Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

The current development in the intramolecular aromatic-ring stacking interactions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions in several important systems about ternary mixed-ligand complexes, including nucleotide-metal ion-po-lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleo-tide-metal ion-amino acid, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interac-tions in the complexes. Based on the study of stacking inter-action in the complexes, the mechanism of interaction be-tween DNA molecules and complexes of heteroaromatic N-bases has been established, which is crucial for the design and synthesis of the complexes acting as molecular devices of DNA.

Injection modulation of p^+-n emitter junction in 4H-SiC light triggered thyristor by double-deck thin n-base

To overcome hole-injection limitation of p^＋-n emitter junction in 4H-SiC light triggered thyristor, a novel high- voltage 4H-SiC light triggered thyristor with double-deck thin n-base structure is proposed and demonstrated by two- dimensional numerical simulations. In this new structure, the conventional thin n-base is split to double-deck. The hole- injection of p^＋-n emitter junction is modulated by modulating the doping concentration and thickness of upper-deck thin n- base. With double-deck thin n-base, the current gain coefficient of the top pnp transistor in 4H-SiC light triggered thyristor is enhanced. As a result, the triggering light intensity and the turn-on delay time of 4H-SiC light triggered thyristor are both reduced. The simulation results show that the proposed 10-kV 4H-SiC light triggered thyristor is able to be triggered on by 500-mW/cm^2 ultraviolet light pulse. Meanwhile, the turn-on delay time of the proposed thyristor is reduced to 337 ns.

Optical polarization characteristics for AlGaN-based light-emitting diodes with AlGaN multilayer structure as well layer

The optical properties of AlGaN-based quantum well(QW)structure with two coupled thin well layers are investigated by the six-by-six K-P method.Compared with the conventional structure,the new structure,especially the one with lower Al-content in the barrier layer,can enhance the TE-/TM-polarized total spontaneous emission rate due to the strong quantum confinement and wide recombination region.For the conventional QW structure,the reduction of well thickness can lead the degree of polarization(DOP)to decrease and the internal quantum efficiency(IQE)to increase.By using the coupled thin well layers,the DOP for the structure with high Al-content in the barrier layer can be improved,while the DOP will further decrease with low Al-content in the barrier layer.It can be attributed to the band adjustment induced by the combination of barrier height and well layer coupling.The IQE can also be further enhanced to 14.8%-20.5%for various Al-content of barrier layer at J=100 A/cm^(2).In addition,the efficiency droop effect can be expected to be suppressed compared with the conventional structure.

SYNTHESIS OF ORGANOMETALLIC PRECURSORS FOR Si/Zr/C/N-BASED CERAMICS

A new kind of organometallic precursor for Si/Zr/C/N-based ceramics was synthesized from the amine exchangereaction of hexamethylcyclotrisilazane (D_3~N) and tetrakis(diethylamino) zirconium (Zr[NEt_2]_4). Pyrolysis was performedunder nitrogen at 800℃ in a tube furnace equipped with a temperature program controller. The highest pyrolytic yield was67.5%.

Studies on Intramolecular Stacking Interaction of Ternary Complexes M（Ⅱ）（ATP）￣（2－） with Heteroaromatic N－Base Ligands

o understand the driving forces leading to mixed-ligand complexes in biologi-cal systenis.ternary complexes of M (ATP(L￣(2-) type, where M = Cu￣(2+), Ni￣(2+) orCo￣(2+) , and L= pyridine(Py) , 4-picoline, 3, 5-lutidine, isoquinoline (lq) or benzimi-dazole(Bi) in aqueous solution were studied by spectropliotometry, some of them(M=Cu￣(2+), L = isoquinoline or benzimidazole) were also separately studied hy po-tentiometric pH titration. The results show that an intramolecular stacking interac-tion exists between the heteroaromatic ring of the ligands and the purine moiety ofATP.

A Novel Method to Synthesize Polyorganozircosilazane

A new kind of polyorganozircosilazane as Si/Zr/C/N-based ceramic precursor was synthesized from the condensation reaction of hexamethylcyclotrisilazane lithium salts (D3NLi) and zirconium tetrachloride (ZrCl4). In the presence of N, N, N, N-tetramethyl ethylene diamine (TMEDA), polyorganozircosilazane was obtained in high yield.

Intramolecular aromatic-ring stacking interaction of ternary Zn(UTP)L^(2-) complexes

THE mechanism of the action of the classic platinum antitumor drugs can be interpreted accord-ing to their bidentate, bifunctional interaction with the DNA of the tumor cell, resulting in in-hibition of the DNA replication. Recently, it was found that a new class of compounds withthe general formula cis-[Pt（NH3）2（N-het）Cl]Cl（N-het is a heteroaromatic N-base like pyri-dine） show effective antitumor activities. However, two possible mechanisms of action