Covalent Organic Frameworks

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Organic Crystalline Materials".

Deadline for manuscript submissions: closed (28 June 2023) | Viewed by 4189

Special Issue Editors

Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
Interests: covalent organic frameworks
Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
Interests: covalent organic frameworks

Special Issue Information

Dear Colleagues,

Covalent organic frameworks (COFs) are a new class of crystalline porous organic material possessing two- or three- dimensional structures. COFs are constructed from pre-designed organic building units connecting by strong covalent bonds between light atoms (e.g., B, C, N, O, P, Si). Since they were firstly reported by Yaghi et al. in 2005, COFs have emerged as a material with a wealth of applications, such as sorption, separation, optoelectronics, catalysis, sensors, drug delivery, energy storage, etc. COFs exemplify the manner in which reticular chemistry is practiced, with the control at molecular level being exercised over matter. The facile bottom-up synthesis of COFs introducing precise perturbations in chemical composition results in the highly controlled tunability of structural diversity and framework properties such as porosity, conjugation property, etc.

As a crystalline material, progress in developing their chemistry often dominates the ability to crystallize them. In most cases, reversible reactions have been used to build COF materials so that self-correction can be realized in the crystal growth of COFs by chemical equilibrium. For example, borate ester condensation reaction and imine condensation reaction are mostly used in the crystal growth of COFs. However, the strength of covalent bonding between the building units often yields polycrystalline products. Hence, structural analysis of COFs usually combines multiple characterization methods, for example, powder X-ray diffraction (PXRD) modeling and TEM techniques. In 2018, large-sized single-crystal COFs were obtained, enabling the use of single-crystal X-ray diffraction to identify atomically precise COF structures.

In this Special Issue, we will focus on the design, synthesis, crystal growth, properties, and emerging applications of COFs.

Dr. Xing Han
Dr. Tianqiong Ma
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • covalent organic frameworks
  • single crystal
  • reticular chemistry
  • framework material
  • porous organic material

Published Papers (2 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

11 pages, 2409 KiB  
Article
Three-Component Covalent Organic Framework Nanosheets for the Detection of MicroRNAs
by Bin Xie, Yilun Yan, Jialin Wu, Xinting Cai, Jiayue Zheng, Yixin Lan, Xihao Tang, Jun Fan, Shengrun Zheng and Songliang Cai
Crystals 2022, 12(11), 1628; https://doi.org/10.3390/cryst12111628 - 13 Nov 2022
Cited by 1 | Viewed by 1453
Abstract
The development of new techniques for the detection of microRNAs (miRNAs) is highly desirable. Herein, a new crystalline three-component covalent organic framework (COF) termed EB-TAPB-TFP COF was synthesized under solvothermal conditions utilizing 1,3,5-triformylphloroglucinol, 1,3,5-tris(4-aminophenyl)benzene and ethidium bromide as monomers. Interestingly, EB-TAPB-TFP COF can [...] Read more.
The development of new techniques for the detection of microRNAs (miRNAs) is highly desirable. Herein, a new crystalline three-component covalent organic framework (COF) termed EB-TAPB-TFP COF was synthesized under solvothermal conditions utilizing 1,3,5-triformylphloroglucinol, 1,3,5-tris(4-aminophenyl)benzene and ethidium bromide as monomers. Interestingly, EB-TAPB-TFP COF can be self-exfoliated into two-dimensional nanosheets (NSs) in an aqueous medium. The obtained EB-TAPB-TFP NSs exhibited a remarkable fluorescence intensity enhancement in the presence of a DNA-miRNA heteroduplex when compared to the presence of single-stranded DNA and other phosphate-based small molecules, making it promising in the detection of miRNA without tagging any fluorescent marker. Moreover, the EB-TAPB-TFP NSs can also be used as sensing material for the detection of a DNA-miRNA heteroduplex using the quartz crystal microbalance technique, which is in good agreement with the fluorescence sensing result. The exploration of COF-based sensors in this work demonstrates a new pathway for the selective detection of miRNAs. Full article
(This article belongs to the Special Issue Covalent Organic Frameworks)
Show Figures

Figure 1

9 pages, 1750 KiB  
Article
2D Microporous Covalent Organic Frameworks as Cobalt Nanoparticle Supports for Electrocatalytic Hydrogen Evolution Reaction
by Jialong Song, Li Liao, Zerong Zhang, Yusran Yusran, Rui Wang, Jing Fang, Yaozu Liu, Yu Hou, Yujie Wang and Qianrong Fang
Crystals 2022, 12(7), 880; https://doi.org/10.3390/cryst12070880 - 21 Jun 2022
Cited by 3 | Viewed by 2023
Abstract
Covalent organic frameworks (COFs) are a new class of porous crystalline polymers, which are considered to be excellent supports for metal nanoparticles (MNPs) due to their highly ordered structure, chemical tunability, and porosity. In this work, two novel ultra-microporous COFs, JUC−624 and JUC−625, [...] Read more.
Covalent organic frameworks (COFs) are a new class of porous crystalline polymers, which are considered to be excellent supports for metal nanoparticles (MNPs) due to their highly ordered structure, chemical tunability, and porosity. In this work, two novel ultra-microporous COFs, JUC−624 and JUC−625, with narrow pore size distribution have been synthesized and used for the confined growth of ultrafine Co nanoparticles (CoNPs) with high loading. In an alkaline environment, the produced materials were investigated as electrocatalysts for the hydrogen evolution reaction (HER). Electrochemical test results show that CoNPs@COFs have a Tafel slope of 84 mV·dec−1, an onset overpotential of 105 mV, and ideal stability. Remarkably, CoNPs@JUC−625 required only 146 mV of overpotential to afford a current density of 10 mA cm−2. This research will open up new avenues for making COF-supported ultrafine MNPs with good dispersity and stability for extensive applications. Full article
(This article belongs to the Special Issue Covalent Organic Frameworks)
Show Figures

Figure 1

Back to TopTop