Synthesis, crystal structure, Kamlet-Taft and Catalan solvatochromic analysis of novel imidazole derivatives.

Novel imidazole derivatives were synthesized and its crystal structure has been studied by single crystal XRD analysis. The photophysical properties of these imidazole derivatives were studied in several solvents, which include a wide range of apolar, polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed to a loss of planarity in the excited state provided by the non co-planarity of the aryl rings attached to C(2) and N(1) atoms of the imidazole ring. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions. The highest fluorescence quantum yield of the imidazole derivatives are observed in polar media.