QUANTITATIVE APPLICATION OF RESONANCE THEORY ON EXCITED STATE BEHAVIOURS AND ITS CONSISTENCY WITH MOLECULAR ORBITAL THEORY

Rcsonance theory, the graphic language of valence bond theory, has been applied quantitatively and successfully to a series of excited state behaviours, the so-called properties related to molecalar orbits, such as the p-bands and β-bands of UV spectra, the oxidation and reduction half-wave potentials of polarography. By taking the Kekulé formulae of ground and excited state of molecules as the bases of corresponding wave functions, it is evidenced that the values of ln(excited structure count/ground structure count) correlate lineally with the above-mentioned properties. In practice, the correlations between calculations and experiments of polycyclic aromatic hydrocarbons are all good (|γ|>0.95). On conjugated polyene, polyyne and benzenoid polyacene homologs, the series with excellent correlation among the 150 calculated series exceed 85% (|γ|≥0.99), and for the remainder series, the correlations are all good (|γ|>0.95).     

脂筏微区超分子聚集体结构的稳定性

生物膜中脂筏微区结构的动态特征与稳定性决定着生物膜的功能。通过从动物细胞提取脂筏,实验不但观测到质膜微囊烧瓶状凹陷结构,而且还观测到大量的球状和椭球状结构.通过模拟脂筏微区结构,重点对二元体系和三元体系的超分子聚集体结构的多形性进行了研究和探索。研究发现随着表面压力的增加,鞘磷脂和胆固醇双层膜出现了紧密聚集不规则的微区结构,在 SM/Chol/DOPC双层膜中,SM/Chol形成的微区结构漂浮在液态DOPC小颗粒上部。当 DOPE加入到SM/Chol中,三种成份形成不稳定的双层膜结构.Ceramide促进了SM/Chol结构发生重排,微区形状从原来的不规则向着紧密聚集的圆形结构演变;混合单层膜的分子面积与表面吉布斯自由能决定了分子间的相互作用, 当过量分子面积与过量吉布斯自由能为负值时,分子间相互作用表现为吸引力, 出现凝聚现象; 为正值时,分子间相互作用表现为排斥力, 促使单层膜出现相分离现象. 过量吉布斯自由能值越小, 单层膜的热稳定性越高.通过动物细胞提取脂筏与体外模拟脂筏相结合的方法,从超分子水平阐述了脂筏微区结构与功能的生物学意义,为生物膜的研究提供了理论依据和实验支持。