Effects of solvent, pH and β-cyclodextrin on the fluorescent behaviour of lomustine

Abstract

Fluorescent behaviour of lomustine, a DNA cross-linking agent, was investigated in different solvents, pH and in the presence of b-cyclodextrin (b-CD). The solvents in which fluorescence spectra were observed play a major role in determining the spectral intensity of fluorophore, since it was found to exhibit new fluorescent properties essentially influenced by intermolecular interactions, particularly by intermolecular H-bonding formed with solvents. The pH-dependence profile was typically U-shape with a maximum at pH between 3.51 and 6.58. It was corroborated that the fluorescence emission band of lomustine is significantly intensified in the presence of b-CD. From the changes in the fluorescence spectra, it was concluded that b-CD forms a 1:1 inclusion complex with lomustine and its association constant was calculated.

Spectrofluorimetric determination of the antineoplastic agent lomustine based on the sensitizing effect of β‐cyclodextrin

“…The above results confirm that only 1:1 complex is present in the solution and the calculated association constant value (500 M −1 ) indicates a relatively weak interaction between β‐CD and lomustine in acetonitrile compared with the association constant value obtained in water (6000 M −1 ) , demonstrating the destabilizing effect of the organic solvent on complex formation. The possible reason is that, in water, there is a hydrophobic driving force for the inclusion of the organic molecule into the endo‐hydrophobic cavity of β‐CD, which is reduced upon replacement of acetonitrile; this is accompanied by a decreased solvent stabilization of the exo‐hydrophilic host/guest complex by this organic solvent as compared to water.…”

“…Table shows the essential solvent parameters required in this study along with the absorption (the absorbance spectra match the excitation spectra) and emission spectral characteristics and Stokes shifts of lomustine in selected solvents.…”

Photoinduced Electron Transfer Switching Mechanism of a Naphthalimide Derivative with its Solvatochromic Behaviour: An Experimental and Theoretical Study with In Cell Investigations

“…A deviation from the linear relationship is observed in different solvents from the plot of Stokes shift against Δ f (Figure S2, Supporting Information). Such deviation elucidates the binding mode and the type of interaction between the solute and the solvent . The deviations are particularly large in hydrogen‐bonding solvents such as water, but since they are also obtained in some non‐hydrogen‐bonding solvents, a second form of hydrogen bond is expected.…”

“…Such deviation elucidates the binding mode and the type of interaction between the solutea nd the solvent. [24] The deviations are particularly large in hydrogen-bonding solvents such as water,b ut since they are also obtained in some non-hydrogen-bonding solvents, as econd form of hydrogen bond is expected. It is possible that both intermolecular andi ntramolecular hydrogen bondingm ay occur in this system.…”

Auxiliary ligand-assisted two novel one-dimensional indium coordination polymers: Synthesis, crystal structures and photoluminescence characterization effected by solvent and temperature

“…The hydrogen bond donor nature of CH 3 OH seems to stabilize the excited state of the electronic transitions through solute-solvent interactions with the uncoordinated carboxyl oxygen atom. CHCl 3 is polar aprotic solvent, which cannot be used as a hydrogen bond donor [44]. As a result, the fluorescence spectra in CH 3 OH and CHCl 3 solvents are almost the same.…”