可逆SCSC转变中铜(Ⅱ)配合物的可视变色:结构对颜色的影响

Visible Color Change of Copper(Ⅱ)Complexes in Reversible SCSC Transformation:The Effect of Structure on Color

设计了一个以单晶-单晶(SCSC)转变这种新的固相无机合成方法为核心的8学时综合化学实验。首先采用直接加成法分别合成了粉末形态与大单晶形态的绿色配合物(H_(3)O)[K(15C5)_(2)][CuCl_(4)](1),其在温度诱导下转变为红色配合物[K(15C5)_(2)][CuCl_(3)](2),这是由于在固相中[K(15C5)_(2)]^(+)的空间位阻效应限制了[CuCl_(3)]−的二聚。并且配合物2在盐酸蒸气诱导下经过SCSC转变恢复为配合物1。配合物1和2之间的SCSC转变也可以通过文字或图画颜色可逆变化的形式在滤纸上呈现,反应迅速,实验现象直观明显,有助于激发学习兴趣。进而,学生可以根据学过的本科无机化学中涉及的晶体场理论内容判断出两种配合物颜色的差异是因为铜(Ⅱ)的配位数不同而导致,有效地促进其将理论知识应用于实践中。通过单晶X射线衍射、粉末X射线衍射、紫外-可见光谱和傅里叶红外变换光谱等对产品进行表征,结果表明,配合物1和2晶型不同而且单晶转化完全,该过程锻炼了学生对剑桥晶体结构数据库的使用,有助于提升学生的数据分析能力和规范安全操作大型仪器的科学素养。本实验学时安排紧凑,可进行模块化教学,试剂成本低廉,适合在化学及相关专业的本科实验教学中推广。

A comprehensive 8-hour chemical experiment was devised around the single crystal-to-single crystal(SCSC)transformation,an emerging method in solid-phase inorganic synthesis.By employing a direct additive process technology,the green complexes(H_(3)O)[K(15C5)_(2)][CuCl_(4)](1)were synthesized in both powder and macrosingle crystal forms.Upon temperature induction,complex 1 transitions to the red complex[K(15C5)_(2)][CuCl_(3)](2),a shift attributed to the restricted dimerization of[CuCl_(3)]−resulting from steric repulsion effects in the solid phase.Notably,complex 2 can revert back to complex 1 when exposed to hydrochloric steam through an SCSC transformation.This SCSC transformation between complexes 1 and 2 is vividly demonstrated on filter paper,showcasing dynamic color changes,either as texts or drawings.This rapid and visually engaging process is poised to spark students’curiosity.Furthermore,learners can bridge theory with practice,recognizing that the distinct colors of the two complexes arise from varying coordination numbers of copper(Ⅱ),grounded in the crystal field theory of inorganic chemistry.Characterization of the complexes was achieved using single crystal X-ray diffraction,powder Xray diffraction,UV-visible spectroscopy,and Fourier transform infrared spectroscopy,confirming the differentiation of the complexes and the successful SCSC transformation.This aspect of the experiment allows students to hone their skills with the Cambridge crystal structure database and enhance their data analysis capabilities,fostering proficiency in operating large-scale instruments safely and accurately.With its streamlined design,modular teaching approach,and cost-effective reagents,this experiment is primed for integration into undergraduate curriculum for chemistry and related disciplines.