Spectroscopic Studies on Co(Ⅱ),Ni(Ⅱ),Zn(Ⅱ) Complexes with 4,4'-Bipyridine

Fourier-transform infrared（FTIR）,Raman and ultraviolet-visible spectra of 4,4＇-bipyridine and its me-tal-organic coordination compounds synthesized from 4,4＇-bipyridine and nitrate of Co（Ⅱ）,Ni（Ⅱ） and Zn（Ⅱ） were measured and analyzed,respectively.The main FTIR and Raman bands were assigned in detail.The relationship between these characteristic bands and the structure of ligands and coordination compounds were discussed.

Molecular Dynamics Simulation of Antipolyelectrolyte Effect and Solubility of Polyzwitterions

In this work, by using coarse-grained molecular dynamics simulations, we found that poly（2-metha-cryloyloxyethyl phosphorylcholine）（PMPC） showed a strong solubility and a so-called antipolyelectrolyte effect（APE）in water. In contrast, obvious aggregations but no APE were found in n-butyl-substituted choline phosphatepolymers（PMBP） solutions. The underlying mechanisms for different solution behaviors of PMPC and PMBP wereinvestigated in detail. Our results indicate that the presence of butyl groups in PMBP enhances both the electrostaticinteractions and the hydrophobicity of PMBP molecules in the system. Both factors were found to contribute to theformations of aggregates in the PMBP system. Further researches revealed that hydrophobicity arising from the butylgroup plays a more important role than electrostatic interactions in inducing the PMBP aggregation. In addition, thestrong hydrophobicity in PMBP was found to be responsible for the absence of APE. These results are expected tocontribute to a better understanding and a better design of the solution properties of polyzwitterions.

Preparation of 9,10-Diarylphenanthrene Derivative and Its Application in Full Color Emitters Synthesis

As a building block with high photo- and thermo-stability, phenanthrene plays an important role in the preparation of blue（or deep-blue） and full color fluorescence materials. However, some critical issues must be addressed before its full potential can be realised, such as its tedious and low-yield modification processes and the red-shift effect in its aggregated state. In this work, the inexpensive raw material 9,10-phenanthrenequinone（PQ） was chosen as the preparatory functional phenanthrene block. After modifying PQ via halo-substituted, nucleophilic and rearrangement reactions with high yields, the corresponding monomers featured high reactivity and solubility. Com- pared with classical synthetic approaches for similar phenanthrene-based derivatives, the low efficiency ring-closed reaction and hazardous lithium-injection operation can be omitted using this approach. This new building block demonstrates a clear steric effect following the introduction of peripheral phenyl and alkoxy groups; moreover~ stacking in the aggregated state is avoided, which benefits controlling the bandgap and maintaining blue emission as either an emitter or a donor. By changing the central building block in three oligomers, emission of the three primary colors was achieved in solution and film via the conjugated increment and charge-transform effect. This work provides a method of modifying phenanthrene by a simple and efficient synthesis route with inhibition of solid-state aggregation and offers an effective strategy to further develop functional phenanthrene-based building blocks.

Dynamic Mechanism of Relaxation Paths Occurring in TPA-DCPP： Roles of Solvent and Temperature

The relaxation paths for triphenylamine（TPA）-2,3-dicyanopyrazino phenanthrene（DCPP）, which has a pull-push structure, were investigated via steady-state, time-resolved spectroscopy involving transient absorption and time-correlated single photon counting. By changing the solvent polarity we found that an intramolecular charge transfer（ICT） state acting as a ＂bright＂ state was responsible for the fluorescence character of TPA-DCPP. Meanwhile, a ＂dark＂ state gradually appeared and competed with the ICT state. This was likely to be responsible for the polarity-dependent evolution of fluorescence intensity and fluorescence lifetime. The temperature-dependent fluorescence character of the TPA-DCPP in toluene exhibited ICT processes at high temperatures prior to the relaxation path from the initial excited state to the ground state. Our results provide useful insight into the optoelectronic properties of these kinds of molecules.

Crosslinked Polystyrene Beads Modified with Sulfonyl Groups and Their Application in Aromatic/Aliphatic Hydrocarbons Separation

The separation of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated with cross- linked polystyrene（CPS） beads modified with sulfonyl groups. Three sulfonating agents, i.e. benzenesulfonyl chlo- ride（BsCl）, 4-toluene sulfonyl chloride（TsC1） and methanesulfonyl chloride（MsC1） were used to prepare sulfonyl CPS beads by Friedel-Crafts reaction. The CPS beads modified with BsC1 exhibited higher sulfonation rate than those modified with MsC1 and TsCI and obtained optimum selectivity in the experiments of toluene/n-heptane separation. Further separation tests with various other aromatic/aliphatic mixtures were carried out at an initial aromatic concen- tration of 13%（mass fraction） with the results showing that the modified beads have preferential selectivity for aro- matic hydrocarbons in all aromatic/aliphatic mixtures, and especially a separation factor of 8.21 and a swelling ratio of 30% for toluene/cyclohexane system. The thermal stability and regeneration test indicate that the used polystyrene beads can be recovered through heat-drying and reused effectively.

Effects of Site-directed Mutagenesis of L469 in Helix-5 of Human Papillomavirus 16 L1 on Pentamer Formation

Located at the carboxyl terminal of the human papillomavirus major capsid protein L1, helix-5（h5） is cru-cial to L1 folding and pentamer formation. Site-directed mutagenesis of the leucine residue on site 469 into lysine, alanine, serine and glycine was performed to explore the effect of the resultant mutations on L 1 pentamer formation. The soluble yields of the L1 pentamers of the L469A and L469K mutants were nearly two fold higher than that of the wild type. Molecular dynamics simulation was then performed to reveal the intrinsic mechanisms involved in the improvement of L 1 pentamer yield. Accordingly, the secondary structures of h5, β-G2, β-B1, β-C, β-D, and β-F were altered. The altered structures improved the hydrophobic interaction between h5 and fl-core ＂jelly＂ and the stability of h5. The hydrophobic surface area of residue 469 was reduced by 50% relative to that of the wild type. The C--O group of residue 469 and C--N group of L470 were both exposed to the solvent in the L469A mutant. These modifications may account for the increased solubility and stability and the promotion of pentamer formation induced by the point mutation. Therefore, the changes in the hydrophobic properties of h5 and the core structure determined the pentamer formation and solubility. This study may assist the development of a cost-effective platform for the production of prophylactic virus-like particle vaccines.