ORCID Profile
0000-0003-2779-7788
Current Organisation
The University of Texas at Austin
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Publisher: Springer Science and Business Media LLC
Date: 18-01-2023
DOI: 10.1038/S41467-023-35970-X
Abstract: Controllable fabrication of angstrom-size channels has been long desired to mimic biological ion channels for the fundamental study of ion transport. Here we report a strategy for fabricating angstrom-scale ion channels with one-dimensional (1D) to three-dimensional (3D) pore structures by the growth of metal-organic frameworks (MOFs) into nanochannels. The 1D MIL-53 channels of flexible pore sizes around 5.2 × 8.9 Å can transport cations rapidly, with one to two orders of magnitude higher conductivities and mobilities than MOF channels of hybrid pore configurations and sizes, including Al-TCPP with 1D ~8 Å channels connected by 2D ~6 Å interlayers, and 3D UiO-66 channels of ~6 Å windows and 9 − 12 Å cavities. Furthermore, the 3D MOF channels exhibit better ion sieving properties than those of 1D and 2D MOF channels. Theoretical simulations reveal that ion transport through 2D and 3D MOF channels should undergo multiple dehydration-rehydration processes, resulting in higher energy barriers than pure 1D channels. These findings offer a platform for studying ion transport properties at angstrom-scale confinement and provide guidelines for improving the efficiency of ionic separations and nanofluidics.
Publisher: American Chemical Society (ACS)
Date: 07-2001
DOI: 10.1021/MA010355I
Publisher: Wiley
Date: 15-01-2000
DOI: 10.1002/(SICI)1099-0488(20000115)38:2<273::AID-POLB1>3.0.CO;2-X
Publisher: Research Square Platform LLC
Date: 20-10-2022
DOI: 10.21203/RS.3.RS-1939091/V1
Abstract: Minimal understanding of the formation mechanism and structure of polydopamine (pDA) and its natural analogues, eumelanin impedes the practical application of these versatile polymers and limits our knowledge of the origin of melanoma. 1–8 The lack of conclusive structural evidence stems from the insolubility of these materials, which has spawned significantly erse suggestions of pDA’s structure in the literature. 9,10 We discovered that pDA is soluble in certain ionic liquids. Using these ionic liquids (ILs) as solvents, we present an experimental methodology to solvate pDA, enabling us to identify pDA’s chemical structure. The resolved pDA structure consists of self-assembled supramolecular aggregates that contribute to the increasing complexity of the polymer. The underlying molecular energetics of pDA solvation and a macroscopic picture of the disruption of the aggregates using IL solvents have been investigated, along with studies of the aggregation mechanism in water.
Publisher: Wiley
Date: 06-2000
DOI: 10.1002/(SICI)1099-0488(20000601)38:11<1474::AID-POLB70>3.0.CO;2-6
Publisher: American Chemical Society (ACS)
Date: 23-01-2023
Publisher: American Chemical Society (ACS)
Date: 28-02-2020
Publisher: American Chemical Society (ACS)
Date: 08-2023
Publisher: American Chemical Society (ACS)
Date: 17-12-2021
Publisher: Elsevier BV
Date: 03-2014
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 12-2018
Publisher: Wiley
Date: 2004
DOI: 10.1002/POLB.20116
Publisher: Elsevier BV
Date: 06-2001
Publisher: Springer Science and Business Media LLC
Date: 09-03-2020
Publisher: Springer Science and Business Media LLC
Date: 11-06-2019
DOI: 10.1038/S41467-019-10420-9
Abstract: Biological fluoride ion channels are sub-1-nanometer protein pores with ultrahigh F − conductivity and selectivity over other halogen ions. Developing synthetic F − channels with biological-level selectivity is highly desirable for ion separations such as water defluoridation, but it remains a great challenge. Here we report synthetic F − channels fabricated from zirconium-based metal-organic frameworks (MOFs), UiO-66-X (X = H, NH 2 , and N + (CH 3 ) 3 ). These MOFs are comprised of nanometer-sized cavities connected by sub-1-nanometer-sized windows and have specific F − binding sites along the channels, sharing some features of biological F − channels. UiO-66-X channels consistently show ultrahigh F − conductivity up to ~10 S m −1 , and ultrahigh F − /Cl − selectivity, from ~13 to ~240. Molecular dynamics simulations reveal that the ultrahigh F − conductivity and selectivity can be ascribed mainly to the high F − concentration in the UiO-66 channels, arising from specific interactions between F − ions and F − binding sites in the MOF channels.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-02-2018
Abstract: Subnanometer metal organic framework pores can selectively transport alkali metal ions of the same valence and similar sizes.
Publisher: Wiley
Date: 02-2000
DOI: 10.1002/(SICI)1099-0488(20000201)38:3<415::AID-POLB8>3.0.CO;2-Z
Publisher: Elsevier BV
Date: 05-2011
Publisher: American Chemical Society (ACS)
Date: 15-07-2022
Publisher: Wiley
Date: 24-11-2020
DOI: 10.1002/JCC.26452
Abstract: We present an inexpensive and robust theoretical approach based on the fragment molecular orbital methodology and the spin‐ratio scaled second‐order Møller–Plesset perturbation theory to predict the lattice energy of benzene crystals within 2 kJ ⋅ mol −1 . Inspired by the Harrison method to estimate the Madelung constant, the proposed approach calculates the lattice energy as a sum of two‐ and three‐body interaction energies between a reference molecule and the surrounding molecules arranged in a sphere. The lattice energy converges rapidly at a radius of 13 Å. Adding the corrections to account for a higher correlated level of theory and basis set superposition for the Hartree Fock (HF) level produced a lattice energy of − 57.5 kJ ⋅ mol −1 for the benzene crystal structure at 138 K. This estimate is within 1.6 kJ ⋅ mol −1 off the best theoretical prediction of − 55.9 kJ ⋅ mol −1 . We applied this approach to calculate lattice energies of the crystal structures of phase I and phase II—polymorphs of benzene—observed at a higher temperature of 295 K. The stability of these polymorphs was correctly predicted, with phase II being energetically preferred by 3.7 kJ ⋅ mol −1 over phase I. The proposed approach gives a tremendous potential to predict stability of other molecular crystal polymorphs.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 27-01-2023
Abstract: Single-ion selectivity with high precision has long been pursued for fundamental bioinspired engineering and applications such as in ion separation and energy conversion. However, it remains a challenge to develop artificial ion channels to achieve single-ion selectivity comparable to their biological analogs, especially for high Na + /K + selectivity. Here, we report an artificial sodium channel by subnanoconfinement of 4′-aminobenzo-15-crown-5 ethers (15C5s) into ~6-Å-sized metal-organic framework subnanochannel (MOFSNC). The resulting 15C5-MOFSNC shows an unprecedented Na + /K + selectivity of tens to 10 2 and Na + /Li + selectivity of 10 3 under multicomponent permeation conditions, comparable to biological sodium channels. A co–ion-responsive single-file transport mechanism in 15C-MOFSNC is proposed for the preferential transport of Na + over K + due to the synergetic effects of size exclusion, charge selectivity, local hydrophobicity, and preferential binding with functional groups. This study provides an alternative strategy for developing potential single-ion selective channels and membranes for many applications.
Publisher: Wiley
Date: 18-07-2000
DOI: 10.1002/(SICI)1097-4628(20000718)77:3<529::AID-APP8>3.0.CO;2-Y
Publisher: Elsevier BV
Date: 11-2004
Publisher: Wiley
Date: 06-2000
DOI: 10.1002/(SICI)1099-0488(20000601)38:11<1461::AID-POLB60>3.0.CO;2-H
Publisher: American Chemical Society (ACS)
Date: 20-02-2001
DOI: 10.1021/MA000628U
Publisher: Wiley
Date: 22-08-2002
DOI: 10.1002/POLB.10276
Publisher: American Chemical Society (ACS)
Date: 19-04-2012
DOI: 10.1021/IE202546Z
Publisher: Research Square Platform LLC
Date: 06-10-2022
DOI: 10.21203/RS.3.RS-2133327/V1
Abstract: Melanin, a bio-polymer responsible for visible pigmentation in the human body, works as a protective layer in our skin by absorbing UV radiation and efficiently dissipating it into heat, preventing DNA damage. The primary structure of eumelanin, one of the two main forms of melanin, is presumed to be a co-polymer of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) monomers, with DHI being the major component. The solution phase investigation into the origin of broadband monotonic absorption spectrum of melanin has been realized through the polymerization of dopamine and L-DOPA, the molecular precursors of DHI and DHICA, respectively, in an ionic liquid (IL). The evolution of the electronic absorption spectrum of polymerized L-DOPA did not mimic the electronic spectrum of eumelanin, which was attributed to their inability to form stable redox states, as elucidated via structural characterization. In contrast, polymerized DA (pDA) mimics the eumelanin absorption spectrum, and the structural characterization of the polymerization process performed with 1 H and 13 C NMR and DOSY spectroscopy allowed us to identify chromophores responsible for the absorption profile of pDA. Furthermore, the identified chromophores were subjected to quantum chemical calculations, and the predicted absorption spectra not only supported their presence in the experimental UV-Vis spectra but also allowed us to identify their gradual evolution during polymerisation. The knowledge of the chromophores responsible for the optical properties of melanin will undoubtedly result in their increased application in functional materials.
Publisher: Elsevier BV
Date: 07-2000
Publisher: Informa UK Limited
Date: 13-01-2020
Publisher: American Chemical Society (ACS)
Date: 27-03-2002
DOI: 10.1021/MA0119631
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 12-2014
Publisher: Wiley
Date: 15-04-2000
DOI: 10.1002/(SICI)1099-0488(20000415)38:8<1078::AID-POLB8>3.0.CO;2-2
Publisher: Wiley
Date: 2000
DOI: 10.1002/1099-0488(20000701)38:13<1749::AID-POLB80>3.0.CO;2-I
Publisher: American Chemical Society (ACS)
Date: 08-03-2000
DOI: 10.1021/MA991566E
Publisher: American Chemical Society (ACS)
Date: 1999
DOI: 10.1021/MA9814402
Publisher: Wiley
Date: 05-2000
DOI: 10.1002/(SICI)1099-0488(20000501)38:9<1222::AID-POLB14>3.0.CO;2-P
Location: United States of America
No related grants have been discovered for Benny Freeman.