Self-Assembled Architectures of Alkynylplatinum(II) Amphiphiles and Their Structural Optimization: A Balance of the Interplay Among Pt···Pt, π–π Stacking, and Hydrophobic–Hydrophobic Interactions

Abstract

A series of alkynylplatinum(II) terpyridine complexes with triethylene glycol units was synthesized, and their self-assembly properties were investigated in solution by UV-vis absorption, emission, and H NMR spectroscopy. The aggregation behaviors of several water-soluble complexes were investigated in aqueous media. Some of them were found to give rise to uniform fibers, suggesting the important role that triethylene glycol units has in regulating their self-assembly properties. Further modifications of these structures through the incorporation of alkyl chains and changes in counter-anions have rendered the complexes more amphiphilic in nature, and the effect of their alkyl chain lengths was studied and optimized. The distinguishable color and spectral changes upon variations in solvent compositions might have potential applications in developing colorimetric and luminescent probes for the detection of microenvironment change. Furthermore, an optimum chain length, i.e., n-butyl chain, is required for the formation of stable and ordered nanostructures. This represents a delicate balance among Pt···Pt, π-π stacking, and hydrophobic-hydrophobic interactions and provides guiding principles into the construction of supramolecular materials with practical applications.

Supramolecular assembly of bent dinuclear amphiphilic alkynylplatinum(ii) terpyridine complexes: diverse nanostructures through subtle tuning of the mode of molecular stacking

“…The more negative DG value for 6 compared to 5 can be attributed to the additional hydrophobic interactions by the longer alkoxy chains. [65][66][67] This observation, which highlights the importance of long alkoxy substituents in the self-assembly of transition-metal complexes, agrees with other works in the literature. [65][66][67] The more negative DG value for 7 compared to 5 and 6 might hint that the interactions between the hydrophilic substituents with water can constitute another dominating factor relative to hydrophobic interactions in promoting self-assembly in DMSO-H 2 O mixtures.…”

Supramolecular adhesive materials from small‐molecule self‐assembly

“…have been developed by the self-assembly of building blocks. Diverse noncovalent interactions include hydrogen-bonding, 12,13 π-π stacking, 14,15 van der Waals interactions, 16,17 electrostatic interactions, 18 hydrophobic effects, 19,20 host-guest interactions 21,22 and dynamic covalent bonds. [23][24][25] Precisely tuned precursor molecules organize into desired ensembles with distinct physicochemical properties via the "bottom-up" approaches.…”

“…36,37,47 Generally, there has been a family of supramolecular toolboxes whose fundamentals have been well established, such as hydrogen bonds, host-guest interactions, metal coordination, hydrophilic/hydrophobic force, and Columbic force. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] The reversibility of noncovalent interactions enables the dynamic modulation of intermolecular interactions by external stimuli, including light, temperature, pH, chemical redox, and microenvironments. 48,49 The related studies about macromolecular adhesives and coatings have emerged over the past two decades, which have been well summarized in several outstanding reviews.…”

Self-healing, luminescent metallogelation driven by synergistic metallophilic and fluorine–fluorine interactions

“…It is well documented in the literature that achiral gelators tend to form helical structures with both handedness. 64,65 Importantly, triazine-containing alkynylplatinum(II) terpyridine complexes with appropriate substituents on terpyridine units have been shown to assemble into a mixture of right-and left-handed helical fibres in DMSO-water mixtures. 66 It has been hypothesized that in such complexes, the terpyridine units are bent with respect to the alkynyl ligand, inducing directional PtÁ Á ÁPt interactions and p-stacking.…”