Costa Ana L, Gomes Ana C, Pillinger Martyn, Gonçalves Isabel S, Seixas de Melo J Sérgio
†Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
‡Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Langmuir. 2015 Apr 28;31(16):4769-78. doi: 10.1021/acs.langmuir.5b00063. Epub 2015 Apr 15.
Zn-Al layered double hydroxides (LDHs) containing solely 1-pyrenesulfonate (PS) or 1-heptanesulfonate (HS) anions, or a mixture of the two with HS/PS molar ratios ranging between ca. 7.5 and 82, were prepared by the direct synthesis method and characterized by powder X-ray diffraction, thermal and elemental analyses, scanning electron microscopy, and FT-IR, FT-Raman, and (13)C{(1)H} CP MAS NMR spectroscopies. Well-ordered intercalates were obtained with basal spacings of 18.8 Å for the LDH intercalated by PS and 19.2-19.4 Å for the other materials containing HS. The photophysics of the solids, as well as the PS probe dissolved in water and common organic solvents (aiming to compare the behavior of the "isolated" molecule with that in the solid), were investigated by steady-state and time-resolved fluorescence techniques. The fluorescence spectra of the solid samples display two bands with maxima at 376 and 495 nm. Depending on the HS/PS ratios, the band intensity ratio (obtained at 375 and 520 nm) changes, reflecting different contributions from monomer and dimer species. The decays collected at 375 nm are biexponentials with a major component (∼97% of the total fluorescence) of 105 ns for the highest HS/PS ratio, which further loses importance with an increase in the PS content. When the decays are collected at 480 and 520 nm, the fits are triexponentials with a major component varying from 108 to 124 ns, attributed to an excimer. Steady-state and time-resolved measurements with PS in solution (ethanol, methanol, DMF, DMSO, and water) were also measured, and a comparison of the vibronic I1/I3 ratio and lifetimes in water (65 ns) with those in the LDHs indicates that the PS probe in the cointercalated LDHs is surrounded by the HS surfactant.
通过直接合成法制备了仅含有1-芘磺酸盐（PS）或1-庚烷磺酸盐（HS）阴离子，或两者混合物（HS/PS摩尔比在约7.5至82之间）的锌铝层状双氢氧化物（LDH），并通过粉末X射线衍射、热分析和元素分析、扫描电子显微镜以及傅里叶变换红外光谱（FT-IR）、傅里叶变换拉曼光谱（FT-Raman）和（13）C{(1)H}交叉极化魔角旋转核磁共振光谱（CP MAS NMR）对其进行了表征。对于PS插层的LDH，获得了层间距为18.8 Å的有序插层物，对于其他含HS的材料，层间距为19.2 - 19.4 Å。通过稳态和时间分辨荧光技术研究了固体的光物理性质，以及溶解在水和常见有机溶剂中的PS探针（旨在比较“孤立”分子与固体中分子的行为）。固体样品的荧光光谱显示出两个峰，最大值分别在376和495 nm处。根据HS/PS比例，在375和520 nm处获得的峰强度比会发生变化，反映了单体和二聚体物种的不同贡献。在375 nm处收集的衰减是双指数衰减，对于最高HS/PS比例，主要成分（约占总荧光的97%）为105 ns，随着PS含量的增加，该成分的重要性进一步降低。当在480和520 nm处收集衰减时，拟合为三指数衰减，主要成分在108至124 ns之间变化，归因于准分子。还对PS在溶液（乙醇、甲醇、二甲基甲酰胺、二甲基亚砜和水）中的稳态和时间分辨测量进行了研究，将水中的振动I1/I3比例和寿命（65 ns）与LDH中的进行比较，结果表明共插层LDH中的PS探针被HS表面活性剂包围。
