智能化自振荡高分子凝胶

自振荡高分子凝胶是一种智能化软物质材料,其体积无需外界刺激即能自发膨胀收缩,实现化学能向机械能转化,具有良好的研究和应用前景。本文介绍了自振荡凝胶的设计和自振荡机理、不同尺度的自振荡行为,以及温度、浓度、胶结构和外界刺激等因素对自振荡行为的影响等内容。从凝胶自驱动运动和物质运输两方面介绍仿生驱动凝胶在组织工程、生命科学、药物缓释和材料等领域的潜在应用,并展望了自振荡凝胶未来研究趋势。     

Belousov-Zhabotinsky反应驱动的智能高分子材料:拓扑结构及仿生功能

化学自振荡反应驱动的智能高分子材料常被称为自振荡高分子材料(self-oscillating polymer materials, SOPMs),其中以Belousov-Zhabotinsky(BZ)反应驱动的SOPMs研究最为深入,为高分子材料领域的一大研究热点。与传统智能高分子材料不同,SOPMs体系具有高度的自调节性,即可以不需要外界“开-关”转换的刺激就能自动、可逆、周期性地发生状态转变。本文结合SOPMs的最新研究结果,介绍该类材料在新型拓扑结构设计和仿生功能研究两个方面的新思想和新方法。在拓扑结构设计方面,主要介绍梳形自振荡高分子凝胶、“聚轮烷”互锁自振荡高分子凝胶、多级结构自振荡高分子凝胶、超级交联自振荡高分子凝胶、支化自振荡高分子、自振荡高分子刷以及嵌段自振荡高分子材料。在仿生功能研究方面,主要阐述自振荡高分子囊泡、人工细胞、自主肠状运动、趋光避光运动。最后,对SOPMs今后的发展作了展望。     

光驱动一维活性凝胶定向运动

许多生物都具备一种响应环境刺激而进行自动运动的本能。光照是一种强有力的外部刺激,且对生物系统具有正负驱动的双重效应。本文设计了一个一维活性BZ凝胶体系,利用钌催化BZ反应的光敏性,控制凝胶振荡频率,驱动凝胶进行定向运动。同时,笔者对Yashin提出的BZ响应胶模型进行了修正并依此对活性凝胶光强频率曲线进行模拟,揭示光驱动活性凝胶运动的本质。这有助于研发新型仿生智能机器人来对生物系统响应外部刺激的运动进行研究。     

光驱动一维活性凝胶自发定向运动

许多生物都具备一种自发响应环境刺激进行自动运动的本能。光照是一种强有力的外部刺激,且对生物系统具有正负驱动的双重效应;本实验设计了一个一维活性BZ凝胶体系,利用钌催化BZ反应的光敏性,控制凝胶振荡频率,驱动凝胶进行定向自发运动。同时,我们修正了V. V. Yashin 提出的BZ响应胶模型活性凝胶光强频率曲线进行模拟,揭示光驱动活性凝胶运动的本质。这有助于研发新型仿生智能机器人来对生物系统响应外部刺激的自发运动进行研究。     

从生物矿化到仿生矿化：构筑新功能生命体

生物矿化是生命体通过调控无机矿物的成核、取向、生长和组装来制造有机-无机复合材料的过程。借鉴生物矿化的原理,可利用有机基质实现无机材料的可控合成,制备出性能优异的新型复合材料。更有趣的是,将材料和生物体从结构和功能两个层面整合,利用材料-生物之间的协同调控,可构筑出新功能生命体,这也是仿生矿化发展的重要方向。本论文首先介绍生物矿化的基本理论和自然界中的生物矿化现象。随后通过对生物矿物结构和功能的阐述,提出仿生构筑新功能生命体的概念,并系统介绍构筑新型材料-生物体的方法,在此基础上系统总结新功能生命体在环保、能源、医学等领域的应用。最后,针对目前该领域存在的局限和问题展开讨论,对实现智能仿生构筑生命体的研究进行展望。我们认为基于仿生矿化构筑新功能生命体的研究能够推动学科边界不断融合,为材料学、化学生物学、生物无机化学以及医学等领域的发展提供新的方向。     

粘性水凝胶的发展及应用

本文系统介绍了近年来粘性水凝胶相关研究的最新进展,并从结构仿生、材料仿生、原理仿生方面细致梳理了典型案例的设计理念,总结概括了粘性水凝胶在可穿戴传感器、生物医用材料、执行器机器人、吸附分离等领域的应用。在此基础上,探讨了粘性水凝胶现存的挑战,并展望了其在亚微米颗粒的吸附分离、痕量爆炸物颗粒原位采样检测等方面将有蓬勃发展,为粘性水凝胶的创新设计及实际应用提供指导和参考。     

凝胶介质中仿生矿化过程的研究*

本文综述了凝胶介质中仿生矿化过程的研究进展。仿生矿化是当前化学、生物学和材料科学的研究前沿和热点。近年来,越来越多的生物学证据表明：生物体中的蛋白质和多糖等生物大分子,往往通过超分子组装形成凝胶状基质网络,进而对生物矿化过程施加影响。因此,凝胶介质中的仿生矿化研究对深入了解生物矿化机理,以及从理论上指导先进功能材料的设计和合成具有重要意义。迄今为止,研究人员已经对天然和合成高分子凝胶、超分子水凝胶和无机凝胶等多种凝胶介质中的仿生矿化过程进行了研究。结果表明：凝胶介质主要通过其三维网络结构限制反应离子在其内部的扩散速率,并掺杂到无机矿物的晶体结构中,从而影响生成晶体的形貌和构造。而且在有机基质(如水溶性有机高分子和自组装单层等)的协同作用下,凝胶介质中的仿生矿化过程也呈现出与水溶液中不同的特点。此外,本文还介绍了当前对凝胶介质中矿物形貌的调控和矿化机理的几种不同观点,并对该领域未来的研究和应用进行了展望。     

基于Belousov-Zhabotinsky自振荡反应的智能高分子

自振荡高分子是基于Belousov-Zhabotinsky自振荡反应(BZ反应)设计的一类新型智能高分子,其物理、化学性质可以在相对封闭且无外界刺激的BZ反应溶液中发生自主、可逆和循环的变化。本文从概念、设计原理、设计方法及潜在应用4个方面系统介绍了自振荡高分子,其中重点结合自振荡高分子的化学结构设计与物理结构设计介绍了这一领域的研究进展:详细归纳了目前已成功制备的具有不同化学结构或物理结构的自振荡高分子或凝胶,阐述了不同的设计方法的优点、存在的问题及可能的解决办法,最后介绍了自振荡高分子在自动运输智能表面、凝胶机器人、自主转动马达等方面的设计实例,并分析了该领域面临的问题及今后发展趋势。     

阿拉伯糖和丙酮作混合底物的B—Z振荡反应

化学振荡反应在近年来得到了广泛的研究,研究由组成生命体的物质参与的振荡器对探索生命运动中的振荡规律具有重要意义。本文报道由糖类参加的B—Z体系:阿拉伯糖(以Ara表示)—丙酮(以Act表示)—BrO_3~--Mn~(2+)—H_2SO_4体系。并对振荡反应中二种有机物的作用作了初探。实验部分     

聚合物纳米粒子的制备及其新型物理水凝胶结构的AFM和SEM研究

凝胶材料是生物系统的重要组成物质,在生物模拟、仿生等方面具有重大意义.最近凝胶方面的研究日益受到关注^[1,2],高分子凝胶体系的研究也得到深入开展^[3,4].在智能水凝胶、凝胶特性基础研究和医用凝胶材料等领域已取得了较大进展.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.