Polymer‐Induced Self‐Assembly of Alkynylplatinum(II) Terpyridyl Complexes by Metal⋅⋅⋅Metal/π⋅⋅⋅π Interactions

Multiaddressable molecular rectangles with reversible host–guest interactions: Modulation of pH-controlled guest release and capture

“…The electronic absorption spectra of alkynylplatinum(II) terpyridine molecular rectangles 1−4 in dichloromethane solution at room temperature displayed intense intraligand [π → π*] transitions of the terpyridine and the alkynyl ligands at 250−345 nm together with the moderately intense absorptions at 420−490 nm, which are assigned as admixtures of metal-to-ligand charge transfer (MLCT) [dπ(Pt) → π*(terpyridine)] and ligand-to-ligand charge transfer (LLCT) [π(C≡CR) → π*(terpyridine)] transitions according to previous spectroscopic studies on alkynylplatinum(II) terpyridine systems (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). Molecular rectangles 1−4 in degassed acetonitrile solution and solid state at 298 K exhibited structure-less emission bands at 620−700 nm, which are tentatively assigned as originated from the 3 MLCT/ 3 LLCT [dπ(Pt)/ π(C≡CR) → π*(terpyridine)] excited state with similar trends to their electronic absorptions.…”

“…2). It is believed that the newly formed low-energy absorptions and emissions are derived from a metal-metal-to-ligand chargetransfer (MMLCT) transition and 3 MMLCT excited state, respectively, as a result of the Pt(II)···Pt(II) and π−π interactions associated with the host-guest interaction on guest capture (23)(24)(25)(26)(27)(28). However, the flexible molecular rectangle 4 only resulted in The Job's method of continuous variation, electrospray ionization mass spectrometry (ESI-MS), and 2D NMR studies have been performed to provide a more thorough understanding of the binding mode in the host-guest assembly.…”

“…It was not until 2001 that the first successful synthesis of platinum(II) terpyridine alkynyl complexes, which possess enhanced solubility and luminescence compared with the chloro counterpart, was reported (16). Additional efforts have been devoted to the use of the system to respond to external stimuli, such as variation in solvent composition (17, 18), pH (19, 20), temperature (21, 22), addition of ionic (24-26), and polymeric species (27,28), in which spectral changes induced by strong Pt(II)···Pt(II) and π−π interactions have been displayed.In the past few decades, enormous efforts have been devoted to the construction of molecular architectures by fusing the organic framework to the transition metal centers through selfassembly processes (29-57). There has been continuous interest in the construction of stimuli-responsive metallosupramolecular architectures with diverse sizes, shapes, and symmetries to rationalize the criteria for molecular recognition and impart them on unique areas of applications, such as stereoselective guest encapsulation and molecular transporting devices (45-65).…”

“…It was not until 2001 that the first successful synthesis of platinum(II) terpyridine alkynyl complexes, which possess enhanced solubility and luminescence compared with the chloro counterpart, was reported (16). Additional efforts have been devoted to the use of the system to respond to external stimuli, such as variation in solvent composition (17,18), pH (19,20), temperature (21,22), addition of ionic (24)(25)(26), and polymeric species (27,28), in which spectral changes induced by strong Pt(II)···Pt(II) and π−π interactions have been displayed.…”

Self-assembly of alkynylplatinum(II) terpyridine amphiphiles into nanostructures via steric control and 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).…”