The diproto
nated form of a
n orga
nic-solubilized cyclo[8]pyrr
ole derivative, beari
ng eight u
ndecyl chai
ns o
n the <
IMG SRC="/images/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-pyrrolic positio
ns, was fou
nd to extract sulfate a
nio
n effectively from
neutral aqueous media i
nto a tolue
ne orga
nic phase. The ki
netics of sulfate a
nio
n excha
nge betwee
n the two phases were fou
nd to be exceedi
ngly slow i
n the abse
nce of the phase-tra
nsfer catalyst, Aliquat 336-
nitrate (A336N), but appreciable i
n its prese
nce. The bis
nitrate a
nio
n bou
nd form of this cyclo[8]pyrr
ole could be ge
nerated i
n situ by subjecti
ng the tolue
ne phase co
ntai
ni
ng i
nitially 0.5 mM of the sulfate a
nio
n bou
nd form a
nd 0.1 mM trioctylami
ne (TOA) to successive equilibratio
ns with aqueous 0.1 M HNO
3 u
ntil sulfate was
no lo
nger detected i
n the aqueous phase. This bis
nitrate complex, whe
n studied as a 0.5 mM solutio
n i
n tolue
ne i
n the prese
nce of 0.1 mM (TOAH)
+(NO
3-), was also fou
nd to be a
n effective extracta
nt for sulfate a
nio
n.
DSO4 values of 0.001 a
nd 1000 were observed at 1 M NaNO
3(aq) a
nd 0.3 mM NaNO
3(aq), respectively, a
nd the logarithm of the co
nditio
nal excha
nge co
nsta
nt, log(
![](/isubscribe/jour<font color=)
nals/jacsat/129/i36/eq
n/ja074568ke10001.gif">), was calculated to be 4.9 ± 0.4. The prese
nt cyclo[8]pyrr
ole system is thus
noteworthy as bei
ng the first sy
nthetic receptor that displays a high selectivity for sulfate a
nio
n i
n the prese
nce of excess
nitrate u
nder co
nditio
ns of solve
nt extractio
n.