MOFs@Top J 2017.2.5-2017.2.11

J. Am. Chem. Soc.: The Postsynthetic Renaissance in Porous Solids

Seth M. Cohen* 

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b11259

Publication Date (Web): January 24, 2017

Copyright © 2017 American Chemical Society

*[e-mail]

Metal–organic frameworks (MOFs) have rapidly grown into a major area of chemical research over the last two decades. MOFs represent the development of covalent chemistry 「beyond the molecule」 and into extended structures. MOFs also present an unprecedented scaffold for performing heterogeneous organic transformations in the solid state, allowing for deliberate and precise preparation of new materials. The development of these transformations has given rise to the 「postsynthetic renaissance」, a suite of methods by which these materials can be transformed in a single-crystal-to-single-crystal manner. Postsynthetic modification, postsynthetic deprotection, postsynthetic exchange, postsynthetic insertion, and postsynthetic polymerization have exploited the unique features of both the organic and inorganic components of MOFs to create crystalline, porous solids of unique complexity and functionality.

http://pubs.acs.org/doi/abs/10.1021/jacs.6b11259

J. Am. Chem. Soc.: Multifunctional Nanoparticles by Coordinative Self-Assembly of His-Tagged Units with Metal–Organic Frameworks

Ruth Röder†, Tobias Prei߇, Patrick Hirschle§, Benjamin Steinborn†, Andreas Zimpel§, Miriam Höhn†, Joachim O. Rädler‡, Thomas Bein§, Ernst Wagner† , Stefan Wuttke*§, and Ulrich Lächelt*† 

† Pharmaceutical Biotechnology, Department of Pharmacy and Center for NanoScience (CeNS), LMU Munich, 81377 Munich, Germany

‡ Department of Physics and Center for NanoScience (CeNS), LMU Munich, 80539 Munich, Germany

§ Department of Chemistry and Center for NanoScience (CeNS), LMU Munich, 81377 Munich, Germany

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b11934

Publication Date (Web): January 11, 2017

Copyright © 2017 American Chemical Society

*[e-mail], *[e-mail]

Self-assembly of individual units into multicomponent complexes is a powerful approach for the generation of functional superstructures. We present the coordinative interaction of oligohistidine-tags (His-tags) with metal–organic framework nanoparticles (MOF NPs). By this novel concept, different molecular units can be anchored on the outer surface of MOF NPs in a self-assembly process generating multifunctional nanosystems. The article focuses on two main objectives: first, the detailed investigation of the assembly process and fundamental establishment of the novel functionalization concept; and second, its subsequent use for the development of biomacromolecule (e.g., peptides and proteins) delivery vehicles. Three exemplary MOF structures, MIL-88A, HKUST-1, and Zr-fum, based on different metal components, were selected for the external binding of various His-tagged synthetic peptides and recombinant or chemically H6-modified proteins. Evidence for simultaneous assembly of different functional units with Zr-fum MOF NPs as well as their successful transport into living cells illustrate the promising potential of the self-assembly approach for the generation of multifunctional NPs and future biological applications. Taking the high number of possible MOF NPs and different functional units into account, the reported functionalization approach opens great flexibility for the targeted synthesis of multifunctional NPs for specific purposes.

http://pubs.acs.org/doi/abs/10.1021/jacs.6b11934

ChenSusChem：Inside Back Cover: Significantly Improved Electrocatalytic Activity of Copper-Based Structures that Evolve from a Metal-Organic Framework Induced by Cathodization Treatment (ChemElectroChem 2/2017)

Dr. Libo Shi,Dr. Xiangheng Niu,Prof. Hongli Zhao,Prof. Minbo Lan

First published: 23 January 2017

DOI: 10.1002/celc.201700010

The Inside Back Cover pictureshows that the cathodization treatment on Cu–MOF results in the evolution of a structure with improved electrocatalytic activity for glucose oxidation. More information can be found in the Communication by H. Zhao, M. Lan and co-workers on page 246 in Issue 2, 2017(DOI: 10.1002/celc.201600625).

http://onlinelibrary.wiley.com/doi/10.1002/celc.201700010/abstract

Whereas metal-organic frameworks (MOFs) are being widely explored in the application of electrocatalysis, the electro-inert organic ligands in MOFs have negative effects on electron transfer. Here, we suggest a facile electrochemical cathodization treatment for the controllable evolution of a Cu-MOF to improve its electrocatalytic performance. When a cathodic potential was applied, Cu-based structures evolving from Cu-MOF with different crystal phases, surface compositions, and morphologies were harvested by controlling the cathodization time. The obtained copper-based structures were found to have much higher activities than the as-synthesized Cu-MOF for glucose electrocatalysis in alkaline media. A 60 second cathodization treatment resulted in the largest sensitivity for glucose electrocatalytic sensing.

http://onlinelibrary.wiley.com/doi/10.1002/celc.201600625/abstract

ChenSusChem： Cover Picture: Electrochemical Water Oxidation by a Catalyst-Modified Metal–Organic Framework Thin Film (ChemSusChem 3/2017)

Shaoyang Lin,Yuliana Pineda-Galvan,Dr. William A. Maza,Charity C. Epley,Jie Zhu,Matthew C. Kessinger,Dr. Yulia Pushkar,Dr. Amanda J. Morris

First published: 31 January 2017

DOI: 10.1002/cssc.20170010

The Front Cover picture shows a leaf consisting of a conductive substrate. Onto this, a metal–organic framework (MOF) modified with ruthenium is grown, which then can electrochemically oxidize water. The synthesis of the MOF was conducted in a one-pot method resulting in a poly-dispersed distribution of the catalytic centers throughout the framework, with electron transport occurring through a redox hopping mechanism. The MOF film provides 70x the current possible for a homogeneous catalyst approach. More details can be found in the Full Paper by Lin et al. on page 514 in Issue 3, 2017 (DOI: 10.1002/cssc.201601181).

Water oxidation, a key component in artificial photosynthesis, requires high overpotentials and exhibits slow reaction kinetics that necessitates the use of stable and efficient heterogeneous water-oxidation catalysts (WOCs). Here, we report the synthesis of UiO-67 metal–organic framework (MOF) thin films doped with [Ru(tpy)(dcbpy)OH2]2+ (tpy=2,2′:6′,2′′-terpyridine, dcbpy=5,5′-dicarboxy-2,2′-bipyridine) on conducting surfaces and their propensity for electrochemical water oxidation. The electrocatalyst oxidized water with a turnover frequency (TOF) of (0.2±0.1) s−1 at 1.71 V versus the normal hydrogen electrode (NHE) in buffered solution (pH∼7) and exhibited structural and electrochemical stability. The electroactive sites were distributed throughout the MOF thin film on the basis of scan-ratedependent voltammetry studies. This work demonstrates a promising way to immobilize large concentrations of electroactive WOCs into a highly robust MOF scaffold and paves the way for future photoelectrochemical water-splitting systems.

http://onlinelibrary.wiley.com/doi/10.1002/cssc.201601181/abstract

Acc. Chem. Res.: Postsynthetic Tuning of Metal–Organic Frameworks for Targeted Applications

Timur Islamoglu†§ , Subhadip Goswami†§, Zhanyong Li† , Ashlee J. Howarth†, Omar K. Farha*†‡ , and Joseph T. Hupp*† 

† Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States

‡ Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

Acc. Chem. Res., Article ASAP

DOI: 10.1021/acs.accounts.6b00577

Publication Date (Web): February 8, 2017

Copyright © 2017 American Chemical Society

*E-mail: [e-mail]., *E-mail: [e-mail].

Conspectus

Metal–organic frameworks (MOFs) are periodic, hybrid, atomically well-defined porous materials that typically form by self-assembly and consist of inorganic nodes (metal ions or clusters) and multitopic organic linkers. MOFs as a whole offer many intriguing properties, including ultrahigh porosity, tunable chemical functionality, and low density. These properties point to numerous potential applications, including gas storage, chemical separations, catalysis, light harvesting, and chemical sensing, to name a few. Reticular chemistry, or the linking of molecular building blocks into predetermined network structures, has been employed to synthesize thousands of MOFs. Given the vast library of candidate nodes and linkers, the number of potentially synthetically accessible MOFs is enormous. Nevertheless, a powerful complementary approach to obtain specific structures with desired chemical functionality is to modify known MOFs after synthesis. This approach is particularly useful when incorporation of particular chemical functionalities via direct synthesis is challenging or impossible. The challenges may stem from limited stability or solubility of precursors, unwanted secondary reactivity of precursors, or incompatibility of functional groups with the conditions needed for direct synthesis. MOFs can be postsynthetically modified by replacing the metal nodes and/or organic linkers or via functionalization of the metal nodes and/or organic linkers.

Here we describe some of our efforts toward the development and application of postsynthetic strategies for imparting desired chemical functionalities in MOFs of known topology. The techniques include methods for functionalizing MOF nodes, i.e., solvent-assisted ligand incorporation (SALI) and atomic layer deposition in MOFs (AIM) as well as a method to replace structural linkers, termed solvent-assisted linker exchange (SALE), also known as postsynthethic exchange (PSE). For each functionalization strategy, we first describe its chemical basis along with the requirements for its successful implementation. We then present a small number of examples, with an emphasis on those that (a) convey the underlying concepts and/or (b) lead to functional structures (e.g., catalysts) that would be difficult or impossible to access via direct routes. The examples, however, are only illustrative, and a significant body of work exists from both our lab and others, especially for the SALE/PSE strategy. We refer readers to the papers cited and to the references therein. More exciting, in our view, will be new examples and new applications of the functionalization strategies—especially applications made possible by creatively combining the strategies. Underexplored (again, in our view) are implementations that impart electrical conductivity, enable increasingly selective chemical sensing, or facilitate cascade catalysis. It will be interesting to see where these strategies and others take this compelling field over the next few years.

http://pubs.acs.org/doi/abs/10.1021/acs.accounts.6b00577

Chem. Sci: High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks

Wenbin Li,a   Lei Sun,b   Jingshan Qi,c   Pablo Jarillo-Herrero,d   Mircea Dincă*b and    Ju Li*c  

Show Affiliations

Chem. Sci., 2017, Advance Article

DOI: 10.1039/C6SC05080H

Received 17 Nov 2016, Accepted 20 Jan 2017

First published online 08 Feb 2017

We use first-principles calculations to show that the square symmetry of two-dimensional (2D) metal–organic frameworks (MOFs) made from octaamino-substituted phthalocyanines and square planar Ni2+ ions, which enable strong conjugation of π electrons, has a critical impact on the magnetic properties of the lattice. In particular, we predict the unexpected emergence of a rare high-temperature ferromagnetic half-metallic ground state in one case. Among charge neutral MOFs made from (2,3,9,10,16,17,23,24)-octaiminophthalocyanine (OIPc) metallated with divalent first-row transition metal ions (M-OIPc; M = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) and connected through square planar Ni-bisphenylenediimine moieties, NiMn-OIPc exhibits a half-metallic and ferromagnetic ground state with a large exchange energy resulting from the unique strong hybridization between the d/π orbitals of Mn, the Pc ring, and the Ni-bisphenylenediimine nodes. Notably, we show that for NiMn-OIPc there is a considerable difference between the ferromagnetic ordering temperature (Tc) predicted by a 2D Ising model, which exceeds 600 K, and a Tc of 170 K predicted by our more realistic Monte Carlo simulation that includes magnetic anisotropy. Critically, our simulations adopt two spin models that incorporate magnetic anisotropy in the form of exchange anisotropy and single-ion anisotropy. We further show that in the bulk, 2D layers of NiMn-OIPc adopt a slipped-parallel stacking configuration, and exhibit interlayer magnetic coupling that is sensitive to the relative in-plane displacement between adjacent layers. These results highlight the critical role of magnetic anisotropy in modeling the properties of 2D magnetic systems. More generally, it demonstrates that strong hybridization between open-shell ions and delocalized aromatic π systems with appropriate symmetry, combined with large magnetic anisotropy, will be an effective design strategy to realize ferromagnetic 2D MOFs with high Tc.

http://pubs.rsc.org/en/Content/ArticleLanding/2017/SC/C6SC05080H

Angew. Chem. Int. Ed.：A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect-free Metal–Organic Framework Composite Membrane

Eva Barankova,Xiaoyu Tan,Luis Francisco Villalobos,Dr. Eric Litwiller,Prof. Klaus-Viktor Peinemann

First published: 6 February 2017

DOI: 10.1002/anie.201611927

Since the discovery of size-selective metal–organic frameworks (MOFs), researchers have tried to incorporate these materials into gas separation membranes. Impressive gas selectivities were found, but these MOF membranes were mostly made on inorganic supports, which are generally too bulky and expensive for industrial gas separation. Forming MOF layers on porous polymer supports is industrially attractive but technically challenging. Two features to overcome these problems are described: 1) a metal chelating support polymer to bind the MOF layer, and 2) control of MOF crystal growth by contra-diffusion, aiming at a very thin nanocrystalline MOF layer. Using a metal chelating poly-thiosemicarbazide (PTSC) support and adjusting the metal and organic ligand concentrations carefully, a very compact ZIF-8 (ZIF=zeolitic imidazolate framework) layer was produced that displayed interference colors because of its smooth surface and extreme thinness—within the range of visible light. High performances were measured in terms of hydrogen/propane (8350) and propylene/propane (150) selectivity.

http://onlinelibrary.wiley.com/doi/10.1002/anie.201611927/full

Angew. Chem. Int. Ed.：NiII Coordination to Al-Based Metal–Organic Framework Made from 2-Aminoterephthalate for Photocatalytic Overall Water Splitting

Yang An,Prof. Dr. Yuanyuan Liu,Pengfei An,Juncai Dong,Benyan Xu,Prof. Dr. Ying Dai,Xiaoyan Qin,Xiaoyang Zhang,Prof. Dr. Myung-Hwan Whangbo,Prof. Dr. Baibiao Huang

First published: 7 February 2017

DOI: 10.1002/anie.201612423

The aluminum-based metal–organic framework (MOF) made from 2-aminoterephthalate is a photocatalyst for oxygen evolution. This MOF can be modified by incorporating Ni2+ cations into the pores through coordination to the amino groups, and the resulting MOF is an efficient photocatalyst for overall water splitting.

http://onlinelibrary.wiley.com/doi/10.1002/anie.201612423/abstract

J. Am. Chem. Soc.: Stable Covalent Organic Frameworks for Exceptional Mercury Removal from Aqueous Solutions

Ning Huang, Lipeng Zhai, Hong Xu, and Donglin Jiang* 

Field of Environment and Energy, School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi 923-1292, Japan

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.6b12328

Publication Date (Web): January 25, 2017

Copyright © 2017 American Chemical Society

*[e-mail]

The pre-designable porous structures found in covalent organic frameworks (COFs) render them attractive as a molecular platform for addressing environmental issues such as removal of toxic heavy metal ions from water. However, a rational structural design of COFs in this aspect has not been explored. Here we report the rational design of stable COFs for Hg(II) removal through elaborate structural design and control over skeleton, pore size, and pore walls. The resulting framework is stable under strong acid and base conditions, possesses high surface area, has large mesopores, and contains dense sulfide functional termini on the pore walls. These structural features work together in removing Hg(II) from water and achieve a benchmark system that combines capacity, efficiency, effectivity, applicability, selectivity, and reusability. These results suggest that COFs offer a powerful platform for tailor-made structural design to cope with various types of pollution.

http://pubs.acs.org/doi/abs/10.1021/jacs.6b12328