Extended First Hyperpolarizability of Quasi-Octupolar Molecules by Halogenated Methylation: Whether the Iodine Atom is the Best Choice

Abstract

Inspired by a previous report, in which the quasi-octupolar molecules DPATSB, DPATSP, and (DPATSP−Me) + I − were synthesized and the iodized salt was proposed as a suitable optical limiting chromophore, we performed linear and nonlinear optical analyses on the synthesis molecules and several extension halogenated dyes ((DPATSP−Me) + X − (X = F, Cl, and Br)) by using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The energy gap of frontier molecular orbitals (FMOs) was diminished by introducing the pyridinium ion into the system, and a charge-separated state was formed in halogenated salts. The N-methylation of the dye leads to a sharp increase in response characteristics, accompanied by a red-shift of the absorption spectrum from the ultraviolet region to the visible light region. Importantly, our studies show that there exists a significant halogen atomic-species dependence of the nonlinearity of the salts. Fluorination and bromination of the molecule seem to be more potential in improving the nonlinearity in zero-frequency and frequency-dependent incident light, respectively, without causing the undesirable red-shift of the absorption band relative to their halogenated analogues. The nonlinear optical (NLO) responses calculated by different DFTs are identical in trend.

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 polarizability of molecules is indeed insensitive to the external field, which has been observed in our previous studies on optical nonlinearity of other systems. 6,54 Under the same electric field, on the other side, the iso ( )  � of the molecule calculated in solvent is slightly higher than that in vacuum, but there is little difference of it in different sorts of solvents. By comparing Figure 6(b) and (c), it can be seen that the external field resonance or solvation effect has the similar effect on vec ( )   and || ( )   , which trend similar to that of the HRS ( )   in response to these influence discussed above.…”

“…Therefore, the field of optical materials has been exploring how to develop new compounds with tunable photophysical properties or enhanced (hyper)polarizabilities for a long time. [4][5][6] So far, researchers have successfully recognized a variety of molecules with exciting optical properties, including inorganic complexes, [7][8][9] organic molecules, [10][11][12][13] metal clusters, 14,15 doped polarizable electrides, 16,17 and even macrocyclic compounds with special topology, 6,18,19 and applied some of them into practice. Among them, the conjugated organic chromophores with electron donating and electron accepting groups at both ends were one of the most popular optical units, partially due to their convenient structural tailoring.…”

Push–pull effect to improve the electronic and optical properties of [7] circulene

“…Note that we report the magnitudes for the tumbling averaged α , and β, defined as in refs. [38–40].…”

Synthesis, characterization, DFT, and TD-DFT studies of (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite)

“…H index is employed in the assignment of the breath of the approximate distribution of hole and electron of a particular excitation [33,37]. No significant differences in the H indices were observed for the various excitations under consideration, as evident in Table 2.…”