Construction of Discrete Pentanuclear Platinum(II) Stacks with Extended Metal–Metal Interactions by Using Phosphorescent Platinum(II) Tweezers

Abstract

Discrete pentanuclear PtII stacks were prepared by the host‐guest adduct formation between multinuclear tweezer‐type PtII complexes. The formation of the PtII stacks in solution was accompanied by color changes and the turning on of near‐infrared emission resulting from Pt⋅⋅⋅Pt and π–π interactions. The X‐ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five PtII centers with extended Pt⋅⋅⋅Pt interactions was observed. Additional binding affinity and stability have been achieved through a multinuclear host‐guest system. The binding behaviors can be fine‐tuned by varying the spacer between the two PtII moieties in the guests. This work provides important insights for the construction of discrete higher‐order supramolecular metal‐ligand aggregates using a tweezer‐directed approach.

Investigating the Impact of Packing and Environmental Factors on the Luminescence of Pt(N^N^N) Chromophores

“…The emission spectra of all the systems were recorded at room temperature upon excitation the samples at 450 nm. A broad emission band between 500 and 600 nm is recorded in all cases that is attributed to 3 MMLCT transition based on previous reports with similar Pt­(N^N^N) compounds. ,,− This means that some kind of aggregation/intermolecular packing should be expected in all cases. An 3 IL contribution is also observed only in the case of 1A with the presence of a vibronic resolution band at higher energies overlapped with the previous one, due to the possibility of several metal environments or different numbers of M···M interactions …”

Supramolecular luminescent Pt(ii) tweezers: aggregation studies and 1O2 production

“…The observed emissions have been attributed to metal perturbed 3 IL transition in the case of 13–15 (considering the emission energies and lifetimes and due to the vibronically structural shape 41 ) and to 3 MMLCT (due to the presence of intermolecular contacts, that is, aggregates) 34 for the broad phosphorescence bands of 10–12 transitions and metal perturbed 3 IL for the vibronically structured phosphorescence bands in 16–18 as described in the literature for similar N^N^N compounds and in agreement with the recorded values of decay times. 34,38–40,42,44–46…”

“…The observed emissions have been attributed to metal perturbed 3 IL transition in the case of 13-15 (considering the emission energies and lifetimes and due to the vibronically structural shape 41 ) and to 3 MMLCT (due to the presence of intermolecular contacts, that is, aggregates) 34 for the broad phosphorescence bands of 10-12 transitions and metal perturbed 3 IL for the vibronically structured phosphorescence bands in 16-18 as described in the literature for similar N^N^N compounds and in agreement with the recorded values of decay times. 34,[38][39][40]42,[44][45][46] Taking this into consideration, we can say that (i) the insertion of the chlorine atom at the para position of the pyridyl rings plays an important role in the emissive properties of the tweezers favoring fluorescence emission and (ii) the presence of the CF 3 substituents does not favor the intermolecular contacts probably due to the spherical bulkiness of this group. Some preliminary assays were performed to analyze the potential role of our tweezer compounds as sensors of polyaromatic hydrocarbon (PAH) guest molecules, which are well known as contaminants.…”

Multicomponent Assembled Systems Based on Platinum(II) Terpyridine Complexes

“…Mixing 15 of 16 facilitated the formation of a discrete ADADA-type . 37 Our research group has exploited the photocatalytic efficiency of multilayer tweezering architectures. 38 The discrete DADA-type complex 14/17 (K a = 2.89 × 10 6 M −1 in CHCl 3 ; Figure 7) shows enhanced binding affinity compared with the DAD-and ADA-type counterparts (K a = 5.05 × 10 3 and 5.67 × 10 4 M −1 , respectively).…”