Phosphorescent nematic hydrogels and chromonic mesophases driven by intra- and intermolecular interactions of bridged dinuclear cyclometalated platinum(ii) complexes

Abstract

A new class of dinuclear cyclometalated platinum(II) complexes with [Pt II (C^N^N)CNR] + (HC^N^N ¼ 6phenyl-2,2 0 -bipyridyl, CNR ¼ 2,6-dimethylphenyl isocyanide) motifs covalently connected by oligo(oxyethylene) chains form luminescent lyotropic chromonic liquid crystals or hydrogels in aqueous dispersions with intra-and intermolecular Pt/Pt and p-p interactions as the driving force. Their solution behaviour is modulated by the length of the oligo(oxyethylene) chain connecting the two cyclometalated platinum(II) motifs. One of the dinuclear Pt(II) complexes with a long oligo(oxyethylene) bridge and which does not display intramolecular Pt/Pt and p-p interactions can act as an effective 'gelling stimulus' for mononuclear [Pt II (C^N^N)CNR] + complexes in aqueous solutions, resulting in the formation of a nematic hydrogel that is persistent and displays red photoluminescence.

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)…”

Simple and Versatile Preparation of Luminescent Amphiphilic Platinum(II)‐containing Polystyrene Complexes With Transformable Nanostructures Assisted by Pt⋅⋅⋅Pt and π–π Interactions

“…[45] As ar esult,t he exploration of new classes of amphiphilic polymers through simple and versatile synthetic pathways can be advantageous for further development of self-assembled functional materials.Pt···Pt interaction is an example of non-covalent interactions and can be found in sterically unhindered d 8 platinum(II) complexes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] WithP t···Pt and p-p interactions, square-planar d 8 platinum(II) complexescan undergo self-assembly into avariety of superstructures, such as micelles, [More interestingly,t he Pt···Pt and p-p interactions can modulate the energy levels of ds*(Pt n )a nd p*(tridentate ligand)o rbitals, and hence platinum(II) complexes with different extents of Pt···Pt and p-p interactions show different spectroscopic andl uminescence properties in their superstructures. [1][2][3][4][5][6][7][8][9][10][11]…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] This has allowed the platinum(II) moietiest os erve as spectroscopic and luminescence reporters of morphological transformations of superstructures. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Recently,o ur group reported several classes of alkynylplatinum(II)t erpyridine-based metallopolymers, and pH-and/or temperature-induced micellizationsh ave been successfully probedb yt he changes in the UV/Vis and emission spectra of the complexes. [8][9][10] This suggests that terpyridine coordination [a] HSupporting information and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.…”