hncact3d with DIPSI

Ingmar Sethson (ingmar@indra.chem.umu.se)
Fri, 5 Aug 94 09:12:22 +0200

I have tried to modify the hncact3d-exp which utitlizes 180-deg. pulses
for proton dec. and implement DIPSI-2 dec. instead as described by Bax et al
in JMR,96,432-40 (1992). However, I could not get the experiment to work.
Is there any one out there who could give me so hints what might be wrong.
For your information, this is how I modified the pp:

1. the lines
'd0 ;t1/2
(p14 ph1):dp4
d21'
postioned after the 1st INEPT transfer were replaced with
'(d0 p14 ph1):dp4 (d27 hl4 d13 cpdts)
d25'
where d27 was set to 4.5 ms and d25=d21-d27.
2. All proton 180-deg. pulses during the DIPSI-2 dec. were removed.
3. the lines prior to the final INEPT back-transfer
'd21'
were replaced by
'd25
d13 to
d27 hl1'
where d25 and d27 are defined as described above.

The gamma_B1-field for the DIPSI-2 was 5.7 kHz. I tried the sequence with
setting d27 to both J-NH(4.5ms) and J-NH'(5.5ms) but with the same poor
result.

Any suggestions or ideas would be most welcome.

Ingmar Sethson

*****************************************************************
* *
* Ingmar Sethson *
* Dep. Org. Chem., *
* Umea University *
* S-901 87 UMEA, Sweden *
* Ph.nr. : +46-90-16 62 86 *
* Fax.nr. : +46-90-13 88 85 *
* *
* *
*****************************************************************