N-Methylquinolinium derivatives for photonic applications: Enhancement of electron-withdrawing character beyond that of the widely-used N-methylpyridinium

Jeong, Jae-Hyeok; Kim, Ji-Soo; Campo, Jochen; Lee, Seung-Heon; Jeon, Woo-Yong; Wenseleers, Wim; Jazbinšek, Mojca; Yun, Hoseop; Kwon, O‐Pil

doi:10.1016/j.dyepig.2014.07.016

Cited by 40 publications

(27 citation statements)

References 49 publications

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“…We chose the benzimidazolium group (1,3‐dimethyl‐1H‐benzoimidazol‐3‐ium) which is a relatively weak electron acceptor compared to the quinolinium groups used in benchmark low‐bandgap nonlinear optical crystals including HMQ‐TMS crystals. [ 27,28 ] Since the van der Waals volume and most of the chemical structure of the HMI chromophore is very similar to the mother HMQ chromophore, the HMI‐based crystals may exhibit similar overall molecular ordering features and corresponding physical properties, even though the refractive index decreases. As a result, introducing the HMI cation keeps the overall characteristics of the long‐wavelength refractive index of the benchmark HMQ‐TMS crystals unimpaired (including the overall characteristics for THz wave generation), but the refractive index in the near‐IR region is expected to decrease due to the wide bandgap of the HMI cation, as illustrated in Figure 1a.…”

Section: Resultsmentioning

confidence: 99%

Wide‐Bandgap Organic Crystals: Enhanced Optical‐to‐Terahertz Nonlinear Frequency Conversion at Near‐Infrared Pumping

Kim

Han

et al. 2020

Advanced Optical Materials

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Enhanced terahertz (THz) wave generation is demonstrated in nonlinear organic crystals through refractive index engineering, which improves phase matching characteristics substantially. Unlike conventional low‐bandgap nonlinear organic crystals, the newly designed benzimidazolium‐based HMI (2‐(4‐hydroxy‐3‐methoxystyryl)‐1,3‐dimethyl‐1H‐benzoimidazol‐3‐ium) chromophore possesses a relatively wide bandgap. This reduces the optical group index in the near‐infrared, allowing better phase matching with the generated THz waves, and leads to high optical‐to‐THz conversion. A unique feature of the HMI‐based crystals, compared to conventional wide‐bandgap aniline‐based crystals, is their remarkably larger macroscopic optical nonlinearity, a one order of magnitude higher diagonal component in macroscopic nonlinear susceptibility than NPP ((1‐(4‐nitrophenyl)pyrrolidin‐2‐yl)methanol) crystals. The HMI‐based crystals also exhibit much higher thermal stability, with a melting temperature Tm above 250 °C, versus aniline‐based crystals (116 °C for NPP). With pumping at the technologically important wavelength of 800 nm, the proposed HMI‐based crystals boost high optical‐to‐THz conversion efficiency, comparable to benchmark low‐bandgap quinolinium crystals with state‐of‐the‐art macroscopic nonlinearity. This performance is due to the excellent phase matching enabled by decreasing optical group indices in the near‐infrared through wide‐bandgap chromophores. The proposed wide‐bandgap design is a promising way to control the refractive index of various nonlinear organic materials for enhanced frequency conversion processes.

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Section: Resultsmentioning

confidence: 99%

Wide‐Bandgap Organic Crystals: Enhanced Optical‐to‐Terahertz Nonlinear Frequency Conversion at Near‐Infrared Pumping

Kim

Han

et al. 2020

Advanced Optical Materials

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“…The value of log UH was calculated and found to be −0.48. The experimental procedures obey in the evaluation of acid dissociation constants pKa and their calculations from the A-pH data and are as literature described in the literature [ 17 ]. The pKa values were reproducible to ±0.02 pKa unit.…”

Section: Methodsmentioning

confidence: 99%

“…Also merocyanines are well known to be sensitive to the polarity of solvents so these dyes show very interesting spectral, photochemical behavior and solvatochromic properties [ 14 ], as well as being photoreactive compounds sensitive to the acidity of the medium [ 15 ], so that in acidic or basic medium these dyes can undergo protonation or deprotonation reactions [ 16 ]. Due to these properties, these dyes are very attractive for numerous photonic applications [ 17 ] such as laser phototherapy [ 18 ], molecular electronics [ 19 ], nonlinear optics [ 20 ], solar photovoltaic′s [ 21 ] and laser materials [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, Tautomeric Structure and Solvatochromic Behavior of Novel 4-(5-Arylazo-2-Hydroxystyryl)-1-Methylpyridinium Iodide as Potential Molecular Photoprobe

et al. 2016

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A novel series of the title compound 4-(5-arylazo-2-hydroxystyryl)-1-methylpyridinium iodide 6 has been synthesized via condensation reactions of the arylazosalicylaldehyde derivatives 4a–i with 1-methyl-picolinium iodide 5. The structures of the new arylazo compounds were characterized by 1H NMR, IR, mass spectroscopy, as well as spectral and elemental analyses. The electronic absorption spectra of arylazomerocyanine compounds 6 were measured in different buffer solutions and solvents. The pK′s and pK*′s in both the ground and excited states, respectively, were determined for the series and their correlations with the Hammett equation were examined. The results indicated that the title arylazomerocyanine dyes 6 exist in the azo form 6A in both ground and excited states. The substituent and solvent effects (solvatochromism) of the title compound arylazomerocyanine dyes were determined using the Kamlet-Taft equation and subsequently discussed.

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“…) is a versatile light‐absorbing dye used in non‐linear optics, spectroscopy, and zeolite morphology research . Two absorption maxima are observed in organic solvents, one around 500 nm and one upwards of 300 nm . The molecular structure suggests push‐pull behavior in which electrons move from the aniline moiety to its electron‐poor pyridinium group .…”

Section: Long Range Charge Transfer In a Donor‐bridge‐acceptor Dyementioning

confidence: 99%

A quantitative analysis of light‐driven charge transfer processes using voronoi partitioning of time dependent DFT‐derived electron densities

2017

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An analytical method is presented that provides quantitative insight into light-driven electron density rearrangement using the output of standard time-dependent density functional theory (TD-DFT) computations on molecular compounds. Using final and initial electron densities for photochemical processes, the subtraction of summed electron density in each atomcentered Voronoi polyhedron yields the electronic charge difference, Q VECD . This subtractive method can also be used with Bader, Mulliken and Hirshfeld charges. A validation study shows Q VECD to have the most consistent performance across basis sets and good conservation of charge between electronic states. Besides vertical transitions, relaxation processes can be investigated as well. Significant electron transfer is computed for isomerization on the excited state energy surface of azobenzene. A number of linear anilinepyridinium donor-bridge-acceptor chromophores was examined using Q VECD to unravel the influence of its pi-conjugated bridge on charge separation. Finally, the usefulness of the presented method as a tool in optimizing charge transfer is shown for a homologous series of organometallic pigments. The presented work allows facile calculation of a novel, relevant quantity describing charge transfer processes at the atomic level.

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N-Methylquinolinium derivatives for photonic applications: Enhancement of electron-withdrawing character beyond that of the widely-used N-methylpyridinium

Cited by 40 publications

References 49 publications

Wide‐Bandgap Organic Crystals: Enhanced Optical‐to‐Terahertz Nonlinear Frequency Conversion at Near‐Infrared Pumping

Wide‐Bandgap Organic Crystals: Enhanced Optical‐to‐Terahertz Nonlinear Frequency Conversion at Near‐Infrared Pumping

Synthesis, Characterization, Tautomeric Structure and Solvatochromic Behavior of Novel 4-(5-Arylazo-2-Hydroxystyryl)-1-Methylpyridinium Iodide as Potential Molecular Photoprobe

A quantitative analysis of light‐driven charge transfer processes using voronoi partitioning of time dependent DFT‐derived electron densities

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