【作者】 郁建灿；

【导师】 钱国栋； 崔元靖；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2013， 博士

【摘要】 有机非线性光学(Nonlinear optical, NLO)材料具有非线性光学活性高、响应快等优点,是未来光电集成信息技术的物质基础；作为一类新型无机-有机杂化材料,金属-有机框架材料(Metal-organic frameworks, MOFs)在气体存储和分离、催化、传感等领域具有广泛的应用前景。针对分子基非线性光学材料中高浓度生色团均匀、有序分散和组装的难题,本文提出以离子型金属-有机框架材料作为有机非线性光学离子的载体,采用离子交换和固溶等方式获得高NLO生色团含量的主-客体复合材料的设计和制备思路。探索和研究了这类复合材料表现出的双光子泵浦的激射、激光倍频和双光子诱导的图案化和成像等非线性光学效应,为离子型框架及其复合体系在微型激光器、激光倍频和高密度三维光存储器件等光信息领域的应用提供实验和理论依据。设计合成了两组共8个形状和尺寸不同、兼具非线性光学和发光性能的吡啶季铵盐类离子型生色团,以及3个中性非线性光学生色团。以中性生色团作为活性组分,采用溶胶-凝胶法制备了不同浓度的无机-有机杂化非线性光学薄膜。所得薄膜的非线性光学系数d33值均在32-53pm.V-1范围内,研究表明这些材料的宏观非线性光学性能对生色团微观非线性光学性能和含量不敏感,需要探索更合适的分子有序组装的体系。离子型非线性光学生色团的合成为其在离子型金属-有机框架材料中组装及其性能研究奠定了物质基础。通过离子交换的方法,实现了双光子荧光离子4-(4-二甲氨基苯乙烯)-1-甲基吡啶(DMASM)在阴离子型框架(Me2NH2)2[Zn8(Ad)4(BPDC)6O]·guests (bio-MOF-1, HAd=腺嘌呤,H2BPDC=对苯二甲酸)中的高浓度可控组装,获得了新型主-客组装体DMASM@bio-MOF-1。研究了这类发光材料中生色团组装方式和荧光增强效应。通过离子交换量的控制,实现了单光子发光颜色的调谐,优化了双光子发光性能。由晶体天然表面和高双光子荧光增益介质协同构成Fabry-Perot微谐振腔,在厚度为30-85μm的DMASM@bio-MOF-1单晶中实现了室温双光子泵浦的激射(泵浦激光波长1064nm)。这类微型激光器的研制为MOFs材料在新型固态光子材料和器件的应用上开辟了新的方向。设计合成了具有一维通道的阴离子型金属.有机框架材料(Me2NH2)3[In3(BTB)4]-guests (ZJU-28, ZJU=Zhejiang University, BTB=1,3,5-三(4-苯羧基)苯)。通过阳离子型有机非线性光学功能分子形状和尺寸的调节,控制其在晶体ZJU-28孔道中离子交换和组装的过程,并在中心对称结构的晶体中获得了高浓度生色团有序组装的极性结构,实现了二阶NLO性能。探明了生色团形状和长度对其在该框架组装行为和非线性光学性能的影响规律。最长分子链的有机非线性光学生色团4-(4-(二苯氨基)苯乙烯基)-1-十二烷基吡啶离子DPASD在ZJU-28中组装后形成DPASD@ZJU-28,其二次谐波信号达石英的29倍。分析了非线性光学生色团进入离子通道前后的角度分布,确认了分子几何结构和晶体孔道尺寸的匹配是DPASD@ZJU-28获得高非线性光学性能的原因。上述主-客体材料的组装思路为发展新型非线性光学材料提供了重要的理论范例,为优化MOFs光学性能提供了更大的自由度和可控性。将具有光敏活性的两性离子型配体2,5-二(3,5-二甲酸苯基)-1-甲基吡啶内盐(H4L2.OH)部分替代相似配体2,,5-二(3,5-二甲酸苯基)吡啶(H4L1),设计合成了基于混合配体的置换固溶型金属-有机框架晶体Zn2(L1)0.78(L2)0.22(OH)0.22·guests (ZJU-36-0.20,0.20指L2的名义含量为20%)。活性组分L2固溶含量高达22%,在晶体内部分布均匀。晶体ZJU-36-0.20在紫外光或710nm的飞秒激光作用下,活性组分L2发生快速的光化学反应,显示出发光颜色的改变。利用晶体的光敏特性,用710nm的飞秒激光对单晶内部进行空间选择性扫描,诱导出多层结构的高分辨双光子荧光微图案,其体积分辨率达1×1×5μm3(体存储密度在Tbits·cm-3量级)。提供了首个利用非线性光学效应在MOFs单晶内部进行光信息存储和读取的例子,拓展了用于高密度三维光信息存储的材料体系。更多还原

【Abstract】 Organic nonlinear optical (NLO) materials, which feature excellent activities and ultra-fast response, are essential substances for the integrated optoelectronic information technology in the future. As a new member of the novel inorganic-organic hybrid materials, metal-organic frameworks (MOFs) have broad applications in gas storage and separation, catalysis and sensing, etc. To solve the problems in the homogeneous and ordered distribution and assembling of nonlinear optical chromophores in molecular NLO materials at a high doping level, we propose that ionic metal-organic frameworks serve as hosts for NLO chromophores, with the aim to achieve host-guest systems via ion exchange and solid solution strategy. Particular attention has been paid to the exploration in the exceptional performance derived from the synergistic effects of functional guests and crystalline frameworks, which will fuel the application of ionic frameworks-guest systems in NLO materials.1. Eight cationic and three neutral nonlinear optical chromophores with varying structure and geometry were synthesized. Hybrid films with various neutral chromophores and concentration were prepared by a sol-gel procedure through the hydrolysis and condensation of alkoxysilane modified chromophores and tetraethylorthosilicate (TEOS). The resulting films exhibit moderate nonlinear optical activities, with nonlinear optical coefficients in the range of32-53pm-V"1, showing weak dependence on the active species and their concentration. It implies that an alternative assembly should be explored to improve the performance of nonlinear optical molecular materials, and we resort to the novel assembly of cationic NLO chromophores in metal-organic frameworks.2. A novel efficient fluorescent system DMASM@bio-MOF-1(DMASM=(E)-4-(4-(dimethylamino)styryl)-1-methylpyridinium) with tunable DMASM content (up to0.813mmol·cm-3) was developed by the assembly of two-photon fluorescent cations in an anionic framework (Me2NH2)2[Zng(Ad)4(BPDC)6O]·guests (bio-MOF-1, Ad=adeninate, BPDC=biphenyldicarboxylate). One-photon and two-photon excited fluorescence properties of DMASM@bio-MOF-1was studied and optimized by controlling the amount of exchanged dye cations. The combination of natural surfaces of the bio-MOF-1crystal and efficient two-photon excited fluorescent media affords a Fabry-Perot micro-cavity, and two-photon pumped lasing from single crystals (30-85μm in thickness) was explored at room temperature. This kind of micro-laser opens the door to new solid-state photonic materials and devices. 3. An anionic metal-organic framework (Me2NH2)3[In3(BTB)4]-guests (ZJU-28, ZJU=Zhejiang University, BTB=1,3,5-benzenetribenzoate) with ID channels was synthesized solvothermally. The oriented assembling of massive nonlinear optical cations in the noncentrosymmetric crystals of ZJU-28affords polar structure and nonlinear optical properties. The influences of the shapes and lengths of the nonlinear optical chomophores on the resulting oriented assembly and NLO activity were investigated. Among these assemblies, the crystals containing chromophore with the longest molecular chain,4-(4-(diphenylamino)styryl)-1-dodecylpyridinium (DPASD), exhibit the highest second harmonic generation (SHG) intensity, about29times that of a reference a-quartz, which is rationalized by the match of chromophore geometry and the channel size through analyzing the angular distribution of dipolar chromophores before and after the entrance of the anionic channels. This approach provides a flexible and efficient way to control the orientation of molecules, and the resulting MOF-dye ensemble is a proof-of-concept for the potential development of nonlinear optical materials.4. A substitutional solid solution like cationic frameworks ZJU-36-0.20was constructed by a Iigand2,5-bis(3,5-dicarboxyphenyl)-1-methylpyridine (H4L1), which was partially replaced by a photon-sensitive zwitterionic linker2,5-bis(3,5-dicarboxyphenyl)-1-methylpyridinium hydroxide (H4L2·OH) that shares a similar geometry, and the Zn center. With a high substitutional rate of22%, the active component L2exhibits homogeneous distribution within the crystal of mixed ligands. The resulting crystals ZJU-36-0.20shows fast and significant response to UV light irradiation and a710-nm femtosecond laser, generating photochemical products with yellow light emission. Two-photon fluorescent mircro-patterns are induced by spatial selectively scanning within an individual crystal of ZJU-36-0.20with a710-nm laser. High voxel resolution of1×1×5μm3is achieved in this kind of patterns, reaching optical data storage capacity around1.3Tbits in a DVD size, if this medium is used for3D data storage. We present a first MOF crystal within which optical data could be recorded and read out both by nonlinear absorption effects, and extend the storage media for3D optical data storage systems as well.更多还原