XLOC experiments

Over the following years many experiments were developed whereby the signal structure contains a lot of information on the coupling constants, cf. E-COSand P.E.COSY. Others stem from heteronuclear experiments, such as the method of Bermel et which is a good illustration of the way problems were approached at the time, and, more recently, the heteronuclear XLOC experiments which show structures similar to E.COSY spectra. 

Several new pulse sequences have been designed for the detection of hetero-nuclear long-range couplings. This includes a new 2D pulse sequence (BIRd-HMBC) proposed by Burger et and new broadband XLOC and /-HMBC experiments suitable for the measurement of /hh and /hx couplings in small molecules, designed by Meissner and Sorensen. ... 

In 2001, Meissner and Sprensen described methods for the measurement of Jhh anO "Jch couplings employing the broadband excitation approach (see Section 3.3.7) with the report of the broadband XLOC and broadband J-HMBC experiments, respectively. In a further extension of the idea of accordion optimization, Williamson ef reported the development of the J-IMPEACH-MBC pulse sequence. This approach is similar to the EXSIDE experiment previously described by Krishnamurthy and the J-resolved HMBC experiments of Furihata and Seto"- in its use of J-scaling to render small, long-range heteronuclear couplings conveniently measurable. Finally, Williamson e/ also described a new method, G-BIRDr-HSQMBC, that was reported in their survey of the available methods. 

Several F-F and F-C 2D correlation experiments, which were already known or which were modified for the use with fluorine detection by the authors have been presented by Aspers et al. It included /-HMBC, XLOC, HMQC and COSY-10 experiments... 

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