Su, Ning et al. published their research in Journal of Organometallic Chemistry in 2018 | CAS: 19959-77-4

2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4) belongs to pyrazole derivatives. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugated acid 2.49 at 25 °C).Pyrazole used as a ligand to prepare organometallic compounds. The presence of both electronegative nitrogen atoms in the pyrazole ring reduces the electron density of the C3- and C5-positions leaving electron density of C4-position unaltered. Thus the C4-position is vulnerable to electrophilic attack. The C3 electrophilic-position may undergo deprotonation in the presence of a strong base leading to ring opening.SDS of cas: 19959-77-4

Photoluminescence and electroluminescence of four orange-red and red organic iridium(III) complexes was written by Su, Ning;Zheng, You-Xuan. And the article was included in Journal of Organometallic Chemistry in 2018.SDS of cas: 19959-77-4 This article mentions the following:

Using 1-(4-(trifluoromethyl)phenyl)isoquinoline (tfmpiq) and 4-(4-(trifluoromethyl)phenyl) quinazoline (tfmpqz) as the main ligands and pyrazole pyridine derivatives (mepzpy: 2-(3-methyl-1H-pyrazol-5-yl)pyridine, cf3pzpy: 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine) as the ancillary ligands, four iridium(III) complexes (PIQ-Ir1-me, PIQ-Ir2-cf3, PQZ-Ir3-me and PQZ-Ir4-cf3) were synthesized and investigated. Due to the variation of the ligands, these Ir(III) complexes showed different emissions peaking from 602 to 628 nm with the phosphorescence quantum yields of 0.40-0.67. Moreover, applying these Ir(III) complexes as emitters, the organic light-emitting diodes (OLEDs) with the configuration of ITO/HATCN (hexaazatriphenylenehexacabonitrile, 5 nm)/TAPC (bis[4-(N,N-ditolylamino)-phenyl] cyclohexane, 50 nm)/Ir(III) complexes (8 wt%): TCTA (4,4′,4”-tri(9-carbazoyl)triphenylamine, 20 nm)/TmPyPB (1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 40 nm)/LiF (1 nm)/Al (100 nm) exhibited good performances. Especially, the device with orange-red PQZ-Ir4-cf3 emitter obtained the best device performances with the maximum current efficiency of 40.04 cd A-1 and the maximum power efficiency of 33.98 lm W-1. For the pure red complex PQZ-Ir4-me with CIE coordinates at (0.64, 0.34) showed the maximum external quantum efficiency of 22.3%. In the experiment, the researchers used many compounds, for example, 2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4SDS of cas: 19959-77-4).

2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4) belongs to pyrazole derivatives. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugated acid 2.49 at 25 °C).Pyrazole used as a ligand to prepare organometallic compounds. The presence of both electronegative nitrogen atoms in the pyrazole ring reduces the electron density of the C3- and C5-positions leaving electron density of C4-position unaltered. Thus the C4-position is vulnerable to electrophilic attack. The C3 electrophilic-position may undergo deprotonation in the presence of a strong base leading to ring opening.SDS of cas: 19959-77-4

Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics