Basheer Sabeel M, Kumar Saravana Loganathan Ashok, Kumar Moorthy Saravana, Sreekanth Anandaram
Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, India.
Department of Chemistry, GRT Institute of Engineering Technology, Tiruttani, India.
Mater Sci Eng C Mater Biol Appl. 2017 Mar 1;72:667-675. doi: 10.1016/j.msec.2016.11.131. Epub 2016 Dec 5.
1,5-Bis(2-fluorene)thiocarbohydrazone (FBTC) was designed and synthesized for selective sensing of fluoride and copper ions. The binding constants of FBTC towards fluoride and copper ions have been calculated using the Benesi-Hildebrand equation, and FBTC has more binding affinity towards copper ion than fluoride ion. The H NMR and C NMR titration studies strongly support the deprotonation was taken from the N-H protons followed by the formation of hydrogen bond via N-HF. To understand the fluoride ion sensing mechanism, theoretical investigation had been carried out using the density functional theory and time-dependent density functional theory. The theoretical data well reproduced the experimental results. The deprotonation process has a moderate transition barrier (481.55kcal/mol). The calculated ΔE and ΔG values (-253.92 and -192.41kcal/mol respectively) suggest the feasibility of sensing process. The potential energy curves give the optimized structures of FBTC-F complex in the ground state and excited state, which states the proton transition occurs at the excited state. The excited state proton transition mechanism was further confirmed with natural bond orbital analysis. The reversibility of the sensor was monitored by the alternate addition of F and Cu ions, which was explained with "Read-Erase-Write-Read" behaviour. The multi-ion detection of sensor used to construct the molecular logic gate, such as AND, OR, NOR and INHIBITION logic gates.
1,5-双（2-芴基）硫代碳腙（FBTC）被设计并合成用于选择性传感氟离子和铜离子。已使用贝内西-希尔德布兰德方程计算了FBTC对氟离子和铜离子的结合常数，并且FBTC对铜离子的结合亲和力比对氟离子的更强。1H NMR和13C NMR滴定研究有力地支持了去质子化是从N-H质子处发生，随后通过N-H···F形成氢键。为了理解氟离子传感机制，已使用密度泛函理论和含时密度泛函理论进行了理论研究。理论数据很好地再现了实验结果。去质子化过程具有适度的过渡能垒（481.55 kcal/mol）。计算得到的ΔE和ΔG值（分别为-253.92和-192.41 kcal/mol）表明传感过程的可行性。势能曲线给出了基态和激发态下FBTC-F配合物的优化结构，这表明质子跃迁发生在激发态。通过自然键轨道分析进一步证实了激发态质子跃迁机制。通过交替添加F和Cu离子监测了传感器的可逆性，并用“读-擦除-写-读”行为进行了解释。该传感器的多离子检测用于构建分子逻辑门，如与门、或门、或非门和抑制逻辑门。
