Photophysical properties of izomeric N-chlorobenzyl substituted (E)-2′ (3′-or 4′)-hydroxy-4-stilbazolium chlorides in alcohols

Abstract

Absorption and steady-state fluorescence spectra of nine N-p-(m- and o-) chlorobenzyl substituted (E)-2'-(3' and 4')-hydroxy-4-stilbazolium chlorides belonging to the hemicyanine class of compounds were studied in extra dry alcohols of different polarity. Derivatives with 2'-hydroxy or 4'-hydroxy substituent in the benzene moiety of stilbazol molecule displayed negative solvatochromizm. On the other hand, the excited state decay of compounds with a 3'-hydroxy group in the benzene moiety was dominated by non-radiative processes in protic solvents. Solutions of each of the compounds are yellow in extra dry solvents, red in solvents with small amount of water and yellow again if more water is added. The absorbance and steady-state fluorescence methods were used to explain the protonation/deprotonation processes for N-p-chlorobenzyl-(E)-4'-hydroxy-4-stilbazolium chloride and its zwitterionic or quinoid form in 2-propanol responsible for these phenomena.

Interaction of Crown Ether‐Annelated Styryl Dyes with Double‐Stranded DNA

“…Nevertheless, the deviation from an ideal linear correlation indicates that other interactions with the solvent, most likely hydrogen bonding, also contribute to the stabilization or destabilization of the ground and excited state. Similar solvatochromic behavior is well-known for structurally related dyes, especially for hemicyanine dyes bearing amino-type substituents in the styryl fragment (45)(46)(47)(48)(49). No fluorescence was detected for the solutions of compound 4b at room temperature, presumably due to a very efficient non-radiative deactivation of the exitedstate.…”

Influence of water on photophysical properties of N-bromobenzyl- or nitrobenzyl derivatives of substituted 4-hydroxystilbazolium hemicyanines

“…This agrees with previous observations of similar effects for other hemicyanines. 30 Note that the excitation spectrum does not correspond to the absorption spectrum for concentrations from 3.1 ¥ 10 -5 M to 6.5 ¥ 10 -5 M in the RA mode. However, the excitation spectra recorded in the FF mode are much closer to the absorption spectra, indicating the importance of the reabsorption phenomena obvious in the RA mode.…”