Influences on the Dynamics and Stability of Self-Assembly: Solvent, Substrate, and Concentration
Influences on the Dynamics and Stability of Self-Assembly: Solvent, Substrate, and Concentration
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对自组装动力学和稳定性的影响：溶剂、底物和浓度
DOI：
10.1021/acs.jpcc.2c06013
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Hipps, K. W.
中科院分区：
文献类型：
--
作者：
Gurdumov, Kirill;Mazur, Ursula;Hipps, K. W.
利用扫描隧道显微镜（STM）在室温下动态溶液流动池中对CoOEP在溶液/Au（111）界面的形成动力学和稳定性进行了原位观测。捕获CoOEP自组装成有序单层的中间步骤，并测量作为时间函数的分数覆盖率以提取自组装过程的特征参数。吸附层的结构和形成在各种溶剂进行比较，以前的研究HOPG。发现基底的选择对吸附层的结构和稳定性有显著的影响。结果发现，HOPG上的CoOEP吸附层组装是一个平衡过程，并且单层可以在与溶液接触的几分钟内容易地形成（高于溶剂依赖性阈值溶液浓度）;所形成的吸附层的溶解是可行的，尽管溶解速率是溶剂依赖性的。吸附层在Au（111）上的组装是动力学驱动的，单层形成在几分钟内发生，并且溶解非常缓慢-在纯溶剂流动数小时后仅实现最小的岛溶解。在HOPG和Au上均观察到1，2，4-三氯苯（TCB）的溶剂掺入形成CoOEP伪矩形吸附层结构（REC）（111），尽管在HOPG上的CoOEP浓度比在Au上高得多时出现无溶剂伪六方结构（HEX）（111）。这可能是由于CoOEP与Au（111）的结合比HOPG更强，这在较低浓度下促进了Au（111）上的REC至HEX转变。观察到甲苯（Tol）溶剂掺入到Au（111）上的CoOEP吸附层中，但其不掺入到HOPG上的吸附层中。有一个显着增加的Arrhenius解吸速率因子（350）的甲苯上HOPG相对于Au，这可能是一个驱动因素的Tol共吸附Au。还观察到一种非常短寿命的癸烷结合的吸附层。在1 μM CoOEP的Tol溶液中，Au（111）从REC结构到HEX结构的转变需要约10 min，而在470 μM CoOEP的TCB溶液中，从REC结构到HEX结构的转变需要约102 min。这种差异主要是由于溶剂分子在Au（111）表面上的相对停留时间，其中Tol的估计解吸速率是TCB的500倍。CoOEP吸附层的晶胞也是基底依赖性的。在Au（111）上的相称的TCB并入的REC结构包含两个CoOEP，但在HOPG上仅包含一个CoOEP。因此，CoOEP在Au（111）上的吸附层形成受溶剂的影响比在HOPG上的吸附更显著。
The formation dynamics and stability of CoOEP at the solution/Au(111) interface are captured in situ using scanning tunneling microscopy (STM) in a dynamic solution flow cell at room temperature. The intermediate steps of self-assembly of CoOEP into an ordered monolayer were captured, and fractional coverage as a function of time was measured to extract characteristic parameters of the self-assembly process. Adlayer structure and formation under various solvents are compared to previous studies conducted on HOPG. The choice of substrate is found to have a dramatic influence on adlayer structure and stability. It was found that the CoOEP adlayer assembly on HOPG is an equilibrium process, and the monolayer can be readily formed within minutes of contact with solution (above a solvent-dependent threshold solution concentration); the dissolution of the formed adlayer is feasible, though the rate of dissolution is solvent-dependent. The assembly of an adlayer on Au(111) is kinetically driven, monolayer formation occurs within minutes, and dissolution is very slow─only minimal island dissolution was achieved after hours of pure solvent flow. Solvent incorporation of 1,2,4-trichlorobenzene (TCB) was observed to form a CoOEP pseudorectangular adlayer structure (REC) on both HOPG and Au(111), though a solvent-free pseudohexagonal structure (HEX) occurred at much higher concentrations of CoOEP on HOPG than on Au(111). This is likely due to the fact that CoOEP binds more strongly to Au(111) than HOPG, which promotes the REC to HEX transition on Au(111) at lower concentrations. Solvent incorporation of toluene (Tol) into a CoOEP adlayer on Au(111) was observed, but it did not incorporate into the adlayer on HOPG. There is a significant increase in the Arrhenius desorption rate factor (∼350) of toluene on HOPG relative to Au that is likely a driving factor for Tol coadsorption on Au. A very short-lived decane incorporated adlayer was also observed. The transformation on Au(111) from REC to HEX structure under 1 μM CoOEP in Tol occurred within ∼10 min, while under a solution of 470 μM CoOEP in TCB the transformation required ∼102min. This variance is primarily due to the relative residence times of the solvent molecule on the Au(111) surface, where Tol has an estimated desorption rate 500 times greater than TCB. The unit cells of the CoOEP adlayer are also substrate-dependent. The commensurate TCB-incorporated REC structure on Au(111) contains two CoOEP but only one CoOEP on HOPG. Thus, the adlayer formation of CoOEP on Au(111) was more significantly affected by solvent than for adsorption on HOPG.
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DOI：
10.1021/acs.jpcc.5b07120
发表时间：
2015
期刊：
The Journal of Physical Chemistry C
影响因子：
--
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