Multiphase Behavior of Tetraphenylethylene Derivatives with Different Polarities at High Pressures

Abstract

Although both pressure and temperature are essential parameters governing thermodynamics, the effects of the pressure on solution phase equilibria have not been well studied compared to those of temperature. Here, we demonstrate the interesting pressure-dependent behavior of tetraphenylethylene derivatives in multiphase systems composed of an organic phase and an aqueous phase in the presence and absence of γcyclodextrin (γ-CD). In this system, tetraphenylethylene monocarboxylic acid (TPE1H) and its dicarboxylic acid (TPE2H2) are distributed in the aqueous phase and dissociated into the corresponding anions, that is, TPE1and TPE2 2-, when the pH is sufficiently high.The distribution ratios of TPE1H/TPE1and TPE2H/TPE2 2show opposing pressure dependencies: the distribution of the former in the organic phase increases with increasing pressure, whereas that of the latter decreases. The 1:1 complexation constants of TPE1and TPE2 2with γ-CD, which can be determined from the distribution ratios in the presence of γ-CD, also show opposing pressure dependencies: the former shows a positive pressure dependence, but the latter exhibits a negative one. These pressure effects on the distribution and complexation of TPE derivatives can be interpreted based on the differences in the molecular polarity of these solutes. The water permittivity is enhanced at high pressure, thus stabilizing the more polar TPE2 2in the aqueous phase to a larger extent than TPE1 − and, as a result, reduces its distribution in the organic phase, as well as its complexation with γ-CD. Fluorescence spectra in the aqueous phase suggest that the TPE derivatives form aggregates with γ-CD molecules, as detected by specific fluorescence. In addition, the fluorescence intensities of the γ-CD complexes are enhanced at high pressures because of the restricted rotation of the phenyl rings in the TPE molecules. This study provides new perspectives for multiphase partitioning and an attractive alternative to conventional extraction methods.

Ground- and excited-state dynamic control of an anion receptor by hydrostatic pressure

“…21 Since the hydrostatic pressure effect on the red shi is generally observed as ca. 1 cm À1 MPa À1 in using common organic dyes, [54][55][56][57][58][59][60][61][62][63] the a A values obtained in toluene, chloroform and dichloromethane are reasonably pronounced as the general hydrostatic-pressureinduced spectral change, which means that a particular conformational change in the foldamer skeleton does not occur upon pressurization. Very interestingly, only in acetonitrile, the 0-0 absorption band is quite suppressed under low pressures, compared to the 0-1 band.…”

“…Indeed, we have recently revealed that optical properties, molecular and biomolecular recognition behavior and photo-physical/chemical processes in solutions of various molecular, supramolecular, macromolecular and biomacromolecular systems are precisely regulated by hydrostatic pressure. [53][54][55][56][57][58][59][60][61][62][63] Hence, these trends prompted us to newly investigate an applicable supramolecular recognition system under hydrostatic pressures.…”

Hydrostatic Pressure-Regulated Cellular Calcium Responses

“…Fluorescence spectra were recorded on a JASCO FP-8500 spectrofluorometer. All fluorescence experiments were performed by a custom-built high-pressure apparatus (see Figure S1 in the Supporting Information (SI)), and the detailed methods have been described in previous reports in the literature. ,− Phase-contrast and fluorescence images (Figure d) were captured by a fluorescence microscope (BZ-9000, Keyence) with an objective lens (Plan Fluor EL 20×, Nikon). An excitation filter, a dichroic mirror, and an emission filter for DAPI were 360/40, 400, and 460/50 nm, respectively.…”

“…This fact means that precisely controlling equilibria/rates seems to be quite difficult from the sensitive entropy drift’s perspective. , On the other hand, one notices that a pressure regulation, rather than the enthalpy–entropy combination, may undoubtedly be better for precise control based on eq . Indeed, it is well-known that hydrostatic pressure as one of the isotropic mechanical forces can manipulate not only ground-state equilibria in biomacromolecular conformational changes − and artificial host–guest systems − but also excited-state rates in photophysical properties − and photoreactions. − Recently, we have also demonstrated that colorimetric, fluorimetric, and chiroptical properties of functional chromophores are notably controlled by hydrostatic pressurization. − Hence, these statements indicate the evident importance of hydrostatic pressure regulation for broad chemical and/or biological events.…”

Polypseudorotaxanes Derived from Tetraphenylethylene: Preparation and Tandem-Activated Aggregation-Induced Emission

“…The reversible process of assembly and disassembly through host–guest interactions ,− has emerged as a powerful and flexible strategy to assemble supramolecular structures and attracted interest in optical sensing and imaging, drug and gene delivery, and so on. ,, Cyclodextrins (CDs), a class of cyclic oligosaccharides, are extensively employed as host building blocks owing to their hydrophobic cavities and hydrophilic exteriors, facilitating the formation of inclusion complexes with some hydrophobic guest molecules (for example, adamantine derivatives) in aqueous media . Therefore, the hydrophobic molecules could become more hydrophilic or disperse once the host–guest complexes with CDs in aqueous solutions are formed, which may be used to tune the aggregation and fluorescence of AIE molecules. ,− For example, Tang et al engineered a γ-CD-TPE host–guest inclusion complex, resulting in the disaggregation of TPE and no fluorescence in water . Multiple host–guest inclusion complexes linked by spacers with or without bulky end-caps could form stable polyrotaxanes (PRs) and polypseudorotaxanes (PPRs).…”