Synthesis of Fluoro and Cyanoaryl‐Containing Pyrene Derivatives and their Optical and Electrochemical Properties

Strong Electronic Coupling-Induced Ultrafast Charge Transfer in Donor-Pyrene-Acceptor Systems

In this study, we decipher the charge transfer (CT) processes in donor-pyrene-acceptor (DPA) molecules via various time-resolved spectroscopic measurements. It has been challenging to unravel the ultrafast CT dynamics in DPA molecules because they exhibit an initial CT emission in the same spectral range as the locally excited (LE) emission. However, we finally observed the CT rate of ∼200 fs in DPA molecules from the time-resolved fluorescence anisotropy decay profiles. Our measurements allow us to suggest that the LE and CT states of DPA systems have isoenergetic potential surfaces and that the introduction of the acceptor to the pyrene moiety gives rise to strong electronic coupling between the LE and CT states. Therefore, we determined that this solvent-independent ultrafast CT occurs through the adiabatic potential energy surface and that the CT characteristics are enhanced in DPA compared to the donor-pyrene-donor system.

2- and 2,7-Substituted para-N-Methylpyridinium Pyrenes: Syntheses, Molecular and Electronic Structures, Photophysical, Electrochemical, and Spectroelectrochemical Properties and Binding to Double-Stranded (ds) DNA

Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm-1 . The N-methylpyridinium compounds have a single reduction at ca. -1.5 V vs. Fc/Fc+ in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents.

Non-K Region Disubstituted Pyrenes (1,3-, 1,6- and 1,8-) by (Hetero)Aryl Groups-Review

Disubstituted pyrenes at the non-K region by the same or different (hetero)aryl groups have proven to be an increasingly interesting area of research for scientists over the last decade due to their optical and photophysical properties. However, in this area, there is no systematization of the structures and synthesis methods nor their limitations. In this review, all approaches to the synthesis of these compounds, starting from the commercially available pyrene are described. Herein, the ways of obtaining of disubstituted intermediates based on bromination and acylation reaction are presented. This is crucial in the determination of the possibility of further functionalization by using coupling, cycloaddition, condensation, etc. reactions. Moreover, the application of disubstituted pyrenes in the synthesis of 1,3,6,8-tetrasubstituted was also reviewed. This review describes the directions of research on chemistry of disubstituted pyrenes.