We are interested in quantitative determination of heteronuclear coupling
constants in organotin compounds (both nJ(CH) and nJ(SnH)). For this purpose
we implemented a J-HMBC experiment, where a constant time period is introduced
into the period where antiphase heteronuclear coherence due to the long-range
couplings evolves. By varying the position of the 180 degree pulse in this
period, one gets variable evolution times for the heteronuclear couplings.
For instance, when tau = 0.5tau(max), no couplings will evolve. When the
position
of the nX 180 degree pulse is stepped towards the 90 X pulse, the net evolution
time for the heteronuclear couplings increases until tau = tau(max). As
tau(max)
is a constant, the amount of relaxation and chemical shift+ homonuclear
coupling
evolution will be the same for all individual experiments, leading to a simple
sinusoidal dependance of the crosspeaks in the series of resulting 2D spectra.
The intensities can be integrated using uxnmr's integration routine, and
after transfer, a non linear regression in any soft yields the J values.
Alterna
tively, one can do a 3D FT and get a 3D-J resolved like spectrum, however, due
to limited tau(max) values (generally not longer than 200ms), the resolution
is about 5Hz, and smaller coupings cannot be measured.
1H: ___90___________________________180_______acquisition
|-------------------|
tau(max)
nX _____________180________90_______________90
|tau
So much for the intro, now comes the problem.In most of the cases we are
looking
at, only one tin nucleus is present, so
that it suffises to record a series of 1D HMBC spectra, each with different
evolution time for the coupings. Either one does a 2D FT, yielding a 2D-J resol
ved spectrum, but for the reasons mentioned above, it is better to integrate
the individual peaks in the 1D and transfer the intensities to a file.
Since that would mean integrating each 1D seperately, doing that in 1D is
quite involved, and I'm looking for an easier way of doing this.
The easiest seems to be to use the T1/T2 routine, which does a lot of
peak picking etc. automatically, and returns you al of the intensities.
However,
it seems impossible to dump the results in a disk file. One can print the
data of all the points on paper, but transfering the values manually to
the analysis software is not what I'm paid to do!The t1peaks and t1results file
are
data files and cannot be used for this.
So:
Does anyone have or know of an easy means to do integration of a lot of 1D's,
returning the values eventually into one file, keeping absolute intensities in
mind?
IS there a way to get an ascii output of data points in the t1/t2 subroutine
oin a diskfile.
Any comments or help greatly appreciated!
Thats all folks!!
jose
-- Jose Martins High Resolution NMR Centre HNMR (ORGC) Vrije Universiteit Brussel Pleinlaan 2, B-1050 Brussel phone: 32-2-629-33-05 fax : 32-2-629-33-04 e-mail jose@hnmr.vub.ac.be