m-Benziporphodimethenes 21 are m-benziporphyrin analogues but with two sp
3 -
hybridized meso-carbon atoms adjacent to the m-phenylene unit. The original
synthesis was based on the reaction between the proper dicarbinol 20 (R ¼ Aryl),
pyrrole, and arylaldehyde (Scheme 9) [16]. Subsequently, the methyl derivatives
(R ¼ Me) were explored [59–61]. It was also documented that the tetraethyl
derivative can potentially be used as long-wavelength zinc(II)-specific
chemosensors [59]. The zinc(II) complexes of 21 (R ¼ Ph) acted as an interesting
building block capable of self-assembling and continually growing into
multidimensional nanostructure arrays [62].
2.3 meso-Alkylidenyl-m-Benziporphyrins
R 1
R 1
R 3
R 3
Another derivate of m-benziporphyrin – a macrocycle with an exocyclic double
bond – has been reported by Lee and coworkers [11, 63]. The first step of 23
synthetic pathways is based on the reaction bis-malonate derivative of
isophthalaldehyde with pyrrole giving 22. Next, benzitripyrrane 22 undergoes
condensation with pyrrole and pentafluorobenzaldehyde resulting in mesoalkylidene benziporphyrin 23, as well as expanded macrocycles, such as
benzipentaphyrin and dibenzioctaphyrin (Scheme 10).
Benzitripyrrane 22 also reacts with furan or thiophene dicarbinol 24, generating
meso-alkylidene
heterobenziporphyrins:
oxabenziporphyrin
25-O
and
thiabenziporphyrin 25-S, respectively (Scheme 11).
OH
Ph
R OH
pyrrole,
ArCHO,
BF 3
.
Et 2 O
21
H
N
N
N
R
Ar
R
Ar
20
R
R
R
R
R = Ph, Me
Scheme 9 Synthesis of
m-benziporphodimethene
21
A Pincer Motif Etched into a meta-Benziporphyrin Frame
189
3 -
hybridized meso-carbon atoms adjacent to the m-phenylene unit. The original
synthesis was based on the reaction between the proper dicarbinol 20 (R ¼ Aryl),
pyrrole, and arylaldehyde (Scheme 9) [16]. Subsequently, the methyl derivatives
(R ¼ Me) were explored [59–61]. It was also documented that the tetraethyl
derivative can potentially be used as long-wavelength zinc(II)-specific
chemosensors [59]. The zinc(II) complexes of 21 (R ¼ Ph) acted as an interesting
building block capable of self-assembling and continually growing into
multidimensional nanostructure arrays [62].
2.3 meso-Alkylidenyl-m-Benziporphyrins
R 1
R 1
R 3
R 3
Another derivate of m-benziporphyrin – a macrocycle with an exocyclic double
bond – has been reported by Lee and coworkers [11, 63]. The first step of 23
synthetic pathways is based on the reaction bis-malonate derivative of
isophthalaldehyde with pyrrole giving 22. Next, benzitripyrrane 22 undergoes
condensation with pyrrole and pentafluorobenzaldehyde resulting in mesoalkylidene benziporphyrin 23, as well as expanded macrocycles, such as
benzipentaphyrin and dibenzioctaphyrin (Scheme 10).
Benzitripyrrane 22 also reacts with furan or thiophene dicarbinol 24, generating
meso-alkylidene
heterobenziporphyrins:
oxabenziporphyrin
25-O
and
thiabenziporphyrin 25-S, respectively (Scheme 11).
OH
Ph
R OH
pyrrole,
ArCHO,
BF 3
.
Et 2 O
21
H
N
N
N
R
Ar
R
Ar
20
R
R
R
R
R = Ph, Me
Scheme 9 Synthesis of
m-benziporphodimethene
21
A Pincer Motif Etched into a meta-Benziporphyrin Frame
189