Ethynylated Acene Synthesis and Photophysics for an Organic Chemistry Laboratory Course

Abstract

An operationally simple, reliable synthesis of ethynylated acenes suitable for an upper-division undergraduate organic chemistry laboratory course has been developed. This experiment requires students to synthesize two acene derivatives and can be completed in 6−8 laboratory sessions (3 h each); a shorter experiment could be realized in the synthesis of only one product. Synthesis is carried out by first treating a terminal alkyne with n-butyllithium in an oven-dried flask under nitrogen at 0 °C. An acene quinone is added, which produces a doubly ethynylated diol. Dehydration with SnCl 2 /HCl yields a bis(ethynylated) acene, which is purified via a short pad or column of silica gel. The intense colors of the products allow for great ease in determining reaction completion and following the products in chromatography. UV−vis and fluorescence spectroscopy may be used to better understand the effect of molecular structure on electronic properties.

Supramolecular-scaffold-directed two-dimensional assembly of pentacene into a configuration to facilitate singlet fission

“…S28). Since the absorption and emission behaviors of 1 and 2 are similar to those reported for the corresponding diethynyl-appended acene derivatives 53,54 , the presence of the triptycene scaffolds has no influence on the electronic properties of the acene chromophores in solution.…”

“…4B). With the disappearance of the S-S absorption, a T-T band for the pentacene chromophore at around 530 nm [35][36][37]54 rapidly appeared after a delay time of 0.2 ps (Fig. 4A).…”

Synthesis and Characterization of a Metal-Free Organic Dye-Sensitizer for Solar Cell: An Advanced Organic Chemistry Research-Based Laboratory

“…In order to gain insight into the light-harvesting properties of dyes, students collect the UV–vis and emission spectra of 4 in CH 2 CI 2 as shown in Figures and . − The absorption spectrum of the dye molecule is red-shifted and extends in the visible region showing that it is able to absorb solar energy (Figure ). − The red-shifting of the spectrum for 4 is attributed to the narrowing of the HOMO–LUMO band gap due to the attachment of the pyrene molecules to the triphenylamine donor moiety which increases its conjugation and enhances its electron-donating properties. − The concept of narrowing the HOMO–LUMO gap to lengthen the absorption wavelength is normally taught in the second year of organic chemistry on the topic “Conjugated Dienes and Ultraviolet Spectroscopy”. Therefore, this principle is reinforced during this part of the project.…”