- Since T1 longitudinal (or called spin lattice) relaxation time for C13 is very long ( several tens or about 60 sec? ), and further the recycle delay time D1 needs even much longer (5 x T1), about 5 minutes? If no other measures are taken, this expt. will be very time-consuming! So adding paramagnetic reagents is a good idea.
- Cr(acac)3 is a commonly used one, about 35 mg of Cr(acac)3 in 1 ml of solution is a good starting try! (Make its concertation as 0.1M; the reported highest case could be 0.4M, refer the book “200 and More NMR Experiments” p302 and p318.)
- C13IG (the pulse sequence is zgig30) is used, in which only proton decoupling is added during the acquisition time. Also D1 could be: 1 to 2s; NS > = 64 if sample [C] >= 50mg/ml.
Hongwei edited on 1/31/2024