A symmetrical organometallic Pt(II) based molecular turnstile 1, composed of a rotor bearing two benzonitrile units as coordinating sites and a stator equipped with a dianionic tridentate coordinating pole, undergoes a reversible switching process between two open and one closed states. In the absence of an effector, the turnstile is in its open state defined by the free rotation of the rotor around the stator. In the presence of Pd(II), the latter is simultaneously complexed by both the rotor and the stator (1-Pd) leading to the first closed state owing to locking of the rotational movement. The turnstile can be unlocked to its second open state 1-Pd-DMAP by addition of para-dimethylaminopyridine (DMAP) behaving as an external competitive ligand replacing the bound benzonitrile in the coordination sphere of the Pd centre. Upon addition of PdCl2(CH3CN)2, a competitive metal complex to remove DMAP, the turnstile is switched back to its closed state. The same process can also be achieved upon addition of MsOH causing the protonation of DMAP into DMAP-H+ and its decomplexation and replacement by one of the two benzonitrile groups of the rotor. Finally, the deprotonation of DMAP-H+ by addition of Et3N as a base regenerates the second open state of the turnstile.
一个基于
铂(II)的对称有机
金属分子转门1由一个带有两个
苯甲腈配位位的转子和一个带有二阴离子三叉形配位极的定子组成,在两个开放和一个闭合状态之间进行可逆切换。在没有效应物的情况下,转门处于开放状态,转子围绕定子自由旋转。在存在Pd(II)的情况下,转子与定子同时与Pd(II)络合(1-Pd),由于旋转运动被锁定,导致转门进入第一个闭合状态。通过添加对二甲
氨基吡啶(
DMAP)作为外部竞争性
配体,取代Pd中心配位域中结合的
苯甲腈,转门可以解锁到第二个开放状态1-Pd-
DMAP。在添加PdCl2(CH3CN)2(一种竞争性
金属络合物,用于去除
DMAP)后,转门会切换回其闭合状态。添加MsOH(一种质子化剂)后,
DMAP也会发生同样的过程,转化为
DMAP-H+,并解络合,由转子的两个
苯甲腈基团之一取代。最后,通过添加乙基
三氮烯作为碱,
DMAP-H+脱质子化,转门会恢复到第二个开放状态。