Synthesis and Characterization of Quinone Compounds Derived from Doubly and Triply Linked Diporphyrins and Tuning of Their Absorption Properties.

Porphyrins are attracting increasing attention in materials science and photochemistry owing to their unique properties and diverse applications. This study focuses on modifying and tuning the absorption properties of porphyrins, specifically those of quinoidal porphyrins, to extend their spectral range into the near-infrared (NIR) region. We report the synthesis and structural and physical properties of quinone compounds derived from doubly and triply linked diporphyrins and their metal complexes. Doubly linked diporphyrinquinone exhibits broad panchromatic absorption properties in solution owing to its low symmetry. Metal complexation markedly extends its absorption range into the near-infrared region. In contrast, the metal complexes of the triply linked diporphyrinquinones exhibit sharp and strong absorption bands in the visible to near-infrared region owing to their higher symmetry. The longest absorption wavelength of the triply linked diporphyrinquinones was approximately 1500 nm, which was significantly more red-shifted than that of the doubly linked ones.

Transmission properties of microwaves at an optical Weyl point in a three-dimensional chiral photonic crystal.

Microwave transmission measurements were performed for a three-dimensional (3D) layer-by-layer chiral photonic crystal (PhC), whose photonic band structure contains 3D singular points, Weyl points. For the frequency and wavevector in the vicinity of a Weyl point, the transmitted intensity was found to be inversely proportional to the square of the propagation length. In addition, the transmitted wave was well-collimated in the plane parallel to the PhC layers, even for point-source incidence. When a plane wave was incident on the PhC containing metal scatters, the planar wavefront was reconstructed after the transmission, indicating a cloaking effect.

Anisotropic light-matter coupling and below-threshold excitation dynamics in an organic crystal microcavity.

Organic semiconductors are promising candidates as platforms for room temperature polaritonic devices. An issue for practical implementation of organic polariton devices is the lowering of condensation threshold. Here we investigate anisotropic light-matter coupling characteristics in an organic crystal microcavity showing strong molecular orientation. Furthermore, the below-threshold excitation dynamics are investigated to clarify the spontaneous transition pathways from reservoir to polariton states. Time-resolved photoluminescence measurements reveal that photonic/excitonic hybrid transition processes coexist in the microcavity system. This finding provides valuable insights into a detailed understanding of polariton dynamics and help in the design of polaritonic devices showing a low-threshold condensed phase.

Effects of Calyculin a on the Motility and Protein Phosphorylation in Frozen-Thawed Bull Spermatozoa.

In this study, we examined the effects of calyculin A, a phosphatase inhibitor, on motility, protein phosphorylation, and the distribution of phospho-(Ser/Thr) PKA substrates in frozen-thawed bull spermatozoa that are actually used by most farmers for breeding. The data showed that calyculin A, which has been reported to have a positive effect on the motility of ejaculated fresh spermatozoa, distinctly decreased the motility of frozen-thawed bull spermatozoa even if a cell activator, such as caffeine, was present in the incubation medium and that the suppressive effect of calyculin A was dose-dependent and continued for at least 200 min. Immunoblot analyses revealed that de novo protein phosphorylation was not detected in spermatozoa exposed to caffeine or dbcAMP (a cell-permeable cAMP analog), while the addition of calyculin A to the medium brought about the appearance of several phosphorylated proteins at 50 kDa and 75 kDa, suggesting that 50 kDa and 75 kDa proteins, which were phosphorylated by activation of cAMP-dependent PKA, were not dephosphorylated and were accumulated in spermatozoa due to the suppression of calyculin A-sensitive protein phosphatases. Immunofluorescence microscopy revealed that calyculin A caused, alone or in conjunction with caffeine or dbcAMP, the accumulation of phospho-PKA substrates at the annulus, although caffeine or dbcAMP alone did not. This study suggested that calyculin A decreases the motility of frozen-thawed bull spermatozoa concomitant with the accumulation of phospho-(Ser/Thr) PKA substrates at the annulus of flagella.

Live births from artificial insemination of microfluidic-sorted bovine spermatozoa characterized by trajectories correlated with fertility.

Selection of functional spermatozoa plays a crucial role in assisted reproduction. Passage of spermatozoa through the female reproductive tract requires progressive motility to locate the oocyte. This preferential ability to reach the fertilization site confers fertility advantage to spermatozoa. Current routine sperm selection techniques are inadequate and fail to provide conclusive evidence on the sperm characteristics that may affect fertilization. We therefore developed a selection strategy for functional and progressively motile bovine spermatozoa with high DNA integrity based on the ability to cross laminar flow streamlines in a diffuser-type microfluidic sperm sorter (DMSS). The fluid dynamics, with respect to microchannel geometry and design, are relevant in the propulsion of spermatozoa and, consequently, ultrahigh-throughput sorting. Sorted spermatozoa were assessed for kinematic parameters, acrosome reaction, mitochondrial membrane potential, and DNA integrity. Kinematic and trajectory patterns were used to identify fertility-related subpopulations: the rapid, straighter, progressive, nonsinuous pattern (PN) and the transitional, sinuous pattern (TS). In contrast to the conventional notion that the fertilizing spermatozoon is always vigorously motile and more linear, our results demonstrate that sinuous patterns are associated with fertility and correspond to truly functional spermatozoa as supported by more live births produced from predominant TS than PN subpopulation in the inseminate. Our findings ascertain the true practical application significance of microfluidic sorting of functional sperm characterized by sinuous trajectories that can serve as a behavioral sperm phenotype marker for fertility potential. More broadly, we foresee the clinical application of this sorting technology to assisted reproduction in humans.

Facile Redox-Induced Aromatic-Antiaromatic Interconversion of a ß-Tetracyano-21,23-Dithiaporphyrin under Ambient Conditions.

Facile redox-induced aromatic-antiaromatic interconversions were accomplished by using ß-tetracyano-21,23-dithiaporphyrin (CN4 S2 Por). Introduced cyano groups not only increased the reduction potential of the porphyrin core but also stabilized the antiaromatic isophlorin (CN4 S2 Iph) by π conjugation. The reduction of CN4 S2 Por with hydrazine in polar solvents quantitatively affords CN4 S2 Iph, even under ambient conditions. CN4 S2 Iph retains a nearly planar conformation and exhibits considerable antiaromaticity. Aerobic oxidation of CN4 S2 Iph to CN4 S2 Por occurs in nonpolar solvents. This study was conducted to contribute to the understanding of the structure-antiaromaticity relationship.

Compact solid-state organic laser with fine and broadband wavelength tunability.

An organic dye-doped polymer laser with a novel wavelength-tuning mechanism is proposed. This device is a vertical cavity surface-emitting laser realized by using a couple of distributed Bragg reflectors (DBRs), on which a dye-doped polymer thin film and a polydimethylsiloxane film are deposited individually. One of the DBRs is electrically driven to vary the effective cavity length. Under the optical excitation, tunable lasing operation with high stability can be achieved when immersion oil is used for the refractive index matching in the cavity. Since the device operation mechanism proposed here is quite simple, it is promising for designing a compact laser device with wide, precise, and electrically driven wavelength tunability.

Stable Singlet Biradicals of Rare-Earth-Fused Diporphyrin-Triple-Decker Complexes with Low Energy Gaps and Multi-Redox States.

Dinuclear rare-earth (TbIII , YIII ) triple-decker complexes with a fused diporphyrin (FP) and two tetraphenylporphyrin (TPP) ligands were synthesized in neutral, dianionic, and diprotonated forms. The neutral forms have large open shell biradical character, as determined from the temperature dependency of the magnetic susceptibility measurements and theoretical calculations. The coupling value (J=-1.4 kcal mol-1 , -487 cm-1 ) of the radical centers in the neutral form of the YIII complex indicates weak pairing interactions. Theoretical calculations on the neutral form reveal a significant biradical character (y=68 %). Furthermore, the TbIII complex exhibits multi-redox states, having more than eight clear peaks in the voltammetry curves. The optical (3700 nm, 0.33 eV) and electrochemical measurements (3400 nm, 0.36 eV) indicate that the neutral form has very small HOMO-LUMO energy gap. Despite the large biradical character, the neutral complexes are thermally stable and do not decompose on heating at 120 °C. These complexes with unique characteristics are promising candidates for use in molecular electronics, optics, and spintronics.

Quantitative evaluation of light-matter interaction parameters in organic single-crystal microcavities.

Investigation of physics on light-matter interaction and strong coupling formation in organic microcavities is important to characterize the device structure enabling efficient room-temperature polariton condensation. In this study, we evaluate quantitatively the light-matter interaction parameters for three types of organic single-crystal microcavities and discuss the effects of microcavity structures on the strong coupling formation. We found that improvement in cavity quality factor causes a reduction in the photon damping constant, which results in an increase in the Rabi splitting energy. Moreover, when we used a metal thin film as the cavity mirror, it was revealed that the exciton damping became 30 times stronger than that in a dielectric mirror cavity. These experimental findings are very intriguing to achieve low-threshold or electrically pumped organic polariton devices.

High-gain and wide-band optical amplifications induced by a coupled excited state of organic dye molecules co-doped in polymer waveguide.

We investigated optical gain and lasing characteristics of a polymer thin film co-doped with Rhodamine 6G and 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye molecules. By the co-doping of these dyes, the optical gain coefficient and its spectral range were enhanced and widened, respectively. These results cannot be accounted for by the linear combination of the optical gain properties of single-doped films. Owing to this high-gain and wide-band optical amplification property, a distributed feedback lasing with a low threshold of 70 µJ/cm2 as well as a widely tunable wavelength range of 587-613 nm was achieved. We attribute this amplification property of the co-doped film, which cannot be achieved with the single-doped films, to the appearance of a coupled excited state between the two molecules.

Metal-Free Synthesis of meso-Aminoporphyrins through Reduction of meso-Azidoporphyrins Generated in Situ by Nucleophilic Substitution Reactions of meso-Bromoporphyrins.

A facile and metal-free method for the preparation of free base meso-aminodiarylporphyrins from readily available meso-bromodiarylporphyrins is described. Simple treatment of meso-bromoporphyrins with sodium azide and sodium ascorbate in DMF affords the corresponding meso-aminoporphyrins in very good yields. This method involves the aromatic nucleophilic substitution (SNAr) of a bromo group with an azido group and the subsequent in situ reduction of the introduced azido group by sodium ascorbate. This amination reaction can be scaled up to gram scale without any decrease of the product yield. The amination reaction of free base meso-dibromoporphyrin affords a monoaminated product selectively, whereas that of the Ni(II) complex furnishes a diaminated product that is oxidized by air under ambient conditions but isolable as a trifluoroacetyl ester. Metal-insertion reactions of the obtained free base aminoporphyrins afford the corresponding metal complexes (Ni(II), Cu(II), Zn(II), and Pd(II)) all in good yields except the Pd(II) complex. Synthetic methods for the preparation of N-mono- or dialkylaminoporphyrins from the free base meso-aminoporphyrins have been also established.

Systematic Structural Elucidation for the Protonated Form of Rare Earth Bis(porphyrinato) Double-Decker Complexes: Direct Structural Evidence of the Location of the Attached Proton.

Direct structural evidence of the presence and location of the attached proton in the protonated form of rare earth bis(porphyrinato) double-decker complexes is obtained from an X-ray diffraction study of single crystals for a series of protonated forms of bis(tetraphenylporphyrinato) complexes [M(III)(tpp)(tppH)] (M = Tb, Y, Sm, Nd, and La). When CHCl3 is used as a solvent for crystallization of the complexes, their nondisordered molecular structures are obtained and the attached proton is identified on one of the eight nitrogen atoms. Use of other solvents affords another type of crystal, in which the position of the proton is disordered and thus the molecular structure is averaged. La complex also affords the disordered average structure even when CHCl3 is used for crystallization. A variable-temperature diffraction study for the Tb complex reveals that the dynamics of the proton in the nondisordered crystal is restricted.

A method of cryoprotection for protein crystallography by using a microfluidic chip and its application for in situ X-ray diffraction measurements.

We demonstrate a seamless and contactless method from protein crystallization to X-ray analysis using a microfluidic chip with the aim of obtaining a complete crystallographic data set of a protein crystal under cryogenic conditions. Our microfluidics-based approach did not require direct manipulation of the protein crystal. Therefore, the microfluidic chip approach is suitable for novices of X-ray analysis of protein crystals. We also investigated the effect of stepwise cryoprotection on the quality of protein crystals. Protein crystals with cryoprotection via on-chip manipulation did not show deterioration of crystallographic quality of the protein crystal. The complete diffraction data set of a protein crystal, which is required for determining the 3D structure of the target protein, is obtainable by a simple manipulation.

Controlling protein crystal nucleation by droplet-based microfluidics.

Herein, we demonstrate the potential of droplet-based microfluidics for controlling protein crystallization and generating single-protein crystals. We estimated the critical droplet size for obtaining a single crystal within a microdroplet and investigated the crystallization of four model proteins to confirm the effect of protein molecular diffusion on crystallization. A single crystal was obtained in microdroplets smaller than the critical size by using droplet-based microfluidics. In the case of thaumatin crystallization, a single thaumatin crystal was obtained in a 200 µm droplet even with high supersaturation. In the case of ferritin crystallization, the nucleation profile of ferritin crystals had a wider distribution than the nucleation profiles of lysozyme, thaumatin, and glucose isomerase crystallization. We found that the droplet-based microfluidic approach was able to control the nucleation of a protein by providing control over the crystallization conditions and the droplet size, and that the diffusion of protein molecules is a significant factor in controlling the nucleation of protein crystals in droplet-based microfluidics.

Michrochip chromatography using an open-tubular microchannel and a ternary water-ACN-ethyl acetate mixture carrier solution.

A capillary chromatography system has been developed using a ternary mixed-solvents solution, i.e. water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. Here, we tried to carry out the chromatographic system on a microchip incorporating the open-tubular microchannels. A model analyte solution of isoluminol isothiocyanate (ILITC) and ILITC-labeled biomolecule was injected to the double T-junction part on the microchip. The analyte solution was delivered in the separation microchannel (40 µm deep, 100 µm wide, and 22 cm long) with the ternary water-ACN-ethyl acetate mixture carrier solution (3:8:4 volume ratio, the organic solvent rich or 15:3:2 volume ratio, the water-rich). The analyte, free-ILITC and labeled BSA mixture, was separated through the microchannel, where the carrier solvents were radially distributed in the separation channel generating inner and outer phases. The outer phase acts as a pseudo-stationary phase under laminar flow conditions in the system. The ILITC and the labeled BSA were eluted and detected with chemiluminescence reaction.

Structurally well-defined conjugated meso-aminoporphyrin oligomers analogous to polyanilines.

Polyaniline, which is formed by the oxidative polymerization of aniline, is a widely explored conducting polymer with several stable oxidation states, and can be applied in advanced materials, including sensing devices and electrochemical catalysts. The marriage of polyanilines with the diverse chemistry of porphyrins is expected to confer new properties, including a combination of electrical, optical, magnetic and chemical properties. Herein, we demonstrate that meso-aminodiarylporphyrin, a porphyrin analogue of aniline, undergoes oxidative oligomerization in an acidic solution under an oxygen atmosphere to yield stable oligomeric products that are analogous to fully oxidized polyanilines. The so-formed oligomers are composed of the same number of electron-rich porphyrinoid and electron-deficient quinoid moieties, and they exhibit a broad electronic absorption band in the near infrared (NIR) region, which is attributable to intramolecular charge transfer (ICT) transition from electron-rich porphyrinoid moieties to electron-deficient quinoid ones. The quinoid moieties in the oligomers could be reversibly reduced using sodium ascorbate to obtain all-porphyrinoid oligomers that resemble fully reduced polyanilines. The fully reduced oligomers do not exhibit the NIR ICT band. Furthermore, three types of partially reduced tetramers consisting of a single quinoid moiety were also obtained, among which two interconverted in solution. Their interconversion was significantly accelerated in the presence of a protic solvent. This result is consistent with the high electron conductivity of partially oxidized polyanilines following their protonation.

Observation of the phase-separation multiphase flow using a polyethylene glycol/phosphate mixed solutions and the aqueous two-phase distribution of red blood cells in the flow system.

Phase-separation multiphase flow at a liquid-liquid interface was successfully formed in an aqueous two-phase system of polyethylene glycol/phosphate mixed solutions when fed into a microchannel (100 µm wide and 40 µm deep) on a microchip and a fused-silica capillary tube (100 µm ID). As one example, tube radial distribution flow (annular flow) was observed when 10.0 wt% polyethylene glycol 6000 and 8.5 wt% dipotassium hydrogen phosphate aqueous solution containing 1.0 mM Rhodamine B was fed at 40 â„ƒ, recorded by bright field microscopy. It exhibited a dipotassium hydrogen phosphate-rich inner phase and polyethylene glycol-rich outer phase. Effects of conditions including composition, flow rate, viscosity, and contact angle on tube radial distribution flow were analyzed. It was found out that although the viscosity of PEG-rich solution was much higher than that of phosphate-rich one, the phase configuration in tube radial distribution flow did not necessarily obey the viscous dissipation law in untreated microchannel and capillary tube, as well as for all the types of PEG/phosphate mixed solution the PEG-rich solution occupied the outer phase near the ODS-treated inner wall of both microchannel and capillary tube against the law. To assess the use of microfluidic flow in applications, we examined the distribution of red blood cells in the inner and outer phases fed into double capillary tubes with different inner diameters. Cell distribution was found to concentrate in the inner (dipotassium hydrogen phosphate-rich) phase compared to the outer (polyethylene glycol-rich) phase at a ratio of 1.8.

UV ozone treatment for oxidization of spiro-OMeTAD hole transport layer.

For practical application of perovskite photovoltaic devices, it is vital to choose an appropriate carrier extraction material with high mobility, high conductivity, and appropriate molecular energy levels. One of the most frequently used hole transport materials, spiro-OMeTAD, is known to show an improvement in its electrical properties after the oxidation reaction. However, this oxidation reaction is generally accomplished by simple atmospheric exposure, often taking one or more nights under atmospheric conditions, and thus the development of a rapid oxidation strategy without the degradation of device performance is strongly required. Here, we propose a rapid and reproducible oxidation route employing a UV ozone treatment process that enables quick oxidation of spiro-OMeTAD in solution, as short as 30 seconds. Optical and electrical characterization reveals that this method modifies the highest occupied molecular orbital energy level of spiro-OMeTAD to reduce the voltage loss, and also improves the conductivity and mobility, leading to the enhancement in the photovoltaic properties. This finding will provide useful insights into the further development of spiro-OMeTAD-based perovskite solar cell devices.

Three-dimensional Raman spectroscopic imaging of protein crystals deposited on a nanodroplet.

Confocal Raman spectroscopic imaging has been used to find the location of protein crystals deposited in a nanodroplet. The depth of the protein crystal has been clearly identified by comparing the three-dimensional Raman spectroscopic images of the protein with those of water. Additionally, the low concentration region around a growing protein crystal in the nanodroplet was visualized using two-dimensional Raman spectroscopic imaging.

Drastic transitions of excited state and coupling regime in all-inorganic perovskite microcavities characterized by exciton/plasmon hybrid natures.

Lead-halide perovskites are highly promising for various optoelectronic applications, including laser devices. However, fundamental photophysics explaining the coherent-light emission from this material system is so intricate and often the subject of debate. Here, we systematically investigate photoluminescence properties of all-inorganic perovskite microcavity at room temperature and discuss the excited state and the light-matter coupling regime depending on excitation density. Angle-resolved photoluminescence clearly exhibits that the microcavity system shows a transition from weak coupling regime to strong coupling regime, revealing the increase in correlated electron-hole pairs. With pumping fluence above the threshold, the photoluminescence signal shows a lasing behavior with bosonic condensation characteristics, accompanied by long-range phase coherence. The excitation density required for the lasing behavior, however, is found to exceed the Mott density, excluding the exciton as the excited state. These results demonstrate that the polaritonic Bardeen-Cooper-Schrieffer state originates the strong coupling formation and the lasing behavior.