摘要
雄黄As4S4和雌黄As2S3是低毒的中国画传统矿物质颜料的黄色颜料,而砒霜As2O3是剧毒物,砷化物的毒性与其水溶性有关.为研究雄黄和雌黄的稳定性和水溶性,应用B3LYP/6-31G(d)方法计算了As4S4、As2S3、As2O3、As2O5、As4S3和As4S5的分子结构.研究表明:由于S的价轨道能比O的高,更接近As的价原子轨道能,故As—S键强度远高于As—O键,极性远小于As—O键.砷的硫化物还具有较强的As—As非极性σ键,故砷的硫化物均具有较高的稳定性.与砷的氧化物中原子的高电荷密度相反,砷的硫化物中As、S的正、负电荷密度很小,与水的相互作用很弱.因此,砷的硫化物水溶性很小,尤其是D2d点群的雄黄As4S4和D3h点群的雌黄As2S3是非极性分子,难溶于水,故毒性低,作为颜料画成的壁画或宣传画不怕受潮,不容易受雨水侵蚀变色.
The realgar As4S4 and orpiment As2S3, used as yellow pigment in traditional Chinese painting, are low toxic minerals. However, it is well known that the arsenic As203 is a virulent poison. The toxic effect of arsenide is relative to its water-solubility. In order to study the stabilities and water-solubility of realgar and orpiment, the arse- ntde As4S4, As2S3, As203, As2Os, As4S3, and As4S5 were calculated by density functional theory B3LYP/6-31G （d） method. The results reveal that the energies of valent orbitals in S atom are higher than those in O atom and closer to those in As atom. Therefore, the As-S bonds are much stronger than the As-O bonds, and the polarity of As-S bonds is much weaker than the As-O bonds. Besides the strong As-S bonds, there is strong As-As cr bond in arsenic sulfides. This is the reason of high stabilities of arsenic sulfides. Contrary to the notable positive charge of As and negative charge of O in As203 and AszOs, the little positive charge on As and negative charge on S lead to the very weak interactions between arsenic sulfides and water. Therefore, all the arsenic sulfides possess poor water solubility. Especially for the As4S4 and As2S3 possessing D2d and D3h symmetry respectively, they are all nonpolar molecules and more poorly soluble in water. This results in the low toxicity of As4S4 and As2S3. As a resuit, the murals or picture posters painted with realgar and orpiment can not be spoiled by dampness and rain.
出处
《华南师范大学学报（自然科学版）》
CAS
北大核心
2014年第4期65-69,共5页
Journal of South China Normal University(Natural Science Edition)
基金
广东省自然科学基金项目(S2012010008763)
国家级大学生创新创业计划资助项目(1057413124)
关键词
雄黄
雌黄
密度泛函理论
稳定性
水溶性
realgar
orpiment
density functional theory
stabilities
water-solubility
作者简介
谢少威，教授，Email：xsw7@163．com．
通讯作者：许旋，教授，Email：xuxuan@scnu．edu．cn；
