies, potential application in organic electronics [6–8] and as adaptive scaffolds for designing new biomaterials [9] . In the recent past it has been recognized that the co‐existence of multiple competitive pathways may lead to different assemblies (and sometimes mixtures of products) [10–27] with distinct internal order or morphology, similar to what has been frequently observed in the formation and growth process of protein fibrils [28] or polymorphic crystals [29] of small molecules. Therefore, controlling the polymerization pathway becomes imperative to produce a specific desired product with well‐defined molecular packing and mesoscopic structure, which may strongly influence the optical properties, charge transport and other features and thus the functional utility.…”

“…Therefore, controlling the polymerization pathway becomes imperative to produce a specific desired product with well‐defined molecular packing and mesoscopic structure, which may strongly influence the optical properties, charge transport and other features and thus the functional utility. In presence of different competing pathways, it is a challenging task to steer the supramolecular polymerization in a selective pathway, which has been exemplified in the recent past [10–27] by tuning the experimental conditions such as the monomer concentration, cooling rate, solvent composition, solvent shape or solution preparation method. In contrast, molecular chaperones assist specific folding pathways and inhibit an undesired aggregation of proteins or other biomacromolecules by specific binding [30] .…”

Emerging applications for living crystallization-driven self-assembly

“…Other examples of molecular amphiphiles that undergo living supramolecular polymerization include amphiphilic square planar Pt(II) phenanthroline and related complexes, [225][226][227][228][229] perylene bisimides, 221,230 and a wide range of additional π-stacking and hydrogen-bonding species. 210,231,232 Complex architectures, such as well-defined supramolecular block copolymers, have also been successfully prepared and their study represents an exciting new area within the flourishing field of supramolecular polymers.…”

Intense Red‐Blue Luminescence Based on Superfine Control of Metal–Metal Interactions for Self‐Assembled Platinum(II) Complexes

“…Assembly-induced luminescence has been investigated based on the design of ligands for the assembled systems to develop sensor materials for heat, pressure,v olatile organic compounds,a nd other stimuli. [4,5] However,s ince self-assembled structures are controlled by various factors kinetically and thermodynamically, [11] the construction of desired structures with precisely controlled Pt•••Pt distances is difficult not only in solution, but also in the crystal state. [12] Self-assembly systems with metalmetal interactions have been developed for other metal complexes such as Rh I and Pd II complexes with the same d 8 configuration as that of Pt II complexes, [13] and Au I and Ag I complexes with ad 10 configuration.…”