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Light-emitting materials, especially those with tunable wavelengths, attract considerable attention for applications in optoelectronic devices, fluorescent probes, sensors and so on. Many species evaluated for these purposes either emit as a dilute solution or on aggregation, with the former often self-quenching at high concentrations, and the latter falling dark when aggregation is disrupted. Here we preserve emissive behaviour at both low- and high-concentration regimes for two discrete supramolecular coordination complexes (SCCs). These tetragonal prismatic SCCs are self-assembled on mixing a metal acceptor, Pt(PEt3)2(OSO2CF3)2, with two organic donors, a pyridyl-decorated tetraphenylethylene and one of two benzene dicarboxylate species. The rigid organization of these fluorescence-active ligands imparts an emissive behaviour to dilute solutions of the resulting assemblies. Furthermore, on aggregation the prisms exhibit variable-wavelength visible-light emission, including rare white-light emission in tetrahydrofuran. The favourable photophysical properties and solvent-dependent aggregation behaviour provide a means to tune emission wavelengths. [ABSTRACT FROM AUTHOR]

The article discusses the importance of metal-organic structural frameworks and self-assembled supramolecular coordination chemical complexes in co-ordination chemistry. It mentions that the structural frameworks are beneficial in study of multicomponent chemical assembly and post self assembly chemical modifications. It mentions that the co-ordination chemistry approach is useful in chemical study involving metal ligands.

A series of endohedral and exohedral amine-functionalized ligands were synthesized and used in the construction of supramolecular D2h rhomboids and a D6h hexagon. These supramolecular polygons were obtained via self-assembly of 1200 dipyridyl donors with 180° or 120° diplatinum precursors when combined in 1:1 ratios. Steady-state absorption and emission spectra were collected for each ligand and metallacycle. Density functional theory (DFT) and time-dependent DFT calculations were employed to probe the nature of the observed optical transitions for the rhomboids. The emissive properties of these bis(phosphine) organoplatinum metallacycles arise from ligand-centered transitions involving π-type molecular orbitals with modest contributions from metal-based atomic orbitals. The D211 rhomboid self-assembled from 2,6-bis(4-pyridylethynyl)aniljne and a 60° organoplatinum(ll) acceptor has a low-energy excited state in the visible region and emits above 500 nm, properties which greatly differ from those of the parent 2,6-bis(4-pyridylethynyl)aniline ligand. [ABSTRACT FROM AUTHOR]

We describe the formation of a suite of [3]catenanes via multicomponent coordination-driven self-assembly and host–guest complexation of a rectangular scaffold comprising a 90° Pt-based acceptor building block with a pseudorotaxane bis(pyridinium)ethane/dibenzo-24-crown-8 linear dipyridyl ligand and three dicarboxylate donors. The doubly threaded [3]catenanes are formed from a total of 10 molecular components from four unique species. Furthermore, the dynamic catenation process is reversible and can be switched off and on in a controllable manner by successive addition of KPF6 and 18-crown-6, as monitored by 1H and 31P NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The 90° and 60° bimetallic platinum complexeswith specialstructures are widely used in coordination-driven self-assembled metallosupramoleculararchitectures, and these complexes are the key components of triangular,rectangular, and polygonal metallacycle and metallocage supramolecules.Therefore, spectroscopic techniques and quantum chemistry calculationswere employed in this article to investigate the photophysical propertiesof these bimetallic platinum complexes. Compared with spectra forthe ligands, the absorption spectra of these Pt complexes are red-shifted,and the fluorescence spectra become wider and are also red-shifted.Moreover, the reasons for the low fluorescence quantum yields andshort fluorescence lifetimes of these compounds were investigatedusing quantum chemistry calculations. We demonstrate that the fluorescentstates of the bimetallic platinum complexes can be considered as localexcited states, and that they possess a ligand-centered π–π*transition feature. Meanwhile, the platinum metals act as perturbationfor these transitions, whereas the nonfluorescent states are classifiedas intramolecular charge-transfer states. Furthermore, a new fluorescencemodulation mechanism is developed to explain the different emissionprocesses of these complexes with different ligands. [ABSTRACT FROM AUTHOR]

A new approach for the construction of functionalized metallosupramolecular tetragonal prisms via multicomponent, coordination-driven, template-free self-assembly is described. The combination of tetra-(4-pyridylphenyl)ethylene, a 90° Pt(II) acceptor, and ditopic bipyridine or carboxylate ligands functionalized with hydroxyl or amine groups, hydrophobic alkyl chains, or electrochemically active ferrocene, yields a suite of seven self-assembled tetragonal prisms under mild conditions. These three-dimensional metallosupramolecules were characterized by multinuclear NMR (31P and ¹H) and mass spectrometry. Their shapes and sizes were established using Merck Molecular Force Field (MMFF) simulations. In addition, their approximate sizes were further supported by pulsed-field-gradient spin-echo (PGSE) NMR experiments. [ABSTRACT FROM AUTHOR]

Two new tetracationic hetero-bimetallacycles, compounds 4 and 5, have been constructed from an N, N′-bis(4-(pyridin-4-ylethynyl)phenyl)pyridine-2,6-dicarboxamide ligand ( 1), and cis-blocked complexes [M(dppf)(OTf)2] (dppf=1,1′-bis(diphenylphosphino)ferrocene; OTf=trifluoromethanesulfonate; M=Pd ( 2), Pt ( 3)) in CH3NO2/CH2Cl2 (1:1) solvent. Both complexes were isolated with adequate yields as triflate salts and were then characterized using 1H, 13C, and 31P NMR spectroscopy, elemental analysis, UV/Vis spectroscopy, and high-resolution electrospray mass spectrometry (HR-ESMS). The molecular structure of 4 was determined by molecular mechanics force-field calculations. The cytotoxic effect of both new complexes were analyzed against T98G (brain tumor), KB (head and neck cancer), SNU-80 (thyroid cancer), and HEK-293 non-malignant cell lines. The cytotoxicity of complexes 4 and 5 were found to be considerably more effective against cancer cells than reference drug cisplatin. Annexin-V/PI staining, caspase-3/7 activity, and the reduction in mitochondrial membrane potential justify a significant level of apoptosis in complex-treated cells. [ABSTRACT FROM AUTHOR]