Functional Pyrimidinyl Pyrazolate Pt(II) Complexes: Role of Nitrogen Atom in Tuning the Solid‐State Stacking and Photophysics

Pt(II) metal complexes are known to exhibit strong solid‐state aggregation and are promising for realization of efficient emission in fabrication of organic light emitting diodes (OLED) with nondoped emitter layer. Four pyrimidine–pyrazolate based chelates, together with four isomeric Pt(II) metal complexes, namely: [Pt(pm2z)₂], [Pt(tpm2z)₂], [Pt(pm4z)₂], and [Pt(tpm4z)₂], are isolated and systematically investigated for their structure–property relationships for practical OLED applications. Detailed single molecular and aggregated structures are revealed by photophysical and mechanochromic measurements, grazing‐incidence X‐ray diffraction, and theoretical approaches. These results suggest that these Pt(II) emitters pack like a deck of playing cards under vacuum deposition, and their emission energy is not only affected by the single molecular designs, but notably influenced by their intermolecular packing interaction, i.e., Pt···Pt separations that are arranged in the order: [Pt(tpm4z)₂] > [Pt(pm4z)₂] > [Pt(tpm2z)₂] > [Pt(pm2z)₂]. Nondoped OLED with emission ranging from green to red are prepared, to which the best performances are recorded for [Pt(tpm2z)₂], giving maximum external quantum efficiency (EQE) of 27.5% at 10³ cd m^?2, maximum luminance of 2.5 × 10⁵ cd m^?2 at 17 V, and with stable CIE_x,y of (0.56, 0.44).     

Tetrahedral n-type materials: efficient quenching of the excitation of p-type polymers in amorphous films

Tetrahedral naphthalenediimide compound 1 has been synthesized as an example of a new class of amorphous n-type materials, in which the nondirectionality obtained by its shape is decoupled from its optoelectronic properties. 1 forms bicontinuous films with p-type polymers and effectively quenches the excited state, yielding long-lived mobile charge carriers on pulsed illumination.     

Native fluorescence spectroscopy of blood plasma in the characterization of oral malignancy

Native fluorescence characteristics of blood plasma were studied in the visible spectral region, at two different excitation wavelengths, 405 and 420 nm, to discriminate patients with different stages of oral malignancy from healthy subjects. The fluorescence spectra of blood plasma of oral malignant subjects exhibit characteristic spectral differences with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values at those emission wavelengths that give characteristic spectral features of each group of experimental subjects studied. These fluorescence intensity ratios were used as input variables for a multiple linear discriminant analysis across different groups. Leave-one out cross-validation was used to check the reliability of each discriminant analysis performed. The discriminant analysis performed across normal and oral cancerous subjects classified 94.7% of the original grouped cases and 93.7% of the cross-validated grouped cases. A classification algorithm was developed on the basis of the score of the discriminant functions (discriminant score) resulted in the analyses. The diagnostic potentiality of the present technique was also estimated in the discrimination of malignant subjects from normal and nonmalignant diseased subjects such as liver diseases. In the discriminant analysis performed across the three groups, normal, oral malignancy (including early and advanced stages) and liver diseases, 99% of the original grouped cases and 95.9% of the cross-validated grouped cases were correctly classified. Similar analysis performed across normal, early stage of oral malignancy, advanced oral malignancy and liver diseases correctly classified 94.9% of the original grouped cases and 91.8% of the cross-validated grouped cases.     

Spin dependent gluon densities from largeP T photon and dimuon production

We investigate spin asymmetries in highp _T photon and dimuon production and show that the spin dependent gluon density can be extracted reliably frompp collisions with these final states. The statement remains true even when the balancing jet is not observed. Hence fixed target experiments can be used to measure the spin dependent gluon density. We also compute the asymmetries in \(p\bar p\) collisions, and show that the EMC measurement of the spin structure function can be verified and the spin dependent gluon density can be extracted from these experiments.     

Synthesis of functionalized 1,5-cyclooctadienes by LICKOR metalation

1,5-Cyclooctadiene was lithiated under LICKOR superbase conditions followed by reaction with alkyl halides or ethylene oxide to yield 3-substituted 1,5-cyclooctadienes in high yield and purity. This procedure is suitable for preparation of 1,5-cyclooctadienes carrying pendant functional groups for immobilization on solid-phase resins.     

In vivo pharmacokinetics of 8-aminolevulinic acid-induced protoporphyrin IX during pre- and post-photodynamic therapy in 7,12-dimethylbenz(a)nthracene-treated skin carcinogenesis in Swiss mice: a comparison by three-compartment model

Delta-aminolevulinic acid-photodynamic therapy (ALA-PDT) has emerged as a useful technique in the treatment of superficial basal cell carcinoma, actinic keratosis, squamous cell carcinoma and tumors of other organs. Earlier reports mention that there is reappearance of protoporphyrin IX (PpIX) after photoirradiation of tumors. This property of reappearance of PpIX is being utilized to treat nodular tumors by fractionated light dose delivery. However, there is still no unanimously accepted reason for this reappearance phenomenon and the rate of resynthesis after PDT. On account of this, studies are carried out on the estimation of the pharmacokinetics of the ALA-induced PpIX in mice tumor models and the surrounding normal tissues before and after PDT. Further, a mathematical model based on a multiple compartment system is proposed to estimate the rate parameter for the diffusion of PpIX from the surrounding normal tissues into the tumor tissue (km) caused by photobleaching during PDT with irradiating fluences of 36.0 and 57.6 J/cm2. The km value at two different fluences, 36.0 and 57.6 J/cm2, are estimated as 3.0636+/-0.7083 h(-1) and 6.9231+/-2.17651 h(-1), respectively. Further, the rate parameter for the cleavage and efflux of ALA (k1) and the rate parameter for the evasion of PpIX from the tumor tissues after PDT (kt) were also estimated by fitting the experimental data to the developed mathematical model. The statistical significance of the estimated parameters was determined using Student's t-test. The experimental results and the rate parameters obtained using the proposed compartment model suggest that in addition to the earlier reported reasons, the invasion or diffusion of PpIX from the surrounding tissues to the tumor tissues after photoirradiation might also contribute to the reappearance of PpIX after PDT.     

可移动半无限垂直圆柱体温度交变振荡时对MHD自由对流的影响

不可压缩粘性流体,流过可移动、温度交变振荡的半无限垂直圆柱体时,对MHD自由对流影响的数值解进行了研究.应用Crank-Nicolson型的隐式有限差分方法,求解无量纲、不稳定、非线性、耦合的偏微分控制方程.在不同参数下研究速度、温度和浓度分布的变化,还分析了局部及平均的表面摩擦力、Nusselt数和Sherwood数,并以图形形式给出.所得结果与其他文献的结果比较,有着很好的一致性.     

Double D–π–A Dye Linked by 2,2′‐Bipyridine Dicarboxylic Acid: Influence of para‐ and meta‐Substituted Carboxyl Anchoring Group

Starting from 2,2′‐bipyridine dicarboxylic acid, two new (D –π–A)₂ sensitizers, including m‐DA with the carboxyl anchoring group substituted meta to the donor‐bridge moiety and p‐DA with a para‐substituted anchoring group, were synthesized in order to evaluate the impact of the position of the anchoring group on the optical, electrochemical, and photovoltaic properties of dye‐sensitized solar cells. p‐DA exhibits red‐shifted absorption behavior compared to m‐DA, owing to the more efficiently extended π‐conjugation with para substitution. Both m‐DA and p‐DA are adsorbed on the mesoporous TiO₂ surface by using both of their carboxylic acid groups in a bianchoring mode, which is confirmed through attenuated total reflectance FTIR analysis. Red‐shifted absorption of p‐DA assists the achievement of a red‐shifted incident photon‐to‐electron conversion efficiency and a higher short‐circuit current density than m‐DA. The photogenerated electron lifetime in TiO₂ is also found to be higher for para substituted p‐DA than the meta‐substituted m‐DA, which results in a higher open‐circuit voltage. All of the results suggest that dicarboxyl‐2,2′‐bipyridine can be used as an acceptor for metal‐free organic sensitizers. However, the anchoring segments should be adjusted to the favorable position of the corresponding donor‐bridge moieties for better conjugation.