Geometrical manipulation of complex supramolecular tessellations by hierarchical assembly of amphiphilic platinum(II) complexes.

Here we report complex supramolecular tessellations achieved by the directed self-assembly of amphiphilic platinum(II) complexes. Despite the twofold symmetry, these geometrically simple molecules exhibit complicated structural hierarchy in a columnar manner. A possible key to such an order increase is the topological transition into circular trimers, which are noncovalently interlocked by metal···metal and π-π interactions, thereby allowing for cofacial stacking in a prismatic assembly.

Supramolecular assembly of bent dinuclear amphiphilic alkynylplatinum(ii) terpyridine complexes: diverse nanostructures through subtle tuning of the mode of molecular stacking.

A new class of bent amphiphilic alkynylplatinum(ii) terpyridine complexes was found to adopt different modes of molecular stacking to give diverse nanostructures. In chlorinated solvents, the complexes aggregate in the presence of water droplets and assist in the formation of porous networks, while in DMSO solutions, they self-assemble to give fibrous nanostructures. The complexes would adopt a head-to-tail tetragonal stacking arrangement, as revealed by X-ray crystallographic studies, computational studies and powder X-ray diffraction (PXRD) studies.

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.

Multiresponsive Luminescent Cationic Cyclometalated Gold(III) Amphiphiles and Their Supramolecular Assembly.

A new class of amphiphilic tridentate cyclometalated gold(III) complexes has been designed and synthesized as luminescent supramolecular building blocks. Positively charged trimethylammonium (-CHNMe) containing alkynyl ligands have been incorporated to introduce the electrostatic interactions. The X-ray crystal structures of two of the complexes have been determined, and the existence of π-π interactions between molecules has been observed.

Rational Design of Multi-Stimuli-Responsive Scaffolds: Synthesis of Luminescent Oligo(ethynylpyridine)-Containing Alkynylplatinum(II) Polypyridine Foldamers Stabilized by Pt···Pt Interactions.

A series of oligo(ethynylpyridine)-containing alkynylplatinum(II) terpyridine/bzimpy (bzimpy = 2,6-bis(-alkylbenzimidazol-2'-yl)pyridine) metallofoldamers has been designed and synthesized to investigate the potential applications of metallofoldamers imparted by the rich spectroscopic responses of Pt···Pt interactions. Apart from the control of the folding/unfolding processes by solvent compositions and temperatures, this class of metallofoldamers has also been found to exhibit reversible folding/unfolding behaviors mediated by the addition of acids/bases due to the incorporation of the acid-sensitive oligo(ethynylpyridine) derivatives. More importantly, the intramolecular Pt···Pt interaction has been found to play a crucial role in governing the folded state conformation.

Directional Self-Assembly and Photoinduced Polymerization of Diacetylene-Containing Platinum(II) Terpyridine Complexes.

A series of newly designed and synthesized diacetylene-containing platinum(II) terpyridine complexes exhibited intriguing self-assembly properties. Facilitated by Pt⋅⋅⋅Pt, π-π stacking, hydrogen-bonding and hydrophobic-hydrophobic interactions, these complexes are preorganized to readily undergo topochemical polymerization reactions upon photoirradiation. The in situ polymerization of the diacetylene units to form polydiacetylene, indicated by the UV/Vis spectral changes, gel permeation chromatography and dynamic light scattering, was found to alter their assembly behaviours, as revealed by TEM images.

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.

Controlling Self-Assembly Mechanisms through Rational Molecular Design in Oligo( p-phenyleneethynylene)-Containing Alkynylplatinum(II) 2,6-Bis( N-alkylbenzimidazol-2'-yl)pyridine Amphiphiles.

The systematic control over association mechanisms of self-assembled materials has been demonstrated through the rational design and synthesis of a series of amphiphilic dinuclear alkynylplatinum(II) bzimpy (bzimpy = 2,6-bis( N-alkylbenzimidazol-2'-yl)pyridine) complexes containing the shape-persistent oligo( p-phenyleneethynylene)s. Multistage morphological transformations from plates to fibers and to spherical nanostructures under different solvent compositions have been demonstrated. The subtle balances between multiple noncovalent interactions including Pt···Pt, hydrophobic, hydrophilic, and π-π stacking interactions are found to have profound impact on the supramolecular assembly of the system, in which a change in the association mechanism from isodesmic to cooperative and back to isodesmic growth has been observed upon increasing hydrophilicity of the complexes.

Supramolecular assemblies of dinuclear alkynylplatinum(ii) terpyridine complexes with double-decker silsesquioxane nano-cores: the role of isomerism in constructing nano-structures.

Isomeric double-decker silsesquioxane-functionalized dinuclear alkynylplatinum(ii) terpyridine complexes demonstrate self-association behaviours via the stabilisation of hydrophobic, PtPt and/or π-π stacking interactions. These supramolecular architectures and molecular packings are found to be closely related to the isomeric configurations of the complexes and have been investigated using various spectroscopic studies.

Formation of 1D Infinite Chains Directed by Metal-Metal and/or π-π Stacking Interactions of Water-Soluble Platinum(II) 2,6-Bis(benzimidazol-2'-yl)pyridine Double Complex Salts.

A new class of water-soluble double complex salts (DCSs), [Pt{bzimpy(TEG)}Cl][Pt{bzimpy(PrSO)}Cl] and its alkylplatinum(II) bzimpy derivatives (bzimpy = 2,6-bis(benzimidazol-2'-yl)pyridine, has been demonstrated to exhibit strong aggregation in water through Pt···Pt and π-π stacking interactions to give a variety of distinctive nanostructures based on the formation of one-dimensional (1D) infinite chains. The self-association process can be systemically controlled by varying the solvent composition and temperature and has been studied by H NMR, 2D NOESY NMR, mass spectrometry, electron and confocal fluorescence microscopy, UV-vis absorption, and emission spectroscopy.

Supramolecular assembly of a phosphole-based moiety into nanostructures dictated by alkynylplatinum(ii) terpyridine complexes through non-covalent Pt···Pt and π-π stacking interactions: synthesis, characterization, photophysics and self-assembly behaviors.

A new class of platinum(ii) terpyridine complexes with a phosphole-derived bridging alkynyl ligand have been prepared. The X-ray crystal structure of complex has been determined, and reveals a polymeric zig-zag chain structure with the existence of π-π stacking interactions. The photophysical properties have also been studied, with MLCT/LLCT phosphorescence exhibited in degassed CHCl; the energy of which is varied by the π-conjugation of the terpyridine ligands.

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.

A rational molecular design of triazine-containing alkynylplatinum(ii) terpyridine complexes and the formation of helical ribbons via PtPt, π-π stacking and hydrophobic-hydrophobic interactions.

The self-assembly of triazine-containing alkynylplatinum(ii) terpyridine complexes has revealed the formation of sophisticated helical ribbons. Fine control of the morphological transition from plates to helical structures has been demonstrated through an interplay of the bent molecular structure and PtPt, π-π stacking and hydrophobic-hydrophobic interactions.

Synthesis of Luminescent Platinum(II) 2,6-Bis(N-dodecylbenzimidazol-2'-yl)pyridine Foldamers and Their Supramolecular Assembly and Metallogel Formation.

Dinuclear alkynylplatinum(II) metallofoldamers with an oligomeric m-phenyleneethynylene backbone have been designed with the incorporation of a sterically undemanding, π-conjugated, and hydrophobic 2,6-bis(N-dodecylbenzimidazol-2'-yl)pyridine pincer ligand. The complex with the optimal chain length has been found to exhibit gelation behavior via stabilization by noncovalent Pt···Pt and π-π stacking interactions in the hierarchical architecture constructed from the single-turn helix. The chain lengths of the complexes have been found to be a critical determinant for their gelation behavior, conformations, and morphologies.

Supramolecular assembly of platinum-containing polyhedral oligomeric silsesquioxanes: an interplay of intermolecular interactions and a correlation between structural modifications and morphological transformations.

A series of alkynylplatinum(ii) terpyridine complexes functionalized with polyhedral oligomeric silsesquioxane (POSS) moieties has been demonstrated to exhibit drastic color changes and give various distinctive nanostructures with interesting multi-stage morphological transformations from spheres to nanoplates in response to solvent conditions through the interplay of various intermolecular interactions, including hydrophilic-hydrophilic, hydrophobic-hydrophobic, Pt···Pt and π-π stacking interactions. These supramolecular architectures can be systematically modified and controlled through the molecular design and the variation of solvent compositions. In particular, drastic changes in color in response to solvent polarity were observed through the incorporation of the charged moieties, representing a new class of potential candidates for functional materials with sensing or imaging capabilities.

Self-Assembled Architectures of Alkynylplatinum(II) Amphiphiles and Their Structural Optimization: A Balance of the Interplay Among Pt···Pt, π-π Stacking, and Hydrophobic-Hydrophobic Interactions.

A series of alkynylplatinum(II) terpyridine complexes with triethylene glycol units was synthesized, and their self-assembly properties were investigated in solution by UV-vis absorption, emission, and H NMR spectroscopy. The aggregation behaviors of several water-soluble complexes were investigated in aqueous media. Some of them were found to give rise to uniform fibers, suggesting the important role that triethylene glycol units has in regulating their self-assembly properties.

Synthesis, Electrochemistry, and Photophysical Studies of Ruthenium(II) Polypyridine Complexes with D-π-A-π-D Type Ligands and Their Application Studies as Organic Memories.

A new class of ruthenium(II) polypyridine complexes with a series of D-π-A-π-D type (D=donor, A=acceptor) ligands was synthesized and characterized by H NMR spectroscopy, mass spectrometry, and elemental analysis. The photophysical and electrochemical properties of the complexes were also investigated. The newly synthesized ruthenium(II) polypyridine complexes were found to exhibit two intense absorption bands at both high-energy (λ=333-369 nm) and low-energy (λ=520-535 nm) regions.

Tuning of Supramolecular Architectures of l-Valine-Containing Dicyanoplatinum(II) 2,2'-Bipyridine Complexes by Metal-Metal, π-π Stacking, and Hydrogen-Bonding Interactions.

A series of newly synthesized dicyanoplatinum(II) 2,2'-bipyridine complexes exhibits self-assembly properties in solution after the incorporation of the l-valine amino units appended with various hydrophobic motifs. These l-valine-derived substituents were found to have critical control over the aggregation behaviors of the complexes in the solution state. On one hand, one of the complexes was found to exhibit interesting circularly polarized luminescence (CPL) signals at low temperature due to the formation of chiral spherical aggregates in the temperature-dependent studies.

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

A series of mono- and dinuclear alkynylplatinum(II) terpyridine complexes containing the hydrophilic oligo(para-phenylene ethynylene) with two 3,6,9-trioxadec-1-yloxy chains was designed and synthesized. The mononuclear alkynylplatinum(II) terpyridine complex was found to display a very strong tendency toward the formation of supramolecular structures. Interestingly, additional end-capping with another platinum(II) terpyridine moiety of various steric bulk at the terminal alkyne would lead to the formation of nanotubes or helical ribbons.

Metal-Metal and π-π Interactions Directed End-to-End Assembly of Gold Nanorods.

The end-to-end aggregation of gold nanorods (GNRs) has been demonstrated to be directed by a thioacetate-containing alkynylplatinum(II) terpyridine complex. The in situ deprotected complex is preferentially attached at the ends of the gold nanorods (GNRs) and induce the aggregation of GNRs in an "end-to-end" manner by Pt···Pt and π-π interactions, which have been characterized by electron microscopy, energy dispersed X-ray (EDX) analysis, and UV-vis absorption spectroscopy. The assembly of the nanorods into chain-like nanostructures can be controlled by the concentration of the Pt(II) complexes.

Transformable nanostructures of platinum-containing organosilane hybrids: non-covalent self-assembly of polyhedral oligomeric silsesquioxanes assisted by Pt···Pt and π-π stacking interactions of alkynylplatinum(II) terpyridine moieties.

An alkynylplatinum(II) terpyridine complex functionalized with polyhedral oligomeric silsesquioxanes (POSS) moieties has been demonstrated to exhibit self-association behavior to give various distinguishable nanostructures with interesting morphological transformation from rings to rods in response to solvent conditions through the stabilization of Pt···Pt and π-π stacking interactions as well as hydrophobic-hydrophobic interactions. These changes can be systemically controlled by varying the solvent composition and have been studied by (1)H NMR, electron microscopy, UV-vis absorption, and emission spectroscopies.

Luminescent cyclometalated alkynylplatinum(II) complexes with a tridentate pyridine-based N-heterocyclic carbene ligand: synthesis, characterization, electrochemistry, photophysics, and computational studies.

A new class of luminescent alkynylplatinum(II) complexes with a tridentate pyridine-based N-heterocyclic carbene (2,6-bis(1-butylimidazol-2-ylidenyl)pyridine) ligand, [Pt(II)(C^N^C)(C≡CR)][PF6], and their chloroplatinum(II) precursor complex, [Pt(II)(C^N^C)Cl][PF6], have been synthesized and characterized. One of the alkynylplatinum(II) complexes has also been structurally characterized by X-ray crystallography. The electrochemistry, electronic absorption and luminescence properties of the complexes have been studied.

Dynamic scaffold of chiral binaphthol derivatives with the alkynylplatinum(II) terpyridine moiety.

Platinum(II)-containing complexes with inherently chiral binaphthol derivatives display a versatile scaffold between random coils and single-turn helical strands, in which the conformational transition is controlled by the Pt···Pt and π-π interactions of alkynylplatinum(II) terpyridine moiety upon solvent and temperature modulation. The bisignate Cotton effect in the circular dichroism spectra is indicative of the cooperative transformation from random coil state to a compact single-turn M- or P-helix. More importantly, as revealed by the appearance of new UV-vis absorption and emission bands during conformational change, the self-assembly of the platinum(II)-containing complex into a helical structure is assisted by the metal···metal and π-π interactions of the alkynylplatinum(II) terpyridine moieties.