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

Abstract

Discrete pentanuclear Pt stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type Pt complexes. The formation of the Pt 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 Pt 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 Pt 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.

Cyclometalated Pt Complexes of CNC Pincer Ligands: Luminescence and Cytotoxic Evaluation

“…15,38 Short Pt•••Pt contacts in such systems have also been intentionally constructed to induce aggregation-induced emission (AIE). 5,8,9,11,18,44,45 This has been observed in related cyclometalated Pt(II) complexes 3−6,37−39,43−46 and might also occur for the complexes presented here. However, excimer formation or AIE can be easily identified by their luminescence properties [3][4][5][6]43,45 and assessed doing dilution studies.…”

“…Tridentate CNC bis-cyclometalating Hph­(py)­phH ligands such as the prototypical 2,6-diphenylpyridine (HPhPyPhH) (Chart ) were introduced to organoplatinum­(II) chemistry about 30 years ago. , Neutral or anionic complexes (Chart ) of these dianionic – CNC – ligands have been studied together with derivatives of the monoanionic CNN or NCN ligands (HCNN = derivatives of 6-phenyl-2,2′-bipyridine, Hphbpy; NC­(H)N = derivatives of 1,3-bis­(2-pyridyl)­benzene, py­(Hph)­py), mainly due to their interesting luminescence properties − and their use as scaffolds with particular chemical reactivity. − …”

Recognition Properties and Self‐assembly of Planar [M(2‐pyridyl‐1,2,3‐triazole)2]2+ Metallo‐ligands

“…These form adducts and/or aggregates due to a combination of the two interactions. Bosnich and co‐workers and Yam and co‐workers have used neutral flat platinum(II) guests for binding within cationic tweezer molecules. Yam and co‐workers have also used stacking in discrete planar platinum(II) complexes to drive aggregation behaviour and generate interesting materials.…”

The New Di-Gold Metallotweezer Based on an Alkynylpyridine System

“…Flexible spacers, however, are more prone to adapting their conformation to maximize substrate binding and hence operate through an 'induced-fit' mechanism, although the binding affinities are normally reduced due to the energy cost and entropy loss associated with the distortions and reduction of conformational changes [22,23]. In this regard, during the last decade, Yam [24][25][26][27][28] and Wang [29][30][31][32][33], prepared a series of alkynylplatinum tweezers bound by a rather flexible diphenylpyridine spacer, whose binding affinities were found to be perturbed by π-π and metal-metal interactions, producing dramatic color changes with diverse applications, such as the amplification of chiroptical signals [33] and visible-light photocatalytic transformations [34].…”