Synthesis Of Pyrene Lab Report

Pyrene is a good luminescent probe as it can undergo fluorescence that has a long lifetime, 1/2  100 ns, and its fluorescence is highly dependent on the polarity of the solution it is in. Pyrene’s emission spectrum can provide information about the microenvironment it is in. The molecule is a rather large elongated pi-conjugated system, making it nucleophilic and impossible for it to have any affinity to a charged surface such as silica. Figure 1: Emission spectrum of small pyrene concentration in acetonitrile From the emission spectrum of pyrene in a specific solvent, there is a fixed ratio between the first and third intensity peaks. These ratios can be compared to ratios formed by other pyrene derivatives, as well as Dimroth’s ET

The methyl in between the amine group and the pyrene portion of the molecule creates a large enough distance so that the NH3+ does not interact with the hydrogen from the pyrene. Thus; allowing 1-pyrenemethylamine to dimerize, and utilize luminescent properties to understand the microenvironment of silica. The process is different from that of pyrene in that, with sufficient concentration in a polar solvent, the dimerization between two ground state 1-pyrenemethylamine molecules occur first. Then, the dimer absorbs a photon at a certain wavelength to excite, forming the excimer. Finally, the excimer emits a photon and reverts back to two ground state 1-pyrenemethylamine molecules. The goal is to compare the luminescent properties of this molecule to pyrene to evaluate how good of a luminescent probe it

For each sample, take the absorption spectra to observe at what wavelength the molecule experiences excitation. The sample then needs to be purged with nitrogen for five minutes to ensure that oxygen does not react with the sample. Using the excitation wavelength found from the absorption spectra, the emission spectra can be performed. Again, nitrogen purging the sample is required immediately before performing laser photolysis on the sample with a 337 nm pulse laser. The 337 nm pulse laser excites the 1-pyrenemethylamine while the oscilloscope measures the light intensity being emitted from the sample over time.

Results and Discussion Figure 2: Absorption spectra of 1-pyrenemethylamine in various