NMR Spectroscopy

Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei. It determines the physical and chemical properties of atoms or the molecules in which they are contained.

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Infrared Spectroscopy

Infrared spectroscopy (IR spectroscopy) is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy.

Mass Spectrometry

Mass spectrometry (MS) is an analytical chemistry technique that helps identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions.

UV-Visible Spectroscopy

Ultraviolet–visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis) refers to absorption spectroscopyor reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent (near-UV and near-infrared [NIR]) ranges.

NMR Spectroscopy

This section consists of all NMR Spectroscopy related articles.

IR Spectroscopy

This section consists of all Infra-Red (IR) Spectroscopy related articles.

Mass Spectrometry

This section consists of all Mass Spectrometry related articles.

UV-Visible Spectroscopy

This section consists of all UV-Visible Spectroscopy related articles.


Structural Elucidation of Small Organic Molecules by 1D, 2D and Multi Dimensional-Solution NMR Spectroscopy

Structural Elucidation of Small Organic Molecules by 1D, 2D and Multi Dimensional-Solution NMR Spectroscopy

For the last fifty years nuclear magnetic resonance spectroscopy, generally referred as NMR, is one of the most versatile techniques for elucidation of structure of organic compounds. Among all available spectrometric methods, NMR is the only technique which offers a complete analysis and interpretation of the entire spectrum. Due to improved experimental technology and novel approaches, over the last decade nuclear magnetic resonance (NMR) has shown a tremendous progress. Generally, NMR spectroscopy makes use of three approaches; those are one dimension (1D), two dimensions (2D) and three dimensions (3D). Usually, the first approach of 1D-NMR (1H DEPT, 13C, 15N, 19F, 31P, etc.) generates good information about the structure of simple organic compounds, but in case of larger molecules the 1D-NMR spectra are generally overcrowded. Hence, the second approach of 2D-NMR (COSY, DQFCOSY, MQFCOSY, HETCOR, HSQC, HMQC, HMBC, TOCSY, NOESY, EXSY, etc.) is used for the further larger molecules, but 2D-NMR spectra also becomes complex and overlapping when used for further very large molecules like proteins. Hence, so as to achieve high resolution and reduced overlapping in spectra of very large molecules, Multi Dimensional-NMR (Homonuclear and Heteronuclear) are generally used. This paper supports interpretation of structure of different organic compounds by different NMR techniques. Introduction NMR spectroscopy was discovered after the second world war and was developed from experiments performed to accurately measure the nuclear magnetogyric ratio about seventy years ago [1]. Purcell et al. at Harvard and Bloch et al. at Stanford in 1945 reported the first observation of nuclear magnetic resonance in bulk matter for which they were jointly awarded with Nobel Prize for physics in 1952. Since... read more
How to Interpret Proton NMR Spectra

How to Interpret Proton NMR Spectra

NMR Spectroscopy Series Nuclear Magnetic Resonance (NMR) Spectroscopy – An Overview  How to Interpret Proton NMR Spectra (you are currently reading) Nuclear Spin: The Origin of the Signal Detecting the Signal: Fourier Transform NMR Spectrometers Shielding and Deshielding of Protons The Chemical Shift Chemical Shift Equivalent and Nonequivalent Protons Signal Splitting: Spin–Spin Coupling Proton NMR Spectra and Rate Processes Carbon-13 NMR Spectroscopy Two-Dimensional (2D) NMR Techniques Now that we have had an introduction to key aspects of 1H NMR spectra (chemical shift, peak area, and signal splitting), we can start to apply 1H NMR spectroscopy to elucidating the structure of unknown compounds. The following steps summarize the process: Count the number of signals to determine how many distinct proton environments are in the molecule (neglecting, for the time being, the possibility of overlapping signals). Use chemical shift tables or charts to correlate chemical shifts with possible structural environments. Determine the relative area of each signal, as compared with the area of other signals, as an indication of the relative number of protons producing the signal. Interpret the splitting pattern for each signal to determine how many hydrogen atoms are present on carbon atoms adjacent to those producing the signal and sketch possible molecular fragments. Join the fragments to make a molecule in a fashion that is consistent with the data. let’s interpret the 1H NMR spectrum for a compound with the molecular formula C3H7Br. First, we observe that there are three distinct signals, with chemical shifts of approximately δ 3.4, 1.8, and 1.1. One of these signals (δ 3.4) is noticeably downfield of the others, indicating hydrogen atoms that are... read more
Nuclear Magnetic Resonance Spectroscopy (NMR spectroscopy) – An Overview

Nuclear Magnetic Resonance Spectroscopy (NMR spectroscopy) – An Overview

Have you known someone who needed an MRI (magnetic resonance imaging) scan for a medical condition, or have you needed one yourself? Have you ever observed someone in an airport security line having their belongings wiped down with a pad which was then placed in some kind of analytical instrument? Have you wondered how scientists determine the structures of compounds found in nature, or have you known a fellow student in a laboratory class who extracted bark, leaves, or fruit to isolate and identify some natural compounds? Or have you wondered how forensic evidence is analyzed in criminal cases, or how pesticides are identified in food samples? If you have wondered about any of these things, then some of your curiosity will be satisfied by learning about spectroscopic methods such as nuclear magnetic resonance (NMR) spectroscopy, which involves the same physical principles as MRI imaging, and MS (mass spectrometry), which is used in some airport screening processes as well as many forensic applications. NMR and MS are workhorse techniques for the study of both biological and nonbiological molecular structure. NMR Spectroscopy Series Nuclear Magnetic Resonance (NMR) Spectroscopy – An Overview (you are currently here) How to Interpret Proton NMR Spectra Nuclear Spin: The Origin of the Signal Detecting the Signal: Fourier Transform NMR Spectrometers Shielding and Deshielding of Protons The Chemical Shift Chemical Shift Equivalent and Nonequivalent Protons Signal Splitting: Spin–Spin Coupling Proton NMR Spectra and Rate Processes Carbon-13 NMR Spectroscopy Two-Dimensional (2D) NMR Techniques   What is Spectroscopy? Spectroscopy is the study of the interaction of energy with matter. When energy is applied to matter, it can be... read more

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