Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C₆₀ Binding Study

A new carbazole-based 90° dipyridyl donor 3,6-di­(4-pyridylethynyl)­carbazole (<b>L</b>) containing carbazole-ethynyl functionality is synthesized in reasonable yield using the Sonagashira coupling reaction. Multinuclear NMR, electrospray ionization-mass spectrometry (ESI-MS), including single crystal X-ray diffraction analysis characterized this 90° building unit. The stoichiometry combination of <b>L</b> with several Pd­(II)/Pt­(II)-based 90° acceptors (<b>1a</b>–<b>1d</b>) yielded [2 + 2] self-assembled metallacycles (<b>2a</b>–<b>2d</b>) under mild conditions in quantitative yields [<b>1a</b> = <i>cis</i>-(dppf)­Pd­(OTf)₂; <b>1b</b> = <i>cis</i>-(dppf)­Pt­(OTf)₂; <b>1c</b> = <i>cis</i>-(tmen)­Pd­(NO₃)₂; <b>1d</b> = 3,6-bis­{<i>trans</i>-Pt­(CC)­(PEt₃)₂(NO₃)}­carbazole]. All these macrocycles were characterized by various spectroscopic techniques, and the molecular structure of <b>2a</b> was unambiguously determined by single crystal X-ray diffraction analysis. Incorporation of ethynyl functionality to the carbazole backbone causes the resulted macrocycles (<b>2a</b>–<b>2d</b>) to be π-electron rich and thereby exhibit strong emission characteristics. The macrocycle <b>2a</b> has a large internal concave aromatic surface. The fluorescence quenching study suggests that <b>2a</b> forms a ∼1:1 complex with C₆₀ with a high association constant of <i>K</i>_sv = 1.0 × 10⁵ M^–1

Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C₆₀ Binding Study

A new carbazole-based 90° dipyridyl donor 3,6-di­(4-pyridylethynyl)­carbazole (<b>L</b>) containing carbazole-ethynyl functionality is synthesized in reasonable yield using the Sonagashira coupling reaction. Multinuclear NMR, electrospray ionization-mass spectrometry (ESI-MS), including single crystal X-ray diffraction analysis characterized this 90° building unit. The stoichiometry combination of <b>L</b> with several Pd­(II)/Pt­(II)-based 90° acceptors (<b>1a</b>–<b>1d</b>) yielded [2 + 2] self-assembled metallacycles (<b>2a</b>–<b>2d</b>) under mild conditions in quantitative yields [<b>1a</b> = <i>cis</i>-(dppf)­Pd­(OTf)₂; <b>1b</b> = <i>cis</i>-(dppf)­Pt­(OTf)₂; <b>1c</b> = <i>cis</i>-(tmen)­Pd­(NO₃)₂; <b>1d</b> = 3,6-bis­{<i>trans</i>-Pt­(CC)­(PEt₃)₂(NO₃)}­carbazole]. All these macrocycles were characterized by various spectroscopic techniques, and the molecular structure of <b>2a</b> was unambiguously determined by single crystal X-ray diffraction analysis. Incorporation of ethynyl functionality to the carbazole backbone causes the resulted macrocycles (<b>2a</b>–<b>2d</b>) to be π-electron rich and thereby exhibit strong emission characteristics. The macrocycle <b>2a</b> has a large internal concave aromatic surface. The fluorescence quenching study suggests that <b>2a</b> forms a ∼1:1 complex with C₆₀ with a high association constant of <i>K</i>_sv = 1.0 × 10⁵ M^–1

A Unique Non-catenane Interlocked Self-Assembled Supramolecular Architecture and Its Photophysical Properties

A novel, interlocked, self-assembled (M₂L₂)₂ molecular architecture was constructed from an arene-Ru acceptor and a 1,4-di(pyridin-4-yl)buta-1,3-diyne donor. Two M₂L₂ units, with cavities of ∼7.21 Å, spontaneously interlock, with one unit encapsulating a twin in a non-catenane fashion. The dimeric host–guest complex thus formed is unique among two-dimensional self-assemblies and is stabilized by π–π interactions between the M₂L₂ units

Electron-Rich Arene–Ruthenium Metalla-architectures Incorporating Tetrapyridyl–Tetrathiafulvene Donor Moieties

A series of arene ruthenium architectures have been prepared from coordination-driven self-assembly using dinuclear <i>p</i>-cymene ruthenium acceptors and π-donating tetratopic tetrapyridyl–tetrathiafulvalene donor ligands. The synthetic strategy, based on a geometric interaction approach, leads to four electroactive metalla-assemblies, <b>1</b>–<b>4</b> (one molecular cube and three metallaplates), that were characterized by NMR, ESI-MS, X-ray diffraction, and cyclic voltammetry. Rationalization of their formation discrepancy was completed by DFT calculations supported by structural features of their constituting TTF and Ru-complex components. Metalla-architectures possessing electron-rich cores (<b>3</b>, <i>cis-</i><b>4</b>, and <i>trans</i>-<b>4</b>) interact strongly with picric acid (PA) to yield cocrystallized products, PA + metalla-assemblies, confirmed by single-crystal X-ray structure analyses

Growth Inhibitory Activity of a Bis-Benzimidazole-Bridged Arene Ruthenium Metalla-Rectangle and -Prism

Two new supramolecular coordination complexes (SCCs) were obtained from the self-assembly of a new bis-benzimidazole bridged Ru acceptor, <b>4</b>, with dipyridyl and tripyridyl donors, respectively. As part of a growing library of anticancer-active Ru-based SCCs, metalla-prism <b>6</b> selectively showed high cytotoxicities relative to cisplatin for a series of cancer cell lines, with IC₅₀ values as low as 8.41 μM for MCF7 cells, as determined from MTS assays

Growth Inhibitory Activity of a Bis-Benzimidazole-Bridged Arene Ruthenium Metalla-Rectangle and -Prism

Two new supramolecular coordination complexes (SCCs) were obtained from the self-assembly of a new bis-benzimidazole bridged Ru acceptor, <b>4</b>, with dipyridyl and tripyridyl donors, respectively. As part of a growing library of anticancer-active Ru-based SCCs, metalla-prism <b>6</b> selectively showed high cytotoxicities relative to cisplatin for a series of cancer cell lines, with IC₅₀ values as low as 8.41 μM for MCF7 cells, as determined from MTS assays