N-fused carbazole-zinc porphyrin-free-base porphyrin triad for efficient near-IR dye-sensitized solar cells

N-fused carbazole-zinc porphyrin-free-base porphyrin triad featuring an ethynyl-linkage was synthesized; efficient sensitization as long as 900 nm was demonstrated and an overall light-to-electricity conversion efficiency of 5.21% was achieved under AM 1.5 G one sun illumination.     

Syntheses and properties of triborane(5)s possessing bulky diamino substituents on terminal boron atoms

The present communication reports the chemistry of three linear triborane(5) compounds possessing bulky diamino substituents on the terminal boron atoms. Fluorotriborane 2 was synthesized by a reaction of boryllithium and BF(3)·OEt(2). Halogen exchange reaction of 2 took place by a treatment with ClSiMe(3) to give the corresponding chlorotriborane(5) 3. Addition of silver tetraarylborate to 3 in ether afforded a hydroxylated triborane(5) compound 5 probably via an unstable cationic boron intermediate 4.     

Homogeneously mixed porphyrin J-aggregates with rod-shaped nanostructures via zwitterionic self-assembly

To tailor functional nanomaterials, the co-assembly of self-assembling dyes in a homogeneous way would be a promising approach because the electronic properties can be tuned by the mixing ratio. Although porphyrins are important supramolecular building blocks with unique optical properties, a homogeneously mixed J-aggregate system of porphyrins has not been reported yet. Herein, we focused on three kinds of zwitterionic porphyrin diacids, H(4)TSPP(2-), H(4)T(5-STh)P(2-) and H(4)T(4-STh)P(2-), due to their capability to form J-aggregates with distinguished optical properties and well-defined nanostructures. In this study, we investigated the co-assembly behaviours of the zwitterionic porphyrins in aqueous solution by UV-vis and RLS, and investigated the morphology of the resultant homogeneously mixed J-aggregates by AFM. In the case of the combination of H(4)TSPP(2-) and H(4)T(5-STh)P(2-), they readily co-assemble to form homogeneously mixed J-aggregates with different types of binary excitonic bands, whereas the combination of H(4)T(4-STh)P(2-) and other porphyrins results in the dominant formation of the individual pure J-aggregates. Deposited homogeneously mixed J-aggregates of H(4)TSPP(2-) with H(4)T(5-STh)P(2-) consist of rod-shaped nanostructures, whose height changes discontinuously upon varying the mixing ratio. These results would provide new insights into the electronic properties and the nanostructure of self-assembled multicomponent materials.     

Polychromatic decoupling of a manifold of homonuclear scalar interactions in solution-state NMR

Window-acquired tetrachromatic irradiation allows one to decouple simultaneously four amide protons in cyclosporine?A (wavy arrows; see figure) leading to simplified multiplets of the alpha protons. By inserting a manifold of polychromatic pulses in each dwell time, several subsystems can be decoupled simultaneously.     

Modulation of structure and dynamics by disulfide bond formation in unfolded states

During oxidative folding, the formation of disulfide bonds has profound effects on guiding the protein folding pathway. Until now, comparatively little is known about the changes in the conformational dynamics in folding intermediates of proteins that contain only a subset of their native disulfide bonds. In this comprehensive study, we probe the conformational landscape of non-native states of lysozyme containing a single native disulfide bond utilizing nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering (SAXS), circular dichroism (CD) data, and modeling approaches. The impact on conformational dynamics varies widely depending on the loop size of the single disulfide variants and deviates significantly from random coil predictions for both NMR and SAXS data. From these experiments, we conclude that the introduction of single disulfides spanning a large portion of the polypeptide chain shifts the structure and dynamics of hydrophobic core residues of the protein so that these regions exhibit levels of order comparable to the native state on the nanosecond time scale.     

Synthesis and properties of cycloparaphenylene-2,5-pyridylidene: a nitrogen-containing carbon nanoring

The first synthesis of a nitrogen-containing cycloparaphenylene, cyclo[14]paraphenylene[4]2,5-pyridylidene ([14,4]CPPy), has been achieved. A palladium-catalyzed stepwise assembly of 2,2'-bipyridine, benzene, and L-shaped cyclohexane units, followed by NaHSO(4)/o-chloranil-mediated aromatization, successfully provided [14,4]CPPy. While the absorption and fluorescence properties of [14,4]CPPy were somewhat similar to those of cycloparaphenylenes (λ(abs) = 344 nm, ε = 7.3 × 10(4) cm(-1) M(-1), λ(em) = 427 nm, Φ(F) = 0.80), it was found that [14,4]CPPy possesses an interesting halochromic property.     

Rapid identification of microorganisms by mass spectrometry: improved performance by incorporation of in-house spectral data into a commercial database

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used as a microbial diagnostic method for species identification of pathogens. However, MALDI-TOF identification of bacteria at the species level remains unsatisfactory, with the major problem being an incomplete database that still needs refinement and expansion. Augmentation of the original MALDI BioTyper 2.0 (Bruker) database by incorporating mass spectra obtained in-house from clinical isolates may increase the identification rate at the species level. We conducted a prospective study to assess whether the augmented database can improve the performance of MALDI-TOF MS for routine identification of species. Cluster analyses revealed distinct differences in MS spectral profiles of clinical isolates obtained in our hospital and those of ATCC strains in the Bruker database. In the first part of the study, which was performed over 3 weeks, 259 bacterial isolates were subjected to analysis by MALDI-TOF MS, and MS spectra of 229 successfully identified isolates (49 species) were incorporated into the original database to give the augmented Bruker-Chiba database. In a second separate analysis, the concordance of identification of 498 clinical isolates of the 49 species with conventional methods was 87.1% (434/498) with the commercial Bruker database and 98.0% (488/498) using the Bruker-Chiba database. These results indicate that refinement of a commercial database can be achieved relatively easy and effectively by incorporating MS spectra of clinical isolates obtained in a clinical laboratory.     

Pd(OAc)2/o-chloranil/M(OTf)n: a catalyst for the direct C-H arylation of polycyclic aromatic hydrocarbons with boryl-, silyl-, and unfunctionalized arenes

Pd(OAc)(2)/o-chloranil/M(OTf)(n) can effectively promote the C-H arylation of fluoranthene with arylboron compounds or arylsilanes. The reaction takes place with high regioselectivity at the C3 position of fluoranthene. Moreover, the new catalytic system allows the use of unfunctionalized arenes as coupling partners in the arylation of polycyclic aromatic hydrocarbons.