scholarly journals Flexible monomer-based covalent organic frameworks: design, structure and functions

CrystEngComm ◽  
2017 ◽  
Vol 19 (33) ◽  
pp. 4868-4871 ◽  
Author(s):  
Lanfang Zou ◽  
Xinyu Yang ◽  
Shuai Yuan ◽  
Hong-Cai Zhou

A new flexible monomer-based COF has been designed and synthesized and its structure and gas adsorption properties have been carefully investigated.

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1205
Author(s):  
Alejandro Orsikowsky-Sanchez ◽  
Christine Franke ◽  
Alexander Sachse ◽  
Eric Ferrage ◽  
Sabine Petit ◽  
...  

A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characterized: (i) pure zeolite powders and (ii) extruded spherical beads composed of pure zeolite powders and an unknown amount of binder used during their preparation process. The coupling of gas porosimetry experiments using argon at 87 K and CO2 at 273 K allowed determining both the amount of the binder and its effect on adsorption properties. It was evidenced that the beads contain approximately 25 wt% of binder. Moreover, from CO2 adsorption experiments at 273 K, it could be inferred that the binder present in both 13X and 5A zeolites does not interact with the probe molecule. However, for the 4A zeolite, pore filling pressures were shifted and strong interaction with CO2 was observed leading to irreversible adsorption of the probe. These results have been compared to XRD, IR spectroscopy, and ICP-AES analysis. The effect of the binder in shaped zeolite bodies can thus have a crucial impact on applications in adsorption and catalysis.


2013 ◽  
Vol 66 (23) ◽  
pp. 4093-4106 ◽  
Author(s):  
Mürsel Arici ◽  
Okan Zafer Yeşılel ◽  
Seda Keskın ◽  
Onur Şahın ◽  
Orhan Büyükgüngör

2021 ◽  
pp. 107135
Author(s):  
Khang D. Pham ◽  
Pham Cong Dinh ◽  
Do Van Diep ◽  
Tuan V. Vu ◽  
Hai L. Luong ◽  
...  

2021 ◽  
Vol 17 ◽  
Author(s):  
Linyu Wang ◽  
Shasha Hong ◽  
Yuxi Yang ◽  
Yonghai Song ◽  
Li Wang

Background: In recent years, electrochemical sensors are widely preferred because of their high sensitivity, rapid response, low cost and easy miniaturization. Covalent organic frameworks (COFs), a porous crystalline polymer formed by organic units connected by covalent bonds, have been widely used in gas adsorption and separation, drug transportation, energy storage, photoelectric catalysis, electrochemistry and other aspects due to their large specific surface, excellent stability, high inherent porosity, good crystallinity as well as structural and functional controllability. The topological structure of COFs can be designed in advance, the structural units and linkage are diversified, and the structure is easy to be functionalized, which are all beneficial to their application in electrochemical sensors. Methods: The types, synthesis methods, properties of covalent organic frameworks and some examples of using covalent organic frameworks in electrochemical sensors are reviewed. Results: Due to their characteristics of a large specific surface, high porosity, orderly channel and periodically arranged π electron cloud, COFs are often used to immobilize metal nanoparticles, aptamers or other materials to achieve the purpose of building electrochemical sensors with high sensitivity and good stability. Since the structure of COFs can be predicted, different organic units can build COFs with different structures and properties. Therefore, organic units with certain functional groups can be selected to build COFs with certain properties and used directly for electrochemical sensors. Conclusion: COFs have a good application prospect in electrochemical sensors.


2019 ◽  
Author(s):  
Jonathan Carney ◽  
David Roundy ◽  
Cory M. Simon

Metal-organic frameworks (MOFs) are modular and adjustable nano-porous materials with applications in gas storage, separations, and sensing. Flexible/dynamic components that respond to adsorbed gas can give MOFs unique or enhanced adsorption properties. Here, we explore the adsorption properties that could be imparted to a MOF by a rotaxane molecular shuttle (RMS) in its pores. In an RMS-MOF, a macrocyclic wheel is mechanically interlocked with a strut. The wheel shuttles between stations on the strut that are also gas adsorption sites. We pose and analyze a simple statistical thermodynamic model of gas adsorption in an RMS-MOF that accounts for (i) wheel/gas competition for sites on the strut and (ii) the entropy endowed by the shuttling wheel. We determine how the amount of gas adsorbed, position of the wheel, and energy change upon adsorption depend on temperature, pressure, and the interactions of the gas/wheel with the stations. Our model reveals that, compared to an ordinary Langmuir material, the chemistry of the RMS-MOF can be tuned to render adsorption more or less temperature-sensitive and release more or less heat upon adsorption. The model also uncovers a non-monotonic relationship between temperature and the position of the wheel if gas out-competes the wheel for its preferable station.


2020 ◽  
Author(s):  
Jonathan Carney ◽  
David Roundy ◽  
Cory M. Simon

Metal-organic frameworks (MOFs) are modular and tunable nano-porous materials with applications in gas storage, separations, and sensing. Flexible/dynamic components that respond to adsorbed gas can give MOFs unique or enhanced adsorption properties. Here, we explore the adsorption properties that could be imparted to a MOF by a rotaxane molecular shuttle (RMS) in its pores. In the unit cell of an RMS-MOF, a macrocyclic wheel is mechanically interlocked with a strut of the MOF scaffold. The wheel shuttles between stations on the strut that are also gas adsorption sites. At a level of abstraction similar to the seminal Langmuir adsorption model, we pose and analyze a simple statistical mechanical model of gas adsorption in an RMS-MOF that accounts for (i) wheel/gas competition for sites on the strut and (ii) gas-induced changes in the configurational entropy of the shuttling wheel. We determine how the amount of gas adsorbed, position of the wheel, and differential energy of adsorption depend on temperature, pressure, and the interactions of the gas/wheel with the stations. Our model reveals that, compared to a rigid, Langmuir material, the chemistry of the RMS-MOF can be tuned to render gas adsorption more or less temperature-sensitive and to release more or less heat upon adsorption. The model also uncovers a non-monotonic relationship between the temperature and the position of the wheel if gas out-competes the wheel for its preferable station.


2018 ◽  
Vol 47 (27) ◽  
pp. 8983-8991 ◽  
Author(s):  
Minghui He ◽  
Yao Wang ◽  
Xiaoxia Gao ◽  
Saidan Li ◽  
Yabing He

The positional effect of the methyl group on structures and gas adsorption properties was explored in a copper-based MOF platform constructed from bent diisophthalate ligands bearing the methyl group at different positions.


2018 ◽  
Vol 5 (6) ◽  
pp. 1423-1431 ◽  
Author(s):  
Dongjie Bai ◽  
Xiaoxia Gao ◽  
Minghui He ◽  
Yao Wang ◽  
Yabing He

The positional effect of nitrogen functional sites on the structural stability and gas adsorption property was explored in a family of ssa-type MOFs.


Sign in / Sign up

Export Citation Format

Share Document