Absorption and emission properties of phenylene ethynylene oligomers: effect of substitution and π-conjugation length

Abstract

The optical properties of a series of -conjugated phenylene-ethynylene oligomers (OPEs) have been studied by advanced quantum chemical methods. The ground state and lowest singlet excited state geometries of unsubstituted and different electron donor and acceptor groups substituted OPEs are optimized by density functional theory and configuration interaction singles methods. The absorption and emission spectra of unsubstituted and substituted OPEs have been calculated using the time-dependent density functional theory (TDDFT) method. The results of theoretical calculations are in good agreement with the available experimental results. It has been found that the substitution of electron donating and withdrawing groups in the phenyl ring and conjugation length of the OPEs has significantly affect both the absorption and emission spectra

Oligo(p‐phenyleneethynylene) (OPE) Molecular Wires: Synthesis and Length Dependence of Photoinduced Charge Transfer in OPEs with Triarylamine and Diaryloxadiazole End Groups

“…Such agreements between observed and computed emission data have been found in a related D-π-A OPE derivative study. [40] The calculated Stokes shifts of 1720-2670 cm -1 are in the same region as the observed Stokes shifts of 1890-2650 cm -1 in cyclohexane (Table 2). Time-resolved emission spectroscopy.…”

Optical Absorption and Emission Properties of Fluoranthene, Benzo[k]fluoranthene, and Their Derivatives. A DFT Study

“…On the basis of these geometries, they calculated the absorption and emission spectra using the TD-DFT method with the B3LYP exchangecorrelation functional, and their results are in good agreement with the experimental results. It has been shown in earlier studies that the results obtained with TD-B3LYP and CIS methods are in good agreement with the available experimental results for phenylene ethynylene oligomers, 45 luciferin, 46 and triphenylene derivatives. 47 Xue et al 48,49 have shown that TD-DFT at PBE1PBE/6-31G//PBE1PBE/6-31G(d) level of theory successfully reproduced the molecular geometry and absorption wavelength of chalcones.…”

An ab initio simulation of the UV/Visible spectra of substituted chalcones

“…On the other hand, using ab initio CIS/HF, Oumi et al [22] studied chalcone and its hydroxyl derivatives, but the differences reported between gas-phase theoretical and solvated experimental λ max are quite large (0.7eV on average). In recent years, time-dependent density functional theory (TD-DFT) has emerged as a reliable standard tool for the theoretical treatment of electronic excitation spectra and recent works demonstrate the good accuracy for a wide range of systems [23][24][25][26][27][28][29][30][31][32][33][34]. Moreover, the computational cost of TD-DFT calculation is comparative to that of a Hartree-Fock based single excitation theory, such as, configuration interaction singles (CIS) or time-dependent Hartree-Fock (TDHF) method.…”