Auvray, Thomas; Del Secco, Benedetta; Dubreuil, Amelie; Zaccheroni, Nelsi; Hanan, Garry S. published an article on January 4 ,2021. The article was titled 《In-Depth Study of the Electronic Properties of NIR-Emissive κ3N Terpyridine Rhenium(I) Dicarbonyl Complexes》, and you may find the article in Inorganic Chemistry.Electric Literature of C20H14N4 The information in the text is summarized as follows:
The structure-properties relationship in a series of carbonyl rhenium(I) complexes based on substituted terpyridine ligands of general formula [Re(κxN-Rtpy)(CO)yL]n+ is explored by both exptl. and theor. methods. In these compounds, the terpyridine ligands adopt both bidentate (κ2N) and terdentate (κ3N) coordination modes associated with three or two carbonyls, resp. Conversion from the κ2N to the κ3N coordination mode leads to large changes in the absorption spectra and oxidation potentials due to destabilization of the HOMO level of each complex. The absorption profiles of the κ3N complexes cover the whole visible spectra with lower maxima around 700 nm, tailing out to 800 nm, while no emission is observed with Br- as the axial ligand L. When the axial ligand is modified from the native halide to pyridine or triphenylphosphine, the lowest absorption band is blue-shifted by 60 and 90 nm, resp. These cationic complexes are near-IR emitters with emission maxima between 840 and 950 nm for the pyridine compounds and 780-800 nm for the triphenylphosphine compounds Conversion from the κ2N to the κ3N coordination mode of the terpyridine ligand in Re(I) carbonyl complexes leads to major changes in their electronic properties. The absorption profiles of the κ3N complexes cover the whole visible spectra and can be finely tuned by changing the ancillary ligand L. For complexes with L = pyridine. PPh3, near-IR emission (780-950 nm) with unusually high quantum yields (0.02-0.7%) for this class of compounds is reported. After reading the article, we found that the author used 4′-(4-Pyridyl)-2,2′:6′,2”-terpyridine(cas: 112881-51-3Electric Literature of C20H14N4)
4′-(4-Pyridyl)-2,2′:6′,2”-terpyridine(cas: 112881-51-3) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. Electric Literature of C20H14N4The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds.