Synthesis of novel bis(beta-cyclodextrin)s and metallobridged bis(beta-cyclodextrin)s with 2,2'-diselenobis(benzoyl) tethers and their molecular multiple recognition with model substrates

To investigate quantitatively the cooperative binding ability of beta-cyclodextrin dimers, a series of bridged bis(beta-cyclodextrin)s with 2,2'-diselenobis(benzoyl) spacer connected by different lengths of oligo(ethylenediamine)s (2-5) and their platinum(IV) complexes (6-9) have been synthesized and their inclusion complexation behavior with selected substrates, such as Acridine Red, Neutral Red, Brilliant Green, Rhodamine B, ammonium 8-anilino-1-naphthalenesulfonate, and 6-p-toluidino-2-naphthalenesulfonic acid, were investigated by means of ultraviolet, fluorescence, fluorescence lifetime, circular dichroism, and 2D-NMR spectroscopy. The spectral titrations have been performed in aqueous phosphate buffer solution (pH 7.20) at 25 degrees C to give the complex stability constants (K(S)) and Gibbs free energy changes (-DeltaG degrees ) for the inclusion complexation of hosts 2-9 with organic dyes and other thermodynamic parameters (DeltaH degrees and TDeltaS degrees ) for the inclusion complexation of 2-5with fluorescent dyes ANS and TNS. The results obtained indicate that beta-cyclodextrin dimers 2-5 can coordinate with one or two platinum(IV) ions to form 1:1 or 1:2 stoichiometry metallobridged bis(beta-cyclodextrin)s. As compared with parent beta-cyclodextrin (1) and bis(beta-cyclodextrin)s 2-5, metallobridged bis(beta-cyclodextrin)s 6-9 can further switch the original molecular binding ability through the coordinating metal to orientate two beta-cyclodextrin cavities and an additional binding site upon the inclusion complexation with model substrates, giving the enhanced binding constants K(S) for both ANS and TNS. The tether length between two cyclodextrin units plays a crucial role in the molecular recognition with guest dyes. The binding constants for TNS decrease linearly with an increase in the tether length of dimeric beta-cyclodextrins. The Gibbs free energy change (-DeltaG degrees ) for the unit increment per ethylene is 0.32 kJ.mol(-)(1) for TNS. Thermodynamically, the higher complex stabilities of both ANS and TNS upon the inclusion complexation with 2-5 are mainly contributed to the favorable enthalpic gain (-DeltaH degrees ) by the cooperative binding of one guest molecule in the closely located two beta-cyclodextrin cavities as compared with parent beta-cyclodextrin. The molecular binding ability and selectivity of organic dyes by hosts 1-9 are discussed from the viewpoints of the multiple recognition mechanism and the size/shape-fitting relationship between host and guest.     

Molecular recognition studies on supramolecular systems. 32. Molecular recognition of dyes by organoselenium-bridged bis(beta-cyclodextrin)s.

A series of novel bis(beta-cyclodextrin)s tethered with organoselenium linkers, i.e., 6,6'-(o-phenylene-diseleno)-bridged bis(beta-cyclodextrin) (2), 6,6'-[2,2'-diselenobis(benzoyloxy)]-bridged bis(beta-cyclodextrin) (3), and 6,6'-[2,2'-diselenobis[2-(benzoylamino)ethylamino]]-bridged bis(beta-cyclodextrin) (4), were synthesized from beta-cyclodextrin (1). The inclusion complexation behavior of 1-4 with some dyes, such as 8-anilinonaphthalenesulfonate (ANS), Brilliant Green, Crystal Violet, Tropaeolin OO, Auramine O, and Methyl Orange, was investigated in aqueous phosphate buffer solution (pH 7.20) at 25 degrees C by UV-vis, fluorescence, and circular dichroism spectrometry, as well as fluorescence lifetime measurements. The complex stability constants (Ks) and Gibbs free energy changes (delta Go) for the stoichiometric 1:1 inclusion complexation of 1-4 with the dyes were obtained by the spectrophotometric or spectropolarimetric titrations. The bis(beta-cyclodextrin)s 2-4 showed much higher affinities toward these guest dyes than native beta-cyclodextrin 1 with fairly good molecular selectivities. The cooperative binding abilities of these bis(beta-cyclodextrin)s are discussed from the viewpoints of size/shape-fit interaction, induced-fit concept, and multiple recognition mechanism.     

Unique fluorescence behavior of rhodamine B upon inclusion complexation with novel bis(beta-cyclodextrin-6-yl) 2,2'-bipyridine-4,4'-dicarboxylate

Newly synthesized bis(beta-cyclodextrin-6-yl) 2,2'-bipyridine-4,4'-dicarboxylate was found to induce an unusual fluorescence enhancement of Rhodamine B (RhB) upon complexation. This effect is attributable to the equilibium shift of RhB to the highly fluorescent carboxylate ion form, which is induced by the cooperative binding by two appropriately preorganized cyclodextrin units in the bis(beta-cyclodextrin). This sandwich complexation behavior was investigated by means of the fluorescence and 2D NMR spectroscopy.     

Selective binding of steroids by 2,2'-biquinoline-4,4'-dicarboxamide-bridged bis(beta-cyclodextrin): fluorescence enhancement by guest inclusion

A novel bis(beta-cyclodextrin) was synthesized, and its binding behavior with steroids was investigated to demonstrate that the cooperative co-inclusion of guest and tether by two cyclodextrin moieties is operative to afford the highest molecular selectivity of up to 3.6 for deoxycholate over taurocholate.     

六氟磷酸二(4,4'-二甲基-2,2'-联吡啶)·(2,2'-联吡啶-4,4'-二羧酸)合钌(Ⅱ)的二维核磁共振

用1H NMR和13C NMR谱研究了新型电化学发光探针六氟磷酸二(4,4'-二甲基-2,2'-联吡啶)·(4,4'-二羧酸-2,2'-联吡啶)合钌(Ⅱ)的立体结构,通过1H-1H COSY、13C-1H HETCOR谱对其氢谱和碳谱中的各谱峰进行了归属,并给出了氢谱和碳谱峰的化学位移值.     

Indium tin oxide electrodes modified with tris(2,2'-bipyridine-4,4'-dicarboxylic acid) iron(II) and the catalytic oxidation of tris(4,4'-di-tert-butyl-2,2'-bipyridine) cobalt(II)

Indium tin oxide (ITO) electrodes modified by attachment of tris(2,2'-bipyridine-4,4'-dicarboxylic acid) iron(II) are examined. The mode of attachment is believed to be via the COOH functions in a manner similar to attachment of similar carboxylate-containing compounds to TiO2 surfaces. On the surface the complex resides as a stable electrochemically active monolayer. These modified electrodes can efficiently catalyze the oxidation of certain cobalt complexes, specifically, tris(4,4'-di-tert-butyl-2,2'-bipyridine) cobalt(II). On the unmodified ITO surfaces this cobalt complex is essentially electrochemically inert. The catalytic process approaches diffusional control at very slow scan speeds. Also, the electro-catalysis is sufficiently efficient that the peak oxidation current for Co2+, under certain conditions, exceeds the i(p) for the surface oxidation of the adsorbed Fe2+ by >x100 and the current for the uncatalyzed oxidation of Co2+ by considerably more than that.     

Spectrophotometric study on the controlling factor of molecular selective binding of dyes by bridged bis(beta-cyclodextrin)s with diselenobis(benzoyl) linkers

A series of beta-cyclodextrin (beta-CD) dimers with 4,4'-diselenobis(benzoyl) linkers, that is, 6,6'-[4,4'-diselenobis(benzoyloxyl)]-bridged bis(beta-CD) (1a), 6,6'-[4,4'-diselenobis[2-(benzoylamino)ethyleneamino]]-bridged bis(beta-CD) (2a), and 6,6'-[4,4'-diselenobis[2-(benzoylamino)-3,6-diazaoctylamino]]-bridged bis(beta-CD) (3a), were synthesized in moderate yields by the reaction of 4,4'-diselenobis(benzoic acid) with beta-CD or oligo(ethylenediamino)-6-deoxy-beta-CD. Their binding behaviors with some structure-related substrates, such as acridine red (AR), neutral red (NR), rhodamine B (RhB), ammonium 8-anilino-1-naphthalenesulfonate (ANS), and 6-p-toluidino-2-naphthalenesulfonic acid (TNS), were investigated in aqueous phosphate buffer solution (pH 7.20) at 298.15 K by means of fluorescence, NMR, as well as circular dichroism spectroscopy and compared with those of their 2,2'-diselenobis(benzoyl)-linked analogues, that is, 6,6'-[2,2'-diselenobis(benzoyloxyl)]-bridged bis(beta-CD) (1b), 6,6'-[2,3'-diselenobis[2-(benzoylamino)ethyleneamino]]-bridged bis(beta-CD) (2b), and 6,6'-[2,2'-diselenobis[2-(benzoylamino)-3,6-diazaoctylamino]]-bridged bis(beta-CD) (3b). The results showed that bis(beta-CD)s 1a-3a, whose Se-Se bonds were located at the para position of the carboxyl group, gave stronger binding abilities toward nonlinear guests (RhB and ANS) than their analogues 1b-3b, whose Se-Se bonds were located at the ortho position relative to the carboxyl group. The molecular binding ability and selectivity of model substrates by these ditopic hosts were sufficiently discussed to reveal not only the cooperative contributions of the linker group and CD cavities upon inclusion complexation with dye guest molecules but also the controlling factors for the molecular selective binding.     

Molecular recognition thermodynamics and structural elucidation of interactions between steroids and bridged bis(beta-cyclodextrin)s

A series of bridged bis(beta-cyclodextrin(CD))s (2-7) were synthesized, i.e., bridged bis(beta-CD)s 2 and 3 bearing binaphthyl or biquinoline tethers and bridged bis(beta-CD)s 4-7 possessing dithiobis(benzoyl) tether, and their complex stability constants (KS), enthalpy (DeltaH degrees), and entropy changes (DeltaS degrees) for the 1:2 inclusion complexation with representative steroids, deoxycholate, cholate, glycocholate, and taurocholate, have been determined in an aqueous phosphate buffer solution of pH 7.20 at 298.15 K by means of titration microcalorimetry. The original conformations of bridged bis(beta-cyclodextrin)s were investigated by circular dichroism and 1H ROESY spectroscopy. Structures of the inclusion complexes between steroids and bridged bis(beta-CD)s in solution were elucidated by 2D NMR experiments, indicating that anionic groups of two steroid molecules penetrate, respectively, into the two hydrophobic CD cavities in one 6,6'-bridged bis(beta-CD) molecule from the secondary rim to give a 1:2 binding mode upon inclusion complexation. The results obtained from titration microcalorimetry and 2D NMR experiments jointly demonstrate that bridged bis(beta-CD)s 2, 3 and 5-7 tethered by protonated amino group possessing different substituted groups can enhance not only the molecular binding ability toward steroids by electrostatic interaction but also molecular selectivity. Thermodynamically, the resulting 1:2 bis(beta-CD)-steroid complexes are formed by an enthalpy-driven process, accompanied by smaller entropy loss. The increased complex stability mainly results from enthalpy gain, accompanied by large conformational change and extensive desolvation effects for the 1:2 inclusion complexation between bis(beta-CD)s and steroids.     

Time-resolved photoacoustics study of the ruthenium(II) bis(2,2'-bipyridine)(4,4'-dicarboxy-2,2'-bipyridine) complex

The formation and the decay of the triplet metal to ligand charge transfer state ((3)MLCT) of ruthenium(II) bis(2,2'-bipyridine)(4,4'-dicarboxy-2,2'-bipyridine) (Ru(bpy)(2)(dcbpy)) were characterized using photoacoustic calorimetry. At pH 6 and 2, the (3)MLCT state formation leads to a volume change of -8 mL mol(-1) and enthalpy changes of 17 kcal mol(-1) and 13 kcal mol(-1), respectively. We attribute the volume contraction to structural changes and to solvent electrostriction. At pH 4, the photoexcitation of the complex leads to an expansion of 14 mL mol(-1) and an enthalpy change of approximately 119 kcal mol(-1) due to protonation of the carboxyl group in the excited state.     

Bridged bis(beta-cyclodextrin)s possessing coordinated metal center(s) and their inclusion complexation behavior with model substrates: enhanced molecular binding ability by multiple recognition.

To investigate quantitatively the cooperative binding ability of several beta-cyclodextrin oligomers bearing single or multiligated metal center(s), the inclusion complexation behavior of four bis(beta-cyclodextrin)s (2-5) linked by 2,2'-bipyridine-4,4'-dicarboxy tethers and their copper(II) complexes (6-9) with representative dye guests, i.e., methyl orange (MO), acridine red (AR), rhodamine B (RhB), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toludino)-2-naphthalenesulfonate (TNS), have been examined in aqueous solution at 25 degrees C by means of UV-vis, circular dichroism, fluorescence, and 2D NMR spectroscopy. The results obtained indicate that bis(beta-cyclodextrin)s 2-5 can associate with one or three copper(II) ion(s) producing 2:1 or 2:3 bis(beta-cyclodextrin)-copper(II) complexes. These metal-ligated oligo(beta-cyclodextrin)s can bind two model substrates to form intramolecular 2:2 host-guest inclusion complexes and thus significantly enhance the original binding abilities of parent beta-cyclodextrin and bis(beta-cyclodextrin) toward model substrates through the cooperative binding of two guest molecules by four tethered cyclodextrin moieties, as well as the additional binding effect supplied by ligated metal center(s). Host 6 showed the highest enhancement of the stability constant, up to 38.3 times for ANS as compared with parent beta-cyclodextrin. The molecular binding mode and stability constant of substrates by bridged bis- and oligo(beta-cyclodextrin)s 2-9 are discussed from the viewpoint of the size/shape-fit interaction and molecular multiple recognition between host and guest.     

Synthesis and molecular recognition of novel oligo(ethylenediamino) bridged bis(beta-cyclodextrin)s and their copper(II) complexes: enhanced molecular binding ability and selectivity by multiple recognition

Four bridged bis(beta-cyclodextrin)s tethered by different lengths of oligo(ethylenediamine)s have been synthesized and their inclusion complexation behavior with selected substrates elucidated by circular dichroism spectroscopy and fluorescence decay. In order to study their binding ability quantitatively, inclusion complexation stability constants with four dye guests, that is, brilliant green (BG), methyl orange (MO), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toluidino)-2-naphthalenesulfonate (TNS), have been determined in aqueous solution at 25 degrees C with spectrophotometric, spectropolarimetric, or spectrofluorometric titrations. The results obtained indicate that the two tethered cyclodextrin units might cooperatively bind to a guest, and the molecular binding ability toward model substrates, especially linear guests such as TNS and MO, could be extended. The tether length plays a crucial role in the molecular recognition, the binding constants for ANS and TNS decrease linearly with an increase in the tether length of dimeric cyclodextrin. The Gibbs free energy changes (-deltaGo) for the unit increment per ethylene are 0.99 kJ mol(-1) for ANS and 0.44 kJmol(-1) for TNS, respectively. On the other hand, the presence of a copper(II) ion in metallobis(beta-cyclodextrin)s oligo(ethylenediamino) tethers enhances not only the original binding ability, but also the molecular selectivity through triple or multiple recognition, as compared with the parent bis(beta-cyclodextrin)s.     

Binding ability and assembly behavior of beta-cyclodextrin complexes with 2,2'-dipyridine and 4,4'-dipyridine

Two channel-type supramolecular aggregations 1 and 2 were prepared by the inclusion complex of beta-cyclodextrin with 2,2'-dipyridine and 4,4'-dipyridine, respectively, and their binding ability and assembly behavior were investigated comprehensively by X-ray crystallography, (1)H NMR, circular dichroism spectra, and microcalorimetric titration in solution and the solid state. The obtained results revealed that the hydrogen bonds and pi-pi stacking interactions are crucial factors for the formation of the molecular aggregations containing beta-cyclodextrin and dipyridines. The disparity of nitrogen atom position in dipyridines leads not only to the distinct crystal system and space group, i.e., monoclinic system (C2) for 1 and triclinic system (P-1) for 2, but also different binding modes and thermodynamical parameters upon complexation of 2,2'-dipyridine and 4,4'-dipyridine with beta-cyclodextrin in aqueous solution.     

Novel synthesis of polyethers by the polyaddition of bis(epoxide)s with bis(phosphinate)s

The polyaddition of bisphenol A diglycidyl ether with bis[4‐(P,P‐diphenylphosphinyloxy)phenyl] sulfone catalyzed by quaternary onium salt, such as tetrabutylammonium chloride afforded a new phosphorus‐containing polyether with good solubility in common organic solvents. Having studied various factors affecting the reaction, such as temperature, catalyst concentration, reaction time, etc., an appropriate polyaddition condition was suggested as using 5 mol % of suitable quaternary ammonium or phosphonium salt in polar solvent at 150°C within 25 h in an ampule for producing high molecular weight polymer. A number of polyethers bearing pendent phosphinate ester groups from the polyaddition of certain bis(epoxide)s and bis(phosphinate)s were synthesized under the above condition and characterized by GPC, IR, and NMR. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1009–1016, 1999     

Spectrophotometric study of fluorescence sensing and selective binding of biochemical substrates by 2,2'-bridged bis(beta-cyclodextrin) and its water-soluble fullerene conjugate

A bis(beta-cyclodextrin)-fullerene conjugate (3) linked at the secondary hydroxyl side was prepared in a good yield from its precursor N,N'-bis(2-(2-aminoethylamino)ethyl)malonamide-bridged bis(beta-cyclodextrin) (2). Spectrophotomeric studies on the conformation and the inclusion complexation behavior of 3 with a variety of organic and biochemical substrates by means of UV-vis, FT-IR, NMR, fluorescence, and circular dichroism spectroscopy showed that the bis(beta-cyclodextrin)-fullerene conjugate displayed an intramolecular capsule-type conformation in aqueous solution. Because of the multiple binding of bis(beta-cyclodextrin) with substrates, 2 can act as an efficient fluorescence sensor for biochemical substrates, while its fullerene conjugate 3 displays a capability of cleaving DNA under visible-light irradiation.     

A novel synthesis of polyethers with pendant hydroxyl groups by polyaddition of bis(oxetane)s with bis(phenol)s

The polyaddition of 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene (BEOB) with 3,3′,5,5′-tetrachlorobisphenol A (TCBPA) was examined with or without catalysts. High molecular weight polymer (polymers 1) (M_n = 13,600) with pendant primary hydroxyl groups was obtained in a 99% yield without any gel products when the reaction was performed with 5 mol % of tetraphenylphosphonium bromide as a catalyst in NMP at 160°C for 96 h. However, when the reaction was carried out without a catalyst under the same conditions, a low molecular weight polymer (M_n = 3200) was obtained in a 51% yield. The structure of the resulting polymer was confirmed by IR, ¹H-NMR, and ¹³C-NMR spectra. In this reaction system, it was also found that tetraphenylphosphonium iodide and crown ether complexes such as 18-crown-6 (18-C-6)/KBr and 18-C-6/KI have high catalytic activity. Polyadditions of 1,4-bis[(3-methyl-3-oxetanyl)methoxymethyl]benzene with TCBPA and BEOB with 3,3′,5,5′-tetrabromobisphenol-S were also examined, and corresponding polymers (polymers 2 and 3) were obtained in good yields. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2781–2790, 1999     

4,4'-(多苯基三联苯)双(有机硅烷)的合成

本文研究了以4,4'-双(三苯基环戊二烯酮基)苯为双烯体,含乙烯基或苯乙炔基有机硅烷为双亲烯体,通过成环反应合成了六个新的4,4'-(多苯基三联苯)双(有机硅烷),产率60%～85%,并用元素分析,IR和'HNM表征了它们的结构。     

ResonanceRaman spectra of Iron(II) complexes with 4,4′-didodecyloxy-2,2′-bipyridine and 4,4′-dioctadecyloxy-2,2′-bipyridine

The resonanceRaman spectra of Fe(LC ₁₂)₃Cl₂ and Fe(LC ₁₈)₃Cl₂ (whereLC ₁₂ andLC ₁₈ denote 4,4′-didodecyloxy-2,2′-bipyridine and 4,4′-dioctadecyloxy-2,2′-bipyridine, respectively) have been measured along with their excitation profiles. The exciting lines of an Ar⁺ laser have been used. The bands appearing in theRR spectra within 1 200–1 600cm^?1 (expected to arise from thebipy moiety C-N and C-C vibrations) suffer the greatest resonance enhancements. Both depolarization ratios of theRaman bands and excitation profiles reveal the interaction of the resonant electronic states.