4518
Zheng, Guo, and Yang
display unusual physical, chemical, or coordination properties, and play
important roles in a number of areas in chemistry and biochemistry.[1–3]
The porphyrin-like macrocycle and their rare earth metal complexes belong
to a novel family of dye molecules, absorb strongly around 760–780 nm,
and were suggested as potential photosensitizers for Photo Dynamic
Therapy.[3] As we know, the formation of macrocyclic complexes depends
significantly on the dimension of the internal cavity, on the rigidity of the
macrocycle, on the nature of its donor atoms, and on the complexing proper-
ties of the anion involved in the coordination.[4] In this article we report the
synthesis of two novel porphyrinogen-like macrocycle schiff base ligands
with different internal cavities.
EXPERIMENTAL
Elemental analyses were determined with the Elementar Vario EL
elemental analyzers. NMR spectra were obtained in CDCl3 with Me4Si as
an internal standard. All melting points were uncorrected. All yields refer to
isolated products.
3-Bromoformylbenzene (12 mmol) and 2-(ethoxycarbony1)-3,4-dimethyl-
pyrrole[4] (24 mmol) were dissolved with heating in 40mL absolute EtOH.
The reaction mixture was then heated to reflux, and 1.2 mL of 6 mol/L HCL
was added. The reaction was placed under N2 and refluxed for 1 h. Upon
cooling, the product crystallized. It was filtrated, washed with cold EtOH,
1
and dried to yield 4.57g (76%) of 2 H NMR: d 7.26 (4H, m, 4 ꢀ ArH,
2 ꢀ NH), d 5.50 (1H, s, CH), d 4.07 (4H, q, CH2CH3), d 2.23 (6H, s, CH3),
d 1.93 (6H, s, CH3), d 1.3 (12H, t, CH2CH3).
Ten mmol of 2 was suspended in 60 mL of absolute EtOH and brought to
reflux. A total of 5 mL of 5 M NaOH solution was added, and the reaction
mixture was refluxed for 20 h under N2. The EtOH was removed under
reduced pressure, and the residue was diluted with 100 mL of H2O and
filtrated. The filtrate was acidified with glacial HOAc, and the diacid was pre-
cipitated as a pink solid. The pink solid was dissolved in 60 mL of degassed
ethanolamine. The mixture was placed under N2 and refluxed for 2 h, after
which the reaction mixture was poured into 80 mL of ice H2O while still
warm. A solid soon separated, which was filtrated and dried to yield 3.11 g
1
(87%) of 3. H NMR: d 7.20 (6H, m, 4 ꢀ ArH, 2 ꢀ NH), d 6.32 (2H, s, a
H), d 5.38 (1H, s, CH), d 2.01 (6H, s, CH3), d 1.87 (6H, s, CH3).
Ten mmol of 3 was added to 30 mL of DMF. The mixture was cooled
to 258C, then 12 mL of POCl3 was added, after which, the reaction mixture
was stilled for 12 h under room temperature. The reaction mixture was
placed under 508C–608C and refluxed for 2 h, after which the reaction