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K S N, Kumar TN, Reddy Singam SS, Chaudhari SR. Selective Homodecoupled 1D- 1H NMR Experiment for Unravelling Enantiomers. Anal Chem 2022; 94:10299-10303. [PMID: 35834712 DOI: 10.1021/acs.analchem.2c01020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1H NMR spectroscopy is a quick and easy tool to resolve enantiomers. However, the paradigm of resolution of enantiomers by 1H NMR is a difficult task due to the minor chemical shift differences and overlap of the resonances of the enantiomers. In the current study, we have performed the conventional selective homodecoupling 1D-1H NMR experiment to achieve chiral resolutions. The predominant features of the proposed methods are (a) high sensitivity as opposed to routinely employed pure shift NMR experiments, (b) easy optimization like conventional 1D-1H NMR, and (c) an artifact-free spectrum. The application of the method has been exhibited in the measurement of proton chemical shift differences between diastereomers and enantiomer excess (ee). The broad use of the proposed method was demonstrated by employing the six samples utilizing the chiral solvating and derivatizing agents.
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Affiliation(s)
- Naresh K S
- Department of Spice and Flavour Science, CSIR - Central Food Technological Research Institute, Mysuru, Karnataka 570020, India.,AcSIR - Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh 201002, India
| | - Theerthan N Kumar
- Department of Spice and Flavour Science, CSIR - Central Food Technological Research Institute, Mysuru, Karnataka 570020, India
| | - Siva Sankara Reddy Singam
- Department of Food Safety and Analytical Quality Control Laboratory, CSIR - Central Food Technological Research Institute, Mysuru, Karnataka 570020, India.,AcSIR - Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh 201002, India
| | - Sachin R Chaudhari
- Department of Spice and Flavour Science, CSIR - Central Food Technological Research Institute, Mysuru, Karnataka 570020, India.,AcSIR - Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh 201002, India
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2
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Groleau RR, James TD, Bull SD. The Bull-James assembly: Efficient iminoboronate complex formation for chiral derivatization and supramolecular assembly. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213599] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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3
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Prasad D, Mogurampelly S, Chaudhari SR. R-VAPOL-phosphoric acid based 1H and 13C-NMR for sensing of chiral amines and acids. RSC Adv 2020; 10:2303-2312. [PMID: 35494596 PMCID: PMC9048436 DOI: 10.1039/c9ra07803g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/04/2020] [Indexed: 01/07/2023] Open
Abstract
Enantiomers have significant importance in pharmaceuticals, biology and modern chemistry and therefore distinguishing and quantifying the enantiomeric forms is of utmost importance. Herein, we propose diphenyl-3,3'-biphenanthryl-4,4'-diyl phosphate (R-VAPOL-PA) as a promising chiral solvating agent to discriminate amines and acids of poly-functional groups such as chiral amines, amino alcohols and hydroxy acids. The methodological approach involves using the nature of hydrogen bonds and ion pairs as a mode of weak interactions to form diastereomers where the probe is associated with enantiomers. The resulting diastereomer difference in the NMR spectrum enables the chiral discrimination with a complete baseline peak separation and an accurate enantiomeric excess (ee) analysis. We also carried out density functional theory (DFT) calculations to understand the complex formation to explain enantiodiscrimination by analysing the formation and stability of different chiral complexes. The binding energy differences between enantiomeric forms revealed by DFT calculations are qualitatively in agreement with the diastereomer difference in the NMR spectrum and unequivocally establishes the suggested experimental protocol of R-VAPOL-PA-based enantiomeric discrimination.
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Affiliation(s)
- Durga Prasad
- Department of Spice and Flavour Science, CSIR-Central Food Technological Research Institute Mysore Karnataka 570020 India
| | - Santosh Mogurampelly
- Department of Physics, Indian Institute of Technology Jodhpur Karwar Rajasthan 342037 India
| | - Sachin R Chaudhari
- Department of Spice and Flavour Science, CSIR-Central Food Technological Research Institute Mysore Karnataka 570020 India
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4
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Lima YR, Peglow TJ, Nobre PC, Campos PT, Perin G, Lenardão EJ, Silva MS. Chalcogen‐Containing Diols: A Novel Chiral Derivatizing Agent for
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Se and
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Te NMR Chiral Recognition of Primary Amines. ChemistrySelect 2019. [DOI: 10.1002/slct.201900097] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yanka Rocha Lima
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
| | - Thiago Jacobsen Peglow
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
| | - Patrick Carvalho Nobre
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
| | | | - Gelson Perin
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
| | - Eder J. Lenardão
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
| | - Márcio S. Silva
- Laboratório de Síntese Orgânica Limpa – LASOLCentro de Ciências Químicas, Farmacêuticas e de Alimentos – CCQFAUniversidade Federal de Pelotas – UFPel, Capão do Leão-RS, Brazil
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5
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Nath N, Bordoloi P, Barman B, Baishya B, Chaudhari SR. Insight into old and new pure shift nuclear magnetic resonance methods for enantiodiscrimination. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:876-892. [PMID: 29411898 DOI: 10.1002/mrc.4719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 01/20/2018] [Accepted: 01/23/2018] [Indexed: 06/08/2023]
Abstract
Enantiodiscrimination and their quantification using nuclear magnetic resonance (NMR) spectroscopy has always been a subject of great interest. Proton is the nucleus of choice for enantiodiscrimination due to its high sensitivity and ubiquitous presence in nature. Despite its advantages, enantiodiscrimination suffers from extensive signal splitting by the proton-proton scalar couplings, which give complex multiplets that spread over a frequency range of some tens of hertz. These multiplets often overlap, further complicating interpretation of the spectra and quantifications. In the present review, we discuss some of the recent developments in the pure shift 1 H NMR based methods for enantiomer resolution and enantiodiscrimination. We also compare various pure shift methods used for enantiodiscrimination and measurement of enantiomeric excess, considering the fact that conventional 1 H NMR fails to provide any detailed insight.
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Affiliation(s)
- Nilamoni Nath
- Department of Chemistry, Gauhati University, Guwahati, Assam, 781014, India
| | - Priyakshi Bordoloi
- Department of Chemistry, Gauhati University, Guwahati, Assam, 781014, India
| | - Bhaskar Barman
- Department of Chemistry, Gauhati University, Guwahati, Assam, 781014, India
| | - Bikash Baishya
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow, Uttar Pradesh, 226014, India
| | - Sachin R Chaudhari
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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6
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Rachineni K, Kakita VMR, Hosur RV. Multiple homonuclear band-selective decoupling NMR: Fast and unambiguous determination of diastereomeric excess. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:1037-1042. [PMID: 28730621 DOI: 10.1002/mrc.4634] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 06/07/2023]
Abstract
Discrimination and quantification of chiral stereoisomers have been studied by different analytical methods, and NMR has emerged as a powerful one with the advancements in pure-shift NMR methods. In the present manuscript, an al-F1F2-MHOBS-DIAG NMR method for the quantification of diastereomeric excess ratio (dr) has been proposed and demonstrated, using hesperidin and naringin mixtures. This method enables simultaneous quantification of dr at multiple resonances, in a single experiment, and it takes only 10 min to record. The present method uses spectral aliasing and thus demands only very few indirect dwell increments. Further, the measured dr values are very reliable, because we consider several spins for the quantification.
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Affiliation(s)
- Kavitha Rachineni
- UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santa Cruz, Mumbai, 400 098, India
| | - Veera Mohana Rao Kakita
- UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santa Cruz, Mumbai, 400 098, India
| | - Ramakrishna V Hosur
- UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santa Cruz, Mumbai, 400 098, India
- Department of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), 1-Homi Bhabha Road, Colaba, Mumbai, 400 005, India
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7
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Ema T, Yamasaki T, Watanabe S, Hiyoshi M, Takaishi K. Cross-Coupling Approach to an Array of Macrocyclic Receptors Functioning as Chiral Solvating Agents. J Org Chem 2018; 83:10762-10769. [PMID: 30126269 DOI: 10.1021/acs.joc.8b01327] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chiral macrocyclic receptors 1 with multiple hydrogen-bonding sites in the cavity were synthesized and used as NMR chiral solvating agents (CSAs). The Suzuki-Miyaura cross-coupling reaction gave rapid access to a series of variants 1b-p of unsubstituted parent compound 1a. Among them, 1d with the 4-cyanophenyl group at the 3,3'-positions of the binaphthyl moiety was the most excellent CSA for a benchmark analyte compound, 2-chloropropionic acid (CPA); both of the quartet and doublet signals of CPA were split most completely in CDCl3. Binding constants ( Ka) determined in CDCl3 by NMR titrations indicated that ( R)-1d was the most enantioselective ( Ka( S)/ Ka( R) = 5.4). Interestingly, the Ka value of ( R)-1d for ( S)-CPA (5900) was greater than that of ( R)-1a for ( S)-CPA (3080), which strongly suggests an attractive interaction between the 4-cyanophenyl group of ( R)-1d and ( S)-CPA. The X-ray crystal structure of 1d indicates that one of the two H atoms meta to the cyano group is directed toward the cavity. DFT calculations suggested that this H atom of the 4-cyanophenyl group of ( R)-1d forms a weak hydrogen bond with the Cl atom of ( S)-CPA (C-H···Cl-C hydrogen bond).
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Affiliation(s)
- Tadashi Ema
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan
| | - Takayuki Yamasaki
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan
| | - Sagiri Watanabe
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan
| | - Mahoko Hiyoshi
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan
| | - Kazuto Takaishi
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan
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8
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Parella T. Current developments in homonuclear and heteronuclear J-resolved NMR experiments. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:230-250. [PMID: 29314247 DOI: 10.1002/mrc.4706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/12/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Two-dimensional J-resolved (Jres) NMR experiments offer a simple, user-friendly spectral representation where the information of coupling constants and chemical shifts are separated into two orthogonal frequency axis. Since its initial proposal 40 years ago, Jres has been the focus of considerable interest both in improving the basic pulse sequence and in its successful application to a wide range of studies. Here, the latest developments in the design of novel Jres pulse schemes are reviewed, mainly focusing on obtaining pure absorption lineshapes, minimizing strong coupling artifacts, and also optimizing sensitivity and experimental measurements. A discussion of several Jres versions for the accurate measurement of a different number of homonuclear (JHH ) and heteronuclear (JCH ) coupling constants is presented, accompanied by some illustrative examples.
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Affiliation(s)
- Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
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9
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Farjon J, Giraud N. 1H NMR analyses of enantiomeric mixtures using chiral liquid crystals. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2017.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Lakshmipriya A, Sumana G, Suryaprakash NR. A versatile ternary ion pair complex of 2′-amino-1,1′-binaphthalen-2-ol for sensing enantiomers and assignment of absolute configuration. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.tetasy.2017.09.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Gunaratne HQN, Laaksonen T, Seddon KR, Wähälä K. 1-(+)-Dehydroabietylimidazolium Salts as Enantiomer Discriminators for NMR Spectroscopy. Aust J Chem 2017. [DOI: 10.1071/ch16545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nine new (+)-dehydroabietylimidazolium salts were synthesised and studied as chiral solvating agents for several different racemic aromatic and non-aromatic carboxylate salts. These cationic chiral solvating agents resolve racemic ionic analytes better than non-ionic ones. Bis(dehydroabietylimidazolium) bis(trifluoromethanesulfonimide) gave the best discrimination for the enantiomers of carboxylate salts. Its resolution behaviour was studied by an NMR titration experiment, which indicated 1 : 1 complexation with the racemic analyte. The dehydroabietylimidazolium salts were also useful in enantiomeric excess (ee) determinations, and for the recognition of chirality of racemic aromatic and non-aromatic α-substituted carboxylic acids.
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12
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Laaksonen T, Heikkinen S, Wähälä K. Synthesis of Tertiary and Quaternary Amine Derivatives from Wood Resin as Chiral NMR Solvating Agents. Molecules 2015; 20:20873-86. [PMID: 26610454 PMCID: PMC6332576 DOI: 10.3390/molecules201119732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/03/2015] [Accepted: 11/08/2015] [Indexed: 11/25/2022] Open
Abstract
Chiral tertiary and quaternary amine solvating agents for NMR spectroscopy were synthesized from the wood resin derivative (+)-dehydroabietylamine (2). The resolution of enantiomers of model compounds [Mosher’s acid (3) and its n-Bu4N salt (4)] (guests) by (+)-dehydroabietyl-N,N-dimethylmethanamine (5) and its ten different ammonium salts (hosts) was studied. The best results with 3 were obtained using 5 while with 4 the best enantiomeric resolution was obtained using (+)-dehydroabietyl-N,N-dimethylmethanaminium bis(trifluoromethane-sulfonimide) (6). The compounds 5 and 6 showed a 1:1 complexation behaviour between the host and guest. The capability of 5 and 6 to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu4N salts in enantiomeric excess (ee) determinations was demonstrated. A modification of the RES-TOCSY NMR pulse sequence is described, allowing the enhancement of enantiomeric discrimination when the resolution of multiplets is insufficient.
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Affiliation(s)
- Tiina Laaksonen
- Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1, P. O. Box 55, FI-00014, Helsinki 00100, Finland.
| | - Sami Heikkinen
- Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1, P. O. Box 55, FI-00014, Helsinki 00100, Finland.
| | - Kristiina Wähälä
- Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1, P. O. Box 55, FI-00014, Helsinki 00100, Finland.
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Enantio sensing property of helicin, the derivative of a natural product: Discrimination of amines and amino alcohols. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.07.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Rachineni K, Kakita VMR, Dayaka S, Vemulapalli SPB, Bharatam J. Precise Determination of Enantiomeric Excess by a Sensitivity Enhanced Two-Dimensional Band-Selective Pure-Shift NMR. Anal Chem 2015; 87:7258-66. [PMID: 26091767 DOI: 10.1021/acs.analchem.5b01288] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Unambiguous identification and precise quantification of enantiomers in chiral mixtures is crucial for enantiomer specific synthesis as well as chemical analysis. The task is often challenging for mixtures with high enantiomeric excess and for complex molecules with strong (1)H-(1)H scalar (J) coupling network. The recent advancements in (1)H-(1)H decoupling strategies to suppress the J-interactions offered new possibilities for NMR based unambiguous discrimination and quantification enantiomers. Herein, we discuss a high resolution two-dimensional pure-shift zCOSY NMR method with homonuclear band-selective decoupling in both the F1 and F2 dimensions (F1F2-HOBS-zCOSY). This advanced method shows a sharp improvement in resolution over the other COSY methods and also eliminates the problems associated with the overlapping decoupling sidebands. The efficacy of this method has been exploited for precise quantification of enantiomeric excess (ee) ratio (R/S) up to 99:1 in the presence of very low concentrations of chiral lanthanide shift reagents (CLSR) or chiral solvating agents (CSA). The F1F2-HOBS-zCOSY is simple and can be easily implemented on any modern NMR spectrometers, as a routine analytical tool.
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Affiliation(s)
- Kavitha Rachineni
- Centre for NMR and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, Telangana, India
| | - Veera Mohana Rao Kakita
- Centre for NMR and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, Telangana, India
| | - Satyanarayana Dayaka
- Centre for NMR and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, Telangana, India
| | - Sahithya Phani Babu Vemulapalli
- Centre for NMR and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, Telangana, India
| | - Jagadeesh Bharatam
- Centre for NMR and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, Telangana, India
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15
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Castañar L, Parella T. Broadband 1H homodecoupled NMR experiments: recent developments, methods and applications. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:399-426. [PMID: 25899911 DOI: 10.1002/mrc.4238] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/23/2015] [Accepted: 02/25/2015] [Indexed: 06/04/2023]
Abstract
In recent years, a great interest in the development of new broadband 1H homonuclear decoupled techniques providing simplified JHH multiplet patterns has emerged again in the field of small molecule NMR. The resulting highly resolved 1H NMR spectra display resonances as collapsed singlets, therefore minimizing signal overlap and expediting spectral analysis. This review aims at presenting the most recent advances in pure shift NMR spectroscopy, with a particular emphasis to the Zangger-Sterk experiment. A detailed discussion about the most relevant practical aspects in terms of pulse sequence design, selectivity, sensitivity, spectral resolution and performance is provided. Finally, the implementation of the different reported strategies into traditional 1D and 2D NMR experiments is described while several practical applications are also reviewed.
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Affiliation(s)
- Laura Castañar
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Barcelona, Catalonia, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Barcelona, Catalonia, Spain
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Pérez-Trujillo M, Parella T, Kuhn LT. NMR-aided differentiation of enantiomers: Signal enantioresolution. Anal Chim Acta 2015; 876:63-70. [DOI: 10.1016/j.aca.2015.02.069] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 02/21/2015] [Accepted: 02/26/2015] [Indexed: 10/23/2022]
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17
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Aguilar JA, Cassani J, Delbianco M, Adams RW, Nilsson M, Morris GA. Minimising Research Bottlenecks by Decluttering NMR Spectra. Chemistry 2015; 21:6623-30. [DOI: 10.1002/chem.201406283] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/27/2015] [Indexed: 11/11/2022]
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18
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Laaksonen T, Heikkinen S, Wähälä K. Synthesis and applications of secondary amine derivatives of (+)-dehydroabietylamine in chiral molecular recognition. Org Biomol Chem 2015; 13:10548-55. [DOI: 10.1039/c5ob01667c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
(+)-Dehydroabietylamine (1a), the novel derivatives (2a–6a) and their NTf2 salts (1b–6b) were tested as chiral NMR solvating agents for the resolution of enantiomers of Mosher's acid and other carboxylic acids, and their n-Bu4N salts.
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Affiliation(s)
- Tiina Laaksonen
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki
- Finland
| | - Sami Heikkinen
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki
- Finland
| | - Kristiina Wähälä
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki
- Finland
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19
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Lakshmipriya A, Chaudhari SR, Suryaprakash N. Enantio-differentiation of molecules with diverse functionalities using a single probe. Chem Commun (Camb) 2015. [DOI: 10.1039/c5cc05290d] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Chiral discrimination of molecules with diverse functionalities using a single CSA.
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Affiliation(s)
- A. Lakshmipriya
- NMR Research Centre
- Bangalore-560012
- India
- Solid State and Structural Chemistry Unit
- Bangalore-560012
| | | | - N. Suryaprakash
- NMR Research Centre
- Bangalore-560012
- India
- Solid State and Structural Chemistry Unit
- Bangalore-560012
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20
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RES-TOCSY: A facile approach for accurate determination of magnitudes, and relative signs of nJHF. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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