Solvent-free synthesis and chiroptical properties of a C-N axially chiral cruciform dimer of benzo[b]phenoxazine.

A novel C-N axially chiral molecule composed of two tert-butyl-substituted benzo[b]phenoxazine (BPO) was synthesized via solvent-free reactions. The absolute configurations of the enantiomers were determined by X-ray single-crystal analysis. The enantiomers had a sufficiently high racemization barrier to ignore racemization at room temperature (149 ± 20 kJ mol-1), and the solutions exhibited dual circularly polarized emissions stemming from fluorescence and phosphorescence of |gCPL| = ca. 1 × 10-3.

Intramolecular Electron Transfer in Multi-Redox Systems Based on Cyclic [3]Spirobifluorenylene Compound.

Cyclic [3]spirobifluorenylene with bulky alkyl groups at the ends (1) was designed and synthesized to investigate the electron transfer phenomena in a π-conjugated system including orthogonal π-conjugated chains. The three bifluorenyl units in 1 are conjugated to each other via spiro-conjugation, resulting in the splitting of the HOMO levels to a small extent. Therefore, the SOMO-HOMO gap of the radical cation species is small, which is considered to allow the facile intramolecular electron transfer. The electronic properties of 1 and its partial structures were characterized by absorption and fluorescence measurements and electrochemical analysis. From the electrochemical oxidation, the interchain Coulombic repulsion was observed. In the TD-DFT calculations for the radical cation species of 1, the geometry-featured interchain electronic transitions were visualized by NTO calculations. The radical cation species of 1 generated by chemical oxidation with SbCl5 exhibited a broadened and lower-energy NIR absorption band exceeding 2000 nm. Considering the results of the TD-DFT calculations, the NIR band of the radical cation of 1 was attributed to the intramolecular electron transfer processes among the bifluorenyl units in the macrocycle. ESR experiments also indicated the delocalization of a spin of 1⋅+ in the whole molecule via hole hopping in the ESR time scale at room temperature. This work demonstrates the usefulness of spiro-conjugation as a bridging unit in molecular wires to facilitate smooth electron transfer.

Postpartum recovery of nulliparous women following scheduled cesarean delivery and spontaneous vaginal delivery: a prospective observational study.

BACKGROUND: Inpatient postpartum recovery trajectories following cesarean delivery and spontaneous vaginal delivery are underexplored. OBJECTIVE: This study primarily aimed to compare recovery following cesarean delivery and spontaneous vaginal delivery in the first postpartum week, and secondarily to evaluate psychometrically the Japanese version of the Obstetric Quality of Recovery-10 scoring tool. STUDY DESIGN: Following institutional review board approval, the EQ-5D-3L (EuroQoL 5-Dimension 3-Level) questionnaire and a Japanese version of the Obstetric Quality of Recovery-10 measure were used to evaluate inpatient postpartum recovery in uncomplicated nulliparous parturients delivering via scheduled cesarean delivery or spontaneous vaginal delivery. RESULTS: A total of 48 and 50 women who delivered via cesarean delivery and spontaneous vaginal delivery, respectively, were recruited. Women delivering via scheduled cesarean delivery experienced significantly worse quality of recovery on days 1 and 2 compared with those who had spontaneous vaginal delivery. Quality of recovery significantly improved daily, plateauing at days 4 and 3 for cesarean delivery and spontaneous vaginal delivery groups, respectively. Compared with cesarean delivery, spontaneous vaginal delivery was associated with prolonged time to analgesia requirement, decreased opioid consumption, reduced antiemetic requirement, and reduced times to liquid/solid intake, ambulation, and discharge. Obstetric Quality of Recovery-10-Japanese is a valid (correlates with the EQ-5D-3L including a global health visual analog scale, gestational age, blood loss, opioid consumption, time until first analgesic request, liquid/solid intake, ambulation, catheter removal, and discharge), reliable (Cronbach alpha=0.88; Spearman-Brown reliability estimate=0.94; and intraclass correlation coefficient=0.89), and clinically feasible (98% 24-hour response rate) measure. CONCLUSION: Inpatient postpartum recovery is significantly better in the first 2 postpartum days following spontaneous vaginal delivery compared with scheduled cesarean delivery. Inpatient recovery is largely achieved within 4 and 3 days following scheduled cesarean delivery and spontaneous vaginal delivery, respectively. Obstetric Quality of Recovery-10-Japanese is a valid, reliable, and feasible measure of inpatient postpartum recovery.

A Dicyanomethyl Radical Conjugated with a Pyridylamino Group: Combining Radical-based Dynamic Covalent Chemistry and Coordination Chemistry.

In this work, we aimed to develop a dicyanomethyl radical that undergoes both reversible C-C bond formation/dissociation and metal-ligand coordination reactions to combine dynamic covalent chemistry (DCC) based on organic radicals with coordination chemistry. We have previously reported a dicyanomethyl radical conjugated with a triphenylamine (1⋅) that exhibits a monomer/dimer equilibrium between the σ-bonded dimer (12 ). We designed and synthesized a novel dicyanomethyl radical with a pyridyl group as a coordination point (2⋅) by replacing the phenyl group of 1⋅ with a 3-pyridyl group. We showed that 2⋅ is also in an equilibrium with the σ-bonded dimer (22 ) in solution and has suitable thermodynamic parameters for application in DCC. 22 coordinates to PdCl2 in a 2 : 2 ratio to selectively form a metallamacrocycle (22 )2 (PdCl2 )2 , and its structure was clarified by single crystal X-ray analysis. Variable-temperature NMR, ESR, and electronic absorption measurements revealed that (22 )2 (PdCl2 )2 also undergoes the reversible C-C bond formation/dissociation reaction. Ligand-exchange experiment showed that 22 was liberated from (22 )2 (PdCl2 )2 by the addition of another ligand with a higher affinity for PdII . This work demonstrated that DCC based on dicyanomethyl radicals works orthogonally to metal-ligand coordination reactions.

Ultrasonographic images of spina bifida before obstetric anesthesia: a case series.

BACKGROUND: Spina bifida is a relatively common congenital malformation. As the functional prognosis of patients with spina bifida has improved over time, the number of cases resulting in pregnancy and delivery has increased. Lumbar ultrasonography has become a standard and helpful technique before neuraxial anesthesia. We believe that it might be valuable if we use lumbar ultrasonography to evaluate pregnant women with spina bifida before obstetric anesthesia. CASE PRESENTATION: We performed lumbar ultrasonography to evaluate four pregnant women with spina bifida. Patient 1 had no history of surgery. Lumbar radiography before pregnancy showed a bone defect from L5 to the sacrum as a result of incomplete fusion. Magnetic resonance imaging showed a spinal lipoma and a bone defect of the sacrum. Lumbar ultrasonography showed similar findings. We performed general anesthesia for emergency cesarean delivery. Patient 2 underwent surgical repair immediately after birth. Lumbar ultrasonography showed the same bone defect as well as a lipoma beyond the bone defect. We performed general anesthesia for cesarean delivery. Patient 3 had vesicorectal disorders but no prior surgery. Lumbar radiography before pregnancy showed congenital abnormalities such as incomplete fusion, scoliosis, rotation, and a notably small sacrum. Lumbar ultrasonography showed the same bone defect. We performed general anesthesia for cesarean section with no complications. Patient 4 complained of lumbago a few years after her first delivery and received a diagnosis of spina bifida occulta by lumbar radiography, with the incomplete fusion of only the 5th vertebra. Lumbar ultrasonography indicated the same abnormalities. We placed an epidural catheter to avoid the bone abnormality and achieved epidural labor analgesia with no complications. CONCLUSIONS: Lumbar ultrasonography shows anatomic structures easily, safely, and consistently, without X-ray exposure or the need for more expensive modalities. It is a helpful technique to explore anatomic structures potentially complicated by spina bifida before anesthetic procedures.

Unveiling a new aspect of oxocarbons: open-shell character of 4- and 5-membered oxocarbon derivatives showing near-infrared absorption.

Oxocarbon derivatives consisting of 4- and 5-membered rings, referred to as croconaine and squaraine dyes and regarded as closed-shell molecules, are found to have an intermediate open-shell character from the experimental results of 1H-NMR, ESR spectroscopy, SQUID magnetometric analysis, and X-ray crystallography. We employed two chalcogenopyrylium moieties with O and S chalcogen atoms as substitutions on oxocarbons. The singlet-triplet energy gaps (ΔE S-T) associated with the degree of diradical nature are smaller for croconaines than for squaraines and smaller for thiopyrylium than for pyrylium groups. The diradical nature impacts the electronic transition energy that decreased with a decreasing degree of diradical contribution. They exhibit substantial two-photon absorption in the region over 1000 nm. The diradical character y of the dye was determined experimentally from the observed one- and two-photon absorption peaks and the triplet energy level. The present finding provides new insight into diradicaloids with the contribution of non-Kekulé oxocarbon and also showcases the correlation between the electronic transition energy and their diradical character.

Comparison between neonatal outcomes of labor and delivery with labor neuraxial analgesia and without analgesia: A propensity score-matched study.

AIM: This single-center observational study aimed to investigate the association between labor neuraxial analgesia (LNA) and neonatal outcomes. METHODS: We conducted a retrospective cohort study at a tertiary perinatal center and included all vaginal deliveries performed between November 2015 and December 2021. Obstetric and neonatal outcomes were compared between deliveries with LNA (LNA group) and without analgesia (control group). Propensity score (PS) matching was used for statistical analysis. RESULTS: We included 2343 singleton deliveries performed in 1367 nulliparous and 976 multiparous women, in whom LNA was induced in 352 and 178 deliveries, respectively. After PS matching, the nulliparous LNA group had a significantly higher incidence of Apgar scores <7 at 1 (7.1% vs. 3.6%, p = 0.0139) and 5 min (2.3% vs. 0.7%, p = 0.0397) and meconium staining (29.8% vs. 23.2%, p = 0.0272) than the nulliparous control group. Other neonatal outcomes, including umbilical artery pH and neonatal intensive care unit admission rate, were comparable between the nulliparous LNA and control groups. No significant differences in neonatal outcomes were seen in multiparous women. Regarding fetal heart rate abnormalities, severe late deceleration (4.8% vs. 1.7%, p = 0.0036) and severe prolonged deceleration (17.0% vs. 11.9%, p = 0.0224) were more common in the nulliparous LNA group than in the nulliparous control group, and the multiparous LNA group exhibited more severe variable deceleration (21.3% vs. 14.3%, p = 0.0485) than the multiparous control group. CONCLUSION: Our findings suggest that LNA is associated with short-term adverse neonatal and obstetric outcomes in vaginal deliveries. LNA should be performed with precautionary measures and adequate medical resources.

A dicyanomethyl radical stabilized by ferrocene: a new building block for radical-based dynamic covalent chemistry with redox activity.

A novel dicyanomethyl radical conjugated with ferrocene as an electron donating unit through a benzene linker is prepared for the first time. This radical is in equilibrium with the σ-dimer in solution, and the structure of the σ-dimer was confirmed by X-ray single crystal structure analysis. Due to the monomer/dimer equilibrium, this radical showed unique electrochemical redox behaviour depending on the temperature and scan rate.

Double Heterohelicenes Composed of Benzo[b]- and Dibenzo[b,i]phenoxazine: A Comprehensive Comparison of Their Electronic and Chiroptical Properties.

Heterohelicenes are potential materials in molecular electronics and optics because of their inherent chirality and various electronic properties originating from the introduced heteroatoms. In this work, we comprehensively investigated two kinds of double NO-hetero[5]helicenes composed of 12H-benzo[b]phenoxazine (BPO) and 13H-dibenzo[b,i]phenoxazine (DBPO). These helicenes exhibit good electron-donor properties reflecting the electron-rich character of their monomers and were demonstrated to work as p-type semiconductors. The enantiomers of these helicenes show the largest class of dissymmetry factors for circularly polarized luminescence (CPL) (|gCPL| > 10-2) among helicenes reported to date. Interestingly, the signs of CPL are opposite for BPO and DBPO double helicenes of the same helicity. The origin of the large gCPL values and the inversion of the CPL sign was addressed by analysis of the transition electronic dipole moments and transition magnetic dipole moments based on TD-DFT calculations.

Synthesis and Electronic Properties of Directly Linked Dihydrodiazatetracene Dimers.

5,12-Dihydro-5,12-diazatetracene (DHDAT) dimers with different substitution patterns are synthesized: a symmetric one with a C-C bond between the monomer units (1) and two asymmetric ones with a C-N bond between the monomer units (2 and 3). The DHDAT units are planar in the C-C linked dimer 1 but perpendicularly oriented in the C-N linked dimers 2 and 3 (from X-ray analysis). The electronic ground-state interaction between the two units is large in 1 and small in 2 and 3. The emission behavior of 3 is different from that of other dimers and its monomer; it displays positive solvatochromism, characteristic for electron donor-acceptor molecules, despite its donor-donor type structure. Compound 3 exhibits a unique multi-step thermochromic emission behavior. The emission behavior is attributed to the asymmetric distribution of the HOMO and LUMO of DHDAT.

Tetrathiafulvalene-Inserted Diphenoquinone: Synthesis, Structure, and Dynamic Redox Property.

A new tetrathiafulvalene (TTF) derivative is synthesized, which is substituted with two phenoxy radicals on one 1,3-dithiole ring, and may have either open-shell diradical or closed-shell extended-quinoidal ground states. X-ray single crystal analysis and NMR measurements prove that this molecule has a closed-shell extended quinoidal structure both in the solid state and in solution. DFT calculations show the donor-acceptor electronic properties of this molecule with a well-separated HOMO-LUMO distribution and a small HOMO-LUMO energy gap. Because of this donor-acceptor character, this molecule gives both the dication and the dianion species by electrochemical oxidation and reduction. Furthermore, during the redox process between the neutral and dication states, this molecule exhibits unique changes in the cyclic voltammogram upon repeating the cycles or varying the scan rate. The observed electrochemical behavior is explained by the conformational changes in the electrochemically generated species, thus indicating that this molecule is classified as a dynamic redox system.

Electronic and Photophysical Properties of 9,10-Anthrylene-Bridged B-π-N Donor-Acceptor Molecules with Solid-State Emission in the Yellow to Red Region.

9,10-Anthrylene-bridged triarylborane-triarylamine donor-acceptor compounds were prepared to examine the influence of the bulky π-bridge on the electronic and photophysical properties of the compounds, with the aim of realizing their solid-state emission. The intramolecular charge-transfer (ICT) absorption and emission between the vacant p orbital on the boron center, p(B), and occupied p orbital on the nitrogen center, p(N), through the π orbital of the anthrylene, π(anthrylene), were observed, and it was demonstrated that the HOMO-LUMO gap decreased with increasing number of introduced anthrylene units because of the effective lowering of LUMO originating from the p(B)-π(anthrylene) orbital interaction. The compounds exhibited solid-state emission with emission maxima at 560 nm and 643 nm, respectively, in the yellow to red region, with the corresponding absolute solid-state quantum yield of 18 % and 31 %, as a result of the combination of the highly congested structure originating from the anthrylene π-bridge and the introduction of bulky tert-butyl protecting groups.

Extreme multi-point van der Waals interactions: isolable dimers of phthalocyanines substituted with pillar-like azaacenes.

How strong are van der Waals interactions in determining the final outcome of self-assembled structures of small molecular systems? Herein we report isolable phthalocyanine (Pc) dimers bound by π-π interactions between monomeric Pcs which can be handled as single entities. Pc dimers have been continuously investigated as one of the simplest models of Pc aggregates. Pcs were substituted with eight dihydrodiazapentacene (DHDAP) moieties on the periphery, which act as pillar-like π-planes and these molecules form H-type dimers with the help of synergetic π-π interactions between two co-facial Pc rings and among the pillar-like DHDAP moieties. The dimer structures were fully confirmed by 1D and 2D NMR, ESR, and electronic absorption measurements. The dissociation of these dimers was observed in particular solvents such as o-dichlorobenzene, due to the good solubility of the larger π-conjugated molecules. On the other hand, in ethyl acetate the monomers were metastable species and underwent selective dimerization. Interestingly in THF, neither the dimerization of the monomers nor the dissociation of dimers was observed, suggesting that both the dimers and the monomers were kinetically well stabilized. For hours to days, we can handle these dimers as "a molecule" not only in solution but also even in mass spectrometry under ionization conditions without significant dissociation.

Landscape of Charge Carrier Transport in Doped Poly(3-hexylthiophene): Noncontact Approach Using Ternary Combined Dielectric, Paramagnetic, and Optical Spectroscopies.

We report on a comprehensive measurement system for mobility and energy states of charge carriers in matter under dynamic chemical doping. The temporal evolution of the iodine doping process of poly(3-hexylthiophene) (P3HT) was monitored directly through electron paramagnetic resonance (EPR) and optical absorption spectroscopy, as well as differential electrical conductivity by the microwave conductivity measurement. The increase in conductivity was observed after the EPR intensity reached a maximum and declined thereafter, and the conductivity finally reached ∼80 S cm-1. The carrier species changed from a paramagnetic polaron with an estimated mobility of µP+ ≈ 2 × 10-3 cm2 V-1 s-1 to an antiferromagnetic polaron pair with µPP+ ≈ 0.6 cm2 V-1 s-1. The technique presented here can be a ubiquitous method for rapid and direct observation of charge carrier mobility and energy states in p-type semiconducting materials as a completely noncontact, experimental, and quantitative technique.

Hash-Mark-Shaped Azaacene Tetramers with Axial Chirality.

The tetramers of azapentacene derivatives with unique hash mark (#)-shaped structures were prepared in a quite facile manner. The #-shaped tetramers are optically active due to possessing extended biaryl skeletons, and the structure of the tetramer composed of four dihydrodiazapentacene (DHDAP) units (1) was investigated as the first example of this kind of molecule. The tetramer 1 showed characteristic chiroptical properties reflecting its orthogonally arranged quadruple DHDAP moieties, as well as redox activity. The solution of enantiopure 1 exhibited intense circularly polarized luminescence (CPL) with a dissymmetry factor of 2.5 × 10-3. The absolute configuration of the enantiomers of 1 was experimentally determined by X-ray crystal analysis for the dication salt of the enantiomer of 1 with SbCl6- counterions. The solutions of enantiopure 12+·2[SbCl6-] also showed NIR circular dichroism (CD) spectra over the entire range from visible to 1100 nm, enabling the modulation of the chiroptical properties by redox stimuli.

Supramolecular assemblies of a nitrogen-embedded buckybowl dimer with C60.

A directly connected azabuckybowl dimer was synthesized via a palladium-catalysed C-H/C-Br coupling. The electron-donating nature of the pyrrolic nitrogen atoms of the azabuckybowl enabled a strong complexation with pristine C60. In the presence of two equivalents of C60, the azabuckybowl dimer formed crystals with a 1 : 2 stoichiometry. Conversely, in diluted solution, complexes with a 1 : 1 stoichiometry of the dimer and C60 were detected predominantly, and these precipitated upon increasing the concentration of C60. Scanning electron microscopy images of the precipitate showed fibre-like aggregates, indicating the formation of supramolecular assemblies with 1D chain structures. A variable-temperature 1H NMR analysis revealed that the precipitate consists of the dimer and C60 in a 1 : 1 ratio.

Unique cohesive nature of the ß1-isomer of [70]PCBM fullerene on structures and photovoltaic performances of bulk heterojunction films with PffBT4T-2OD polymers.

The effects of regioisomer and diastereomer separations of [70]PCBM on structures and photovoltaic properties of PffBT4T-2OD:[70]PCBM blend films have systematically been investigated for the first time. Decreasing the amount of a diastereomer of ß-[70]PCBM with high aggregation tendency (ß1-[70]PCBM) improved the photovoltaic performances.

Tetraaza[14]- and Octaaza[18]paracyclophane: Synthesis and Characterization of Their Neutral and Cationic States.

Two kinds of aza[1n]paracyclophanes, tetraaza[14]paracyclophane (P4) and octaaza[18]paracyclophane (P8), were synthesized as the smallest and the largest monodisperse macrocyclic oligomers of polyaniline ever made. Herein we report the electronic nature of the cationic species of these two macrocycles with different ring size. By combining ESR spectroscopy and DFT calculations it was suggested that P4·+ was classified as delocalized class III or poised on the class II/III borderline while P8·+ was regarded as a localized class II mixed-valence system. We successfully isolated the dication of P4 as a stable dicationic salt P42+·2[SbF6]-, and the structure of P42+ was determined by X-ray crystal analysis. Variable-temperature NMR measurements for P42+·2[SbF6]- unequivocally showed that P42+ was a 22π electron system with a singlet ground state. The supercharged hexacation of P8 was also isolated as P86+·6[SbCl6]-, and X-ray crystal analysis revealed that P86+ includes one SbCl6- anion in its macrocyclic cavity.

The Divergent Dimerization Behavior of N-Substituted Dicyanomethyl Radicals: Dynamically Stabilized versus Stable Radicals.

Herein, we demonstrate that the dimerization behavior of amine-substituted dicyanomethyl radicals can be switched from σ- to π-dimerization simply by varying the electron-donating substituents. For dicyanomethyl radicals with a 4,4'-ditolylamine (DT. ) or a phenothiazine (PT. ) substituent, the monomeric radical form and the corresponding dimer connected by a reversible C-C bond (σ-dimer) are in equilibrium in solution. On the other hand, the radical with the julolidine skeleton (JD. ) does not undergo σ-dimerization and was isolated as a stable radical in spite of the absence of bulky protecting groups. X-ray single-crystal analysis revealed that JD. forms the π-dimer in the crystalline state, and variable-temperature spectroscopy showed that JD. is in equilibrium with the π-dimer in toluene solution. DFT calculations point to the importance of electrostatic interactions as a driving force for the π-dimerization of JD. because of its polarized structure.

Optical and Structural Properties of ESIPT Inspired HBT-Fluorene Molecular Aggregates and Liquid Crystals.

In bulk materials, positional isomers not only help in understanding how slight difference in molecular structure alters the crystal packing and optical properties, but also play a key role in developing new type of materials for functional applications. A detailed study on the photophysical properties of fluorene-HBT positional isomers in solution and in the solid state providing a molecular level understanding of the factors which influence fluorescence behavior is reported. Two molecules Ia and IIa were synthesized by Suzuki coupling reaction and their photophysical properties were compared to positional isomers Ib and IIb. Crystal structure analyses and density functional theory (DFT) computation studies were performed to understand structure-properties relation and the results reveal that changing substitution pattern has a marked influence on their packing modes and luminescence properties. Strong noncovalent interactions (π-π) in the solid state hamper the excited state intramolecular proton transfer (ESIPT) process which causes fluorescence quenching in the solid state (Ia and IIa = Φf, 28-40%; Ib and IIb = Φf, 55-67%). Compounds show solvent-responsive and aggregation induced emission (AIE) properties. Bent structures of Ia with double and symmetric substitution of ESIPT motifs exhibit particularly unique condensed phase upon heating, confirmed as a nematic liquid crystalline phase, and this is the first report on the ESIPT and AIE active liquid crystalline materials with a banana-shaped molecule.