Peter Bigler

With an improved version of the ¹³C DEPTQ NMR experiment all carbon multiplicities (C_q, CH, CH₂ und CH₃) can be identified unequivocally and most conveniently in two experiments and at best with only one scan each. This simplifies the analysis of ¹³C-NMR data on a routine level in general. With higher sample amounts and/or exploiting the high sensitivity of cryogenically cooled ¹³C probeheads the efficiency of such investigations may be improved. This makes this method attractive for fast ¹³C analysis of small-to-medium sized molecules in high-throughput laboratories.

An improved version of the DEPTQ experiment yielding the signal and multiplicity information for all carbon types including the signals of quaternary carbons is proposed. It encompasses all the known advantages of the basic DEPT experiment. In comparison to the original version, signals of the sensitivity‐limiting quaternary carbons are markedly increased: the initial ¹³C pulse may be adjusted to the Ernst angle, the NOE build‐up period is prolonged by the split relaxation delay and a partial recovery of signal losses due to instrumental imperfections is achieved by the incorporation of composite adiabatic ¹³C refocussing pulses. Furthermore, pure absorption lineshapes for all carbon types are obtained with only one single scan. These attributes make this experiment attractive for ¹³C analysis of small molecules (including spectral editing), particularly in high‐throughput analysis laboratories. Copyright © 2007 John Wiley & Sons, Ltd.

We present a new pulse sequence that detects simultaneously ⁿJ(C,H) and ²J(C,H) connectivities. The corresponding coherences are created along independent pathways and therefore can be separated into two different subspectra. One spectrum is to show all ⁿJ(C,H) connectivities and the other is to show exclusively ²J(C,H) connectivities. In contrast to the previously published ²J/ⁿJ experiment, this sequence detects the ²J(C,H) connectivities via a C,H,H‐RELAY pathway leading to an intensification of the ²J(C,H) signals. Strictly, the ²J(C,H) spectrum does not show ²J(C,H) but ³J(H,H) coupling interactions within ¹³CH_k–¹²CH_l fragments. Therefore, ²J(C,H) signals can appear even if the corresponding ²J(C,H) coupling constant is zero. Copyright © 2003 John Wiley & Sons, Ltd.