engleski

Synthesis, spectroscopic characterization and photophysics of new functionalized 2,3-distyrylfurans: substituent and solvent effects on their photobehavior

Two new groups of p-chloro-, p-methoxy- and p- nitro-substituted derivatives of the trans, trans- isomers of 2, 3-distyrylfuran have been synthesized by a sequence of reactions according to known methods. These new conjugated heterocyclic compounds along with the parent one and its methyl-derivative have been characterized spectrally, photophysically and photochemically. These compounds, except for the nitro-derivatives, display high fluorescence quantum yields in the non-polar n-hexane (ΦF = 0.76-0.98). In ethanol of high polarity, the lifetime of their singlet excited state increases from 1.31-2.59 ns to 2.01- 4.77 ns, significantly enhancing the quantum yield of their photochemical reaction from 0.02-0.24 to 0.25-0.46, and diminishing their fluorescence efficiency (ΦF = 0.26-0.64). Deviating from the other compounds studied, the quantum yields for both the fluorescence and the photolysis of the nitro-derivatives are rather low (ΦF < 10-4, Φ= 0.025-0.042 in ethanol), probably due to an efficient intersystem crossing leading to a non- reactive triplet state. Accordingly, their singlet-state lifetime is also relatively short (τ< 0.3 ns).

distyrylfuran ; fluorescence ; oxygen heterocycles ; photophysics ; synthesis ; solvent effect

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