Durable modification of silica aerogel monoliths with fluorescent 2,7-diazapyrenium moieties. Sensing oxygen near the speed of open-air diffusion
Durable modification of silica aerogel monoliths with fluorescent 2,7-diazapyrenium moieties. Sensing oxygen near the speed of open-air diffusion
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DOI：
10.1021/cm9901966
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发表时间：
1999-10-01
影响因子：
8.6
通讯作者：
Merzbacher, CI
中科院分区：
文献类型：
--
作者：
Leventis, N;Elder, IA;Merzbacher, CI
用N-（3-三甲氧基硅丙基）-2，7-二氮杂芘溴化铵（DAP）共价修饰二氧化硅溶胶-凝胶。产生发光气凝胶，其中在制备DAP改性的气凝胶所必需的洗涤或超临界干燥期间没有荧光团从凝胶中浸出。（0.17 g/cm（3））、N-2-吸附表面积（870 m2/g）、以及染料改性的气凝胶的热重和扫描电子显微特征保持与未改性的二氧化硅气凝胶相同，气凝胶中染料的本体浓度为16.6 mM;在这些负载下，气凝胶表现出本体光致发光。基于介孔表面积，染料的表面覆盖率为单层的7-8%。在气凝胶中的二氮杂芘染料的吸收、发射和O-2-猝灭特性与在醇（而不是水）溶液中获得的那些特性平行，这进一步表明掺杂剂分子彼此分离并且它们看到具有类似于OH极性的环境。时间分辨发射研究表明所有DAP部分驻留在单一类型的微环境中。发射淬灭类似于1厘米直径的单块DAP-二氧化硅气凝胶是完全的，
Silica sol-gels were covalently modified with N-(3-trimethoxysilylpropyl)-2,7-diazapyrenium bromide (DAP). Luminescent aerogels are created in which none of the fluorophore leaches from the gels during either the washing or supercritical drying necessary to prepare DAP-modified aerogels, The bulk density (0.17 g/cm(3)), N-2-adsorption surface area (870 m(2)/g), and thermogravimetric and scanning electron micrographic characteristics of the dye-modified aerogels remain identical to those of the unmodified silica aerogels, The bulk concentration of the dye in the aerogels was 16.6 mM; at these loadings the aerogels demonstrate bulk photoluminescence. As based on the mesoporous surface area, the surface coverage of the dye is 7-8% of a monolayer. The absorption, emission, and O-2-quenching characteristics of the diazapyrenium dye in the aerogels parallel those obtained in alcoholic (rather than aqueous) solution, which further indicates that the dopant molecules are Isolated from each other and that they see an environment with a similar to OH polarity, Time-resolved emission studies indicate that all DAP moieties reside in a single type of microenvironment. Emission quenching of similar to 1-cm-diameter monoliths of DAP-silica aerogel is complete in