Bottom-up Synthesis Strategy of a Two-dimensional {Fe5} Cluster-Based Coordination Polymer: Stepwise Formation of {Fe5} Cluster and Its Dimension Augmentation

Author(s):  
Ye Tao ◽  
Huang-Fei Qin ◽  
Zhi-Rong Hu ◽  
Zhao-Ting Pan ◽  
Peng-Fei Yao ◽  
...  

Sophisticated aggregation assembly is challenging in assembly chemistry. Monitoring the assembly process helps to understand the assembly mechanism and the create new building blocks. A two-dimensional (2D) cluster-based coordination polymer...

2021 ◽  
Vol 50 (12) ◽  
pp. 4152-4158
Author(s):  
Kai-Ping Xie ◽  
Si-Guo Wu ◽  
Long-Fei Wang ◽  
Guo-Zhang Huang ◽  
Zhao-Ping Ni ◽  
...  

The first spin-crossover example of a two-dimensional coordination polymer containing [Pd(SCN)4]2− building blocks was explored.


2016 ◽  
Vol 72 (2) ◽  
pp. 166-169 ◽  
Author(s):  
Jiajia Guo ◽  
Wenli Cao ◽  
Shuailei Li ◽  
Kanghua Miao ◽  
Jirong Song ◽  
...  

The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-μ-aqua-[μ4-4,4′-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na2(C4H2N8O2)(H2O)4]n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4′-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolide) (ZTO2−) ligand is located on an inversion centre. The asymmetric unit consists of one Na+cation, half a bridging ZTO2−ligand and two bridging water ligands. Each Na+cation is coordinated in a trigonal antiprismatic fashion by six O atoms,i.e.two from two ZTO2−ligands and the remaining four from bridging water ligands. The Na+cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO2−ligands are on adjacent apices of the trigonal antiprism, rather than being in ananticonfiguration. All water and ZTO2−ligands act as bridging ligands between metal centres. Each Na+metal centre is bridged to a neigbouring Na+cation by two water molecules to give a one-dimensional [Na(H2O)2]nchain. The organic ZTO2−ligand, an O atom of which also bridges the same pair of Na+cations, then crosslinks these [Na(H2O)2]nchains to form two-dimensional sheets. The two-dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.


PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246453
Author(s):  
Connor Murphy ◽  
Yunqi Cao ◽  
Nelson Sepúlveda ◽  
Wei Li

Bottom-up self-assembly of components, inspired by hierarchically self-regulating aggregation of small subunits observed in nature, provides a strategy for constructing two- or three-dimensional intriguing biomimetic materials via the spontaneous combination of discrete building blocks. Herein, we report the methods of ultrasonic wave energy-assisted, fast, two- and three-dimensional mesoscale well-ordered self-assembly of microfabricated building blocks (100 μm in size). Mechanical vibration energy-driven self-assembly of microplatelets at the water-air interface of inverted water droplets is demonstrated, and the real-time formation process of the patterned structure is dynamically explored. 40 kHz ultrasonic wave is transferred into microplatelets suspended in a water environment to drive the self-assembly of predesigned well-ordered structures. Two-dimensional self-assembly of microplatelets inside the water phase with a large patterned area is achieved. Stable three-dimensional multi-layered self-assembled structures are quickly formed at the air-water interface. These demonstrations aim to open distinctive and effective ways for new two-dimensional surface coating technology with autonomous organization strategy, and three-dimensional complex hierarchical architectures built by the bottom-up method and commonly found in nature (such as nacre, bone or enamel, etc.).


2021 ◽  
Vol 7 (3) ◽  
pp. 366
Author(s):  
Xiaoming Liu ◽  
Tao Yue ◽  
Masaru Kojima ◽  
Qiang Huang ◽  
Tatsuo Arai

Blood vessels are essential in transporting nutrients, oxygen, metabolic wastes, and maintaining the homeostasis of the whole human body. Mass of engineered microvessels is required to deliver nutrients to the cells included in the constructed large three-dimensional (3D) functional tissues by diffusion. It is a formidable challenge to regenerate microvessels and build a microvascular network, mimicking the cellular viabilities and activities in the engineered organs with traditional or existing manufacturing techniques. Modular tissue engineering adopting the “bottom-up” approach builds one-dimensional (1D) or two-dimensional (2D) modular tissues in micro scale first and then uses these modules as building blocks to generate large tissues and organs with complex but indispensable microstructural features. Building the microvascular network utilizing this approach could be appropriate and adequate. In this review, we introduced existing methods using the “bottom-up” concept developed to fabricate microvessels including bio-assembling powered by different micromanipulation techniques andbioprinting utilizing varied solidification mechanisms. We compared and discussed the features of the artificial microvessels engineered by these two strategies from multiple aspects. Regarding the future development of engineering the microvessels from the bottom up, potential directions were also concluded.


2018 ◽  
Author(s):  
Erik Leonhardt ◽  
Jeff M. Van Raden ◽  
David Miller ◽  
Lev N. Zakharov ◽  
Benjamin Aleman ◽  
...  

Extended carbon nanostructures, such as carbon nanotubes (CNTs), exhibit remarkable properties but are difficult to synthesize uniformly. Herein, we present a new class of carbon nanomaterials constructed via the bottom-up self-assembly of cylindrical, atomically-precise small molecules. Guided by supramolecular design principles and circle packing theory, we have designed and synthesized a fluorinated nanohoop that, in the solid-state, self-assembles into nanotube-like arrays with channel diameters of precisely 1.63 nm. A mild solution-casting technique is then used to construct vertical “forests” of these arrays on a highly-ordered pyrolytic graphite (HOPG) surface through epitaxial growth. Furthermore, we show that a basic property of nanohoops, fluorescence, is readily transferred to the bulk phase, implying that the properties of these materials can be directly altered via precise functionalization of their nanohoop building blocks. The strategy presented is expected to have broader applications in the development of new graphitic nanomaterials with π-rich cavities reminiscent of CNTs.


Author(s):  
Shiwei Wang ◽  
Anton Chavez ◽  
Simil Thomas ◽  
Hong Li ◽  
Nathan C. Flanders ◽  
...  

This work reports on the assembly of imine-linked macrocycles that serve as models of two-dimensional covalent organic frameworks (2D COFs). Interlayer interactions play an important role in the formation of 2D COFs, yet the effect of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. For example, monomers with both electron-rich and electron-poor π-electron systems have been proposed to strengthen interlayer inter-actions and improve crystallinity. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. <div><br></div><div>Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar ΔHe values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. <br></div><div><br></div><div>Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. <br></div>


2021 ◽  
pp. 019251212110192
Author(s):  
Trix van Mierlo

Oftentimes, democracy is not spread out evenly over the territory of a country. Instead, pockets of authoritarianism can persist within a democratic system. A growing body of literature questions how such subnational authoritarian enclaves can be democratized. Despite fascinating insights, all existing pathways rely on the actions of elites and are therefore top-down. This article seeks to kick-start the discussion on a bottom-up pathway to subnational democratization, by proposing the attrition mechanism. This mechanism consists of four parts and is the product of abductive inference through theory-building causal process tracing. The building blocks consist of subnational democratization literature, social movement theory, and original empirical data gathered during extensive field research. This case study focuses on the ‘Dynasty Slayer’ in the province of Isabela, the Philippines, where civil society actors used the attrition mechanism to facilitate subnational democratization. This study implies that civil society actors in subnational authoritarian enclaves have agency.


2021 ◽  
Author(s):  
Subrata Pandit ◽  
Mrinmoy De

The synthesis of two-dimensional (2D) nanosheets such as graphene and their derivatives through bottom-up approach has many advantages such as growth control and functionalization, but it is always challenging to...


Sign in / Sign up

Export Citation Format

Share Document