A review on linear and non‐linear resonance Raman spectroscopy of the conjugated system polydiacetylene

Abstract

We review resonance Raman investigations of the linear conjugated p-electron system of polydiacetylenes embedded in single-crystalline monomer matrices. Absorption, luminescence, resonance Raman and resonance CARS spectroscopy were used to investigate vibronic properties of the polymers. As an example, we discuss the theoretical model applied for the simulation of the resonance Raman line and excitation profiles obtained from the polymer chains in FBS, TS/FBS and TS6 diacetylene single crystals. The theory is based on a Franck-Condon model, which considers a chain length dependence. The electronic transition energies and matrix elements were calculated by means of an LCAO MO (linear combination of atomic orbitals molecular orbital) calculation in the Hückel approach. An interaction between ensemble and intramolecular properties due to defects can be shown. Besides the well known polymer absorption, the partially polymerized single crystals of the diacetylenes under investigation show blue-shifted absorption bands in sharply separated crystal areas. The spectroscopic investigations of this chromism revealed that most probably growth defects in f111g crystal growth sectors influence the side-group geometry of the polymer chains. Using femtosecond time-resolved CARS spectroscopy, the dynamics of the vibrational excitation in the electronic ground and excited states can be investigated. Here, we report the controlled selective excitation of the polymers. We used a CARS scheme where the difference of pump and Stokes laser wavelengths is chosen to achieve resonance with several chain modes of the polydiacetylenes. By varying the timing and the phases of the femtosecond laser pulses, the timing and the intensity of these modes can be strongly influenced.

Polydiacetylene-based ultrastrong bioorthogonal Raman probes for targeted live-cell Raman imaging

“…PDDA exhibits an exceptionally intense Raman peak at 2120 cm −1 of PDDA in solution, resulting from the large polarizability of polydiacetylenes 46,47 . In addition, the highly planar polymer backbone of PDDA further assists the stretching vibration of alkyne units in the backbone.…”

The Effect of Hydrogen-Bonds of Amino Acid-Derived Diacetylene by Photopolymerization in Supramolecular Hydrogels

“…4(a)), the vibrational band for the diacetylene group at 1462 cm −1 (v C≡C decreased whereas a new band appeared at 1515 cm −1 , which corresponds to the C C stretching vibration region. [18][19][20] In addition, the peak at 2089 cm −1 (v C≡C was shifted to a higher wavenumber, which is due to increased conjugation. After irradiation for 30 min, the original band almost disappeared at 1462 cm −1 (v C≡C whereas the new band at 1515 cm −1 increased markedly.…”

“…Before irradiation, the selfassembled helical nanofiber 1 showed vibrational bands at 2089 cm −1 and 1462 cm −1 (v C≡C . 18 These characteristic peaks have been used in the quantitative assessment of the monomer to polymer conversion. After irradiation by Hg lamp for 30 s (Fig.…”

Coherent multidimensional vibrational spectroscopy

“…It can also increase the C 6 H 5 CH 3 ‡ product yield by ¹4£ if that fragment is to be optimized. In addition to dissociative reactions, coherent control of atomic and molecular state populations has been demonstrated so one can control the spectra that one observes [175,214,215,219,220]. Similar methods should be capable of controlling electron transfer reactions and H bonding interactions.…”