磷酸双乙酸胍分子中基团间作用的量子化学从头算研究  

Ab Initio Study on the Interaction Between Groups in Phosphate bis-Guanidinoacetate Molecule

作　　者：王磊[1] 王党会[1] 肖美霞[1] WANG Lei;WANG Danghui;XIAO Meixia(School of Materials Science and Engineering,Xi’an Shiyou University,Xi’an 710065)

机构地区：[1]西安石油大学材料科学与工程学院

出　　处：《材料导报》2019年第20期3508-3511,共4页Materials Reports

基　　金：国家自然科学基金青年基金(51702257);陕西省自然科学基础研究计划项目(2018JQ5123);陕西省高校科协青年人才托举计划(20160221);西安石油大学《材料科学与工程》省级优势学科(ys37020203)~~

摘　　要：基于磷酸胍基作用在晶体特异性与生物化学功能中的重要意义,含有类似基团间作用的磷酸双乙酸胍(PBGA)晶体引起关注。本研究根据PBGA分子的基团组成建立四个相关分子模型(PBGA、PGA1、PGA2、BGA),采用量子化学从头算研究了不同基团组合模型的结构、前线分子轨道、偶极矩、极化率以及一阶超极化率。研究结果表明,基团间作用会吸引带电乙酸胍分子胍基端,使其构象与分子取向发生明显转变,也会使磷氧四面体发生对称性变形;磷酸与胍基间作用能够影响由胍基贡献的LUMO能级,降低PBGA分子轨道能级间隙,增大分子内电子跃迁概率;带电乙酸胍对偶极矩和一阶超极化率的贡献最大,而磷酸根为负贡献。PBGA分子的一阶超极化率为1.717 24×10^(-30)esu,约为尿素分子的2.3倍,是一种潜在的非线性光学材料,该研究对理解和研究晶体中磷酸胍基间的作用奠定了一定的理论基础。Based on the importance of the interaction between phosphate and guanidine in crystal specificity and biochemical functions,phosphate bis-guanidinoacetate(PBGA)crystal containing the similar groups has attracted much attention.In this paper,four related molecular models(PBGA,PGA1,PGA2,BGA)were established based on the group composition of PBGA molecular,their structural optimization,the frontier molecular orbital analysis,dipole moment,polarizability and first-order hyperpolarizability were investigated by ab initio.The results show that the phosphate group could attract the guanidine end of charged guanidine acetate,which has changed its conformation and molecular orientation,and has also caused the symmetry deformation of the phosphorus-oxygen tetrahedron.The interaction between phosphate and guanidine could affect the LUMO energy level contributed by guanidine group,but the effect of charged guanidine acetate is greater,which could reduce the energy gap of PBGA molecular orbital,and increase the probability of intramolecular electron transition.The charged guanidine acetate has the greatest positive contribution on the dipole moment and the first-order hyperpolarizability while the phosphate group has a negative contribution.All groups have the positively contributed to the average polarizability.The static first-order hyperpolarizability of PBGA molecule is 1.717 24×10-30 esu,which is about 2.3 times of urea,indicating that PBGA crystal is a potential nonlinear optical material.In conclusion,this research can established a good theoretical foundation for further understanding and studying the interaction between phosphate and guanidine groups in crystal.

关 键 词：非线性光学晶体 L-精氨酸磷酸盐 磷酸双乙酸胍 前线分子轨道 一阶超极化率 

分 类 号：O641[理学—物理化学] O742[理学—化学]