A series of neutral, platinum-based macrocycles was synthesized from rigid oxygen donor building blocks via self-assembly. The combination of a platinum-based 60 degrees acceptor unit 1 with several linear and angular dicarboxylate bridging ligands afforded hitherto unknown neutral platinum-based supramolecular triangles and rhomboids. In addition, a similar reaction of the diplatinum molecular clip 6 and three different linear dicarboxylates led to the formation of neutral molecular rectangles. Most of the macrocycles were characterized by X-ray single-crystal structure analysis, and, in all cases, NMR spectra were consistent with the formation of single highly symmetrical species.
The design and self-assembly of novel cavity-cored metallodendrimers via noncovalent interactions are described. By employing [G0]-[G3] 120 degrees ditopic donor linkers substituted with Fréchet-type dendrons and appropriate rigid di-Pt(II) acceptor subunits, [G0]-[G3]-rhomboidal metallodendrimers and [G0]-[G3]-hexagonal, "snowflake-shaped" metallodendrimers with well-defined shape and size were prepared under mild conditions in high yields. The assemblies were characterized with multinuclear NMR ((1)H and (31)P), mass spectrometry (ESI-MS and ESI-FT-ICR-MS), and elemental analysis. Isotopically resolved mass spectrometry data support the existence of the metallodendrimers with rhomboidal and hexagonal cavities, and NMR data are consistent with the formation of all ensembles. The structures of [G0]- and [G1]-rhomboidal metallodendrimers were unambiguously confirmed via single-crystal X-ray crystallography. The shape and size of two [G3]-hexagonal metallodendrimers were investigated with MM2 force-field modeling.
The syntheses, characterizations, and biological activities of three organoplatinum compounds, each containing a triazole ring, are discussed. These organometallic compounds demonstrate superior cytotoxicity against osteosarcoma and human breast cancer cells relative to cisplatin, a well-known chemotherapeutic agent used for chemotherapy.
The
well-known azo coupling reaction was utilized to yield a new
group of triptycene-derived azo polymers (TAPs) bearing phloroglucinol
units. TAPs have hierarchical porosity (presence of micropores and
mesopores) and are thermally stable. TAPs have moderate surface area
(SABET up to 772 m2 g–1) but
demonstrate rather high CO2 uptake (up to 150 mg g–1). Azo functional group is reportedly N2-phobic and hence porous organic polymers (POPs) with azo (−NN−)
units show high CO2/N2 selectivity. TAPs register
CO2/N2 selectivity (273 K) that is higher than
most azo-POPs reported until date. This favorable property of TAPs
is attributed to the simultaneous coexistence of triptycenes (aromatic
and three-dimensional rigid with high internal free volume), phenolic-OH
(polar and CO2-philic), and azo (CO2-philic
and N2-phobic) functional groups in the polymeric framework.
Two Pt(4)-Fe(2) mixed-metal neutral assemblies, 4 and 5, incorporating four bis(triethylphosphine)platinum(II) centers, two flexible bridging 1,1'-ferrocenedicarboxylates, and two rigid 2,9-phenanthrenediyl (4) or 1,8-anthracenediyl (5) bridges, have been synthesized. X-ray characterization of 4 and 5 reveals the formation of discrete and highly symmetrical heterobimetallic neutral species possessing a rhomboidal and rectangular shape, respectively. The rectangular molecules, 5, could be reversibly oxidized in two two-electron steps, separated by 0.21 V. Spectroelectrochemistry in the UV-vis-NIR region confirms the ferrocene groups as primary oxidation sites; however, the intermediate 5(2+) is EPR silent even at 4 K due to enhanced EPR relaxation involving the oxidizable 1,8-anthracenediyl linkers.
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