C8953 NMR strukturní analýza semináˇr Introduction to heteronuclear correlations Ondrej Jurcek jurcekondrej@mail.muni.cz April 4, 2018 Polarization transfer � bigger population diffrenece of 1H nucleus is transfered via J-coupling to less sensitive nucleus X (13C, 15N) � fundamental building block of heteronucler correlation experiments: in 2D-HX experiment each crosspeak manifests interaction of H and X nucleus coupled trough bonds � Task: Draw the evolution of magnetization during basic INEPT pulse sequence. Consider C-H interacting pair. HMQC (Heteronuclear Multiple Quantum Correlation) HSQC (Heteronuclear Single Quantum Correlation) correlate 1 H-X (X=13 C, 15 N,...) based on 1 JHX HMQC (a) + more robust experiment + change of parameters - HMBC - lower sensitivity and worse resolution HSQC (b) + better resolution, sensitivity + part of more complex mutlidimensional experiments - less robust H-1 X acq dec 90 90 90 180 1/2J 1/2J t1 (a) H-1 X acq dec t1 d d d d d = 1/4J (b) Practical notes 1H-X HSQC � resolution of overlaps � routine experiments to control biomolecular sample � easy identification of geminal protons � indirect determination of protons bonded to NMR inactive heteroatom � heteronuclear correlation ⇒ no diagonal crosspeak, no symmetry � X decoupled during acquisition ⇒ singlet crosspeak HMBC(Heteronuclear Multiple-Bond Correlation) heteronuclear correlation based on long-range H-X spin-spin interaction( n JHX , n>1 ) � utilizes polarization transfer from H through 2-5 bonds on heteroatom ( 13C, 15N ) � allows to detect quaternary heteroatoms (Cq) or connect signals among isolated spin systems HMBC correct settings of d1, d2 fo evolution of J-coupling necessary � d1=1/2∗1JC−H - (120-180 Hz) � d2=1/2∗2−5JC−H - (3-12 Hz) 1 H X acq t1/2 t1/2 90 90 90 180 d1 d2 90 1H-13C HMBC + 1H-13C HSQC H4-C4 H2-C2 H10-C10 H9-C9 H7-C7 H8-C8 H7-C9 H7-C8 H7-C10 H9-C10 H2-C7 H4-C6 H2-C6 H4-C1 H7-C1 H7-C2 H9-C1 1H-13C HMBC + 1H-13C HSQC H4-C4 H2-C2 H10-C10 H9-C9 H7-C7 H8-C8 H7-C9 H7-C8 H7-C10 H9-C10 H2-C7 H4-C6 H2-C6 H4-C1 H7-C1 H7-C2 H9-C1