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.     

Bis(m-phenylene)-32-crown-10-based cryptands, powerful hosts for paraquat derivatives

Four new bis(m-phenylene)-32-crown-10-based cryptands with different third bridges were prepared. Their complexes with paraquat derivatives were studied by proton NMR spectroscopy, mass spectrometry, and X-ray analysis. It was found that these cryptands bind paraquat derivatives very strongly. Specifically, a diester cryptand with a pyridyl nitrogen atom located at a site occupied by either water or a PF(6) anion in analogous complexes exhibited the highest association constant K(a) = 5.0 x 10(6) M(-1) in acetone with paraquat, 9000 times greater than the crown ether system. X-ray structures of this and analogous complexes demonstrate that improved complexation with this host is a consequence of preorganization, adequate ring size for occupation by the guest, and the proper location of the pyridyl N-atom for binding to the beta-pyridinium hydrogens of the paraquat guests. This readily accessible cryptand is one of the most powerful hosts reported for paraquats.     

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.     

基于双间苯-32-冠-10穴醚超分子组装体的设计与构筑

由于具有三维空腔结构及良好的应用前景, 穴醚逐渐成为超分子研究领域的热点之一. 近年来, 我们课题组设计合成了一系列基于双间苯-32-冠-10穴醚主体分子, 并利用这些穴醚分子构筑了不同的超分子组装体. 首先, 将双硫代四硫富瓦烯(STTFS)引入到穴醚的第三个臂上, 成功构筑了具有氧化还原响应性的穴醚主体分子. 该穴醚与客体间的解离-穿环过程可以利用STTFS的氧化态来进行控制; 其次, 设计合成了两种含有P=O官能团桥连的穴醚, 在固态结构中得到了近似线型和Z字型的不同超分子聚[2]准轮烷; 最后, 合成了具有两种不同性质空腔的柱[5]芳烃稠合穴醚主体分子, 该穴醚通过正交作用同时络合两个不同的客体分子. 基于两种不同主客体作用力, 我们构筑了一种新型的超分子聚合物. 以上研究为分子器件和超分子材料的进一步研究奠定了良好的基础.     

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.     

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).     

Unique "cradled barbell" complex between a secondary diammonium ion and bis(m-phenylene)-32-crown-10

[formula: see text] The complexation between N,N'-dibenzyl(m-xylylene)diammonium bis(hexafluorophosphate) (2) and bis(m-phenylene)-32-crown-10 (5) was shown to occur in solution by nuclear magnetic resonance with 1:1 stoichiometry and a Ka value of 189 +/- 19 M-1. A crystal structure of 2:5 revealed a unique 1:1 "exo" or "cradled barbell" complex, instead of the expected pseudorotaxane. This unexpected result illustrates that caution be used in interpreting the results from these types of complexes in the solution and "gas" phases on the basis of crystal structures.     

Pseudocryptand-type [2]pseudorotaxanes based on bis(meta-phenylene)-32-crown-10 derivatives and paraquats with remarkably improved association constants

The first dual component pseudocryptand-type [2]pseudorotaxanes were designed and prepared via the self-assembly of synthetically easily accessible bis(meta-phenylene)-32-crown-10 pyridyl, quinolyl, and naphthyridyl derivatives with paraquat. The formation of the pseudocryptand structures in the complexes remarkably improved the association constant by forming the third pseudobridge via H-bonding with the guest and π-stacking of the heterocyclic units.     

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.     

Supramolecular AA-BB-type linear polymers with relatively high molecular weights via the self-assembly of bis(m-phenylene)-32-crown-10 cryptands and a bisparaquat derivative

Two novel bis(m-phenylene)-32-crown-10-based cryptands, one bearing covalent linkages and the other metal-complex linkages, were designed and prepared. By self-assembly of these biscryptands, which can be viewed as AA monomers, and a bisparaquat, which can be viewed as a BB monomer, AA-BB-type linear supramolecular polymers with relatively high molecular weights were successfully prepared.     

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.     

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.     

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.     

Efficient syntheses of bis(m-phenylene)-26-crown-8-based cryptand/paraquat derivative [2]rotaxanes by immediate solvent evaporation method

A novel bis(m-phenylene)-26-crown-8-based cryptand has been synthesized. It has been used to prepare two 1:1 complexes with two paraquat derivatives with high association constants (6.5×10⁵ and 4.0×10⁵ M⁻¹) in acetone. In the solid state the cryptand forms a 2:1 threaded structure with paraquat and an interesting supramolecular poly[2]pseudorotaxane threaded structure with a dihydroxyethyl-substituted paraquat derivative, respectively. It has been further used to prepare cryptand/paraquat derivative [2]rotaxanes efficiently by the immediate solvent evaporation method using easily available 3,5-dimethylphenyl groups as the stoppers.     

A new strategy for folding oligo(m-phenylene ethynylenes)

Backbone-rigidified oligo(m-phenylene ethynylenes) fold into crescent or helical conformations in non-polar organic solvents.     

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.     

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.     

双羟甲基-18-冠-6及其衍生物的合成

报道了双羟甲基-18-冠-6及其正丁基、烯丙基、酯基、羧酸基衍生物的合成。所合成的八种新冠醚化合物的结构已经IR、MS、NMR、元素分析证实。     

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.     

Cation selectivity of 13-crown-4 and bis(13-crown-4) derivatives

The cation selectivity of liquid-membrane electrodes based on 18 derivatives of 13- crown-4 and bis(13-crown-4) is reported. When these compounds are dissolved in 1,2-dichlorobenzene, the electrodes exhibit MgCl⁺ selectivity which depends on the nature of the bonds connecting the crown ether rings.