Theoretical insight into the substituent effects on linear and nonlinear optical properties of azobenzene‐based chromophores

Abstract

The linear and nonlinear optical properties of 4 kinds of experimental synthesized azobenzene-based chromophores were investigated by different density functional theories (DFTs) upon the electronic structures. The structure-property relationship was studied on each single molecule either in the gas phase or in diethylether and tetrahydrofuran (THF) solutions. The substituent effect on optical properties was revealed by checking the positions of substituent groups, and the influence of dynamic perturbation to the optical nonlinearity was investigated by simulating the experimental excitation. The results revealed that the substituent in the metaposition of the azobenzene group affects the optical properties more significantly than that in the ortho-position, which is in agreement with the experimental finding. The modulation of molecular hyperpolarizability of bridge-substituted azobenzene derived by dynamic perturbation is not recommended because of the reduced dynamic hyperpolarizability relative to the static one. The different functions of the DFT method hardly affect the calculated results, while solvent effects of diethylether and THF solutions are significant on the optical properties, especially for optical nonlinearity. The information derived from the single chromophore may be helpful in the design and preparation of high-performance nonlinear optical materials in further.

Effects of External Field Wavelength and Solvation on the Photophysical Property and Optical Nonlinearity of 1,3-Thiazolium-5-Thiolates Mesoionic Compound

“…Generally speaking, the photophysical and nonlinear optical (NLO) properties of these chromophores can be controlled by adjusting their structural modules: electron donor, π-conjugated linker, or electron acceptor. [20][21][22][23][24] Since Baker and coworkers put forward the concept of "mesoionic" in 1949, 25,26 mesoionic rings defined by planar five-or six-membered heterocyclic betaines with at least one side-chain whose -atom in the ring plane have been recognized as a promising candidate for conjugated bridges of optical materials because of their electronic mobility. 27 Numerous mesoionic compounds with different electron donors and electron acceptors have been studied both theoretically and experimentally.…”

Influence of inter- and intramolecular H-bonding on the mesomorphic and photoswitching behaviour of (E)-4-((4-(hexyloxy)phenyl)diazenyl)-N-phenyl benzamides

“…Moreover, the thermal cis-trans isomerization of azo derivatives makes them excellent candidates for optical storage devices due to high stability in the cis form and the reversibility of the isomerization. 14,15 In addition, azobenzene derivatives have been proposed for potential applications in the areas of nonlinear optics, 16 chemo sensors, 17 liquid crystals, 18 photochemical molecular switches, 19 molecular shuttles 20 and drug delivery. 21 Recently, we have designed and studied the optical storage properties of several azobenzene derivatives, namely, the azobenzene dimers with aromatic and aliphatic spacers, 22 uorinated azobenzene esters, 23 photopolymerizable azobenzene derivatives, 24 bent-shaped azobenzene monomers, 25,26 alkoxy azobenzene derivatives with coumarin moieties, 27 siloxane based azobenzene derivatives, 28 hydrophilic/ hydrophobic-based azobenzene mesogens 29 and amide functionalized azobenzene derivatives with intermolecular Hbonding.…”

Calculation of linear and nonlinear optical properties of azobenzene derivatives with Kohn–Sham and coupled-cluster methods

“…For the cis-isomers, the optimized o value in TLC-PBE is B0.17, and for trans, it is B0. 23. The o values are smaller than those of the global paramatrizations of CAM-B3LYP and LC-PBE, and they indicate that the extended p-conjugation in these systems requires a switch from KST exchange to eX at larger electron separations than is provided by typical LC functional parametrization.…”

“…[18][19][20] Studies on NLO properties in azobenzene derivatives have triggered great interest in this class of compounds over recent decades. [21][22][23] Polarizabilities and hyperpolarizabilities calculated at the uncorrelated Hartree-Fock (HF) level are generally not accurate, i.e. electron correlation is important for their theoretical description.…”