Solvent‐Induced and Temperature‐Promoted Aggregation of Bipyridine Platinum(II) Triangular Metallacycles and Their Near‐Infrared Emissive Behaviors

Abstract

A series of bipyridine platinum(II) complexes with different sizes of triangular metallacycles and alkyl/oligoether chains has been synthesized and characterized. They are packed in a zig-zag fashion with the formation of dimeric structures according to their X-ray crystal structures. Different emission origins are observed due to the different sizes of the triangular ligands. Their morphologies could be tuned by the modification of the molecular structures with different metallacyclic alkynyl ligands and alkyl/oligoether chains and solvents. More interestingly, unusual electronic absorption changes and upfield shifts of the aromatic proton resonances are observed upon increasing the temperature, suggesting further aggregation of the architectures. Near-infrared (NIR) emission is also realized through the tuning of the π-π stacking, Pt⋅⋅⋅Pt interactions, and the packing of planar metallacycles.

Synthesis of Platinum-Containing Conjugated Polymers Bearing Optically Active Amide Groups: A Mechanistic Study of Chiral Aggregation

“…Pt–bipyridine bis­(acetylide) [Pt­(bpy)­(CC–Ar) 2 ] complexes with highly square planar conformation are utilized as components of metallacycles, metallacages, and so on. − Such complexes possibly form supramolecular metal complexes and aggregates based on intermolecular Pt–Pt interactions. , They also exhibit unusual photoproperties, such as upconversion, , near-infrared photoluminescence, , aggregation-induced emission, and mechanochromic luminescence . Polymers containing cis -Pt ethynyl complexes are synthesizable by employing chelating ligands, although they are thermodynamically unfavorable to the trans-isomers. − There are only a few reports about the synthesis and examination of secondary structures of polymers containing Pt–bipyridine complex moieties due to their low solubility in organic solvents. − We have synthesized poly­(phenyleneethynylene)­s having optically active amide groups and Pt complex moieties ligated with bipyridine in the main chain, which assemble into regularly twisted ribbonlike structures in the solid state .…”

Aggregation and Tunable Color Emission Behaviors of l‐Glutamine‐Derived Platinum(II) Bipyridine Complexes by Hydrogen‐Bonding, π–π Stacking and Metal–Metal Interactions

“…of 1.76×10 −4 m , which suggests the importance of the glutamate moieties in the formation of strong aggregates through cooperative interactions of hydrogen‐bonding, π–π stacking, and metal–metal interactions . For comparison, our group previously reported a related triangular platinum(II) bipyridine complex without hydrogen‐bonding interactions that showed only a certain extent of molecular aggregation, but no gelation . The metallogels show rather quite different morphologies as observed from the SEM and TEM images (Figure and Figure S17).…”

“…[8a] For comparison, our group previ- ously reported ar elatedt riangularp latinum(II) bipyridine complex without hydrogen-bonding interactions that showedo nly ac ertain extento fm olecular aggregation, but no gelation. [18] The metallogels show rather quite differentm orphologies as observedf rom the SEM and TEM images (Figure 7a nd Figure S17). Fibrouss tructures weref ormed for the metallogels prepared from 1 in THF/chloroform (4:1 v/v)a nd 3 in n-butanol, respectively,w hereas nanospheresw ere obtained for the metallogel prepared from 2 in acetone.…”

Designing a highly stable coordination-driven metallacycle for imaging-guided photodynamic cancer theranostics

“…[11][12][13][14][15][16][17][18][19] Since the assembly of metallic molecular squares by Fujita and Stang in the early 1990s, 20,21 more efforts have been dedicated to design of metallacycles possessing increased structural complexity and functionality. [22][23][24][25][26][27][28][29][30] Especially, luminescent metallacycles have attracted intense attention due to their important and burgeoning biomedical applications, such as drug delivery, 31 sensing, 22,32 bio-imaging, 33,34 and cancer therapy. [35][36][37] Photodynamic therapy (PDT) is now considered as a promising treatment modality for a variety of solid tumors, and in general relies on the singlet oxygen production ability of photosensitive dyes.…”