具有一定普适性的表面活性剂辅助的卟啉一维超分子纳米结构的可控组装及性能调控

In the frontier field of supramolecular chemistry, one-dimensional (1D) supramolecular nanoassemblies based on porphyrins, which are usually called "the pigments of life", have received considerable attention from numerous areas of paramount importance, including but not confined to, energy conversion, optoelectronic device, optical waveguide, sensor, etc. So far, various sophisticated protocols, such as physical vapor/molecular beam deposition, ionic/zwitterionic self-assembly, interfacial organization, organic gelation, mixed-solvent-, sonication-, coordination-, template-assisted assembly, amphiphilic assembly, host-guest assembly, surfactant-assisted self-assembly (SASA) etc., have been developed for the production of 1D porphyrin nanostructures. Nevertheless, a common insurmountable limitation of these methods is their lack of generality such that they could only workable on some specific porphyrins, or elaborately-designed yet tediously-synthesized ad hoc porphyrins. It sometimes is necessary that the assembly has to be conducted with an accurate control of the experimental conditions or the requirement of expensive instruments. Among these methods, SASA has drawn particular interests because of its intrinsic advantages such as outstanding reproducibility, excellent controllability, and operational simplicity under ambient conditions. However, a formidable challenge this protocol encounters is that most of the currently existing 1D porphyrin nanostructures constructed via SASA are limited to pyridyl porphyrins. Considering the above-mentioned broad interest of porphyrin 1D nanoassemblies, and together with the above-addressed merits of SASA, the inauguration of a new SASA strategy widely applicable to general porphyrins is strongly desired. ..To meet these formidable challenges, we herein propose an original yet general SASA protocol for the assembly of 1D porphyrin nanoassemblies, wherein not only pyridyl porphyrins but also free-base porphyrins and metalloporphyrins of various substituents could be facilely assembled to form 1D nanostructures of controlled morphology (the shape of the cross section, aspect ratio, solid and hollow architectures) under ambient conditions. Different from the traditional SASA, wherein only simple single-head single-chain or polymer surfactants are employed and the assembly is commonly conducted without the use of additives, in our new strategy, the assembly will be conducted with surfactants of various structures, such as single-head single-chain, single-head multiple-chain, zwitterionic, bola-type surfactants of different hydrophobic tails or spacers. The effect of surfactant structure, additives, pH value and ionic strength of the system, and the ratio/type/concentration of the host and guest solutions will be disclosed. This could help us launch a general protocol for the production of 1D porphyrin nanostructures. Importantly, the advanced functions of the as-assembled 1D nanoarchitectures in terms of photocatalysts, molecular electronics (organic field-effect transistors, single 1D nanostructures-based nanoelectronics of sensing and photoswitching capabilities) will be investigated. The underlying correlation of surfactant structure—assembly parameter—template effect of surfactant—molecular structure of porphyrin—the morphology of the as-produced 1D nanostructures—the function/property of the 1D nanostructures will be revealed. Based on the possible achievements of the proposed investigations, the cooperative principle of pi-pi stacking and other noncovalent interactions, and the electron/energy transfer principle within the 1D nanoassemblies, which are the basic scientific issues of the interdisciplinary communities of supramolecular and soft matter sciences, will be disclosed. Our proposal is an important subject of sufficient novelty and creativity worth of investigation and support.

本申请拟以表面活性剂辅助的自组装技术(SASA)为平台，以卟啉类分子为组装基元，通过使用具有不同结构特征的表面活性剂或多元表面活性剂、调控主客体溶液的浓度/比例/种类、在组装体系中引入添加剂、调控组装介质的离子强度/酸碱度等构思，发展具有一定普适性的构筑卟啉类分子1D纳米结构的新手段，并研究其在催化、分子电子器件等方面的先进性能。该构思将克服以往SASA和其他组装手段通常仅适用于特定卟啉分子、缺乏普适性的难点和挑战，有助于揭示表面活性剂结构—各种组装参数—表面活性剂的模板效应—卟啉分子结构—所构筑1D纳米结构的形貌—所构筑1D纳米结构的性能等的内在科学关联，为发展基于卟啉类分子1D结构的新型软物质功能材料提供技术支持与科学依据、为诠释pi-pi堆积作用与其他非共价键作用的协同性规律、电子/能量的转移/转换规律等核心科学问题提供信息，具有重要的科学与实践意义，是一个颇具特色和创新性的构思。

按照任务计划书所拟定研究内容和目标，本课题主要旨在发展一种基于表面活性剂调控组装技术的具有一定普适性的构筑卟啉基1D超分子纳米结构的方法。课题执行期间，我们通过采用在经典表面活性剂调控的组装体系中引入添加剂的策略，在常温常压下将分子骨架中带有不同外围取代基、带有Co, Ni, Fe, V, Zn, Sn等不同中心金属离子、带有一个或两个轴向配体的23种非金属或金属卟啉分子组装，成功得到了具有1D形貌特征的超分子纳米结构，并基于此诠释了组装参数、构筑基元间各种非共价键相互作用的协同性等在组装过程中的贡献和影响机制，创建了具有广泛普适性的构筑卟啉基1D超分子纳米结构的手段。同时，以一种非金属酞菁和一种具有更大共轭pi体系的金属萘酞菁为例，我们还研究发现，该手段可能在酞菁这类重要的卟啉类化合物的姊妹化合物1D超分子纳米结构的组装方面做出贡献。基于该手段所积累的科学与技术信息，我们还视具体研究进展情况，将组装手段从表面活性剂调控的组装进一步拓展到了无表面活性剂参与的组装体系以及发生于液/固二维界面体系中的组装，构筑了基于卟啉、酞菁及氧化石墨烯等pi体系分子的功能材料，研究了其在光催化、传感、分子电子器件方面的先进功能，并从这些pi体系基元分子的堆叠模式、纳米结构的形貌特征等层面，诠释了其电子/能量的转移/传输构效关系科学规律。考虑到卟啉、酞菁等pi体系化合物广泛的多样性、丰富的功能性，表面活性剂调控的组装方法及无表面活性剂参与的组装方法的重要性，这些研究为实现基于pi体系分子的先进功能体系的材料化提供了良好科学与技术平台，为研究材料的各种物理化学性能提供了丰富的材料基础，亦为设计性能更为优良的基于卟啉等pi体系分子的先进功能软物质材料提供了新契机。