Guest-dependent complexation of triptycene-based macrotricyclic host with paraquat derivatives and secondary ammonium salts: a chemically controlled complexation process

The triptycene-based macrotricyclic host containing two dibenzo-[24]-crown-8 moieties has been found to form stable 1:1 or 1:2 complexes in different complexation modes with different functional paraquat derivatives and secondary ammonium salts in solution and in the solid state. Consequently, the alkyl-substituted paraquat derivatives thread the lateral crown cavities of the host to form 1:1 complexes. It was interestingly found that the paraquat derivatives containing two beta-hydroxyethyl or gamma-hydroxypropyl groups form 1:2 complexes, in which two guests thread the central cavity of the host. Other paraquat derivatives containing terminal hydroxy, methoxy, 9-anthracylmethyl, and amide groups were included in the cavity of the host to form 1:1 complexes. Moreover, the host also forms a 1:2 complex with two 9-anthracylmethylbenzylammonium salts, in which the 9-anthracyl groups were selectively positioned outside the lateral crown cavities. The competition complexation process between the host and two different guests (the propyl-substituted paraquat derivative and a dibenzylammonium salt) could be chemically controlled.     

Self-assembly of 1:2 inclusion complexes between a metallocycle host and dihydroxyaromatic guests: a redox controlled complexation process

Two new 1:2 inclusion complexes were prepared by self-assembly of three components: a ligand based on 4,4'-bipyridinium, a square-planar Pd complex, and a dihydroxyaromatic guest (hydroquinone or 1,5-dihydroxynaphthalene) in a 2:2:2 ratio. Their X-ray structural analyses revealed that the complexes are stabilized by pi-pi stacking and [C-H...pi] interactions.     

Novel triptycene-based cylindrical macrotricyclic host: synthesis and complexation with paraquat derivatives

[reaction: see text] A novel triptycene-based cylindrical macrotricyclic polyether containing two dibenzo[24]crown-8 cavities has been synthesized and proved to be a highly efficient host for the complexation with paraquat derivatives. Consequently, a new kind of very stable pseudorotaxane-type complex was formed in solution and in the solid state.     

Li+-templated complexation of cylindrical macrotricyclic host with naphthalene diimide: Cation-controlled switchable complexation processes

Anthracene-based cylindrical macrotricyclic polyether (1) containing two dibenzo-30-crown-10 cavities has been proved to be an efficient host for the templated complexation with N,N’-dipropyl-1,4,5,8-naphthalenetetracarboxylic diimide in the presence of lithium ions in both solution and solid state. Host 1 could also form 1:1 complex with the bispyridinium salt with two β-hydroxyethyl groups in solution and in the solid state. Moreover, it was also found that the switchable complexation processes between the macrotricyclic host and two different kinds of guests could be chemically controlled by the addition and removal of lithium ions.     

Selective templated complexation of a cylindrical macrotricyclic host with neutral guests: three cation-controlled switchable processes

A novel triptycene-based cylindrical macrotricyclic host 1 containing an anthracene unit and two dibenzo [24]crown-8 moieties was synthesized, and its cation binding properties were studied. It was found that the host could not only form complex with the paraquat derivative 4, but also show selective templated complexation with pyromellitic diimide 2 and anthraquinone 3 in the presence of lithium and potassium ions, respectively. Consequently, two novel cascade complexes with neutral molecules as bridging species were formed in solution and in the solid state, which were structurally studied by NMR, MS spectra, and X-ray methods. Moreover, we also found that the association and dissociation of the complexes could be easily achieved by the addition and removal of lithium or potassium ions, which resulted in three cation-controlled switchable processes.     

Guest-dependent complexation of triptycene-derived macrotricyclic host containing one anthracene moiety with paraquat derivatives: construction of [2]rotaxanes

Complexation between the triptycene-derived macrotricyclic polyether containing an anthracene unit and paraquat derivatives in both solution and solid state was investigated. It was found that the macrotricyclic host with multi-cavity structure could form a series of [2]pseudorotaxanes with different terminal functionalised paraquat derivatives in different threading modes, which subsequently resulted in the construction of two novel [2]rotaxanes.     

Formation of ternary excited donor-acceptor complexes in systems containing benzophenone and an amine

On the basis of data on the influence of butyl methacrylate on the primary processes of photoreduction of benzophenone by triethylamine, an analysis has been made of the concept that ternary exciplexes (donor + acceptor + unsaturated compound) participate in electron phototransfer processes. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, 109–112, March–April, 1998.     

Formation and transformations of polyelectrolyte gel-ampholyte dendrimer-surfactant ternary complexes

The reactions of complex gels formed via the sorption of a poly(propylenimine) ampholyte dendrimer of the fourth generation by oppositely charged lightly cross-linked polyelectrolyte hydrogels with ionogenic micelle-forming surfactants have been studied. The sorption of surfactant ions likely charged relative to the complexed ampholyte dendrimer by complex gels is associated with two parallel chemical reactions controlled by the concentration of the surfactant and pH which give rise to the formation of network-dendrimer-surfactant tertiary complexes. The reactions of complex gels with surfactant ions likely charged relative to the network polyelectrolyte make it possible at different solution pHs to prepare both negatively and positively charged hydrogels reinforced by disperse particles of the dendrimer-surfactant complex.     

Synthesis of triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties and its complexation with paraquat derivatives: Li(+)-ion-controlled binding and release of the guests in the complexes

A new triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties was synthesized and shown to form 1:1 complexes with paraquat derivatives in solution, in which the guests all thread the central cavity of the host. However, it was interestingly found that, depending on the paraquat derivatives with different functional groups, the host can form stable 1:1 or 1:2 complexes in different complexation modes in the solid state, which is significantly different from those of the macrotricyclic host containing two dibenzo-[24]-crown-8 moieties. The formation of the complexes was also proved by the ESI MS and electrochemical experiments. Moreover, it was found that the binding and release of the guests in the complexes could be easily controlled by the addition and removal of lithium ions.     

Enhanced ternary 1:2 host–guest complexation of amino-γ-cyclodextrins with 2-anthracenecarboxylic acid

The complexation behavior of 6-amino-6-deoxy-γ-cyclodextrin (CD), 6^A,6^X-diamino-6^A,6^X-deoxy-γ-CDs and 3^A-amino-3^A-deoxy-altro-γ-CD with 2-anthracenecarboxylic acid (AC) was studied by NMR, UV–vis and circular dichroism spectroscopy. These modified γ-CD derivatives were found to form stable 1:2 host-guest ternary complexes with AC in aqueous solution. Compared with native γ-CD, the primary-face-aminated γ-CDs exhibited remarkably enhanced overall association constants as a result of the additional electrostatic interactions between the oppositely charged host and guest. In contrast, the ternary complex formation of the secondary-face-aminated γ-CD with AC was hindered.     

Interpolymer complexation between polyacrylic acid and cellulose ethers: Formation and properties

The interaction between polyacrylic acid and two water‐soluble cellulose ethers (methylcellulose and hydroxyethylcellulose) was studied. Viscometry, velocity sedimentation, small‐angle neutron scattering, and potentiometric titration methods show the formation of stable water‐soluble interpolymer complexes due to hydrogen bonding between nondissociated groups of polyacrylic acid and proton‐acceptor groups of the cellulose ether. Both complexes exhibit polyelectrolyte properties and keep the conformation of the semirigid chain component. The hydrophobic groups in the methylcellulose macromolecule are responsible for the absence of complexes at temperatures greater than 60 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1323–1330, 2000     

Resolution of enantiomers and isotopic compositions by selective complexation gas chromatography on metal complexes

Summary The high selectivity of complexation gas chromatography has been employed for enantiomer resolution and isotope separation. Thus, a chiral olefin, 3-methylcyclopentene, has been resolved analytically on optically active dicarbonyl-rhodium(I)-3-trifluoroacetyl-1R-camphorate in squalane. The deuterated ethylenes C₂H_4–nD_n have been separated on the same rhodium(I)-containing stationary phase. The chiral aliphatic oxiranes epoxypropane andtrans-2,3-epoxybutane have been resolved on optically active nickel(II)-bis-3-trifluoroacetyl-1R-camphorate in squalane.     

Qualitative comparison between the quantum calculations and electrospray mass spectra o complexes of polyammonium macrotricyclic ligands with dicarboxylic acids

The host-guest interactions play a very important role in chemical and biological processes. It is therefore important to be able to characterize these complexes. Electrospray mass spectrometry can be used to characterize the complex formation. It provides information on the mass and the charge of these ionic complexes. In this article, we show that the use of ab initio and semiempirical calculations, in addition to the results obtained by electrospray mass spectrometry, reveal to be a promising tool for the study of these noncovalent complexes. In this article, host-guest complexes formed by macropolycyclic polyammonium host molecules and dicarboxylic acids are studied.     

Cryptates XXIV: Structure and stability of mononuclear and binuclear cation inclusion complexes of cylindrical macrotricyclic ligands

The cylindrical macrotricyclic ligands 1–3 yield inclusion complexes, [3]-cryptates, with various metal cations. NMR. studies indicate the successive formation of a mononuclear and a binuclear complex. The former is probably unsymmetrical undergoing fast intramolecular cation exchange; the latter is symmetrical, with a cation located on each macrocyclic subunit of the macrotricyclic system. A heteronuclear (Ag²⁺, Pb²⁺) complex has been observed. The stability constants of the mononuclear and binuclear alkali and alkaline-earth cation complexes of ligands 1–3 have been determined by potentiometric methods. The stabilities are comparable to those of the complexes of the isolated macrocyclic subunit 5b . The binuclear complexes are almost as stable as the mononuclear one even in highly charged species like for instance the complex of ligand 2 with two barium cations. Cylindrical macrotricyclic ligands are topologically well suited for the designed positioning of two metal cations in a binuclear inclusion complex.     

Concerted attack of frustrated Lewis acid-base pairs on olefinic double bonds: a theoretical study

A computational approach reveals cooperative action of the preorganized acidic and basic centers of the frustrated P(t-Bu)(3)/B(C(6)F(5))(3) Lewis pair on olefinic bonds as the key to the observed regioselective addition reaction.     

Formation of complexes between alkyl polyglycosides and potato starch

The formation of complexes between soluble potato starch and three commercial alkyl polyglycosides has been studied by means of surface tension measurements at 37 degrees C. All surfactants assayed form complexes with starch, the quantity of bound surfactant being proportional to the amount of starch present in the solution. For all alkyl polyglycoside-starch systems tested, there is a direct proportional relationship between the bound and total surfactant concentrations, so that the formation of the surfactant-starch complex continues until the minimum surface tension is reached without detectable starch saturation prior to the occurrence of surfactant micelles. Binding isotherms and Scatchard plots support the idea that alkyl polyglycosides are bound to amylose by positive cooperative binding and to amylopectin by non-cooperative Langmuir-type binding.     

The photophysics of some intramolecular ternary complexes formed between aryl and amino groups

The fluorescence properties of (3)–(6) in solvents of varying polarity have been examined and the conclusion reached that in non-polar solvents they exhibit fluorescence (low quantum yield) from an intramolecular ternary complex. In polar solvents very little fluorescence is observable. Although each compound exhibits extensive intramolecular fluorescence quenching, the quantum yield of localised triplet naphthalene in non-polar solvents remains relatively high indicating that intersystem crossing occurs in the non-relaxed exciplex.     

Macromolecular metal complexes with transition-metal ions: Structure of a polymer and efficiency of complexation

A quantitative method of estimating the efficiency of formation of macromolecular metal complexes of carboxyl-containing (co)polymers with transition-metal ions in dilute solutions was developed. This method is based on the luminescence quenching of luminescently labeled macromolecules by transition-metal ions. With the use of this method, the effect of the chemical (including isomeric) structure of carboxyl-containing (co)polymers and external conditions on the stability of macromolecular metal complexes based on copper, nickel, and silver ions was assessed. With consideration for the data obtained, a targeted variation in the functional characteristics of macromolecular metal complexes may be accomplished.     

Self-assembly of luminescent ternary complexes between seven-coordinate lanthanide(III) complexes and chromophore bearing carboxylates and phosphonates

Luminescent lanthanide complexes have been prepared by exploiting the interaction between lanthanide DO3A complexes and chromophore bearing carboxylates or phosphonates. This interaction can be utilised to probe the choice of sensitising chromophore suited to a given lanthanide. Furthermore, ternary complexes obtained from chromophore appended carboxylates dissociate in the presence of phosphate, while those obtained from phosphonates do not.