27
卷
7
期
2008.
7
结构化学
(J
IEGOU
HUAXUE)
Chinese
J.
Strucl.
Chem.
Vo
l.
27
,
No.7
871-876
Crystal
Structures
of
Fluoride
and
Chloride Complexes
of
Tris[(2-benzimidazolyl)methyl]amine
①
YIN
Zhen-Ming
(
DONG
Li
LIU
Shang-
Yuan
(College
of
Chemist
η
,
and
Life Science,
Ti
anjin
Normal
Univers
仰"
Tianjin 300387, China)
ABSTRACT
The
crystal structures
of
fluoride
and
chloride
complexes
of
tris[(2-benzimida-
zolyl)methyl]amine 1 were characterized
by
X-ray crystallography. 1
adopts
C3
symmetrical
geometry
and
cone-like
conformation
so
as
to
allow its three
NHs
to
associate
with
the anions
through
hydrogen
bonds.
Despite
the different sizes
of
the
anions
, the
two
crystals are
unexpectedly isostructura
l. The binding ability
of
the anions
of
1 in solution was
also
studied
by
using
of
UV
-vis spectroscopy.
Keywords:
tris[(2-benzimidazolyl)methyl]amine
,
anion
binding
,
structure
1
INTRODUCTION
Anion
complexation
of
synthetic
host
molecules
has
become
an important
theme
in supramolecular
chemistry
because
of
the
amazing
impact
of
anions
in
many chemical and biological processes
fl
.
2].
Since
Alcalde
f31
and Sato
f4
]
proved
由
at
由
e
1,3-disubstituent
imidazolium
compounds
can
bind anions through
(C-Ht...
:x-
type ionic
hydrogen
bonds
,
much
atten-
tion
has been paid
to
the
design
and
synthesis
of
imidazolium[5-7]
and
benzoimidazolium
凹,
9]
based
anion
receptors.
Th
e
NH
pKas
of
imidazole and
benzoimidazole
in
water
are
12.7
and
12.17[10
1
, res-
pectively
, which are
more
acidic
than pyrrole
NH
(pKa
16.5
flll
).
It
means
that
the
imidazole and ben-
zimidazole
would
be
neutral anion receptors which
can
bind
anions
by
N-H...anion
hydrogen
bonds.
Indeed
,
some
neutral
anions
receptors
based
on
benzimidazole
have
been
reported recentl
y
f
l2
.
131.
To
date
,
however
,
no
structure
about
benzimidazole-
Received
22
October
2007;
accepted
7
March
2008
(CCDC
626114
and
626115)
anions
complex
has
been
fully
il1
us- trated. Herein,
因
s[(2-be
皿
imi
由
zolyl)me
由
yl]amine
1, a well-known
ligand for metal
ion
fl4
斗
6
1
,
was
synthesized. Its fluo-
ride and chloride
complexes
were
obtained and the
structures
were
characterized
by
X-ray crystallo-
graphy.
Moreover
, crystal
s
位
uc-
ture comparison
reveals that 1
would
be
a
better
anion receptor than
tri(2-pyrrolylmethyl)amine 2
f171
.
2
EXPERIMENTAL
2. 1
Synthesis
and
characterization
Compound
1
was
prepared
according
to
the
litera-
ture
procedure
fl81
.
The
1.
P-
and
I.C
l"
complexes
were
prepared
by
dissolving
equal
amounts
of
anions
(n-Bu~
,
13 mg;
n-Bu~Cl
,
14 mg) and 1
(20
mg)
in a 2:1 (v/v) ethyl acetate
and
petroleum
ether
solution, followed
by
slow
evaporation giving
colorless
crystals.
Compound
1,
1.
P-
and
I.C
l"
complexes
have
been characterized
by
I
H
NM
R.
For
(
Supported
by
the
National
Natural
Science
Foundation
of
China
(No.
20702038)
,由
e
University
Science
Foundation
of
Ti
anjin
Ed
ucation
Committee
(20050609)
and
Ti
anjin
Nonnal
University
(
Corresponding
au
阳
r.
E-mail:
tjyinzm@yahoo.com.cn