Premium
Anion‐Sensitive 2,4‐Dinitrophenylhydrazone‐Containing Terpyridine Derivative and Its Platinum Chloride Complex
Author(s) -
Zhang Bingguang,
Li Yunjing,
Sun Wenfang
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100537
Subject(s) - chemistry , deprotonation , excited state , photochemistry , platinum , absorption band , ultrafast laser spectroscopy , terpyridine , absorption (acoustics) , absorption spectroscopy , chloride , ion , fluorescence , spectroscopy , metal , organic chemistry , catalysis , physics , quantum mechanics , nuclear physics , acoustics , optics
Abstract Terpyridine derivative 1 , bearing 2,4‐dinitrophenylhydrazone, and its platinum chloride complex 2 were synthesized and characterized. The UV/Vis, emission, and triplet transient difference absorption spectra of 1 and 2 were investigated. Both 1 and 2 exhibit broad and strong absorption in the visible spectral region ( λ max = 404 nm for 1 and 433 nm for 2 ), which are dominated by the 1 π–π* transition of the ligand. When excited at the respective absorption band maximum, 1 and 2 exhibit charge‐transfer fluorescence atapproximately 550 nm. Compounds 1 and 2 also exhibit a broad and strong 3 π–π* excited‐state absorption band in the visible region ( λ max = 520 nm with ϵ T1–T n = 4.74 × 10 4 L mol –1 cm –1 for 1 , and λ max = 590 nm with ϵ T1–T n = 3.45 × 10 4 L mol –1 cm –1 for 2 ). The triplet excited states of 1 and 2 are both long‐lived, with lifetimes longer than 2 ms. Compounds 1 and 2 are sensitive to basic anions such as F – , AcO – , and H 2 PO 4 – . Upon addition of these anions, the UV/Vis absorption spectra of these two compounds are significantly redshifted, which is reflected by the color change from yellow to purple for 1 and from yellow to blue for 2 . These anions also quench the charge‐transfer emission band at 550 nm. Moreover, the triplet transient absorption of 1 and 2 in DMSO solution is quenched upon addition of these anions. These spectroscopic changes are attributed to the deprotonation of the hydrazone NH group, which causes intramolecular electron transfer. The deprotonation mechanism is supported by the upfield shifts of the 1 H NMR signals of the 2,4‐dinitrophenylhydrazone group, the imine group, and the phenyl group, following the addition of excess F – .