Tetraaryl‐Substituted Benzo[1,2‐b:4,5‐b′]dipyrroles: Synthesis,Properties, and Applications to Hole‐Injection Materials in OLED Devices

Yes, HIMs can! A series of 2,3,6,7‐tetraarylbenzo[1,2‐b:4,5‐b′]dipyrroles (BDPs) were synthesized using zinc‐mediated double cyclization. Organic light‐emitting diodes consisting of BDP:PPB as a hole‐injection layer could be driven at a lower voltage than a PEDOT:PSS‐based device. Correlation of the IP values with the driving voltage shed some light on the mechanism of hole‐injection processes.

     

Characterization of alkyl monolayer covalently bonded to Si(111) and soft-landing of vanadium-benzene sandwich clusters onto the alkyl monolayer substrate

A hexadecyl monolayer covalently attached to Si(111) surfaces (C₁₆–Si(111)) was prepared at 200 ^○C from 1-hexadecene. Formation of the monolayer was characterized by water contact angle measurement, attenuated total reflection infrared (ATR-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Gas phase synthesized vanadium (V)-benzene (Bz) 1:2 (VBz₂) sandwich clusters were size-selectively deposited onto the C₁₆–Si(111) substrate thus prepared and an oxidized Si substrate. Investigation of the resultant clusters was implemented by thermal desorption spectroscopy (TDS). About 30 K increase in threshold desorption temperature of the landed clusters was observed on going from the oxidized Si to the C₁₆–Si(111) substrate, a result indicating that the clusters are more strongly bound to the C₁₆–Si(111) than to the oxidized Si. This result was explained by the penetration of the landed clusters into the hexadecyl monolayer.     

Development of 125Te synchrotron-radiation-based Mössbauer spectroscopy

The Mössbauer spectra of the 35.49 keV excited state of ¹²⁵Te were observed in the energy domain using synchrotron radiation for the first time. The obtained isomer shifts and Debye temperature agree with previous experiments. These results show that this method will be applicable to various compounds.     

Semiconductor-metal phase diagram of Co-doped NiS2

The phase diagram of the semiconductor-metal and antiferromagnetic transitions in 5 at.% Co- and 7 at.% Co-doped NiS₂ is determined from the electrical resistance measurements below room temperature to 77 K at pressures up to 35 kbar. It is indicated that the antiferromagnetic transition occurs in both semiconducting and metallic phases.     

γ Radiolysis of polyethylene grafted with styrene

γ Radiolysis of polyethylene grafted with styrene of 0–76 wt % was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 10⁵ rad/hr. The formation of hydrogen and trans-vinylene unsaturation decreased as the content of styrene unit in polymer increased and the rate of formation was described by zero-order formation kinetics with respect to each concentration combined with first-order disappearance. The gel fraction changed with the content of styrene unit according to irradiation time and temperature. The gel data were evaluated by using the Charlesby–Pinner equation. Kinetic analysis showed that in γ radiolysis of polyethylene grafted with styrene the formation of hydrogen is somewhat retarded, the crosslinking and main chain scission are accelerated, and the disappearance of hydrogen and formation and disappearance of trans-vinylene unsaturation are almost entirely unaffected. On the basis of these results the reactions induced by γ rays in graft polymer were discussed in connection with the reaction mechanisms of the γ radiolyses of polyethylene and polystyrene.     

Synthesis of platinum complexes of 2-aminomethylpyrrolidine derivatives for use as carrier ligands and their antitumor activities

In order to study a new antitumor platinum complex, various platinum complexes were prepared from 2-amino-methylpyrrolidine derivatives synthesized to serve as carrier ligands and tested for their antitumor activity against Colon 26 carcinoma (s.c.-i.p. system) and P388 leukemia (i.p.-i.p. system) in mice. 2-Aminomethylpyrrolidine proved to be the most effective carrier ligand in its amine derivatives. The structure-activity relationships of the carrier ligands in the platinum complexes with dichloro, oxalato, 1,1-cyclobutanedicarboxylato and dichlorodihydroxo as leaving group were clearly shown on the Colon 26 carcinoma screen and were as follows: the antitumor activity of the platinum complexes with any leaving groups was considerably decreased by the substitution of hydrogen by alkyl group (Me, Et) on nitrogen of aminomethyl and the effects of 1,1-cyclobutanedicarboxylato Pt(II) complexes completely disappeared with the same substitution on nitrogen of pyrrolidine. In all the tested platinum complexes 2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato)platin um(II) (15) exhibited the most potent antitumor activity. 15 was superior to 1,1-cyclobutanedicarboxylatodiammineplatinum(II) (CBDCA) and similar to cis-diamminedichloroplatinum(II) (CDDP) on the Colon 26 carcinoma screen but it was inferior to CBDCA and CDDP on the P388 leukemia screen. Furthermore, 15 showed more potent antitumor activity than CBDCA against Colon 38 carcinoma (s.c.-i.p. system).     

Ion chromatography for determination of nitrite and nitrate in seawater using monolithic ODS columns

A fast and highly sensitive ion chromatographic method using monolithic ODS columns was developed for the determination of nitrite (NO2-) and nitrate (NO3-) in seawater. Two monolithic ODS columns (50 mm x 4.6 mm i.d. + 100 mm x 4.6 mm i.d.) connected in series were coated and equilibrated with 5 mM cetyltrimethylammonium chloride (CTAC) aqueous solution. The column efficiency with 0.5 M NaCl as the mobile phase did not decrease in spite of the increase in flow rate of the mobile phase. Thus, good chromatograms were obtained within 3 minutes for NO2- and NO3 in artificial seawater without interferences by coexisting ions. The detection limit (S/N = 3) with UV detection at 225 nm was 0.8 and 1.6 microg/L for NO2- and NO3-, respectively. The characteristics of the monolithic CTA(+)-coated ODS columns were discussed. The present method was successfully applied to the fast and sensitive determination of NO2- and NO3- in real seawater samples.