Tuning the photophysical properties of 4′-substituted terpyridines – an experimental and theoretical study

Abstract

Several 2,2':6',2''-terpyridines substituted in the 4'-position were synthesized and their photophysical properties were investigated by absorption and photoluminescence spectroscopy in dilute solutions and solid state. The studies confirmed that the absorption and emission wavelengths, fluorescence quantum yields and lifetimes of 1-R(1-16) are strongly structure-related, demonstrating a decisive role of the nature of the substituent in determining the photophysical properties of 4'-functionalized terpyridines. Additionally, the density functional theory (DFT) calculations were performed for 1-R(1-16) to get insight into their electronic structure and spectroscopic properties.

2,2′:6′,2′′‐Terpyridine Analogues: Structural, Electrochemical, and Photophysical Properties of 2,6‐Di(thiazol‐2‐yl)pyridine Derivatives

“…The fluorescence of the 2,6‐di(thiazol‐2‐yl)pyridines with the R 5 , R 7 , R 8 , and R 9 substituents appeared in a lower energy region than those observed for the other 2,6‐di(thiazol‐2‐yl)pyridines with substituents with stronger π‐acceptor properties (R 1 , R 2 , R 3 , R 4 , and R 6 ). Compared with the corresponding 4′‐R‐terpy compounds, the reported 2,6‐di(thiazol‐2‐yl)pyridines show higher quantum yields, as presented in Table .…”

“…(a) Energy‐level diagram of the calculated IP, EA, and E g values of 2,6‐di(thiazol‐2‐yl)pyridines (black) determined by DPV and compared with the data for the corresponding 2,2′:6′,2′′‐terpyridines (red) . (b) Reductive and (c) oxidative scans of R 8 ‐dtpy.…”

“…The effect of the solvent polarity is reflected mostly in the band intensities. The change from CHCl 3 to CH 3 CN leads to a significant increase in the intensity of the band originating from the HOMO→LUMO transition (HOMO = highest occupied molecular orbital; LUMO = lowest unoccupied molecular orbital) for R 5 ‐dtpy, R 7 ‐dtpy, R 8 ‐dtpy, and R 9 ‐dtpy The introduction of an electron‐donating substituent (2,2′‐bithiophen‐5‐yl in R 5 ‐dtpy and N ‐ethylcarbazol‐4‐yl in R 9 ‐dtpy), which stabilizes the charge‐separated excited state of the molecule, results in a clear redshift of the absorption originating from the HOMO→LUMO transition. The lowest energy absorptions of R 5 ‐dtpy and R 9 ‐dtpy in CH 3 CN were redshifted by more than 20 nm compared with those of the other reported 2,6‐di(thiazol‐2‐yl)pyridines.…”

“…Recently, we discussed the structure–property relationship of a series of 4′‐substituted 2,2′:6′,2′′‐terpyridines . This paper concerns the synthesis and photophysical properties of 2,6‐di(thiazol‐2‐yl)pyridine derivatives (R n ‐dtpy).…”

Carbazole‐Terpyridine Donor‐Acceptor Dyads with Rigid π‐Conjugated Bridges

“…A vast number of derivatives containing carbazole or terpyridine units can be found in the literature, but relatively few reports on compounds carrying both units separated by a π–conjugated system . Therefore, there is room for developing new carbazole‐terpyridine derivatives with enhanced optoelectronic features, also to widen our knowledge on the relationship between the structure and the electronic properties . Our earlier work carried out on this type of molecules showed that the absorption and emission properties of carbazole‐terpyridine dyads can be finely tuned by changing the spacers between the two terminal subunits …”