Alkyl chain length effects on solid-state difluoroboron β-diketonate mechanochromic luminescence
作者:Nguyen D. Nguyen、Guoqing Zhang、Jiwei Lu、Arianna E. Sherman、Cassandra L. Fraser
DOI:10.1039/c1jm00067e
日期:——
Solid-state difluoroboron β-diketonate dyes display reversible mechanochromic luminescence (ML). To test the effects of alkyl chain length on solid state photoluminescence and ML, a series of dyes, BF2dbmOR, with dibenzoylmethane (dbm) ligands and alkoxyl substituents (âOR) were prepared, where R = CnH2n+1 and n = 1, 2, 3, 5, 6, 12, 14, 16, 18. Emission properties were investigated in solution and in the solid state. Fluorescence spectra and lifetimes were nearly identical for dyes in CH2Cl2 solution; whereas, in the solid state, as powders, thin films or spin cast films, emission maxima, and lifetimes were different among the samples. Solid-state ML emission spectra were monitored at room temperature as a function of time for smeared powders on quartz surfaces. The recovery time generally increased with alkyl chain length, ranging from minutes (n = 3) to days (n = 18). Longer chain analogues (n = 6, 12, 14, 16, 18) did not fully return to the original annealed emissive state even after months on quartz, though the dynamics are substrate dependent. Solid-state dyes were also investigated by XRD and DSC (powders), and by AFM (spin cast films).
固态二氟硼δ-²-二酮染料显示出可逆的机械变色发光(ML)。为了测试烷基链长度对固态光致发光和 ML 的影响,制备了一系列具有二苯甲酰甲烷(dbm)配体和烷氧基取代基(âOR)的染料 BF2dbmOR,其中 R = CnH2n+1 和 n = 1、2、3、5、6、12、14、16、18。对溶液和固态下的发射特性进行了研究。在 CH2Cl2 溶液中,染料的荧光光谱和寿命几乎相同;而在固态下,作为粉末、薄膜或旋铸膜,不同样品的发射最大值和寿命也不同。在室温下监测了石英表面涂抹粉末的固态 ML 发射光谱与时间的函数关系。恢复时间一般随烷基链长度的增加而增加,从几分钟(n = 3)到几天(n = 18)不等。长链类似物(n = 6、12、14、16、18)在石英上即使经过数月也不能完全恢复到原来的退火发射状态,尽管其动态与基质有关。固态染料还通过 XRD 和 DSC(粉末)以及 AFM(旋塑薄膜)进行了研究。