Pyrene

Benzo [ def ] phenanthrene

In the pure state of colorless crystals

Fixed

1.27 g · cm -3 ( 23 ° C)

156 ° C.

394 ° C

65 mPa (63.5 ° C)

• Insoluble in water ( 0.135 mg · l-1 at 25 ° C)
• Soluble in diethyl ether, and aromatic solvents

Attention

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Pyrene is a whitish yellow solid which was obtained as a powder or as flakes. Pyrene is one of the polycyclic aromatic hydrocarbons. Auguste Laurent synthesized pyrene for the first time.

Pyrene is found in coal tar. It is classified as irritating, it reddens the skin and eyes, a MAK value is still not fixed. Pyrene can be made by porcelain tubes at 650 ° C from acetylene and hydrogen while conveying a mixture.

It is used as a probe molecule in fluorescence spectroscopy.

The absorption spectrum is typical for many PAHs, triple comb -like structure ( compared perylene, Diindenoperylen ). The longest-wavelength absorption band is located at 335 Main nm The main fluorescence band at about 388 nm has it

Pyrene forms in concentrated solution (hexane, cyclohexane, decalin or similar hydrocarbons ) to itself when excited by UV light called excimers (exited dimer ). These excimers have solutions, unlike dilute solutions of pyrene, a fluorescent band at about 466 nm excimer formation depends mainly on the viscosity of the solvent used, which in turn depends on the temperature. In the presence of quencher ( quencher ), such as oxygen, the fluorescence quantum yield of the excimer drops significantly. This is related that an excimer from an excited and an unexcited pyrene arises and the excited pyrene replaced by the presence of oxygen as a quencher back to the ground state. Pyrene is, unlike, for example, anthracene, with no UV excitation [4 4 ] cycloaddition with itself one, so that the excimers only have the option to either dissociate or bright or not bright switch in the ground state.