150.24, 149.81, 143.04, 136.47, 130.35, 123.36, 122.70, 121.62, 112.62, 112.02, 40.38. m/z (ESI) calcd [M+H]+ for
C34H31N7 538.7, found 538.2.
1
5c Yield: 6 mg, 0.13%. H (CDCl3) δ (ppm) 8.54 (d, 1H, J = 6.6 Hz, H in pyridine); 8.49 (d, 1H, J = 6.6 Hz, H in
pyridine); 7.99 (br t, 1H, J = 6.6 Hz, H in pyridine); 7.60-7.52 (m, 3H, H in pyridine and benzene); 7.39-7.42 (m, 3H, H
in benzene and pyrrole); 2.46 (s, 3H, CH3). 13C (CDCl3) δ (ppm) 143.47, 141.29, 135.07, 134.83, 130.42, 128.84,
128.49, 127.76, 124.42, 120.63, 119.99, 113.92, 109.47, 21.56. m/z (ESI) calcd [M-C4H5 (pyridine dissociation)]+ for
C28H20N5 426.2, found 426.3.
1
5d Yield: 250 mg, 5.2% H (CDCl3) δ (ppm) 7.99 (d, 1H, J = 5 Hz, H in benzene); 7.79 (d, 1H, J = 5 Hz, H in
benzene); 7.37-7.42 (m, 3H, H in benzene); 7.26-7.28 (m, 3H, H in benzene and pyrrole); 7.02 (d, 2H, J = 5 Hz, H in
benzene). 13C NMR data cannot be obtained due to solubility issue.
1
5e Yield: 479 mg, 7.9% H (CDCl3) δ (ppm) 7.96 (d, 1H, J = 7.0 Hz, H in benzene); 7.70 (d, 2H, J = 7.0 Hz, H in
benzene); 7.59 (br d, 2H, J = 7.0 Hz, H in benzene); 7.53 (br d, 1H, J = 7.0 Hz, H in benzene); 7.35 (t, 1H, J = 7.0 Hz, H
in benzene); 7.25-7.31 (m, 2H, H in benzene); 7.08 (s, 1H, H in pyrrole). 13C (CDCl3) δ (ppm) 175.79, 132.39, 132.04,
131.02, 129.05, 128.27, 127.80, 127.38, 124.47, 114.90, 104.99.
5f Yield: 111 mg, 1.4% 1H (CDCl3) δ (ppm) 8.15-8.26 (m, H in benzene); 7.80 (s, 1H, H in pyrrole); 7.72-7.83 (m,
3H, H in benzene); 7.49-7.55 (m, 3H, H in benzene). 13C NMR data cannot be obtained due to solubility issue.
6d-f Boron aza-dipyrromethenes synthesis: The azadipyrromethene (0.15 mmol, 1 eq.) was dissolved in
dichloromethane (15 mL) and diisopropylethylamine (0.27 mL, 1.50 mmol, 10 eq.) and BF3·OEt2 (0.29 mL, 2.25 mmol,
15 eq.) were added dropwise. The solution was stirred at room temperature for 24 h. The organic layer was evaporated
under vacuum. The crude product was purified by chromatography on silica gel (1:1 CH2Cl2: hexane) to afford dark
green solid. Single crystals of 6f were grown by slow evaporation from dichloromethane.
6d Yield: 36.7 mg, 50% 1H (CDCl3) δ (ppm) 8.16 (d, 2H, J = 7.2 Hz, H in benzene); 7.87 (dd, 1H, J = 7.2, 1.2 Hz, H
in benzene); 7.48 (m, 2H, H in benzene); 7.40-7.44 (m, 2H, H in benzene); 7.25 (s, 1H, H in pyrrole); 7.12 (t, 1H, J =
7.2 Hz, H in benzene); 7.03 (d, 1H, J = 7.2 Hz, H in benzene). 13C (CDCl3) δ (ppm) 155.89, 149.84, 142.24, 133.37,
132.39, 129.28, 129.02, 128.72, 126.60, 125.49, 120.95, 120.22, 118.88, 113.32.
1
6e Yield: 55 mg, 56% H (CDCl3) δ (ppm) 8.05-8.08 (m, 2H, H in pyridine); 7.92 (dd, 1H, J = 7.0, 1.0 Hz, H in
benzene); 7.87 (s, 1H, H in pyrrole); 7.74 (d, 1H, J = 7.0 Hz, H in benzene); 7.63-7.66 (m, 2H, H in benzene); 7.55 (t,
1H, J = 7.0 Hz, H in benzene); 7.46-7.51 (m, 1H, H in benzene). 13C (CDCl3) δ (ppm) 156.42, 150.69, 138.15, 131.96,
131.89, 129.39, 129.19, 128.68, 127.20, 123.68, 117.19.
6f Yield: 51 mg, 42% 1H (CDCl3) δ (ppm) 8.01-8.05 (m, 3H, H in benzene); 7.73 (br t, 1H, H in benzene); 7.50-7.52
(m, 3H, H in benzene); 7.44 (br t, 1H, H in benzene); 7.05 (s, 1H, H in pyrrole). 13C NMR data cannot be obtained due
to solubility issue.
3. RESULTS AND DISCUSSION
3.1 Synthesis
Work on ADPMs has primarily focused on the end products, and thus research in to their fundamental properties has
been sporadic. The most comprehensive study was carried out by Bessette and coworkers, who examined a series of
arene substituted ADPMs, which included the unmodified tetraphenyl and bis-pyridyl compounds [13-14]. We became
interested in pyridine-substituted ADPMs as possible tetradentate chelates, but we found that these compounds were
unstable and thus unsuitable for metal chelation. Bessette and coworkers reported the same issues, as will be noted
below. We have also investigated bis-phenol substituted ADPMs with greater success and have carried out some