NUCLEAR MEGNETIC RESONANCE SPECTROSCOPY

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detail of nmr

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NUCLEAR MaGNETIC RESONANCE SPECTROSCOPY : 

NUCLEAR MaGNETIC RESONANCE SPECTROSCOPY PRESENTED BY SRAVYA.K (MPHARMACY ) PHARMACEUTICAL ANALYSIS AND QUALITY ASSURANCE AVANTHI INSTITUTE OF PHARMACEUTICAL SCIENCES

Aim : 

Aim To understand the details of how N m r works Objective Structural elucidation drug design

INTRODUCTION TO NMR : 

INTRODUCTION TO NMR N m r spectroscopy is a powerful analytical technique used to characterize organic molecules by identifying carbon-hydrogen frame works within molecules. NMR = Nuclear: properties of atomic nuclei Magnetic: magnetic field is required Resonance: interaction magnetic field and radio frequency The source of energy in NMR is radio waves which have long wavelengths, and thus low energy and frequency

N m r spectroscopy range : 

N m r spectroscopy range There is no NMR signal for the nuclei having even atom number or even mass number The radio frequency radiation has the frequency range of 4-600 MHz corresponded to the wavelength region of 75-0.5 m.

NMR Theory : 

NMR Theory That means that the nucleus acts as a small magnet Nuclei with odd atomic number (1H, 13C, 15N, etc.) have half integer nuclear spin.

NMR THEORY : 

NMR THEORY In the absence of a magnetic field these nuclei point in random directions. In the presence of a magnetic field B0 they will align either parallel or anti-parallel to the magnetic field. The parallel orientation is lower in energy.

NMR Theory : 

NMR Theory Depending on the environment of a nucleus and the interactions it makes, a specific amount of energy will be required to make it resonant. The amount of energy absorbed for flipping is detected by the NMR spectrometer.

Spin quantum of various nuclei : 

Spin quantum of various nuclei

Principle : 

Principle When energy in the form of radio frequency is applied and when l Absorption of energy occurs and N m r signal is recorded

Principle : 

Principle The nuclei are said to be in resonance and the energy they emit when flipping from the high to the low energy state can be measured

FLOW CHART OF NMR INSTRUMENTATION : 

FLOW CHART OF NMR INSTRUMENTATION According to resolution NMR spectroscopy can be a. low resolution/wide line instrument b. high resolution instrument

INSTRUMENTATION : 

INSTRUMENTATION

Chapter 13 14 The NMR Spectrometer =>

Sample holder and probe : 

Sample holder and probe Sample cell consists of 5mm out side diameter glass tube containing 500-650µLof liquid Contain air turbine to spin the sample. Houses the coils that permit excitation & detection of NMR signal.

Magnet : 

Magnet It is the heart of NMR instrument. Sensitivity & resolution of spectrometer are dependent on strength & quality of magnet. Sensitivity & resolution increases with increase in field strength. Field strength must be homogeneous and reproducible. Two types of magnets one is permanent magnet other one is convectional electro magnet

Super conducting selnoids : 

Super conducting selnoids Wounded from niobium-tin, niobium-titanium. Operates in liquid helium crystal at temp.4K & used in high resolution instrument. Magnet attain field as large as 23T & frequency of 1GHz Most S.S. are filled with nitrogen. Advantage-High stability, -simplicity-high field strength ,-small size

RADIOFREQUENCY GENERATOR /TRANSMITTER : 

RADIOFREQUENCY GENERATOR /TRANSMITTER Used to generate R/F radiation & consists of a coil. To obtain max. interaction of R/F radiation with sample, the coil wound around sample cell. The coil wound at 90 to magnetic field to achieve max. resonance. The frequency of 60, 90, 100, 220, 300,400 MHz are used.

Radio Frequency Detector : 

Radio Frequency Detector Measure the un absorbed radiofrequency. When R/F passes through the magnetised sample ,then-absorption-dispersion of signal occurs. So , it should capable of distinguish absorption signal from dispersion signal. Two method of detection used

Recorder : 

Recorder Give spectrum as a plot of strength of resonance signal on Y-axis & strength of M/F on X-axis. Strength of resonance signal is proportional to number of nucleus at that particular field strength. Area under peak is direct measure of resonating nuclei.

NMR SPECTRUM : 

NMR SPECTRUM A spectrum of absorption of radiation vs applied magnetic strength is called as NMR spectrum The number of signals : Show how many different kinds of protons are present The location of the signals: Show how shielded or de shielded the proton is

N M R parameters employed for determining structure : 

N M R parameters employed for determining structure 1. Chemical Shift Indices: Determining secondary structure. 2. J-coupling: Determine dihedral angles. ( Karplus equation) 3. Nuclear Overhauser Effect (NOE): Determine inter-atomic distances (NOE µ R-6) 4. Residual dipolar coupling: Determine bond orientations. 5. Relaxation rates (T1, T2 e t c): Determine macromolecular dynamics

DIFFERENT ISOTOPES USED IN NMR : 

DIFFERENT ISOTOPES USED IN NMR Carbon-13 is a naturally occurring isotope of carbon that has nuclear spin. It is used in NMR spectroscopy to identify different carbon atoms environments within a molecule. OTHER TYPES:

Applications : 

Applications Chemistry: 1H, 13C Bio-sciences: 1H, 13C, 15N, 19F, 31P, etc. Medicine: 1H, 17O Based on nuclei available for 3-D structure

APPLICATIONS IN CHEMISTRY : 

APPLICATIONS IN CHEMISTRY Chemical analysis : A matured technique for chemical identification and conformational analysis of chemicals whether synthetic or natural.

APPLICATIONS IN BIOSCIENCE : 

APPLICATIONS IN BIOSCIENCE Chemical shift mapping – structural and functional information on the binding modes and site positions High throughput compound screening and drug design

Applications In Medicine : 

Applications In Medicine NMR principle is applied in obtaining clinical images and of studying tissue metabolism in vivo. Image courtesy of James Danckert http://www.arts.uwaterloo.ca/~jdancker/fMRI

COMMERCIALLY AVAILABLE NMR AND THEIR APPLICATIONS : 

COMMERCIALLY AVAILABLE NMR AND THEIR APPLICATIONS Biological complex Dynamic Nuclear Polarization (DNP) experiments at 263 GHz/ 400 MHz used biological complexes. The new AVANCE III HD is the Ultimate NMR Platform for Life Science and Materials Research, Pharma /Biotech, Chemistry, Metabolics , Nutritional Science and Molecular Diagnostics Research HPLC-SPE-NMR in pharmaceutical development: capabilities of identified drug impurity and metabolites Other types of N m r A .Multi-dimensional NMR Spectroscopy B. Solid-state NMR spectroscopy r

References : 

References Skoog Holler. Crouch. Page-551-598 Inst. method of chemical analysis.page619-736 Pharma analysis by Kasture page 222- 230 NMR Spectroscopy, Basic Principles and Applications, by Roger S. Macomber http://www.cis.rit.edu/htbooks/nmr/