| A series of alkyl rhodamine B esters were designed and synthesized from rhodamine B. The synthetic process was optimized and established. Thus, SOCl2 was used as the acylating agent, Rh B to alcohol=1:10(mole ratio), reaction temperature 70℃and reaction time 7h, the product yields are over 80%. The fluorescence analytical results indicated that the alkyl structures of Rh B esters hardly affected their fluorescence behaviors . The maximum absorption(λex) and emission wavelengths (λem) of methylrhodamine B esters are not affected by its concentration while the fluorescence intensity enhances as the concentration increases. Theλex andλem generate red shift with the enhancing of the solvent polarity while the fluorescence intensity weakens. Theλex andλem do not change with increasing of the irradiation time, but the fluorescent intensity obviously decreased. The rate of fluorescent intensity to reduce in polar solvent is larger than in apolar solvent.Amino-Rh B, nitro-Rh B and Halogenated Rh B derivatives were synthesized. The fluorescence intensity of nitro-Rh B was lower than that of Rh B while theλex andλem were larger. The fluorescence intensity,λex andλem of amino -Rh B were stronger than those of Rh B, respectively. Theλex andλem of amino-Rh B or nitro-Rh B shifted towards the red light with increasing the solvent polarity while the fluorescence intensity decreased. The fluorescence intensity of halogenated Rh B derivatives were larger than that of RhB in a sequence of I |
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