921619-89-8Relevant articles and documents
Molecular dopant determines the structure of a physisorbed self-assembled molecular network
Steeno, Roelof,Minoia, Andrea,Gimenez-Lopez, Maria C.,Blunt, Matthew O.,Champness, Neil R.,Lazzaroni, Roberto,Mali, Kunal S.,De Feyter, Steven
, p. 1454 - 1457 (2021)
A small percentage of an impurity was shown,viascanning tunneling microscopy, to drastically change the on-surface self-assembly behavior of an aromatic tetracarboxylic acid, by initiating the nucleation and growth of a different polymorph. Molecular modelling simulations were used to shed further light onto the dopant-controlled assembly behaviour.
Metal-hydrogen-pi-bonded organic frameworks
Bailey, Jake B.,Chiong, Jerika A.,Cohen, Seth M.,Huang, Zhehao,Kalaj, Mark,Samperisi, Laura,Sikma, R. Eric,Tezcan, F. Akif,Yu, Chung-Jui,Zhang, Zhiyin,Zhu, Jie,Zou, Xiaodong
supporting information, p. 1927 - 1935 (2022/02/10)
We report the synthesis and characterization of a new series of permanently porous, three-dimensional metal-organic frameworks (MOFs), M-HAF-2 (M = Fe, Ga, or In), constructed from tetratopic, hydroxamate-based, chelating linkers. The structure of M-HAF-2 was determined by three-dimensional electron diffraction (3D ED), revealing a unique interpenetrated hcb-a net topology. This unusual topology is enabled by the presence of free hydroxamic acid groups, which lead to the formation of a diverse network of cooperative interactions comprising metal-hydroxamate coordination interactions at single metal nodes, staggered π-π interactions between linkers, and H-bonding interactions between metal-coordinated and free hydroxamate groups. Such extensive, multimodal interconnectivity is reminiscent of the complex, noncovalent interaction networks of proteins and endows M-HAF-2 frameworks with high thermal and chemical stability and allows them to readily undergo postsynthetic metal ion exchange (PSE) between trivalent metal ions. We demonstrate that M-HAF-2 can serve as versatile porous materials for ionic separations, aided by one-dimensional channels lined by continuously π-stacked aromatic groups and H-bonding hydroxamate functionalities. As an addition to the small group of hydroxamic acid-based MOFs, M-HAF-2 represents a structural merger between MOFs and hydrogen-bonded organic frameworks (HOFs) and illustrates the utility of non-canonical metal-coordinating functionalities in the discovery of new bonding and topological patterns in reticular materials.
High capacity hydrogen adsorption in Cu(II) tetracarboxylate framework materials: The role of pore size, ligand functionalization, and exposed metal sites
Lin, Xiang,Telepeni, Irvin,Blake, Alexander J.,Dailly, Anne,Brown, Craig M.,Simmons, Jason M.,Zoppi, Marco,Walker, Gavin S.,Thomas, K. Mark,Mays, Timothy J.,Hubberstey, Peter,Champness, Neil R.,Schroeder, Martin
experimental part, p. 2159 - 2171 (2009/07/30)
A series of isostructural metal-organic framework polymers of composition [Cu2(L)(H2O)2](L= tetracarboxylate ligands), denoted NOTT-nnn, has been synthesized and characterized. Single crystal X-ray structures confirm the complexes to contain binuclear Cu(II) paddlewheel nodes each bridged by four carboxylate centers to give a NbO-type network of 6 4? 82 topology. These complexes are activated by solvent exchange with acetone coupled to heating cycles under vacuum to afford the desolvated porous materials NOTT-100 to NOTT-109. These incorporate a vacant coordination site at each Cu(II) center and have large pore volumes that contribute to the observed high H2 adsorption. Indeed, NOTT-103 at 77 K and 60 bar shows a very high total H2 adsorption of 77.8 mg g -1 equivalent to 7.78 wt% [wt% = (weight of adsorbed H 2)/(weight of host material)] or 7.22 wt% [wt% = 100(weight of adsorbed H2)/(weight of host material + weight of adsorbed H 2)]. Neutron powder diffraction studies on NOTT-101 reveal three adsorption sites for this material: at the exposed Cu(II) coordination site, at the pocket formed by three {Cu2} paddle wheels, and at the cusp of three phenyl rings. Systematic virial analysis of the H2 isotherms suggests that the H2 binding energies at these sites are very similar and the differences are smaller than 1.0 kJ mol-1, although the adsorption enthalpies for H2 at the exposed Cu(II) site are significantly affected by pore metrics. Introducing methyl groups or using kinked ligands to create smaller pores can enhance the isosteric heat of adsorption and improve H2 adsorption. However, although increasing the overlap of potential energy fields of pore walls increases the heat of H2 adsorption at low pressure, it may be detrimental to the overall adsorption capacity by reducing the pore volume.
