A bis(m-phenylene)-32-crown-10-based fluorescence chemosensor for paraquat and diquat

A bis(m-phenylene)-32-crown-10-based host to which are covalently attached two pyrene groups as fluorescence chromophores was designed and synthesized. Its complexations with paraquat (PQ) and diquat (DQ) were studied by proton NMR, ESI mass spectrometry, and UV-vis spectroscopy. Its chemosensor behavior to PQ and DQ was revealed by fluorescence emission spectroscopy. This new host can function as a fluorescence chemosensor for PQ and DQ due to the inhibition of photoinduced electron transfer between the bis(m-phenylene)-32-crown-10 moiety and the pyrene groups by the addition of PQ (or DQ).     

Bis(m-phenylene)-32-crown-10/monopyridinium [2]pseudorotaxanes

The first crown ether/monopyridinium threaded structures, which are [2]pseudorotaxanes based on a new bis(m-phenylene)-32-crown-10/monopyridinium recognition motif, were successfully prepared as confirmed by proton NMR spectroscopy, electrospray ionization mass spectrometry, and X-ray analysis.     

An acid-base adjustable pseudocryptand-type [2]pseudorotaxane based on a bis(meta-phenylene)-32-crown-10 derivative and paraquat

A pseudocryptand-type [2]pseudorotaxane was formed via the self-assembly of a dipyridyl bis(meta-phenylene)-32-crown-10 (BMP32C10) derivative and a paraquat derivative. Due to the basicity of the pyridyl group, which forms the third pseudo-bridge of the pseudocryptand, this pseudorotaxane possesses two finite acid-base adjustable association constants.     

Two protocols for the preparation of [2]rotaxanes based on the dibenzo-24-crown-8-based cryptand/paraquat recognition motif

Host–guest complexation between a dibenzo-24-crown-8-based cryptand and a paraquat derivative was studied. Subsequently, two novel [2]rotaxanes based on the dibenzo-24-crown-8-based cryptand/paraquat recognition motif were prepared by threading-followed-by-stoppering method and single-pot method, respectively. The obtained mechanically interlocked structures were confirmed by ¹H NMR, ¹³C NMR, 2D NMR, and ESI-MS.     

Host size effect in the complexation of two bis(m-phenylene)-32-crown-10-based cryptands with a diazapyrenium salt

N,N′-Dimethyl-2,7-diazapyrenium bis(hexafluorophosphate) binds a C₃-symmetric bis(m-phenylene)-32-crown-10-based cryptand more strongly than N,N′-dimethyl-4,4′-bipyridinium bis(hexafluorophosphate) partly because of its better fit in size with the cryptand host cavity, while it binds a relatively smaller pyridyl cryptand less strongly due to its worse fit in size with the cryptand host cavity and the lack of hydrogen bonding to the pyridyl nitrogen atom of the host.     

High-yield preparation of [2]rotaxanes based on the bis(m-phenylene)-32-crown-10-based cryptand/paraquat derivative recognition motif

Based on the complexation between bis(m-phenylene)-32-crown-10-based cryptands and a paraquat derivative, two [2]rotaxanes were synthesized by using a threading-followed-by-stoppering method. Due to the strong associations between the cryptands and the paraquat derivative, high yields were achieved even in dilute solution.     

Taco grande: a dumbbell bis(crown ether)/paraquat [3](taco complex)

The first paraquat-based [3](taco complex) was successfully prepared from a linear bis(crown ether) host and paraquat as shown by proton NMR characterization and X-ray analysis. It has a dumbbell shape in the solid state. The two crown ether binding sites are independent of each other during their complexation in solution.     

Preparation of two new [2]rotaxanes based on the pillar[5]arene/alkane recognition motif

Based on the pillar[5]arene/alkane recognition motif, two [2]rotaxanes were successfully prepared. Their formation was confirmed by NMR spectroscopy and ESI mass spectrometry. We also demonstrated that 3,5-dinitrophenyl group and 3,5-bis(trifluoromethyl)phenyl group are big enough to work as stoppers for DPPillar[5]arene, which lays a foundation for the preparation of more complex and functional supramolecular structures.     

Two bis(p-phenylene)-34-crown-10-based cryptand constitutional isomers: different binding abilities induced by structural alterations

Two novel bis(p-phenylene)-34-crown-10-based cryptand constitutional isomers were prepared and their host–guest complexations with paraquat were studied by ESI-MS, UV–vis spectroscopy, ¹H NMR spectra, and X-ray crystal structures. Notably, though the only difference between the two hosts is the location of the nitrogen atom on the third arms, they exhibited quite different binding abilities with paraquat. Competitive complexation was carried out and it may provide a simple way to construct sophisticated supramolecular materials with reversibility and adaptability.     

Bis(meta-phenylene)-32-crown-10-based cryptand/diquat inclusion [2]complexes

Bis(meta-phenylene)-32-crown-10-based cryptands have been proved to complex diquat much more strongly than bis(meta-phenylene)-32-crown-10 itself; in fact, one containing a pyridyl moiety has one of the highest Ka values yet reported.     

Paraquat guest induced hydrogen-bonding modes of a hydrazide-derived bis(meta-phenylene)-32-crown-10 host in the solid state

A hydrazide-derived bis(meta-phenylene)-32-crown-10 host showed a dimeric structure via quadruple N-H?O hydrogen bonds, but a polymeric structure via two N-H?O hydrogen bonds and two C-H?O hydrogen bonds at each knot in the presence of paraquat in the solid state, which led to a novel poly(taco complex) and ordering arrangement of the guest molecules indirectly.     

The first [2]pseudorotaxane and the first pseudocryptand-type poly[2]pseudorotaxane based on bis(meta-phenylene)-32-crown-10 and paraquat derivatives

By the self-assembly of a bis(meta-phenylene)-32-crown-10 bearing two electron-donating groups (carbazoles) with electron-accepting paraquat derivatives, the first [2]pseudorotaxane and the first pseudocryptand-type poly[2]pseudorotaxane based on bis(meta-phenylene)-32-crown-10 were isolated as crystalline solids as shown by X-ray analyses.     

二甲基·[4-硝基-2-(氮杂苯并-15-冠-5)-1-酚氧基]合镓(Ⅲ)配合物的晶体结构

The complex dimethylgallium- [4-nitro-2-(N-benzo-15-crown-5)-1-phenoxide ](C₂₃H₃₁N₂O₇Ga) has been synthesized by the method reported.The crystal X-ray diffraction analysis shows that the crystal belongs to the triclinic with space group P1, M = 517.23 and the unit cell parameters: a = 1.4501 (2), b = 1.5090(2), c = 1.3865 (6)nm, a = 105.58(1 ), β = 117.26(2), γ = 66.812(8)°, V= 2.464546nm³, Z =4, Dc = 1.39g·cm^-3, u = 11.6cm^-1, F(000) = 1080, R = 0.051, Rw = 0.064.The coordination number of Ga is four and the gallium atom is located in a distorted tetrahedron structure.     

A chemical-responsive bis(m-phenylene)-32-crown-10/2,7-diazapyrenium salt [2]pseudorotaxane

A chemical-responsive bis(m-phenylene)-32-crown-10/2,7-diazapyrenium salt [2]pseudorotaxane was prepared. It was found to form a supramolecular poly[2]pseudorotaxane in the solid state driven by π-π stacking interactions.     

Synthesis and structural characterization of (COT)Pr(C13H8CH2CH2OMe)(THF) containing the chelating 9-(2-methoxyethyl)fluorenyl ligand

Treatment of 9-(2-methoxyethyl)fluorene, C₁₃H₉CH₂CH₂OMe (1), with potassium hydride in THF/toluene in the presence of 18-crown-6 afforded orange-red crystalline K(18-crown-6)C₁₃H₈CH₂CH₂OMe (2) in 59% yield. A “constrained geometry”-type praseodymium complex containing the 9-(2-methoxyethyl)fluorenyl ligand, (COT)Pr(C₁₃H₈CH₂CH₂OMe)(THF) (3), was prepared by treatment of dimeric [(COT)Pr(μ-Cl)(THF)₂]₂ (COT = η⁸-cyclooctatetraenyl) with in situ prepared KC₁₃H₈CH₂CH₂OMe. The molecular structures of 1, 2, and 3 were determined by single-crystal X-ray diffraction.     

Pseudocryptand-type [3]pseudorotaxane and "hook-ring" polypseudo[2]catenane based on a bis(m-phenylene)-32-crown-10 derivative and bisparaquat derivatives

The first pseudocryptand-type supramolecular [3]pseudorotaxane was designed and prepared via the self-assembly of a bispicolinate BMP32C10 derivative and a bisparaquat. The complexation behavior was cooperative. In addition, the complex comprised of the BMP32C10 derivative and a cyclic bisparaquat demonstrated strong binding; interestingly, a poly[2]pseudocatenane structure was formed in the solid state for the first time.     

Branched [n]rotaxanes (n = 2-4) from multiple dibenzo-24-crown-8 ether wheels and 1,2-bis(4,4'-dipyridinium)ethane axles

To investigate the possibility of incorporating the 1,2-bis(pyridinium)ethane[subset or is implied by]24C8 [2]pseudorotaxane motif into dendrimer like macromolecules, a series of branched [n]rotaxanes were prepared employing multiple dibenzo-24-membered crown ether wheels with various aromatic core structures and the 1,2-bis(4,4'-dipyridinium)ethane axle. Yields of branched [2]-, [3]- and [4]rotaxanes were dependent on the size of the core and the relative proximity of the crown ethers arranged around the core unit.     

Synthesis and structure of the silylated benzene radical anion salts [K([18]crown-6){C6H4(SiMe3)2-1,4}] and [K([18]crown-6)(THF)2][C6H2(SiMe3)4-1,2,4,5]

The crystalline compound [K([18]crown-6){C₆H₄(SiMe₃)₂-1,4}] (1) was prepared by the low-temperature reduction of the para-disilylated benzene with K/[18]crown-6 in toluene followed by recrystallisation from the same solvent. Reduction of 1,2,4,5-tetrasilylated benzene with 2(K/[18]crown-6) in toluene produced a hydrocarbon-insoluble powder identified as the dianionic derivative [K([18]crown-6)]₂[C₆H₂(SiMe₃)₄-1,2,4,5)] (2), which upon crystallisation from THF/Et₂O yielded [K([18]crown-6)(THF)₂][C₆H₂(SiMe₃)₄-1,2,4,5] (3). An X-ray diffraction study revealed that 1 comprised a contact ion pair with the crown-encapsulated K cation η⁵-connected to the planar ring of the substituted benzene radical anion, while 3 contained a well separated cation and anion.     

Luminescent silver nitrate complexes of bis[2-(diphenylphosphano)phenyl]ether (DPEphos): Crystal structure of [Ag(DPEphos)(py2SH)2]NO3

Heteroleptic silver(I) nitrate complexes containing the bis[2-(diphenylphosphano)phenyl]ether (DPEphos) ligand and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH), 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH), 1,4,5,6-tetrahydropyrimidine-2-thione (thpymtH) or 1,3-imidazolidine-2-thione (imtH₂) have been synthesized and characterized by IR and UV-Vis spectroscopy, elemental analyses and melting point determinations. The complexes can be obtained by the addition of the thioamide ligand to an AgNO₃-diphosphane adduct in dichloromethane/ethanol solution. The molecular structure of [Ag(DPEphos)(py2SH)₂]NO₃ complex has been established by single-crystal X-ray diffraction. The structure features a tetrahedral silver(I) center with two phosphorus atoms from the chelating diphos ligand, and the exocyclic sulfur atom of two heterocyclic thioamide units. Intense blue-green emission is observed in the region 470-483 nm for all the complexes in the solid state and in solution at ambient temperature.