Platinum(II)-Based Host-Guest Coordination-Driven Supramolecular Co-Assembly Assisted by Pt···Pt and π-π Stacking Interactions: A Dual-Selective Luminescence Sensor for Cations and Anions.

A cationic water-soluble dipicolylamine (DPA)-containing alkynylplatinum(II) terpyridine complex has been synthesized and employed as a dual-selective probe for the detection of cations and anions. The complex was shown to exhibit a strong binding affinity toward Zn, whereas the zinc-bound adduct was found to demonstrate the capability of recognizing pyrophosphate (PPi). As evidenced by molecular modeling and various spectroscopic and spectrometric studies, including HR-ESI mass spectrometry, NMR spectroscopy, PXRD measurements, and UV-vis absorption and emission spectroscopy, a PPi anion was found to be capable of bridging two zinc-bound complex molecules in a clip-shaped fashion, which was further oligomerized through intermolecular Pt···Pt and π-π stacking interactions to form nanofibers with a hexagonal columnar phase.

Platinum(II) Probes for Sensing Polyelectrolyte Lengths and Architectures.

Platinum(II) polypyridine complexes of a square-planar geometry have been used as spectroscopic reporters for quantification of various charged species through non-covalent metal-metal interactions. The characterization of molecular weights and architectures of polyelectrolytes represents a challenging task in polymer science. Here, we report the utilization of platinum(II) complex probes and non-covalent metal-metal interactions for sensing polyelectrolyte lengths and architectures.

Amyloid Protein-Induced Supramolecular Self-Assembly of Water-Soluble Platinum(II) Complexes: A Luminescence Assay for Amyloid Fibrillation Detection and Inhibitor Screening.

Amyloid fibrillation has been acknowledged as a hallmark of a number of neurodegenerative ailments such as Alzheimer's disease. Accordingly, efficient detection of amyloid fibrillation will allow for great advances in the field of biomedical applications as well as in achieving early medical diagnosis. In this work, a luminescence assay for the sensitive and specific detection of amyloid fibrillation was developed by using platinum(II) complexes as sensing platforms.

A Luminescence Turn-On Assay for Acetylcholinesterase Activity and Inhibitor Screening Based on Supramolecular Self-Assembly of Alkynylplatinum(II) Complexes on Coordination Polymer.

A new approach toward acetylcholinesterase (AChE) detection has been demonstrated based on the electrostatic interactions between anionic alkynylplatinum(II) complex molecules and cationic coordination polymer, together with the spectroscopic and emission characteristics of alkynylplatinum(II) complexes upon supramolecular self-assembly. This process involves strengthening of distinct noncovalent Pt(II)···Pt(II) and π-π stacking interactions, which is evidenced by UV-vis absorption, emission, and resonance light scattering results. Such a method has been applied to AChE inhibitor screening, which is important as the demand for AChE inhibitor assays arises along with the drug development for Alzheimer's disease.

Energy Landscape in Supramolecular Coassembly of Platinum(II) Complexes and Polymers: Morphological Diversity, Transformation, and Dilution Stability of Nanostructures.

Establishment of energy landscape has emerged as an efficient pathway for improved understanding and manipulation of both thermodynamic and kinetic behaviors of complicated supramolecular systems. Herein, we report the establishment of energy landscapes of supramolecular coassembly of platinum(II) complexes and polymers, as well as the fabrication of nanostructures with enhanced complexity and intriguing properties from the coassembly systems. In the energy landscape, coassembly at room temperature has been found to only allow the longitudinal growth of platinum(II) complexes and block copolymers into core-shell nanofibers that are the kinetically trapped products.

Arginine-Rich Peptide-Induced Supramolecular Self-Assembly of Water-Soluble Anionic Alkynylplatinum(II) Complexes: A Continuous and Label-Free Luminescence Assay for Trypsin and Inhibitor Screening.

A water-soluble anionic alkynylplatinum(II) 2,6-bis(benzimidazol-2'-yl)pyridine (bzimpy) complex has been strategically designed and synthesized to show supramolecular self-assembly with cationic arginine-rich peptides through unique noncovalent Pt(II)···Pt(II) and π-π stacking interactions. Upon introduction of trypsin, the arginine-rich peptides can be hydrolyzed into small fragments and deaggregation of the platinum(II) complex molecules is observed. The aggregation-deaggregation process has been probed by UV-vis absorption, emission, and resonance light scattering (RLS) studies.

Living supramolecular polymerization achieved by collaborative assembly of platinum(II) complexes and block copolymers.

An important feature of biological systems to achieve complexity and precision is the involvement of multiple components where each component plays its own role and collaborates with other components. Mimicking this, we report living supramolecular polymerization achieved by collaborative assembly of two structurally dissimilar components, that is, platinum(II) complexes and poly(ethylene glycol)--poly(acrylic acid) (PEG--PAA). The PAA blocks neutralize the charges of the platinum(II) complexes, with the noncovalent metal-metal and π-π interactions directing the longitudinal growth of the platinum(II) complexes into 1D crystalline nanostructures, and the PEG blocks inhibiting the transverse growth of the platinum(II) complexes and providing the whole system with excellent solubility.

Molecular Engineering of Platinum(II) Terpyridine Complexes with Tetraphenylethylene-Modified Alkynyl Ligands: Supramolecular Assembly via Pt···Pt and/or π-π Stacking Interactions and the Formation of Various Superstructures.

A series of platinum(II) terpyridine complexes with tetraphenylethylene-modified alkynyl ligands has been designed and synthesized. The introduction of the tetraphenylethylene motif has led to aggregation-induced emission (AIE) properties, which upon self-assembly led to the formation of metal-metal-to-ligand charge transfer (MMLCT) behavior stabilized by Pt···Pt and/or π-π interactions. Tuning the steric bulk or hydrophilicity through molecular engineering of the platinum(II) complexes has been found to alter their spectroscopic properties and result in interesting superstructures (including nanorods, nanospheres, nanowires, and nanoleaves) in the self-assembly process.

Luminescent cation sensors: from host-guest chemistry, supramolecular chemistry to reaction-based mechanisms.

Other than traditional cation detection strategies, which are solely based on the ion-receptor complementarity, the extension of the concept of supramolecular chemistry and the mechanisms of irreversible analyte-specific reactions have also been integrated into the design of luminescent probes for the detection of cation in view of the exploration of highly sensitive and selective sensors. In this highlight, a versatile range of organic and organometallic architectures with cation-sensing capabilities based on the above mechanisms will be discussed.

Anion Binding Properties of Alkynylplatinum(II) Complexes with Amide-Functionalized Terpyridine: Host-Guest Interactions and Fluoride Ion-Induced Deprotonation.

Molecular sensors able to detect ions are of interest due to their potential application in areas such as pollutant sequestration. Alkynylplatinum(II) terpyridine complexes with an amide-based receptor moiety have been synthesized and characterized. Their anion binding properties based on host-guest interactions have been examined with the use of UV-vis absorption and emission spectral titration studies.

Aptamer-induced self-assembly of a NIR-emissive platinum(II) terpyridyl complex for label- and immobilization-free detection of lysozyme and thrombin.

With the aptamer-induced self-assembly feature of NIR-emissive platinum(ii) terpyridyl complex, a "proof-of-principle" concept in label- and immobilization-free probing strategies of lysozyme and thrombin has been demonstrated with good selectivity and specificity.