Adsorption of diisocyanides on gold
Adsorption of diisocyanides on gold
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DOI：
10.1021/la9906323
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发表时间：
2000-07-25
期刊：
影响因子：
3.9
通讯作者：
Kubiak, CP
中科院分区：
文献类型：
--
作者：
Henderson, JI;Feng, S;Kubiak, CP
用四种已知的二异氰酸酯1,6-二异氰酸酯(1)、1,12-二异氰酸酯(2)、1,4-苯基二异氰酸酯(3)、4,4'-联苯二异氰酸酯(4)和两种新的二异氰酸酯4,4'-对terphenyldiisoocyanide(5)和1,4-二（4-异氰苯乙酰基）-2-乙苯(6)在金表面制备了自组装单分子膜（SAMs）。利用椭偏仪、水滴进动接触角测量和反射吸收红外光谱（RAIR）对其进行了表征。由二异氰酸酯1和二异氰酸酯2制备的SAMs，在两个异氰酸酯端基之间有一个柔性的烷基链，被发现形成单层膜，其中两个异氰酸酯基结合在表面。由二异氰酸酯3-6制备的SAMs，在两个异氰酸酯端基之间具有刚性芳基或苯基乙基结构，通过一个CN基团与金结合。这些sam的RAIR光谱分析与吸附物的表面选择规则是一致的，它们的长分子轴与表面垂直。由3-6制备的SAMs的水滴接触角和椭偏膜厚度的测量进一步支持了二异氰酸酯分子垂直定向的表面结构，其中一个CN基团与表面结合，另一个远离表面。
Four known diisocyanides, 1,6-diisocyanohexane (1), 1,12-diisocyanododecane (2), 1,4-phenylenediisocyanide (3), 4,4'-biphenyldiisocyanide (4), and two new diisocyanides, 4,4"-p-terphenyldiisocyanide (5) and 1,4-di(4-isocyanophenylacetelynyl)-2-ethylbenzene (6), were used to prepare self-assembled monolayers (SAMs) on gold. The SAMs were characterized by ellipsometry, by measurement of the advancing water droplet contact angle, and by reflection absorption infrared (RAIR) spectroscopy. SAMs prepared from the diisocyanides 1 and 2, which have a flexible alkyl chain between the two isocyanide end groups, were found to form monolayer films in which both isocyanide groups are bound to the surface. SAMs prepared from the diisocyanides 3-6, which have rigid aryl or phenylethynyl structures between the two isocyanide end groups, were found to bind to gold through one CN group. Analyses of the RAIR spectra of these SAMs are consistent with surface selection rules for adsorbates that are oriented with their long molecular axis normal to the surface. Measurements of advancing water droplet contact angles and ellipsometric film thicknesses of SAMs prepared from 3-6 further support a surface structure in which the diisocyanide molecules are oriented vertically with one CN group bound to the surface and the other remote from the surface.