Environmental effects on the fluorescence behaviour of carbazole derivatization reagents

Abstract

The carbazole ring is the basic structure present in the fluorescence derivatization reagents 9-chlorocarbonylcarbazole and 9-carbazolylacetic acid. The fluorescence behaviour of these carbazole derivatives was studied in solvents with different polarities (cyclohexane, ethanol, acetonitrile, water) and at different pH values (4.5 and 8.8). The influence of the low polarity environment afforded by 2-hydroxypropyl-beta-cyclodextrin (HPbeta-CD) is also described. The behaviour of the fluorescent reagents is compared to the model molecules carbazole and 9-methylcarbazole. For all derivatives studied, a bathochromic shift in the fluorescence emission maxima was observed when the solvent polarity was increased. A bathochromic shift was observed in dioxane solutions, which can be ascribed to the peculiar behaviour of this solvent. The changes in the fluorescence intensity in the case of 9-carbazolylacetic acid can be related to the ionization of the carboxylic acid group. Inclusion into the cavity of HPbeta-CD allows emission spectra to be obtained close to those obtained in ethanolic solutions with a remarkable enhancement in the fluorescence intensity, depending on the chemical structure of the carbazole derivative included.

Molecular Recognition of the Antiretroviral Drug Abacavir: Towards the Development of a Novel Carbazole-Based Fluorosensor

“…Characteristically these compounds show absorbance in the range from 250 to 400 nm. In the case of U1, the fluorescence emission spectrum is broad and positioned in the blue-green range with maxima at 475 nm and 500 nm, which is characteristic for carbazole moieties [25]. All the photophysical properties of all tested biosensors are gathered in Table 1.…”

“…Analysis of the chemosensor fluorescence decays upon addition of the various drug concentrations revealed no change in the lifetime; however the time of measurment was elongated, indicating a loss of fluorescence intensity. This is clear evidence of the static character of the quenching, and the formation of stable complexes in the ground state [25]. …”

Carbazole–azine based fluorescence ‘off–on’ sensor for selective detection of Cu2+ and its live cell imaging

“…Carbazole and its derivatives possess highly conjugated systems, engage in active ICT and are used as electron‐donating chromophores . Carbazole compounds are promising candidates for electroluminescent and photorefractive devices because of their electron‐donating and hole‐transporting properties, and their remarkable application as fluorescent sensors . In the bis‐azine type ligand, the electron density is located on the [C=N−N=C] moiety.…”

“…[59][60][61][62][63] Carbazole compounds are promising candidates for electroluminescent and photorefractive devices because of their electron-donating and hole-transporting properties, and their remarkable application as fluorescent sensors. [64][65][66][67][68][69][70][71][72][73][74][75][76] In the bis-azine type ligand, the electron density is located on the [C=N−N=C] moiety. Binding NMR, Nuclear magnetic resonance spectroscopy; PBS, Phosphate-buffered saline; TDDFT, Time-dependent density functional theory; UV, Ultraviolet; Vis, Visible of metal ions to the ligand affects the electron density and thus influences the fluorescence of the ligand.…”

Sulfobutyl ether β‐cyclodextrin (Captisol®) and methyl β‐cyclodextrin enhance and stabilize fluorescence of aqueous indocyanine green

“…Previous studies have documented that BCyDs exhibit a spectral red shift, also referred as bathochromic shift, in fluorescence spectra. 21,22 A bathochromic spectral shift in the fluorescence emission spectra was noted when HPCyD was complexed with a carbazole derivative, 21 which bears slight structural similarity to ICG due to three benzene rings with nitrogen. Another study reported that upon encapsulation of fluorescent dye molecules, the hydrophobic cavity of cyclodextrins results in spectral red shifts of dye.…”