Solid State Optical Properties of 4-Alkoxy-pyridine Butadiene Derivatives: Reversible Thermal Switching of Luminescence

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• 作者：N. S. Saleesh Kumar ; Shinto Varghese ; Nigam P. Rath ; Suresh Das
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：June 5, 2008
• 年：2008
• 卷：112
• 期：22
• 页码：8429 - 8437
• 全文大小：2269K
• 年卷期：v.112,no.22(June 5, 2008)
• ISSN：1932-7455

文摘

The synthesis and optical properties of a series of alkoxyphenyl-pyridyl butadiene derivatives in solution and in the solid state are described. All the derivatives were practically nonfluorescent in solution but showed good fluorescence in the solid-state. The role of molecular packing in controlling the solid-state fluorescence was investigated by studying the X-ray crystal structure of these molecules. One of the derivatives, 4-((1E,3E)-4-(4-butoxyphenyl)buta-1,3-dienyl)pyridine exhibited polymorphism, with the different polymorphs exhibiting visually distinguishable fluorescence. In the natural state it existed as a polymorph exhibiting blue fluorescence, while it’s cooled melt emitted yellow light. The difference could be attributed to a transformation in the molecular packing of the material from a herringbone to a brickstone arrangement, resulting in a change from monomer to J-type aggregate fluorescence. The polymorph exhibiting yellow fluorescence was fairly stable (>6 months) but could be converted back to the original form by keeping the film at 110 °C for a short period of time (~8–10 min) before slowly cooling to room temperature. The thermally induced changes in fluorescence behavior were clearly reproducible over several cycles, indicating the utility of this material for thermal imaging applications.