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Perras FA, Paterson AL. Automatic fitting of multiple-field solid-state NMR spectra. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2024; 131:101935. [PMID: 38603990 DOI: 10.1016/j.ssnmr.2024.101935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/13/2024]
Abstract
The NMR lineshapes produced by half-integer quadrupolar nuclei are sensitive to 11 distinct fit parameters per inequivalent site. To date, automatic fitting routines have failed to replace manual parameter insertion and evaluation due to the importance of local minima and the need for fitting multiple-field magic-angle spinning (MAS) and static spectra simultaneously. Herein we introduce a new tool, AMES-Fit (Automatic Multiple Experiment Simulation and Fitting), to automatically find the global best-fit simulation parameters for a series of multiple-field NMR lineshapes. AMES-Fit uses an adaptive step size random search algorithm to dynamically probe parameter space and requires minimal human input. The best fits are obtained in a few minutes of computation time that would otherwise have required several person-hours of work. The program is freely available and open-source.
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Affiliation(s)
- Frédéric A Perras
- Chemical and Biological Sciences Division, Ames National Laboratory, Ames, IA, 50011, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011, United States.
| | - Alexander L Paterson
- National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, Madison, WI, 53706, United States
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2
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Uhlig F, Stammler MB, Meurer F, Shenderovich IG, Blahut J, Wisser FM. Monitoring structure and coordination chemistry of Co 4O 4-based oxygen evolution catalysts by nitrogen-14/-15 and cobalt-59 NMR spectroscopy. Dalton Trans 2024; 53:8541-8545. [PMID: 38712528 DOI: 10.1039/d4dt01273a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
The structural features of cobalt-based oxygen evolution catalysts are elucidated by combining high-field MAS NMR spectroscopy and DFT calculations. The superior photocatalytic activity of the heterogeneous system over its homogeneous counterpart is rationalised by the structural features. The higher activity is caused by a more favourable electron-withdrawing character of the framework.
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Affiliation(s)
- Felix Uhlig
- University of Regensburg, Institute of Inorganic Chemistry, Universitätsstraße 31, 93053 Regensburg, Germany.
| | - Michael B Stammler
- University of Regensburg, Institute of Inorganic Chemistry, Universitätsstraße 31, 93053 Regensburg, Germany.
| | - Florian Meurer
- University of Regensburg, Institute of Inorganic Chemistry, Universitätsstraße 31, 93053 Regensburg, Germany.
- Rossendorf Beamline, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Ilya G Shenderovich
- University of Regensburg, Institute of Organic Chemistry, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Jan Blahut
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic.
| | - Florian M Wisser
- University of Regensburg, Institute of Inorganic Chemistry, Universitätsstraße 31, 93053 Regensburg, Germany.
- Erlangen Center for Interface Research and Catalysis, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
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3
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Boopalan S, Antony A, Loyid NS, Vijaikanth V, Murugan S. Synthesis, characterization, X-ray crystal structures and antibacterial properties of cobaloximes with aniline based ligands containing acid functionality. INORG NANO-MET CHEM 2022. [DOI: 10.1080/24701556.2021.2025076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- S. Boopalan
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - Aneesha Antony
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - Nienu Susan Loyid
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - V. Vijaikanth
- Department of Applied Chemistry, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - S. Murugan
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
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4
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Tuning the reactivity of cobalt-based H2 production electrocatalysts via the incorporation of the peripheral basic functionalities. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213335] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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5
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Dolui D, Khandelwal S, Shaik A, Gaat D, Thiruvenkatam V, Dutta A. Enzyme-Inspired Synthetic Proton Relays Generate Fast and Acid-Stable Cobalt-Based H2 Production Electrocatalysts. ACS Catal 2019. [DOI: 10.1021/acscatal.9b02953] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | | | | | - Deepika Gaat
- Chemistry Department, Uka Tarsadia University, Bardoli, Gujarat 394350, India
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6
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Vetrik M, Parizek M, Hadraba D, Kukackova O, Brus J, Hlidkova H, Komankova L, Hodan J, Sedlacek O, Slouf M, Bacakova L, Hruby M. Porous Heat-Treated Polyacrylonitrile Scaffolds for Bone Tissue Engineering. ACS APPLIED MATERIALS & INTERFACES 2018; 10:8496-8506. [PMID: 29437373 DOI: 10.1021/acsami.7b18839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Heat-treated polyacrylonitrile (HT-PAN), also referred to as black orlon (BO), is a promising carbon-based material used for applications in tissue engineering and regenerative medicine. To the best of our knowledge, no such complex bone morphology-mimicking three-dimensional (3D) BO structure has been reported to date. We report that BO can be easily made into 3D cryogel scaffolds with porous structures, using succinonitrile as a porogen. The cryogels possess a porous morphology, similar to bone tissue. The prepared scaffolds showed strong osteoconductive activity, providing excellent support for the adhesion, proliferation, and mitochondrial activity of human bone-derived cells. This effect was more apparent in scaffolds prepared from a matrix with a higher content of PAN (i.e., 10% rather than 5%). The scaffolds with 10% of PAN also showed enhanced mechanical properties, as revealed by higher compressive modulus and higher compressive strength. Therefore, these scaffolds have a robust potential for use in bone tissue engineering.
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Affiliation(s)
- Miroslav Vetrik
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Martin Parizek
- Institute of Physiology of the Czech Academy of Sciences , Videnska 1083 , 14220 Prague 4 , Czech Republic
| | - Daniel Hadraba
- Institute of Physiology of the Czech Academy of Sciences , Videnska 1083 , 14220 Prague 4 , Czech Republic
| | - Olivia Kukackova
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Jiri Brus
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Helena Hlidkova
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Lucie Komankova
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Jiri Hodan
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Ondrej Sedlacek
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Miroslav Slouf
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
| | - Lucie Bacakova
- Institute of Physiology of the Czech Academy of Sciences , Videnska 1083 , 14220 Prague 4 , Czech Republic
| | - Martin Hruby
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences , Heyrovsky Sq. 2 , 162 06 Prague 6 , Czech Republic
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Cerreia Vioglio P, Chierotti MR, Gobetto R. Pharmaceutical aspects of salt and cocrystal forms of APIs and characterization challenges. Adv Drug Deliv Rev 2017; 117:86-110. [PMID: 28687273 DOI: 10.1016/j.addr.2017.07.001] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/23/2017] [Accepted: 07/03/2017] [Indexed: 11/28/2022]
Abstract
In recent years many efforts have been devoted to the screening and the study of new solid-state forms of old active pharmaceutical ingredients (APIs) with salification or co-crystallization processes, thus modulating final properties without changing the pharmacological nature. Salts, hydrates/solvates, and cocrystals are the common solid-state forms employed. They offer the intriguing possibility of exploring different pharmaceutical properties for a single API in the quest of enhancing the final drug product. New synthetic strategies and advanced characterization techniques have been recently proposed in this hot topic for pharmaceutical companies. This paper reviews the recent progresses in the field particularly focusing on the characterization challenges encountered when the nature of the solid-state form must be determined. The aim of this article is to offer the state-of-the-art on this subject in order to develop new insights and to promote cooperative efforts in the fascinating field of API salt and cocrystal forms.
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Affiliation(s)
| | - Michele R Chierotti
- Department of Chemistry, University of Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Roberto Gobetto
- Department of Chemistry, University of Torino, Via P. Giuria 7, 10125 Torino, Italy.
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Gunther WR, Michaelis VK, Griffin RG, Román-Leshkov Y. Interrogating the Lewis Acidity of Metal Sites in Beta Zeolites with 15N Pyridine Adsorption Coupled with MAS NMR Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:28533-28544. [PMID: 28479940 PMCID: PMC5419043 DOI: 10.1021/acs.jpcc.6b07811] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The Lewis acidity of isolated framework metal sites in Beta zeolites was characterized with 15N isotopically labeled pyridine adsorption coupled with magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The 15N chemical shift of adsorbed pyridine was found to scale with the acid character of both Lewis (Ti, Hf, Zr, Nb, Ta, and Sn) and Brønsted (B, Ga, and Al) acidic heteroatoms. The 15N chemical shift showed a linear correlation with Mulliken electronegativity of the metal center in the order Ti < Hf < Zr < Nb < Ta < Sn < H+. Theoretical calculations using density functional theory (DFT) showed a strong correlation between experimental 15N chemical shift and the calculated metal-nitrogen bond dissociation energy, and revealed the importance of active site reorganization when determining adsorption strength. The relationships found between 15N pyridine chemical shift and intrinsic chemical descriptors of metal framework sites complement adsorption equilibrium data and provide a robust method to characterize, and ultimately optimize, metal-reactant binding and activation for Lewis acid zeolites. Direct 15N MAS NMR detection protocols applied to the Lewis acid-base adducts allowed the differentiation and quantification of framework metal sites in the presence of extraframework oxides, including highly quadrupolar nuclei that are not amenable for quantification with conventional NMR methods.
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Affiliation(s)
- William R. Gunther
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Vladimir K. Michaelis
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yuriy Román-Leshkov
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Corresponding Author: . Tel: +1-617-253-7090
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9
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Kumar K, Gupta BD. Synthesis, characterization and structure–property relationship studies of cobaloximes with dithienylglyoxime as the equatorial ligand. J Organomet Chem 2011. [DOI: 10.1016/j.jorganchem.2011.08.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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10
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Helten H, Schnakenburg G, Daniels J, Arduengo AJ, Streubel R. When Sterics Overcome Electronics: An Unusual Haptotropic P→N Pentacarbonyltungsten Shift. Organometallics 2010. [DOI: 10.1021/om1007709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Holger Helten
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
| | - Gregor Schnakenburg
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
| | - Jörg Daniels
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
| | - Anthony J. Arduengo
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Rainer Streubel
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
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12
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Ooms KJ, Bernard GM, Kadziola A, Kofod P, Wasylishen RE. Solid-state 13C and 59Co NMR spectroscopy of 13C-methylcobalt(iii) complexes with amine ligands. Phys Chem Chem Phys 2009; 11:2690-9. [PMID: 19421527 DOI: 10.1039/b820753d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Five octahedral Co(iii) cations, [trans-Co(en)(2)(X)((13)CH(3))](n+) where en = ethylenediamine, X = CN(-), N(3)(-), NH(3), NO(2)(-) or H(2)O and n = 1 or 2, as well as [Co(NH(3))(5)(13)CH(3)](2+), have been investigated by solid-state (13)C and (59)Co NMR spectroscopy. We show that the determination of the (59)Co nuclear quadrupolar parameters both directly via(59)Co NMR and indirectly via(13)C NMR provide complementary information that is unavailable if one investigates only one nucleus. Specifically, (1)J((59)Co,(13)C) and the orientation of the largest component of the EFG were determined via(13)C NMR spectroscopy, which also established the negative sign of C(Q)((59)Co). Cobalt-59 NMR spectroscopy was used to characterize the cobalt magnetic shielding tensor, to verify the magnitudes of C(Q)((59)Co) and to establish the value of eta(Q), which is difficult to determine indirectly. The measurements show that the EFG tensors are either axially symmetric or close to being so, but there is a wide range of C(Q) values, from -40 MHz for the complex with X = H(2)O to -105 MHz with X = CN(-). The Co chemical shift tensors are approximately axially symmetric with the spans, delta(11)-delta(33), ranging from 3700 to 5600 ppm for X = H(2)O and CN(-), respectively. The latter measurements also established the relative orientations of the Co EFG and chemical shift tensors. Density functional theory calculations of the (59)Co EFG and magnetic shielding tensors as well as of (1)J((59)Co,(13)C) for the NO(2)(-) and N(3)(-) complexes were undertaken. These calculations confirm the experimental observation that the sign of C(Q) is negative and that the largest component of the EFG is along the Co-methyl-carbon bond.
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Affiliation(s)
- Kristopher J Ooms
- Gunning-Lemieux Chemistry Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, CanadaT6G 2G2
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13
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Hamaed H, Lo AYH, May LJ, Taylor JM, Shimizu GH, Schurko RW. Investigation of Silver-Containing Layered Materials and Their Interactions with Primary Amines Using Solid-State 109Ag and 15N NMR Spectroscopy and First Principles Calculations. Inorg Chem 2008; 47:11245-56. [DOI: 10.1021/ic801549p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hiyam Hamaed
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Andy Y. H. Lo
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Leslie J. May
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Jared M. Taylor
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - George H. Shimizu
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Robert W. Schurko
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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Pazderski L. 15N NMR coordination shifts in Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2'-terpyridine and their alkyl or aryl derivatives. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2008; 46 Suppl 1:S3-S15. [PMID: 18855335 DOI: 10.1002/mrc.2301] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The 15N NMR data for 105 complexes of Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with simple azines such as pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2''-terpyridine and their alkyl or aryl derivatives have been reviewed. The 15N NMR coordination shifts, i.e. the differences between the 15N chemical shifts of the same nitrogen in the molecules of the complex and the ligand (Delta(15N) (coord) = delta(15N) (compl)--delta(15N) (lig)), have been related to some structural features of the reviewed coordination compounds, like the type of the central ion and the character of auxiliary ligands (mainly in trans position). These Delta(15N) (coord) parameters are negative, their absolute magnitudes (ca 30-150 ppm) generally increasing in the metal order Au(III) < Pd(II) < Pt(II) and Rh(III) < Co(III) < Pt(IV) < Ir(III), as well as with the enhanced trans influence of the other donor atoms (H, C << Cl < N).
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Affiliation(s)
- Leszek Pazderski
- Faculty of Chemistry, Nicholas Copernicus University, Gagarina 7, PL-87100 Toruń, Poland.
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Hua L, Huang X, Liu P, Zhou R, Berne BJ. Nanoscale dewetting transition in protein complex folding. J Phys Chem B 2007; 111:9069-77. [PMID: 17608515 PMCID: PMC3047478 DOI: 10.1021/jp0704923] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a previous study, a surprising drying transition was observed to take place inside the nanoscale hydrophobic channel in the tetramer of the protein melittin. The goal of this paper is to determine if there are other protein complexes capable of displaying a dewetting transition during their final stage of folding. We searched the entire protein data bank (PDB) for all possible candidates, including protein tetramers, dimers, and two-domain proteins, and then performed the molecular dynamics (MD) simulations on the top candidates identified by a simple hydrophobic scoring function based on aligned hydrophobic surface areas. Our large scale MD simulations found several more proteins, including three tetramers, six dimers, and two two-domain proteins, which display a nanoscale dewetting transition in their final stage of folding. Even though the scoring function alone is not sufficient (i.e., a high score is necessary but not sufficient) in identifying the dewetting candidates, it does provide useful insights into the features of complex interfaces needed for dewetting. All top candidates have two features in common: (1) large aligned (matched) hydrophobic areas between two corresponding surfaces, and (2) large connected hydrophobic areas on the same surface. We have also studied the effect on dewetting of different water models and different treatments of the long-range electrostatic interactions (cutoff vs PME), and found the dewetting phenomena is fairly robust. This work presents a few proteins other than melittin tetramer for further experimental studies of the role of dewetting in the end stages of protein folding.
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Affiliation(s)
- Lan Hua
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Xuhui Huang
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Pu Liu
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Ruhong Zhou
- Department of Chemistry, Columbia University, New York, New York 10027
- Computational Biology Center, IBM Thomas J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598
| | - Bruce J. Berne
- Department of Chemistry, Columbia University, New York, New York 10027
- Computational Biology Center, IBM Thomas J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598
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Maccarini M, Steitz R, Himmelhaus M, Fick J, Tatur S, Wolff M, Grunze M, Janecek J, Netz RR. Density depletion at solid-liquid interfaces: a neutron reflectivity study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:598-608. [PMID: 17209611 DOI: 10.1021/la061943y] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Neutron reflectivity experiments conducted on self-assembled monolayers (SAMs) against polar (water) and nonpolar (organic) liquid phases reveal further evidence for a density reduction at hydrophobic-hydrophilic interfaces. The density depletion is found at the interface between hydrophobic dodecanethiol (C12) and hexadecanethiol (C16) SAMs and water and also between hydrophilic SAMs (C12/C11OH) and nonpolar fluids. The results show that the density deficit of a fluid in the boundary layer is not unique to aqueous solid-liquid interfaces but is more general and correlated with the affinity of the liquid to the solid surface. In water the variation of pH has only minor influence, while different electrolytes taken from the Hofmeister series seem to increase the depletion. On hydrophobic SAMs an increase in density depletion with temperature was observed, in agreement with Monte Carlo simulations performed on corresponding model systems. The increase in the water density depletion layer is governed by two effects: the surface energy difference between water and the substrate and the chemical potential of the aqueous phase.
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Affiliation(s)
- M Maccarini
- Institut für Angewandte Physikalische Chemie, Ruprecht Karls Universität Heidelberg, Im Neuenheimer Feld 253, D-69120, Heidelberg, Germany.
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Ooms KJ, Wasylishen RE. NMR spectroscopy of the solid-state isomerization of nitrito- and nitro-pentamminecobalt(III) chloride. CAN J CHEM 2006. [DOI: 10.1139/v06-001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cobalt-59 and nitrogen-15 NMR spectra of the nitritopentamminecobalt(III) chloride, [(NH3)5Co-ONO]Cl2, and nitropentamminecobalt(III) chloride, [(NH3)5Co-NO2]Cl2, isomers in the solid state have been obtained at several applied magnetic field strengths. The 59Co NMR line shapes indicate that both the cobalt nuclear quadrupolar coupling constant (CQ) and the span of the chemical shift tensor (Ω) decrease when the complex isomerizes from [(NH3)5Co-ONO]2+ to [(NH3)5Co-NO2]2+; CQ decreases from 23 to 10.3 MHz and Ω changes from 1650 to 260 ppm. The 15N NMR line shapes also show a significant change in the nitrogen magnetic shielding tensor upon isomerization, with Ω decreasing from 710 to 547 ppm; also, an indirect spin-spin coupling, 1J(59Co,15N) = 63 Hz, is observed in the 15N NMR spectra of the nitro isomer. The NMR parameters are rationalized based on differences in the molecular structure of the two isomers. NMR spectra have also been recorded as the isomerization progresses with time and demonstrate the practicality of the technique for the study of solid-state isomerizations.Key words: 15N, 59Co, solid-state NMR, linkage isomerization, chemical shift tensor, electric field gradient tensor.
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Facey GA, Kuang W, Detellier C. Multinuclear Magnetic Resonance Spectroscopy Studies of the Structuration of the Tunnels of Sepiolite in the Presence of Intracrystalline Pyridine Molecules. J Phys Chem B 2005; 109:22359-65. [PMID: 16853912 DOI: 10.1021/jp053832y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sepiolite, a naturally occurring magnesiosilicate nanoporous clay mineral with a tunnel structure, contains two types of water molecules in the structure: zeolitic water trapped inside the tunnels and structural water molecules which interact strongly with magnesium cations. The zeolitic water was removed by heating the sepiolite to 120 degrees C. The partially dehydrated sepiolite absorbed pyridine vapor to produce an intercalated material where the pyridine takes the place of the zeolitic water. 1H solid-state MAS NMR spectroscopy showed that there is isotopic H/D exchange between pyridine-d5 and the remaining structural water molecules of the sepiolite framework. The exchange takes place at room temperature over several days. Wide line solid state 2H NMR of the sequestered pyridine-d5 showed that two populations of pyridine molecules coexist in the material: one very mobile physisorbed population, which can be removed by heating at 90 degrees C, and a population due to pyridine trapped in the tunnels. Except for small in-plane librations, the trapped pyridine was shown to be held rigidly by the sepiolite. When the pyridine intercalated material is heated at 400 degrees C the structural water and some of the pyridine is lost. The remaining pyridine takes the place of the structural water to produce a new inorganic-organic nanohybrid material with the pyridine bound to the terminal Mg(II) in the structure. The pyridine in this material as well as the intercalated material was characterized by slow-spinning 15N and 13C CP/MAS NMR spectroscopy. The 15N NMR was shown to be a very sensitive probe to characterize the various types of pyridine. The data indicate that pyridine molecules in the inorganic-organic nanohybrid material are directly bound to magnesium cations exposed in the tunnels of sepiolite.
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Affiliation(s)
- Glenn A Facey
- Center for Research and Innovation in Catalysis and Department of Chemistry, University of Ottawa, Ottawa (Ontario), Canada K1N6N5
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19
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Mandal D, Gupta BD. Cobaloximes with Dimesitylglyoxime: Synthesis, Characterization, and Spectral Correlations with the Related Cobaloximes. Organometallics 2005. [DOI: 10.1021/om049096m] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Debaprasad Mandal
- Department of Chemistry, Indian Institute of Technology, Kanpur, India 208016
| | - B. D. Gupta
- Department of Chemistry, Indian Institute of Technology, Kanpur, India 208016
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20
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Forgeron MAM, Bryce DL, Wasylishen RE, Rösler R. A Solid-State Multinuclear Magnetic Resonance Investigation of Hexamethylborazine. J Phys Chem A 2003. [DOI: 10.1021/jp022139x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michelle A. M. Forgeron
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - David L. Bryce
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Roderick E. Wasylishen
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Roland Rösler
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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21
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Gee M, Wasylishen RE, Ragogna PJ, Burford N, McDonald R. Characterization of indirect 31P-31P spin-spin coupling and phosphorus chemical shift tensors in pentaphenylphosphinophosphonium tetrachlorogallate, [Ph3P-PPh2][GaCl4]. CAN J CHEM 2002. [DOI: 10.1139/v02-178] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphorus chemical shift and 31P,31P spin-spin coupling tensors have been characterized for pentaphenylphosphinophosphonium tetrachlorogallate, [Ph3P-PPh2][GaCl4], using solid-state 31P NMR spectroscopy. Spectra obtained with magic-angle spinning yield the isotropic value of the indirect spin-spin coupling, |1J(31P,31P)iso|, 323 ± 2 Hz, while 2D spin-echo and rotational resonance experiments provide the effective dipolar coupling constant, Reff, 1.70 ± 0.02 kHz, and demonstrate that Jiso is negative. Within experimental error, the effective dipolar coupling constant and Jiso are unchanged at 120°C. The anisotropy in 1J(31P,31P), ΔJ, has been estimated by comparison of Reff and the value of the dipolar coupling constant, RDD, calculated from the PP bond length as determined by X-ray diffraction. It is concluded that |ΔJ| is small, with an upper limit of 300 Hz. Calculations of 1J(31P,31P) for model systems H3P-PH+2 and (CH3)3P-P(CH3)+2 using density functional theory as well as multiconfigurational self-consistent field theory (H3P-PH+2) support this conclusion. The experimental spin-spin coupling parameters were used to analyze the 31P NMR spectrum of a stationary powder sample and provide information about the phosphorus chemical shift tensors. The principal components of the phosphorus chemical shift tensor for the phosphorus nucleus bonded to three phenyl groups are δ11 = 36 ppm, δ22 = 23 ppm, and δ33 = 14 ppm with an experimental error of ±2 ppm for each component. The components are oriented such that δ33 is approximately perpendicular to the PP bond while δ11 forms an angle of 31° with the PP bond. For the phosphorus nucleus bonded to two phenyl groups, the principal components of the phosphorus chemical shift tensor are δ11 = 23 ppm, δ22 = 8 ppm, and δ33 = 68 ppm with experimental errors of ±2 ppm. In this case, δ33 is also approximately perpendicular to the PP bond; however, δ22 is close to the PP bond for this phosphorus nucleus, forming an angle of 13°. The dihedral angle between the δ33 components of the two phosphorus chemical shift tensors is 25°. Results from ab initio calculations are in good agreement with experiment and suggest orientations of the phosphorus chemical shift tensors in the molecular frame of reference.Key words: Nuclear magnetic resonance spectroscopy, phosphorus chemical shift tensors, 31P-31P J-coupling tensors, density functional theory, multiconfigurational self-consistent field theory, phosphinophosphonium salts.
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22
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Geller JM, Wosnick JH, Butler IS, Gilson DFR, Morin FG, Bélanger-Gariépy F. X-ray diffraction, Raman spectroscopic, and solid-state NMR studies of the group 14 metal-(tetracarbonyl)cobalt complexes Ph3MCo(CO)4 (M = Si, Sn, Pb). CAN J CHEM 2002. [DOI: 10.1139/v02-110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Single-crystal X-ray diffraction studies illustrate that the three title compounds are isomorphous, belonging to the triclinic space group P[Formula: see text], with slightly distorted trigonal bipyramidal geometry about cobalt. The solid-state 29Si, 119Sn, and 207Pb cross-polarization magic angle spinning (CP MAS) NMR spectra are presented. The indirect spinspin coupling constant (J), quadrupolardipolar shift (d), direct dipolar coupling constant (D' ), anisotropy in spinspin coupling (ΔJ), and the chemical shift tensor were extracted. A plot of the reduced coupling constant vs. s-electron densities at the nucleus indicates that the Fermi contact term may be dominant for the tin and lead complexes; however, the large ΔJ for all complexes indicate that there are also significant anisotropic terms. Trends in the Raman scattering spectra are also discussed.Key words: 29Si, 119Sn, and 207Pb CP MAS NMR, tetracarbonyl cobalt, spinspin coupling, chemical shift tensor, quadrupole coupling, Fermi contact, cobaltgroup 14.
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23
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Mason J, Larkworthy LF, Moore EA. Nitrogen NMR spectroscopy of metal nitrosyls and related compounds. Chem Rev 2002; 102:913-34. [PMID: 11942783 DOI: 10.1021/cr000075l] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joan Mason
- Departments of Chemistry, Cambridge University, University of Surrey, The Open University, U.K
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