Sample records for zhidkogo kristalla mbba

  1. Droplet Breakup of the Nematic Liquid Crystal MBBA

    Nachman, Benjamin


    Droplet breakup is a well studied phenomena in Newtonian fluids. One property of this behavior is that, independent of initial conditions, the minimum radius exhibits power law scaling with the time left to breakup tau. Because they have additional structure and shear dependent viscosity, liquid crystals pose an interesting complication to such studies. Here, we investigate the breakup of a synthetic nematic liquid crystal known as MBBA. We determine the phase of the solution by using a cross polarizer setup in situ with the liquid bridge breakup apparatus. Consistent with previous studies of scaling behavior in viscous-inertial fluid breakup, when MBBA is in the isotropic phase, the minimum radius decreases as tau^{1.03 \\pm 0.04}. In the nematic phase however, we observe very different thinning behavior. Our measurements of the thinning profile are consistent with two interpretations. In the first interpretation, the breakup is universal and consists of two different regimes. The first regime is characterize...

  2. Conformational analysis of MBBA fluorinated analogues by 1H and 13C - NMR

    Pivovarova, N. S.; Boldeskul, I. E.; Shelyagenko, S. V.; Fialkov, Yu. A.


    1H- 13C -chemical shifts correlation analysis for MBBA and a series of its fluorinated analogues have been carried out. The azomethine proton chemical shift is shown to be sensitive to the aniline ring torsion angle and can be used for its approximate estimation.

  3. Surface induced disorder of nematic MBBA near silica with grafted poly(ethylene oxide)

    H. BEN OUADA; Hommel, H.; Legrand, A.P.; Balard, H.; Papirer, E.


    The order of a nematic liquid crystal, MBBA, in contact with a solid silica surface covered with grafted polymers poly(ethylene oxide) 2000, has been investigated by the electron paramagnetic resonance, the nuclear magnetic resonance and the differential scanning calorimetry. The different spectra, the transitions temperatures and the degree of order of the molecules are given. The results are consistent with an overall picture of the interface consisting of an intermediate layer formed by po...

  4. Development of 3-methoxy-4-benzyloxybenzyl alcohol (MBBA) resin as polymer-supported synthesis support: Preparation and benzyl ether cleavage by DDQ oxidation

    Qiang Huang; Bao-Zhong Zheng; Quan Long


    3-Methoxy-4-benzyloxybenzyl alcohol (MBBA) resin was synthesized by a two-step sequence under microwave irradiation involving the reaction of commercially available Merrifield resin with vanillin, followed by reduction with sodium borohydride. MBBA resin was treated with bromides in the presence of sodium hydride to afford the corresponding resin-bound benzyl ethers. Cleavage of the resin-bound benzyl ethers from the MBBA resin was carried out using 2,3-dichloro-5,6-dicyanobenzoqunone (DDQ) to give the corresponding alcohols in good yields. Moreover, the recovery, regeneration, and reuse of this polymer support could be achieved easily. MBBA resin can be developed as a kind of solid-phase synthesis bead of alcohols.

  5. Dielectric and electro-optical properties of polymer-stabilized liquid crystal. II. Polymer PiBMA dispersed in MBBA

    Tripathi, Pankaj Kumar; Pande, Mukti; Singh, Shri


    In continuation of our earlier work (Pande et al. in Appl Phys A 122:217-226, 2016), we report the results of dielectric and electro-optical properties of pure MBBA and PSLC (polymer PiBMA dispersed in MBBA) systems. The polymer networks domains formed are found to be anisotropic and are oriented in the direction of electric field for both the planar and homeotropic alignment cells. The dielectric anisotropy, optical anisotropy, response time, threshold voltage, splay elastic constant and rotational viscosity were observed for both the LC and PSLC systems with electric field. The liquid crystal properties are affected significantly with increasing concentration of polymer in pure LC material. It has been observed that the polymer networks interaction plays a major role in changing the properties of PSLC system. The effect of dielectric loss and dielectric permittivity on both pure LC and PSLC systems is also discussed.

  6. Effect of Potential Range in Pressure-Temperature Behavior in Isotropic-Nematic Transition of 4-4´-Bis(EthyloxyAzoxybenzene (P-Azoxyphenetole, Pap, 4-Pentyl-4´-Cyanobiphenyl (5cb, P-Methoxybenzydidene-P-N-Butylaniline (Mbba and P–Ethoxybenzylidene–P–N-Butylaniline (Ebba

    García-Sánchez E.


    Full Text Available In this work we employed the Density Functional Theory (IPCM model to calculate molecular volume and k, and the perturbation theory proposed by García-Sánchez et al. (2002 to predict phase diagram and experimental behavior pressure-temperature for isotropic-nematic transition of 4-4´-bis(ethyloxyazoxybenzene (p-azoxyphenetole, PAP, 4-pentyl-4´-cyanobiphenyl (5CB, p-methoxybenzydidene-p-n-butylaniline (MBBA and p–ethoxybenzylidene–p–n-butylaniline (EBBA at 1 atm. If during the theoretical prediction bigger potential values of potential range of square well (l > k are considered in the theoretical model, it is possible to get better prediction of the experimental behavior. The above mentioned is according with the theoretical formulation of the Second Order Perturbation Theory since Ponce-Renon approximation is included.

  7. Screening out the non-Arrhenius behaviour of nematic-isotropic transition by room temperature ionic liquid.

    Dan, K; Datta, A; Yoshida, Y; Saito, G; Yoshikawa, K; Roy, M


    Differential Scanning Calorimetry (DSC) and optical polarization microscopy of a mixture of the liquid crystalline material (N-(4-methoxybenzylidene)-4-butylaniline, MBBA) and a Fe-based room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrachloroferrate ([Emim](+) [FeCl4](-), EMIF) indicate a decrease in the nematic-isotropic (N-I) phase transition temperature (T(NI)) with an increase in EMIF concentration, explained by a proposed model of Coulomb "screening" of MBBA quadrupoles by the EMIF ions along with ionic "self screening." DSC studies of EMIF-MBBA and pure EMIF and comparison with pure MBBA results show that the major transitions in pure EMIF have Arrhenius behaviour, but more importantly the previously found convex Arrhenius behaviour of the pristine MBBA [K. Dan et al., Europhys. Lett. 108, 36007 (2014)] becomes Arrhenius in the mixture, indicating a conversion of the entropic N-I activation barrier to an enthalpic one. In presence of EMIF, a drastic decrease in the intensity of out-of-plane distortions of benzene rings in MBBA is found from Fourier transform infrared spectroscopy, consistent with significant reduction in the conformational states of MBBA. This suppression of large amplitude motion is again consistent with a Coulomb screening and gives a molecular basis for the entropic-to-enthalpic conversion of the N-I activation barrier.

  8. An electrochemical study of a liquid crystal used in information displays

    Oglesby, D. M.; Kern, J. B.; Robertson, J. B.


    The operational lifetime of liquid crystal displays were investigated. Electrochemical reaction at the electrodes of the display can cause failure after 2000 to 3000 hours of operation. Studies using cyclic voltametry of electrochemical reactions of N (p-methoxybenzilidene p-butylaniline (MBBA), a nematic liquid crystal were made. These studies indicate the presence of a reversible reduction of MBBA at the cathode, and that the reduction product undergoes a further reaction leading to products which are not reversibly oxidized. It is concluded that the degradation of the liquid crystal in displays can be reduced with a suitable frequency of alternating voltage.

  9. Fluctuation and dissipation in liquid crystal electroconvection

    Goldburg, Walter I.; Goldschmidt, Yadin Y.; Kellay, Hamid


    The power dissipation P( t) was measured in a liquid crystal (MBBA) driven by an ac voltage into the chaotic electroconvective state. In that state, the power fluctuates about its mean value . The quantity measured, and compared with the fluctuation theorem of Gallavotti and Cohen, is the dimensionless standard deviation of the fluctuations, σP/.

  10. Entropic screening preserves non-equilibrium nature of nematic phase while enthalpic screening destroys it

    Dan, K.; Roy, M.; Datta, A. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Saltlake, Kolkata 700064, West Bengal (India)


    The present manuscript describes the role of entropic and enthalpic forces mediated by organic non-polar (hexane) and polar (methanol) solvents on the bulk and microscopic phase transition of a well known nematic liquid crystalline material MBBA (N-(4-methoxybenzylidene)-4-butylaniline) through Differential Scanning calorimetry (DSC), UV-Visible (UV–Vis), and Fourier Transform Infrared (FTIR) spectroscopy. DSC study indicates continuous linear decreases in both nematic-isotropic (N-I) phase transition temperature and enthalpy of MBBA in presence of hexane while both these parameters show a saturation after an initial decay in methanol. These distinct transitional behaviours were explained in terms of the “depletion force” model for entropic screening in hexane and “screening-self-screening” model for methanol. Heating rate dependent DSC studies find that non-Arrhenius behaviour, characteristic of pristine MBBA and a manifestation of non-equilibrium nature [Dan et al., J. Chem. Phys. 143, 094501 (2015)], is preserved in presence of entropic screening in the hexane solution, while it changes to Arrhenius behaviour (signifying equilibrium behaviour) in presence of enthalpic screening in methanol solution. FTIR spectra show similar dependence on the solvent induced screening in the intensities of the imine (—C = N) stretch and the out-of-plane distortion vibrations of the benzene rings of MBBA with hexane and methanol as in DSC, further establishing our entropic and enthalpic screening models. UV–Vis spectra of the electronic transitions in MBBA as a function of temperature also exhibit different dependences of intensities on the solvent induced screening, and an exponential decrease is observed in presence of hexane while methanol completely changes the nature of interaction to follow a linear dependence.

  11. Geometry of third ventricle: radiological measurements supported by neuroendoscopic observations

    Novak, Z.; Chrastina, J. [Neurosurgical Dept., Faculty Hospital, St Anns, MF MU, Brno (Czech Republic); Krupa, P.; Feitova, V. [Dept. of Imaging Techniques, Faculty Hospital, St Anns, MF MU, Brno (Czech Republic); Riha, I. [Neurosurgical Dept., Faculty Hospital, St Anns, MF MU, Brno (Czech Republic); Inst. of Biomedical Engineering, FEEC BUT, Brno (Czech Republic)


    The aim od the study was to analyse the changes of third ventricular geometry caused by hydrocephalus. The data were obtained from planning studies for neuroendoscopic surgeries using stereotactic software Praezis Plus. Parameters CA-CP (intercommisural distance-corresponding to third ventricular length), IMD (intermammillary distance-third ventricular width), H (third ventricular height), BA-DS distance (distance between basilar artery bifurcation and dorsum sellae) and MB-BA distance were studied. After statistical analysis table of normal values is proposed for all the defined parameters. Statistically significant changes were found in all the measured parameters (CA-CP, IMD, H, MB-BA) in hydrocephalic patients except the distance between basilar artery and dorsum sellae, defining safe area for endoscopic third ventriculostomy. (orig.)

  12. Polarized fluorescence measurements of orientational order in a uniaxial liquid crystal

    Chapoy, L. Lawrence; DuPré, Donald B.


    The second and fourth orientational order parameters and , have been measured throughout the liquid crystalline phase of p-methoxybenzylidene-p[prime]-n-butylaniline (MBBA) using small quantities of a fluorescent probe. Complications of rotational Brownian motion and the intramolecular transfer...... of excitation energy were considered in the analysis. The results are in agreement with previous Raman measurements on the doped liquid crystal. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  13. Molecular dynamics in rod-like liquid crystals probed by muon spin resonance spectroscopy.

    McKenzie, Iain; Scheuermann, Robert; Sedlak, Kamil; Stoykov, Alexey


    Muoniated spin probes were produced by the addition of muonium (Mu) to two rod-like liquid crystals: N-(4-methoxybenzylidene)-4'-n-butylaniline (MBBA) and cholesteryl nonanoate (CN). Avoided level crossing muon spin resonance spectroscopy was used to characterize the muoniated spin probes and to probe dynamics at the molecular level. In MBBA Mu adds predominantly to the carbon of the bridging imine group and the muon and methylene proton hyperfine coupling constants (hfccs) of the resulting radical shift in the nematic phase due to the dipolar hyperfine coupling, the ordering of the molecules along the applied magnetic field and fluctuations about the local director. The amplitude of these fluctuations in in the nematic phase of MBBA is determined from the temperature dependence of the methylene proton hfcc. Mu adds to the double bond of the steroidal ring system of CN and the temperature dependence of the Δ(1) line width provides information about the amplitude of the fluctuations about the local director in the chiral nematic phase and the slow isotropic reorientation in the isotropic phase.

  14. Photo-stimulated electro-optic response of liquid-crystalline system with trans-cis photo-isomerizable agent

    Hadjichristov, G. B.; Marinov, Y. G.; Yelamaggad, C. V.


    A rather strong photo-stimulated enhancement of photo-induced bend flexoelectric effect based on trans-cis photoisomerization of azo bond was found in a guest-host system formed from the nematic liquid crystal (LC) N-(4-methoxybenzylidene)-4-butylaniline (MBBA) as a host, and the azobenzene LC 4-hexyloxybenzoloxy-4'-cyanoazobenzene, as a guest photoactive agent at 1 wt.% concentration. Upon application of electric field, thin homeotropic layers of thickness 100 pm containing this photo-sensitized LC mixture were investigated as subjected to a relatively weak illumination with UV light (λ = 375 nm, from narrow-band light-emitting diode, LED). The stimulation of the photoactive electro-optic response of azobenzene-doped MBBA (owing to enhanced photo-induced bend flexoelectric effect driven by the photo-isomerizable dopants) was achieved by pre-resonant excitation of the photoactive agent. The degree of the effect measured is of potential interest for thin-film photoactive electro-optic applications. The UV light-induced effect in azobenzene-doped MBBA was reversible; the back (relaxation) process was stimulated by light in the blue from a LED with broadband spectrum centered at 455 nm.

  15. Liquid Crystal Materials for Matrix Displays.


    TBATPB-doped MBBA, which is shown as a reference curve in Figure 1. More complete data on the scattering angles of HRL-26N3 -26N4, and - 25N2 are shown...D/T is more favorable at 20 V than at 15 V dc,Don since at higher voltage TD increases, and T decreases. For example,on at 20 V and 64*C the TD /Ton...Figure 9) changes with temperature. In the lower temperature range the TD and TON decrease with increasing temperature in the same manner as n

  16. Optical properties of planar nematic liquid crystals samples which are parallel oriented by nanofibers

    Yusuf, Yusril; Kusumasari, Ervanggis Minggar; Ula, Nur Mufidatul; Jahidah, Khannah; Triyana, Kuwat; Sosiati, Harini; Harsojo


    Optical properties of two nematic liquid crystals, i.e., 4-methoxybenzylidene-4-butylaniline (MBBA) and 4-cyano-4'-pentylbiphenyl (5 CB) which are parallel oriented by nanofibers has been successfully performed. Planar samples of liquid crystals were made using polyvinyl alcohol (PVA) nanofiber from electrospinning process. Electrospinning method was modified using copper (Cu) as gap collector. These planar samples area are 15 mm x 25 mm. Optical characteristic of these samples were studied by using optical polarizing microscope. The optical intensity changes by a rotationof crossed polarizers is observed. The sinusoidal intensity change was observedin these samples as such as in the planar sample prepared by the rubbing method.

  17. Virus Sorbents Based on Polyaniline Interpolymer Complexes, Composites and their Sorption Properties

    Ivanov, Victor F.; Ivanova, Valeria T.; Kurochkina, Yanina E.; Gribkova, Oksana L.; Ilyina, Maria V.; Manykin, Anatoly A.; Isakova, Aleksandra A.; Sapurina, Irina Yu.


    Complexes between influenza viruses proteins and antibodies to them create the precipitation lines in polyaniline (PAn) films which were detected by polarization optical microscopy after coating the film from the top the eutectic mixture of nematic liquid crystals MBBA:EBBA. Polyaniline and it's composites interact as sorbents with influenza human and bird viruses apart from antigenic properties of surface proteins as well as with bacteriophage T4-D. The sorption of virions occurred in different solutions in the temperature range (8-25 ° C) during 15-60 min. After contact with sorbent the HA titers of influenza virus in solutions were decreased in 4 -2048 times. The immobilized influenza viruses were able to interact with homological antibodies from immune sera in solution.

  18. Nuclear magnetic resonance study of epoxy- based polymer-dispersed liquid crystal droplets

    Han, J W


    In this work, polymer-dispersed liquid crystals (PDLC) samples were prepared and studied by nuclear magnetic resonance. Proton NMR spectra and spin-lattice relaxations of 4-cyano-4'-pentylbiphenyl(5CB) and p-methoxybenzylidene-p-n-butylaniline (MBBA) liquid crystals confined in microdroplets were measured. The experimental results were compared with those of the liquid crystals in the pores of silica-gels and with those of the mixing components. The experimental results indicated that the nematic ordering in the microdroplets differed markedly from that observed in bulk nematic crystals. In addition, we examined spin-lattice relaxation mechanisms. The proton spin-lattice relaxation mechanisms in bulk nematic liquid crystals are well established. However, when nematic liquid crystals are confined in microdroplets, the relaxation mechanisms are expected to be affected. We examined possible relaxation mechanisms to explain the observed increase in the spin-lattice relaxation rate of liquid crystals confined in m...

  19. Electroosmotically enabled Electrorheological Effects in a Planar Nematic Crystal Flow

    Dhar, Jayabrata; Chakraborty, Suman


    Study of electrokinetics of nematic liquid crystals (LCs) with dissolved impurities hold utmost importance in understanding director distribution characteristics and modified flow rheology. However, no concrete theory for the non-uniform potential and ionic species distribution, due to an induced electrical double layer (EDL) at the LC-substrate interface, derived from fundamental principles have been put forward in this regard. In this work, we have developed coupled governing equations from fundamental free energy considerations for the potential distribution and the director configuration of the nematic LC within the induced electrical double layer which is generated due to certain physico-chemical interactions at the LC-substrate interface. With these considerations, an electroosmotically-enabled nematodynamics for a particular LC, namely, MBBA, with strong planar anchoring at the boundaries is studied. We obtained multiple solution for director configuration, which is an integral characteristics of nemat...

  20. Dynamics of laser-induced electroconvection pulses.

    Giebink, N C; Johnson, E R; Saucedo, S R; Miles, E W; Vardanyan, K K; Spiegel, D R; Allen, C C


    We first report that, for planar nematic 4-methoxy-benzilidene-4-butylaniline (MBBA), the electroconvection threshold voltage has a nonmonotonic temperature dependence, with a well-defined minimum, and a slope of about -0.12 V/degrees C near room temperature at 70 Hz. Motivated by this observation, we have designed an experiment in which a weak continuous-wave absorbed laser beam with a diameter comparable to the pattern wavelength generates a locally supercritical region, or pulse, in dye-doped MBBA. Working 10-20 % below the laser-free threshold voltage, we observe a steady-state pulse shaped as an ellipse with the semimajor axis oriented parallel to the nematic director, with a typical size of several wavelengths. The pulse is robust, persisting even when spatially extended rolls develop in the surrounding region, and displays rolls that counterpropagate along the director at frequencies of tenths of Hz, with the rolls on the left (right) side of the ellipse moving to the right (left). Systematic measurements of the sample-voltage dependence of the pulse amplitude, spatial extent, and frequency show a saturation or decrease when the control parameter (evaluated at the center of the pulse) approaches approximately 0.3. We propose that the model for these pulses should be based on the theory of control-parameter ramps, supplemented with new terms to account for the advection of heat away from the pulse when the surrounding state becomes linearly unstable. The advection creates a negative feedback between the pulse size and the efficiency of heat transport, which we argue is responsible for the attenuation of the pulse at larger control-parameter values.

  1. Optical Anisotropy and Four Possible Orientations of a Nematic Liquid Crystal on the Same Film of a Photochromic Chiral Smectic Polymer

    Blinov, Lev M.; Barberi, Riccardo; Kozlovsky, Mikhail V.; Lazarev, Vladimir V.; de Santo, Maria P.

    Spin coated films of a chiral comb-like liquid crystalline copolymer containing azobenzene chromophores in its side chains are optically isotropic in their twisted smectic-like glassy state. In contact with a nematic liquid crystal (5CB, E7, MBBA) they provide a degenerate planar orientation. When irradiated by unpolarized UV light, they orient the same nematics homeotropically. Treated with linearly polarized UV light they orient nematics homogeneously with the director along the electric vector of the exciting light. After a combined irradiation first with unpolarized UV light and then with linearly polarized visible light, the films again provide a homogeneous liquid crystal orientation, this time with the director perpendicular to the visible light electric vector. The phenomena observed are related to the light induced optical anisotropy. Two main processes are responsible for the anisotropy (1) a UV light depletion of trans-isomers of the azobenzene chromophores from the chosen direction and (2) a reorientation of the chromophores by polarized visible light.

  2. Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

    Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie


    Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

  3. Fluctuations in a system far from equilibrium: electroconvection

    Goldburg, W. I.; Cressman, J. R.


    An ac voltage drives a thin liquid crystal (LC) sample of MBBA into a strongly electroconvective state of chaotic ¡°defect turbulence¡±, where it dissipates mean power P=\\overline P. The phenomenon is analogous to Rayleigh Benard convection, even though the Reynolds number of the fluid is much less than unity. Of special interest was the probability density π(P) of the power dissipated in the LC and its dimensionless standard deviation, σ_P/\\overline P. This function is Gaussian through the measurement range P-\\overline P ˜= 3 σ_P. Assuming that π(P) remains Gaussian even out to negative values of P, one can compare our results with the Fluctuation Theorem of Gallavotti and Cohen (GC). The dynamic temperature tilde T deduced from the GC theory, is many orders of magnitude larger than the true temperature of the LC, which was thermostatted at T close to 25 C^rc.

  4. The effect of quasispherical and chainlike solutes on the nematic to isotropic phase transition in liquid crystals

    Oweimreen, G. A.; Martire, D. E.


    The effects of solute molecular structure (size, shape and flexibility) and solvent molecular structure (length-to-breadth ratio and end-chain flexibility) on nematic phase stability in dilute binary mixtures of nonmesomorphic solutes and nematogenic solvents are examined through experiment and theory. Addition of the perturbing solute to the liquid-crystalline solvent leads to depression of the nematic-isotropic (NI) transition temperature and formation of a two-phase region. Directly determined moduli of the slopes, βn and βi, of the nematic and isotropic phase boundary lines in the reduced NI transition temperature (T*) vs solute mole fraction (x2) diagrams are reported for quasispherical and chainlike solutes with two nematogenic solvents. The systems studied are the quasispheres Et4C (tetraethylmethane) and R4Sn (R = CH3, C2H5, n-C3H7 and n-C4H9) and the chains n-C8H18 through n-C14H30, mixed with p-methoxybenzylidine-p'-n-butylaniline (MBBA) and p-n-pentyl-p'-cyanobiphenyl (5CB). Also reported are indirectly determined β∞n and β∞i values (limit as x2→0), using a novel approach combining differential scanning calorimetry (for the pure solvent contribution) and gas-liquid chromatography (for the solution contribution), for Et4C and n-C5H12 through n-C11H24, with MBBA, 5CB, p-azoxyanisole (PAA), and p,p'-di-n-hexyloxyazoxybenzene (DHAB). For the systems in common, the average difference between the directly and indirectly determined β values is approximately 10% and, qualitatively consistent with lattice model predictions, the comparison suggests slight curvature of the phase boundary lines. The experimental β values, as a function of increasing solute size, are found to double (roughly) for the quasispheres and increase only slightly for the chains, reflecting the concurrent behavior of the solution contribution to β. The thermodynamic results for the quasispherical solutes are compared in some detail with predicted values from statistical

  5. Analysis of the phase solubility diagram of a phenacetin/competitor/beta-cyclodextrin ternary system, involving competitive inclusion complexation.

    Ono, N; Hirayama, F; Arima, H; Uekama, K


    The competitive inclusion complexations in the ternary phenacetin/competitors/beta-cyclodextrin (beta-CyD) systems were investigated by the solubility method, where m-bromobenzoic acid (m-BBA) and o-toluic acid (o-TA) were used as competitors. The solubility changes of the drug and competitors as a function of beta-CyD concentration in the ternary systems were formulated using their stability constants and intrinsic solubilities. The decrease in solubility of phenacetin by the addition of competitors could be quantitatively simulated by the formulation, when both drug and competitor give A(L) type solubility diagrams. On the other hand, when one of the guests gives a B(S) type solubility diagram, its solubility change was clearly reflected in that of the another guest, i.e., phenacetin gave an A(L) type solubility diagram in the binary phenacetin/beta-CyD system and o-TA gave a B(S) type diagram in the binary o-TA/beta-CyD system, but in the ternary phenacetin/o-TA/beta-CyD system, a new plateau region appeared in the original A(L) type diagram of phenacetin. This was explained by the solubilization theory of Higuchi and Connors. The solubility analysis of the ternary drug/competitor/CyD systems may be particularly useful for determination of the stability constant of a drug whose physicochemical and spectroscopic analyses are difficult, because they can be calculated by monitoring the solubility change of a competitor, without monitoring that of a drug. Furthermore, the present results suggest that attention should be paid to the type of the phase solubility diagram, as well as the magnitude of the stability constant and the solubility of the complex, for a rational formulation design of CyD complexes.