Chelerythrine chloride binding of guanosine in aqueous solution

In this work, the interaction between chelerythrine （CHE） and guanosine is studied using UV-vis and fluorescence measurements at various temperatures. The UV-vis spectra show that the increasing guanosine concentrations result in the decreasing absorption intensity and red shift of CHE E absorption band （267 nm）. The fluorescence spectra are fitted to linear analysis, yielding a binding constant of 1.04×10^4 L/tool at 298.15 K of CHE with guanosine. Besides, with △rHm^θ = - 8.26 kJ/mol, △rGm^θ = -22.90 kJ/mol, and △rSm^θ = 49.38 J/（mol K） the interaction should be entropy-driven and exterothermic.

A spectral study of the interaction between chelerythrine chloride and cytidine

To study the possible anticancer mechanisms of chelerythrine (CHE), and its interactions with cytidine were investigated by UV–vis spectrophotometric and spectrofluorimetric measurements and by thermodynamic calculations. The binding of CHE to cytidine could be characterized by the hypochromic and bathochromic effects in the absorption bands, and the quenching of fluorescence intensity. The spectral data were fit by linear analysis, yielding a binding constant of 2.49 × 10(4) L mol(?1)at 25 °C of CHE and cytidine, and a van’t Hoff enthalpy of ?20.02 kJ/mol for the exothermic interaction in the standard state. In addition, with and , the interactions should be entropy-driven.

Photochemical reaction of magnesium tetraphenyl porphyrin with sulfur dioxide

The photochemical reaction of magnesium tetraphenyl porphyrin（MgTPP） with sulfur dioxide（SO_2） was investigated in dichloromethane（CH_2Cl_2） by steady-state fluorescence,UV-vis absorption,MS,and XRD spectroscopic techniques.These spectra showed that under irradiation MgTPP reacted with SO_2 to form 1：1 molecular adduct at first step.During the process of keeping irradiation and maintaining the flow of SO_2,SO_2 was reduced into S^（2-） by MgTPP and the results were detected using MS and XRD techniques.Understanding the photochemical reaction of MgTPP with SO_2 is of key interest in elucidating fundamental photochemical reaction mechanisms associated with this class of chlorophyll in the presence of SO_2.

Photochemical reaction between magnesium tetraphenyl porphyrin and oxygen

The photochemical reaction of magnesium tetraphenyl porphyrin （MgTPP） with O2 was studied in CH2Cl2 by steady-state fluorescence, UV-vis absorption, FTIR and MALDI-TOF MS measurements. These spectra indicate that O2 can react with MgTPP excited by irradiation, forming the stable 1：1 coordinated adduct of MgTPP-O2. In the adduct, the oxygen atoms of O2 may insert in the Mg-N bonds in MgTPP and bind with the nitrogen atoms of MgTPP to form N-O-Mg bonds.

Spectral studies of the interaction between sanguinarine and guanosine

The interaction between sanguinarine and guanosine was investigated by using UV-vis and fluorescence spectra at pH 7.2. The binding of sanguinarine to guanosine was substantiated by the hypochromism and bathochromism in the absorption spectra and the emission quenching in fluorescence spectra. The fluorescence lifetime results, the varieties of the fluorophore absorption spectra and the decrease of the binding constant with the increasing temperature all indicate that the fluorescence quenching is static. The ratio and constant of the binding cytidine to sanguinarine are 2 and 6.44 × 10^7, respectively. The result shows that the binding of sanguinarine to guanosine is not only exothermic but also entropy-driven with △H=-8.53kJ/mol, AS = 0.12 kJ/（molK）, and AG =-44.57 kJ/mol at 298.15 K.