Selective Synthesis and Photoluminescence Study of Pyrazolopyridopyridazine Diones and N-Aminopyrazolopyrrolopyridine Diones

Abstract

The newly designed luminol structures of pyrazolopyridopyridazine diones and N-aminopyrazolopyrrolopyridine diones were synthesized from versatile 1,3-diaryfuropyrazolopyridine-6,8-diones, 1,3-diarylpyrazolopyrrolopyridine-6,8-diones, or 1,3-diaryl-7-methylpyrazolopyrrolopyridine-6,8-diones with hydrazine monohydrate. Photoluminescent and solvatofluorism properties containing UV–Vis absorption, emission spectra, and quantum yield (Φf) study of pyrazolopyridopyridazine diones and N-aminopyrazolopyrrolopyridine diones were also studied. Generally, most of pyrazolopyrrolopyridine-6,8-diones 6 exhibited the significant fluorescence intensity and the substituent effect when compared with N-aminopyrazolopyrrolopyridine diones, particularly for 6c and 6j with a m-chloro group. Additionally, the fluorescence intensity of 6j was significantly promoted due to the suitable conjugation conformation. Based on the quantum yield (Φf) study, the value of compound 6j (0.140) with planar structural skeletal was similar to that of standard luminol (1, 0.175).

Structural Identification between Phthalazine-1,4-Diones and N-Aminophthalimides via Vilsmeier Reaction: Nitrogen Cyclization and Tautomerization Study

“…7-Amino-1,3-diphenylpyrazolo[3,4-b]pyrrolo[3,4-d]pyridine-6,8(3H,7H)-dione ( 2f ) [ 28 ]: White solid; 83% yield; mp 217–219 °C; 1 H NMR (DMSO- d 6 , 400 MHz) δ 4.55 (br, 2H, N H 2 ), 7.42 (t, J = 7.46 Hz, 1H, Ar H ), 7.49–7.55 (m, 3H, Ar H ), 7.60–7.65 (m, 4H, Ar H ), 8.25 (d, J = 8.08 Hz, 2H, Ar H ), 8.82 (s, 1H, Ar H ).…”

“…1,3-Diphenyl-7,8-dihydro-3H-pyrazolo [4’,3’:5,6] pyrido[3,4-d] pyridazine-6,9-dione ( 3f ) [ 28 ]: white solid; 84% yield; mp 292–295 °C; 1 H NMR (DMSO- d 6 , 600 MHz) δ 7.43–7.47 (m, 4H, Ar H ), 7.60–7.64 (m, 4H, Ar H ), 8.20 (d, J = 7.88 Hz, 2H, Ar H ), 9.43 (s, 1H, Ar H ).…”

“…6,7-Dichloropyrazino[2,3-d] pyridazine ( 14 ) [ 28 ]: Black solid; 31% yield; mp 204–206 °C; 1 H NMR (CDCl 3 , 400 MHz) δ 9.14 (s, 1H, Ar H ), 9.17 (s, 1H, Ar H ) [ 28 ].…”

“…Herein, we selectively synthesize N -aminophthalimide and phthalazine 1,4-dione derivatives in via the thermodynamic-kinetic control conditions. They will provide as the precursors for constructing the pharmacological heterocyclic compounds (PDE5 inhibitors) [ 26 , 27 ] or the chemiluminescent luminol derivatives [ 28 ]. Owing to the structural divergence between N -aminophthalimides 2 and phthalazine-1,4-diones 3 , we explored the Vilsmeier amidination derivatization to identify them in this work [ 29 , 30 , 31 , 32 , 33 ].…”

Special Issue “Recent Advances in the Synthesis, Functionalization and Applications of Pyrazole-Type Compounds”

“…They demonstrated that pyrazolopyridopyridazine diones generally exhibited the stronger fluorescence intensity and possessed a significant substituent effect, particularly for a m -chloro substituent, and that a more planar skeletal conformation led to a higher Φf, similar to that of the standard luminol. They also concluded that the introduction of the pyrazole and pyridine chromophores led to an increase in the conjugation and aromaticity of the synthetized compounds when compared with luminol [ 9 ]. Current approaches on the synthesis and post-functionalization of pyrazolo[1,5- a ]pyrimidines were reviewed by Portilla et al, who have also highlighted the anticancer potential and enzyme inhibitory activity of these compounds, thus providing important insights for the rational and efficient design of new drugs bearing the pyrazolo[1,5- a ]pyrimidine core [ 10 ].…”