Fluorescent Logic Gates Chemically Attached to Silicon Nanowires

摘要

In recent years, the use of organic molecules, which are promising candidates for the realization of digital processing, has made remarkable progress in molecular logic gates because of the wide variety of molecular designs, syntheses, and light-emitting properties that are available.Different logic gates based on organic molecules have been constructed, which encompass AND, OR, INH, XOR, XNOR, and NOR gates, and the half-adder and half-subtractor. However, molecular logic gates are still far from operational at the single-molecular level. In order to achieve practical applications, the functional molecules have to be assembled on carriers of sufficiently small dimensions. One approach is to use polymer beads as a carrier and different fluorophores attached to the polymer surfaces to form various logic gates. At the same time, the chemical stability of the materials for logic gates must be improved and the suitability of the logic elements for large-scale integration must also be realized. Silicon nanowires (SiNWs) are an important semiconducting material with high chemical stability and can be prepared in large-area arrays in a controlled fashion. In addition, the ease of modification and compatibility of SiNWs with the prevalent integrated technology of silicon make SiNWs promising for construction of future nanosized chemical logic gate systems. Dansylamide (DA, 3) is a typical intramolecular charge-transfer compound, and has interesting fluorescence properties that can be used in various applications.Herein, we report the covalent immobilization of 3 on SiNWs to form 1 (DA-SiNWs) by the synthesis of derivative 3-(dansylamino)propyltriethoxysilane (2), and that the fluorescence of 1 exhibited selective responses to pH and Hg~(II) as well as Cl or Br ions, which permits a three-input chemical logic gate to be built on SiNWs.