一种三苯胺酰腙荧光探针的合成及其对Al3+的选择性识别

将4-二苯基氨基苯甲酰肼和2,4-二羟基苯甲醛结合,合成了一种新的三苯胺酰腙类荧光探针(N18),并利用核磁共振氢谱(¹H NMR)、碳谱(¹³C NMR)和质谱(MS)技术对其结构进行了表征。在二甲基亚砜(DMSO)/H₂O溶液中对N18的光学性能进行了测定。紫外-可见(UV-vis)吸收光谱和荧光发射光谱结果表明,N18对Al³⁺识别表现出高选择性和高灵敏度,并且对其他金属离子有较强的抗干扰能力。利用Job曲线和¹H NMR测得N18与Al³⁺的结合比为1∶1,通过荧光滴定得到N18对Al³⁺的检出限为4.9×10^-8mol/L,结合常数(K_a)为5.95×10⁵ L/mol。探针N18可以检测实际水样中的Al³⁺,并且可以制备成试纸用于检测Al³⁺,具有一定的应用前景。     

一种吡啶-水杨醛类席夫碱的合成及对Zn2+的特异性识别

通过席夫碱反应将2-氨基4-甲基吡啶与4-(二乙氨基)水杨醛结合,设计并合成出一种新型的荧光探针L,该探针能特异性识别Zn²⁺。通过质谱、¹H NMR以及¹³C NMR表征其结构,并利用荧光光谱、紫外-可见吸收光谱研究了探针L在CH₃OH-H₂O(V:V=8:2,Tris-HCl缓冲液,pH=7.4)中对各种离子的选择识别能力。实验结果显示,向探针L中加入Zn2+之后,溶液从无荧光变成蓝色荧光,且457 nm处出现一发射峰。Job’s plot工作曲线结果和密度泛函理论(DFT)计算表明探针L与Zn2+结合计量比为1:1。荧光滴定结果表明探针L对Zn2+的检测极限可低至2.7×10^-8 mol·L^-1,结合常数为1.32×10⁴ L·mol^-1,pH应用范围4.0～10.0。对真实水样中的Zn2+进行检测,平均回收率大于98%,RSD小于1.61%,表明探针L能够检测真实水样中的Zn2+。     

Absolute stability of the solidification interface in a laser resolidified Zn--2wt.%Cu hypoperitectic alloy

This paper reports on laser surface remelting experiments performed on a Zn--2wt.%}Cu hypoperitectic alloy by employing a 5kW CW CO₂ laser at scanning velocities between 6 and 1207mm/s. The growth velocities of the microstructures in the laser molten pool were accurately measured. The planar interface structure caused by the high velocity absolute stability was achieved at a growth velocity of 210~mm/s. An implicit expression of the critical solidification velocity for the cellular--planar transition was carried out by nonlinear stability analyses of the planar interface. The results showed a better agreement with the measured critical velocity than that predicted by M--S theory. Cell-free structures were observed throughout the whole molten pool at a scanning velocity of 652~mm/s and the calculated minimum temperature gradient in this molten pool was very close to the critical temperature gradient for high gradient absolute stability (HGAS) of the \eta phase. This indicates that HGAS was successfully achieved in the present experiments.