Machine Learning-Inspired Molecular Design, Divergent Syntheses, and X-Ray Analyses of Dithienobenzothiazole-Based Semiconductors Controlled by S⋠⋠⋠N and S⋠⋠⋠S Interactions.

Inspired by the previous machine-learning study that the number of hydrogen-bonding acceptor (NHBA) is important index for the hole mobility of organic semiconductors, seven dithienobenzothiazole (DBT) derivatives 1 a-g (NHBA=5) were designed and synthesized by one-step functionalization from a common precursor. X-ray single-crystal structural analyses confirmed that the molecular arrangements of 1b (the diethyl and ethylthienyl derivative) and 1c (the di(n-propyl) and n-propylthienyl derivative) in the crystal are classified into brickwork structures with multidirectional intermolecular charge-transfer integrals, as a result of incorporation of multiple hydrogen-bond acceptors. The solution-processed top-gate bottom-contact devices of 1b and 1c had hole mobilities of 0.16 and 0.029 cm2 V-1s-1, respectively.

A leaning amine-ketone dyad with a nonconjugated linker: solvatofluorochromism and dual fluorescence associated with intramolecular charge transfer.

Dyad 4, comprising a triphenylamine (TPA) electron donor and 1,4-pentadien-3-one (pentadienone) electron acceptor tethered by a nonconjugated linker, displays solvatofluorochromism (SFC) and dual fluorescence associated with intramolecular charge transfer (ICT) in the excited state. While the fluorescence arises from a locally excited state of 4 (LE-4*) in saturated hydrocarbon solvents, the fluorescence from the ICT state of 4 (ICT-4*) occurs in aprotic solvents. ICT-4* has a much greater dipole moment than its corresponding ground state. The results of theoretical calculations suggest that the conversion of LE-4* to ICT-4* involves a unique structural change like a leaning of the pentadienone moiety. Two factors are responsible for the significant SFC displayed by 4, the first being the high electron-donating and -accepting abilities of the respective locally excited TPA and pentadienone moieties in LE-4* and the other being a rigid ethano bridge that links the two moieties in ICT-4*. The former property facilitates photoinduced electron-transfer (PET) and the latter prevents full single electron transfer (SET) by prohibiting direct π-conjugation and the spatial approach of the two dyad components. Consequently, these electronic and geometrical features lead to SFC arising from a large dipole moment change caused by ICT and partial intramolecular SET.

Correction: A facile and high-yield formation of dipyrrin-boronic acid dyads and triads: a light-harvesting system in the visible region based on the efficient energy transfer.

Correction for 'A facile and high-yield formation of dipyrrin-boronic acid dyads and triads: a light-harvesting system in the visible region based on the efficient energy transfer' by Masaki Yamamura et al., Org. Biomol. Chem., 2015, 13, 2574-2581.

Cooperative effects of o- and m-methyl groups on the intramolecular charge-transfer emission properties of dibenzoylmethanatoboron difluorides.

The photophysical properties of o-tolyl-, m-tolyl-, and p-xylyl-substituted asymmetric diaroylmethanatoboron difluorides in a mixture of CH2Cl2 and c-C6H12, and in the crystalline state were determined. In solution, the fluorescence (FL) properties of these substances are controlled by the position and number of methyl groups on the phenyl rings. An especially interesting finding is that FL from the p-xylyl derivative occurs from an excited state which possesses intramolecular charge-transfer character caused by the o- and m-methyl groups cooperatively. The results of X-ray crystallographic analysis reveal that these asymmetric diaroylmethanatoboron difluorides form dyads through orbital overlap of neighboring molecules. This phenomenon governs the unique FL properties of these substances in the solid state.

Photochemical Intramolecular C-H Addition of Dimesityl(hetero)arylboranes through a [1,6]-Sigmatropic Rearrangement.

A new reaction mode for triarylboranes under photochemical conditions was discovered. Photoirradiation of dimesitylboryl-substituted (hetero)arenes produced spirocyclic boraindanes, where one of the C-H bonds in the ortho-methyl groups of the mesityl substituents was formally added in a syn fashion to a C-C double bond of the (hetero)aryl group. Quantum chemical calculations and laser flash photolysis measurements indicated that the reaction proceeds through a [1,6]-sigmatropic rearrangement. This behavior is reminiscent of the photochemical reaction mode of arylalkenylketones, thus demonstrating the isosteric relation between tricoordinate organoboron compounds and the corresponding pseudo-carbocationic species in terms of pericyclic reactions. Despite the disrupted π-conjugation, the resulting spirocyclic boraindanes exhibited a characteristic absorption band at relatively long wavelengths (λ=370-400 nm).

Age-associated impairment of antitumor immunity in carcinoma-bearing mice and restoration by oral administration of Lentinula edodes mycelia extract.

Because cancer is associated with aging, immunological features in the aged should be considered in anticancer immunotherapy. In this study, we investigated antitumor immunity in aged mice using a CT26 colon carcinoma model. The tumor growth of CT26 was accelerated in aged mice compared with that in young mice, but this difference was not observed in nude mice. The serum levels of IL-6 and TNF-α were higher in aged mice than those in young mice, irrespective of the CT26-bearing state. The in vitro induction of CT26-specific CTLs from aged mice that were vaccinated with doxorubicin (DTX)-treated CT26 cells was impaired. In vivo neutralization of IL-6, but not TNF-α, showed a tendency to restore the in vitro induction of CT26-specific CTLs from vaccinated aged mice. Analyses on tumor-infiltrating immune cells as early as day 5 after CT26 inoculation revealed that monocytic and granulocytic MDSCs preferentially infiltrated into tumor sites in aged mice compared with young mice. Alternatively, oral administration of Lentinula edodes mycelia (L.E.M.) extract, which has the potential to suppress inflammation in tumor-bearing hosts, decreased the serum levels of IL-6 in aged mice. When administration of L.E.M. extract was started 1 week earlier, CT26 growth was retarded in aged mice and the in vivo priming of tumor-specific CTLs was improved in CT26-vaccinated aged mice. These results indicate early infiltration of MDSCs is related to impaired immunity of aged hosts and that oral administration of L.E.M. extract can mitigate the impairment.

Room-Temperature Phosphorescence of Crystalline Metal-Free Organoboron Complex.

The photoluminescence (PL) properties of a metal-free organoboron complex, bis(4-iodobenzoyl)methanatoboron difluoride (1BF2 ), were elucidated. At room temperature, 1BF2 emits blue fluorescence (FL) in nBuCl upon photoexcitation. In contrast, crystals of 1BF2 emit green PL comprised of FL and phosphorescence (PH). The room-temperature PH of crystalline 1BF2 is a consequence of 1) suppression of thermal deactivation of the S1 and T1 excited states and 2) enhancement of intersystem crossing (ISC) from the S1 to T2 or T1 . The results of X-ray crystallographic and theoretical studies supported the proposal that the former (1) is a result of intermolecular interactions caused by π-stacking in the rigid crystal packing structure of 1BF2 . The latter (2) is an effect of not only the heavy-atom effect of iodine, but also the continuous π-stacking alignment of 1BF2 molecules in crystals, which leads to a forbidden S1 →S0 transition and a small energy gap between the S1 and T2 or T1 .

Amorphous Solid Simulation and Trial Fabrication of the Organic Field-Effect Transistor of Tetrathienonaphthalenes Prepared by Using Microflow Photochemical Reactions: A Theoretical Calculation-Inspired Investigation.

The p-type organic semiconductor (OSC) material tetrathieno[2,3-a:3',2'-c:2″,3″-f:3‴,2‴-h]naphthalene (2TTN) and its alkyl-substituted derivatives C(n)-2TTNs (n = 6, 8, and 10) have been developed based on the results of theoretical calculation-inspired investigation. A hole mobility for amorphous C(n)-2TTNs (10(-2)-10(-3) cm(2) V(-1) s(-1)) was accurately predicted by using a novel statistical method in which the geometric mean of the mobilities for many individual small molecular flocks in an amorphous solid was obtained by using molecular mechanical molecular dynamics simulations and quantum chemical calculations. The simulation also suggests that upon increasing the length of alkyl chains in C(n)-2TTNs the mobilities become smaller as a consequence of a decrease in transfer integral values. C(n)-2TTNs are synthesized in a microflow reactor through photoreactions of the corresponding precursors. C(n)-2TTNs are then utilized in the fabrication of organic field-effect transistors (OFETs). Although spin-coated thin films of C(n)-2TTNs are crystalline, the hole mobilities (10(-2)-10(-3) cm(2) V(-1) s(-1)) of trial OFETs decrease upon elongation of the alkyl chains. This finding parallels the results of theoretical simulation. The simulation method for amorphous solids developed in this effort should become a useful tool in studies aimed at designing new OSC materials.

New Fluorescence Domain "Excited Multimer" Formed upon Photoexcitation of Continuously Stacked Diaroylmethanatoboron Difluoride Molecules with Fused π-Orbitals in Crystals.

The crystal-packing structures of seven derivatives of diaroylmethanatoboron difluoride (1 a-gBF2 ) are characterized by no overlap of the π-conjugated main units of two adjacent molecules (type I), overlap of the benzene ring π-orbitals of two adjacent molecules (type II), and overlap of the benzene and dihydrodioxaborinine rings π-orbitals of adjacent molecules (type III). The crystal-packing structures govern the fluorescence (FL) properties in the crystalline states. The FL domain that is present in type I crystals, in which intermolecular orbital interactions are absent, leads to excited monomer-like FL properties. In the case of the type II crystals, the presence of intermolecular overlap of the benzene rings π-orbitals generates new FL domains, referred to as "excited multimers", which possess allowed S0 -S1 electronic transitions and, as a result, similar FL lifetimes at longer wavelengths than the FL of the type I crystals. Finally, intermolecular overlap of the benzene and dihydrodioxaborinine ring π-orbitals in the type III crystals leads to "excited multimer" domains with forbidden S0 -S1 electronic transitions and longer FL lifetimes at similar wavelengths as that in type I crystals.

A facile and high-yield formation of dipyrrin-boronic acid dyads and triads: a light-harvesting system in the visible region based on the efficient energy transfer.

Artificial light-harvesting systems, Ar,O-BODIPY dyads and triads conjugated with a light harvester, were synthesized in high yield by the reaction of an N2O2-type dipyrrin with boronic acids. Dyad 2 having a pyrene unit underwent quantitative Förster resonance energy transfer (FRET) from the antenna unit, pyrene, to the fluorophore unit, Ar,O-BODIPY. Triads 3·5 and 4·5 were quantitatively prepared by mixing pyridine-appended compounds 3 and 4 with saloph·Zn complex 5, respectively. Triad 4·5 underwent efficient FRET from the saloph·Zn complex unit to the fluorophore unit at the rate of 2.0 × 10(11) s(-1). Interestingly, the fluorescence quenching process in the excited state of the triad 3·5 took place following the energy transfer event. Thus, appropriate positioning of the energy donor and acceptor is necessary to construct a highly efficient FRET system.

The lifetime and efficiency of triplet-triplet fluorescence from the excited state of a TMM biradical determined using transient emission spectroscopy by two-color two-laser flash photolysis.

The single laser flash photolysis (FP) of 2-(4-benzoylphenyl)-2-phenyl-1-methylenecyclopropane gave rise to a ground state trimethylenemethane (TMM) biradical with absorption bands at 362 and 545 nm and an excited state of this biradical that displays triplet-triplet fluorescence at 580 nm. The excited biradical is likely formed via an expected two-photon process as well as an unexpected one-photon process. The fluorescence quantum yield of the excited biradical, 0.021, was successfully determined by employing a two-color two-laser FP technique.

Lentinula Edodes Mycelia extract regulates the function of antigen-presenting cells to activate immune cells and prevent tumor-induced deterioration of immune function.

Immune cell activation is essential for cancer rejection; however, the tumor microenvironment leads to deterioration of immune function, which enables cancer cells to survive and proliferate. We previously reported that oral ingestion of Lentinula Edodes Mycelia (L.E.M.) extract enhances the tumor antigen-specific T-cell response and exerts an antitumor effect in a tumor-bearing mouse model. In this study, we focused on antigen-presenting cells (APCs) located upstream of the immune system, induced a T-cell response, then examined the impact of L.E.M. extract on the APCs. L.E.M. extract enhanced the expression of MHC-I, MHC-II, CD86, CD80, and CD40 in bone marrow-derived dendritic cells (DCs) and strongly induced the production of IL-12. L.E.M.-stimulated DCs enhanced IFN-γ production from CD8+ T cells and induced their differentiation into effector cells. Furthermore, L.E.M. extract promoted IL-12 production and suppressed the production of IL-10 and TGF-ß by transforming bone marrow-derived macrophages into M1-like macrophages. Furthermore, in a B16F10 melanoma inoculation model, DCs in the spleen were decreased and their activation was suppressed by the presence of cancer; however, ingestion of L.E.M. extract prevented this functional deterioration of DCs. In the spleen of cancer-bearing mice, the number of CD11b- F4/80+ macrophages in a hypoactivated state was also increased, whereas L.E.M. extract suppressed the increase of such macrophages. These findings suggest that L.E.M. extract may exhibit an antitumor immune response by regulating the function of APCs to induce cytotoxic T lymphocytes, as well as by suppressing the decline in antigen-presenting cell activity caused by the presence of cancer.

Combining a peptide vaccine with oral ingestion of Lentinula edodes mycelia extract enhances anti-tumor activity in B16 melanoma-bearing mice.

New anticancer vaccines must overcome regulatory T cell (Treg)-mediated immunosuppression. We previously reported that oral ingestion of Lentinula edodes mycelia (L.E.M.) extract restores melanoma-reactive T cells in melanoma-bearing mice via a mitigation of Treg-mediated immunosuppression. In this study, we investigated the effect of oral ingestion of the extract on peptide vaccine-induced anti-tumor activity. The day after subcutaneous inoculation in the footpad with B16 melanoma, mice were freely fed the extract and were vaccinated with a tyrosinase-related protein 2(180-188) peptide. The peptide vaccine was repeated thrice weekly. Melanoma growth was significantly suppressed in mice treated with both the peptide vaccine and L.E.M. extract compared with mice treated with vaccine or extract alone, and the effect was CD8(+) T cell-dependent. The combination therapy increased H-2K(b)-restricted and B16 melanoma-reactive T cells in the draining lymph nodes and spleen. Flow cytometric and immunohistological analyses revealed that the combination therapy significantly decreased the percentage of Tregs in the draining lymph nodes and spleen of melanoma-bearing mice compared to treatment with vaccine or extract alone. Kinetic analyses of peptide-specific T cells and Tregs revealed that induction of peptide-specific T cells by the peptide vaccine alone was transient, but when combined with L.E.M. extract, it efficiently prolonged the duration of peptide-specific T cell induction without increasing the percentage of Tregs. These results indicate that combination therapy enhances peptide vaccine-induced anti-tumor activity due to attenuation of the increase in the percentage of Tregs in tumor-bearing hosts.

Diphenyldihydropentalenediones: Wide Singlet-Triplet Energy Gap Compounds Possessing the Planarly Fixed Diene Subunit.

2,2,5,5-Tetramethyl-3,6-diphenyl-2,5-dihydropentalene-1,4-dione (PD-H) and its dimethoxy (PD-OCH3) and bis(trifluoromethyl) derivatives (PD-CF3) were developed as a new class of compounds possessing a wide excited singlet-triplet energy gap. The PD derivatives would also have a high energy level of the triplet-excited state (E T) due to the planarity of the fused-diene subunit. The results of photophysical studies revealed that the energy level of the singlet-excited state (E S) and E T of PD-H are 2.88 and 1.43 eV, respectively. These values indicate that PD-H has the energy relationship, E S > 2E T, required for it to be a singlet fission (SF) material. Moreover, the introduction of electron-donating or -withdrawing groups on the benzene rings in PD-H enables fine-tuning of E S and E T. The results of transient absorption spectroscopic studies show that PD-H, PD-OCH3, and PD-CF3 in CH2Cl2 have respective T1 lifetimes of 71, 118, and 107 µs, which are long enough to utilize its triplet exciton in other optoelectronic systems. These findings suggest that the PDs are potential candidates for SF materials with high E T levels.

Oral ingestion of Lentinula edodes mycelia extract inhibits B16 melanoma growth via mitigation of regulatory T cell-mediated immunosuppression.

Mitigation of regulatory T cell-mediated immunosuppression is crucial for optimal in vivo anti-tumor immune responses. In this study, we examined the anti-tumor effect induced by oral ingestion of an immunomodulating diet comprised of Lentinula edodes mycelia (L.E.M.) extract. C57BL/6 mice were inoculated subcutaneously in the footpad with B16 melanoma and fed L.E.M. extract. Ingestion of L.E.M. extract significantly inhibited tumor growth, and this in vivo anti-tumor effect was not observed in nude mice, suggesting a T cell-dependent mechanism. In addition, ingestion of L.E.M. extract led to significant restoration of H-2K(b) -restricted and melanoma-reactive T cells in the spleen and draining lymph nodes of melanoma-bearing mice. Flow cytometry analysis revealed that the percentage of Foxp3(+) CD4(+) T cells increased in spleen and draining lymph nodes in melanoma-bearing mice, but decreased significantly with ingestion of L.E.M. extract. Importantly, selective depletion of CD8(+) T cells abolished the L.E.M.-induced anti-tumor effect, whereas that of CD4(+) T cells or CD25(+) cells showed no additive influence on the effect. Real-time PCR analysis revealed that ingestion of L.E.M. extract by melanoma-bearing mice decreased the level of Foxp3 mRNA within the tumor tissues, and lowered plasma transforming growth factor (TGF)-ß. Furthermore, an in vitro assay revealed that an immunosuppressive activity of CD4(+) T cells from melanoma-bearing mice was canceled by ingestion of L.E.M. extract. Our results indicate that oral ingestion of L.E.M. extract restores immune responses of class I-restricted and melanoma-reactive CD8(+) T cells in melanoma-bearing mice, presumably by a mitigation of regulatory T cells-mediated immunosuppression.

A probable hydrogen-bonded Meisenheimer complex: an unusually high S(N)Ar reactivity of nitroaniline derivatives with hydroxide ion in aqueous media.

Observations show that nitroanilines exhibit an unusually high S(N)Ar reactivity with OH(-) in aqueous media in reactions that produce nitrophenols. S(N)Ar reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH(2) group far surpasses that of Cl under these conditions. An essential feature of S(N)Ar reactions of nitroanilines is probably that the NH(2) leaving group participates in a hydrogen-bonding interaction with H(2)O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH(-), and H(2)O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S(N)Ar reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.

Elongation of Triplet Lifetime Caused by Intramolecular Energy Hopping in Diphenylanthracene Dyads Oriented to Undergo Efficient Triplet-Triplet Annihilation Upconversion†.

Triplet-triplet annihilation (TTA)-assisted photon upconversion (TTA-UC) in three dyads (DPA-Cn-DPA), comprised of two diphenylanthracene (DPA) moieties connected by nonconjugated C1, C2, and C3 linkages (Cn), has been investigated. The performance of these dyads as energy acceptors in the presence of the energy donor platinum octaethylporphyrin are characterized by longer triplet lifetimes (τT) and different TTA rate constants than those of the parent DPA. The larger τT of the linked systems, caused by "intramolecular energy hopping" in the triplet dyad 3DPA*-Cn-DPA, results in a low threshold intensity, a key characteristic of efficient TTA-UC.

An amperometric biosensor based on a composite of single-walled carbon nanotubes, plasma-polymerized thin film, and an enzyme.

We report on an amperometric biosensor that is based on a nanocomposite of carbon nanotubes (CNT), a nano-thin plasma-polymerized film (PPF), and glucose oxidase (GOx) as an enzyme model. A mixture of the GOx and a CNT film is sandwiched with 10-nm-thick acetonitrile PPFs. Under PPF layer was deposited onto a sputtered gold electrode. To facilitate the electrochemical communication between the CNT layer and GOx, CNT was treated with nitrogen or oxygen plasma. The resulting device showed that the oxidizing current response due to enzymatic reaction was 4-16-fold larger than that with only CNT or PPF, showing that the PPF and/or plasma process is an enzyme-friendly platform for designing electrochemical communication from the reaction center of GOx to the electrode via CNTs. The optimized glucose biosensor showed high sensitivity (sensitivity of 42 microA mM(-1)cm(-2), correlation coefficient of 0.992, linear response range of 0.025-2.2 mM, and a detection limit of 6 microM at signal/noise ratio of 3, +0.8 V versus Ag/AgCl), high selectivity (almost no interference by 0.5 mM ascorbic acid) for glucose quantification, and rapid response (<4 s to reach 95% of maximum response). Additionally, the devices showed a small and stable background current (0.35+/-0.013 microA) compared with the glucose response (ca. 10 microA at 10mM glucose) and suitable reproducibility from sample-to-sample (<3%, n=4).

Singlet-Fission-Born Quintet State: Sublevel Selections and Trapping by Multiexciton Thermodynamics.

Singlet fission (SF) is expected to exceed the theoretical limit of the solar cell efficiency. Quintet (Q) state generation in triplet-triplet pair is essential for preventing the unwanted loss of SF-born multiexciton through singlet channels, although little is known on the primary multiexciton spin dynamics following the intermolecular SF. In this study, time-resolved EPR revealed the intermolecular multiexciton dynamics, energetics and geometries in aggregated 6,13-bis(triisopropylsilylethynyl)pentacene and 2-phenyl-6,11-bis(triisopropylsilylethynyl)tetracene in diluted frozen solution. We have demonstrated sublevel selective generations of excited quintet states (|Q0⟩, |Q-1⟩ and |Q-2⟩) by singlet-quintet (SQ) mixings during triplet-exciton diffusions within geminate multiexcitons. The present fundamental characteristics of the quintet generations shows strong impact of coexistence of molecularly ordered "hot spot" and disordered regions for exergonic SQ mixings driven by entropy, thereby paving a new avenue for rational designs of organic devices with controlled multiexciton dynamics by optimizing film morphologies.

Visible-light, photoredox catalyzed, oxidative hydroxylation of arylboronic acids using a metal-organic framework containing tetrakis(carboxyphenyl)porphyrin groups.

A Zr-based metal-organic framework with tetrakis(carboxyphenyl)porphyrin groups (Zr-MOF-TCPP: MOF-525) has been utilized as a photoredox catalyst to promote oxidative hydroxylation of arylboronic acids under green LED light irradiation. Zr-MOF-TCPP displays a superior catalytic activity for this process over the corresponding homogeneous catalyst (H4TCPP).