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Robust bilinear rotations II
Yannik T Woordes1, Burkhard Luy1
1Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany.
Magnetic Resonance (Gottingen, Germany)
|February 23, 2026
Summary
Robust bilinear rotations in NMR spectroscopy, including BIRD, TANGO, BANGO, and BIG-BIRD, are enhanced using the COB-BIRD principle. This method broadens applicability to diverse coupling ranges and sample conditions, improving NMR experiment robustness.
Area of Science:
- Nuclear Magnetic Resonance (NMR) Spectroscopy
- Quantum Control and Spin Dynamics
- Advanced Pulse Sequence Design
Background:
- Bilinear rotations are fundamental in NMR, enabling selective spin manipulation.
- Existing methods like BIRD, TANGO, BANGO, and BIG-BIRD have limitations with pulse bandwidths and coupling constant ranges.
- Recent advancements introduced the COB-BIRD for robust bilinear rotations, compensating for couplings, offsets, and B1 inhomogeneities.
Purpose of the Study:
- To demonstrate a universal principle for constructing all bilinear rotations using the COB-BIRD.
- To adapt universal rotation pulse design for INEPT-type transfers, enabling bilinear rotations over extended coupling ranges.
- To experimentally validate the derived principles and showcase advanced NMR applications.
Main Methods:
- General optimization procedure for COB-BIRD development.
- Adaptation of universal rotation pulse design principles for INEPT-type elements.
- Theoretical derivation and experimental characterization of novel bilinear rotation sequences.
- Implementation of a supersequence for HMBC/ASAP-HSQC-IPE-COSY and BIRD-decoupled J-resolved INEPT experiments.
Main Results:
- The COB-BIRD principle enables the construction of all bilinear rotation types with enhanced robustness across 120-250 Hz coupling ranges.
- A new method using INEPT-type transfers allows bilinear rotations for higher coupling ranges (120-750 Hz).
- Demonstrated robustness against couplings, offsets, and B1 inhomogeneities in various NMR experiments.
- Successful implementation of a novel HMBC/ASAP-HSQC-IPE-COSY supersequence and BIRD-decoupled J-resolved INEPT experiments for partially aligned samples.
Conclusions:
- The COB-BIRD provides a fundamental and versatile platform for designing robust bilinear rotations in NMR.
- The developed methods significantly expand the applicability of bilinear rotations to a wider range of coupling constants and experimental conditions.
- These advancements offer improved performance and new possibilities for complex NMR investigations, including those involving partially aligned samples.
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