Kannan Palanisamy, Abraham John Swamidoss
Department of Chemistry, Gandhigram Rural University, Dindigul, Gandhigram 624 302, India.
Nanotechnology. 2008 Feb 27;19(8):085602. doi: 10.1088/0957-4484/19/8/085602. Epub 2008 Feb 1.
Gold nanoparticles (AuNPs) stabilized with mercaptothiadiazole ligands, 2,5-dimercapto-1,3,4-thiadiazole (DMT), 5-amino-2-mercapto-1,3,4-thiadiazole (AMT) and 5-methyl-2-mercapto-1,3,4-thiadiazole (MMT), were prepared by the reaction of the respective ligands with HAuCl(4) and NaBH(4) in an aqueous medium. TEM images show that the average size of AuNPs was 6.5 ± 0.5 nm, irrespective of the capping ligands. The colloidal solution of both DMT-capped AuNPs (DMT-AuNPs) and AMT-capped AuNPs (AMT-AuNPs) were highly stable for several months. However, several changes were noticed for MMT-capped AuNPs (MMT-AuNPs) after 2 h from its formation. The SPR band intensity at 518 nm decreases and the narrow SPR absorption band slowly changes into a flat absorption pattern with a broad peak from 518 to 1000 nm which was accompanied by a colour change of the solution from red to purple and then blue and thereafter unchanged. The TEM image of MMT-AuNPs after 96 h shows that most of the spherical shape of the AuNPs assembled to form a nanowire-like structure. The observed changes may be due to the absence of a strong stabilizing force on the surface of the MMT-AuNPs. The amino and thiolate groups on the surface of the AMT-AuNPs and DMT-AuNPs, respectively, were directly self-assembled on Au electrodes. They exhibit excellent electrocatalytic activity towards the oxidation of AA by enhancing its oxidation current twice in addition to more than 200 mV negative shift in the oxidation potential in contrast to bare Au electrode.
通过相应的配体与氯金酸（HAuCl₄）和硼氢化钠（NaBH₄）在水介质中反应，制备了用巯基噻二唑配体2,5 - 二巯基 - 1,3,4 - 噻二唑（DMT）、5 - 氨基 - 2 - 巯基 - 1,3,4 - 噻二唑（AMT）和5 - 甲基 - 2 - 巯基 - 1,3,4 - 噻二唑（MMT）稳定的金纳米颗粒（AuNPs）。透射电子显微镜（TEM）图像显示，无论封端配体如何，AuNPs的平均尺寸为6.5±0.5纳米。DMT封端的AuNPs（DMT - AuNPs）和AMT封端的AuNPs（AMT - AuNPs）的胶体溶液在几个月内都高度稳定。然而，MMT封端的AuNPs（MMT - AuNPs）在形成后2小时就出现了一些变化。518纳米处的表面等离子体共振（SPR）带强度降低，窄的SPR吸收带缓慢变为从518到1000纳米的宽峰的平坦吸收模式，同时溶液颜色从红色变为紫色，然后变为蓝色，此后不变。96小时后MMT - AuNPs的TEM图像显示，大多数球形的AuNPs组装形成了纳米线状结构。观察到的变化可能是由于MMT - AuNPs表面缺乏强大的稳定力。AMT - AuNPs和DMT - AuNPs表面的氨基和硫醇盐基团分别直接自组装在金电极上。与裸金电极相比，它们对AA的氧化表现出优异的电催化活性，除了氧化电位负移超过200毫伏外，还将其氧化电流提高了两倍。
