A Platinum(II) Terpyridine Metallogel with an L‐Valine‐Modified Alkynyl Ligand: Interplay of Pt⋅⋅⋅Pt, π–π and Hydrogen‐Bonding Interactions

Abstract

A series of platinum(II) terpyridine complexes with L-valine-modified alkynyl ligands has been synthesized. A complex with an unsubstituted terpyridine and one valine unit on the alkynyl is shown to be capable of gel formation, which is in sharp contrast to the gelation properties of the corresponding organic counterparts. Upon sol-gel transition, a drastic color change from yellow to red is observed, which is indicative of the involvement of Pt⋅⋅⋅Pt interactions. Through the concentration- and temperature-dependent UV/Vis absorption, emission, circular dichroism, and (1) H NMR studies, the contribution of hydrogen bonding, Pt⋅⋅⋅Pt and π-π stacking interactions as driving forces for gelation have been established, and the importance of maintaining a delicate balance between different intermolecular forces has also been illustrated.

Self-assembly of alkynylplatinum(II) terpyridine amphiphiles into nanostructures via steric control and metal–metal interactions

“…Samples of the clean red gels of complex 1 prepared from slow diffusion of diethyl ether into dichloromethane solution (Fig. S2A) exhibit an irregular network of molecular tapes characteristic of platinum(II)-containing metallogels (28)(29)(30)(31), with widths ranging from ∼50 to 100 nm in the transmission EM (TEM) and SEM images (Fig. S2 B and C).…”

“…Oligo(para-phenylene ethynylene)s (OPEs) with solely π−π stacking interactions are well-recognized to self-assemble into supramolecular system of various nanostructures but rarely result in the formation of tubular scaffolds (70)(71)(72)(73). In view of the rich photophysical properties of square-planar d 8 platinum(II) systems and their propensity toward formation of directional Pt···Pt interactions in distinctive morphologies (27)(28)(29)(30)(31)(39)(40)(41)(42)(43)(44)(45), it is anticipated that such directional and noncovalent metal−metal interactions might be capable of directing or dictating molecular ordering and alignment to give desirable nanostructures of helical ribbons or nanotubes in a precise and controllable manner.Herein, we report the design and synthesis of mono-and dinuclear alkynylplatinum(II) terpyridine complexes containing hydrophilic OPEs with two 3,6,9-trioxadec-1-yloxy chains. The mononuclear alkynylplatinum(II) terpyridine complex with Significance Metallosupramolecular π-conjugated amphiphiles have emerged as a building block for supramolecular architectures owing to their interesting luminescence behavior and their propensity to form noncovalent metal-metal interactions.…”

“…Earlier work by our group showed the first example, to our knowledge, of an alkynylplatinum(II) terpyridine system [Pt(tpy)(C ≡ CR)] + that incorporates σ-donating and solubilizing alkynyl ligands together with the formation of Pt···Pt interactions to exhibit notable color changes and luminescence enhancements on solvent composition change (25) and polyelectrolyte addition (26). This approach has provided access to the alkynylplatinum(II) terpyridine and other related cyclometalated platinum(II) complexes, with functionalities that can self-assemble into metallogels (27)(28)(29)(30)(31), liquid crystals (32,33), and other different molecular architectures, such as hairpin conformation (34), helices (35)(36)(37)(38), nanostructures (39)(40)(41)(42)(43)(44)(45), and molecular tweezers (46,47), as well as having a wide range of applications in molecular recognition (48)(49)(50)(51)(52), biomolecular labeling (48)(49)(50)(51)(52), and materials science (53,54). Recently, metalcontaining amphiphiles have also emerged as a building block for supramolecular architectures (42)(43)(44)(55)(56)(57)…”

Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications

“…54 In this respect, a recent example of the formation of chiral supramolecular structures has been reported by Yi and coworkers 55 who have synthesized a series of amphiphilic bipyridyl alkynylplatinum(II) complexes bearing cholesteric groups and ethylene glycol chains (complex 5 in Chart 1). Although all the three reported complexes can self-assemble forming gel networks, only the derivative without ether chains displayed well-defined right-handed helical structures ( Figure 7).…”

A Phosphorescent Platinum(II) Bipyridyl Supramolecular Polymer Based on Quadruple Hydrogen Bonds

“…[6,7] However,a ne xplicit understanding of the synergistic effects of noncovalent interactions duringt he construction of organometallic supramolecular polymers with structure correlated properties is still lacking. [6,7] However,a ne xplicit understanding of the synergistic effects of noncovalent interactions duringt he construction of organometallic supramolecular polymers with structure correlated properties is still lacking.…”