Terahertz radiation and second-harmonic generation from a single-component polar organic ferroelectric crystal

Venkataramudu, Uppari; Sahoo, Chakradhar; Leelashree, S.; Venkatesh, M.; Ganesh, D Sharma; Naraharisetty, Sri Ram G.; Chaudhary, A.K.; Srinath, S.; Chandrasekar, Rajadurai

doi:10.1039/c8tc02638f

Cited by 33 publications

(28 citation statements)

References 31 publications

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“…Figure displays the absorption and room‐temperature emission spectra of dichloromethane solutions of 4 , 4m , 5 and 6 . The absorption spectra of 4 and 4m are similar to that of a recently reported bpp ligand substituted with a methyl(phenyl)sulfane group, with two charge‐transfer bands at around 260 and 300 nm. The spectrum of 5 slightly differs with three absorption bands at around 250, 275 and 300 nm, while 6 showed two bands shifted to lower energies (at 320 and 350 nm) and a broad absorption band between 250 and 300 nm.…”

Section: Resultssupporting

confidence: 75%

“…According to previous studies on related bpp derivatives, this band can be attributed to ligand fluorescence. [8b] The maxima at 400 and 420 nm for both 4 and 4m are lower in energy than in the related methylthiophenyl‐bpp ligand . The emission is further shifted to still lower energies in 5 (maxima at 410 and 430 nm) and in 6 (425 and 445 nm), showing that the violet fluorescence of the bpp derivative can be red shifted by increasing the number of aromatic rings in the helicene substituent.…”

Section: Resultsmentioning

confidence: 96%

“…[7d] Likewise, 1‐bpp derivatives and 1‐bpp‐based Re I and Ru II complexes have been investigated for their photophysical properties , . Chandrasekar et al have described the violet fluorescence of a series of back‐to‐back coupled 1‐bpp ligands, and reported very recently the luminescence of the methylthiophenyl‐substituted 1‐bpp . Re(CO) 3 X (X = Cl or Br) fragments have been combined with 1‐bpp and a thiophene‐functionalized 3‐bpp to prepare the complexes of formula [Re(1‐bpp)(CO) 3 Cl] and [Re(3‐bpp)(CO) 3 Br] respectively, while [Ru(terpy)Cl 3 ] has been reacted with bpp derivatives to afford luminescent complexes of general formula [Ru(bpp)(terpy)](PF 6 ) 2 .…”

Section: Introductionmentioning

confidence: 99%

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Helicene Bis(pyrazol‐1‐yl)pyridine Ligands for Luminescent Transition‐Metal Complexes

et al. 2019

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We describe herein the synthesis of 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) ligands substituted by helicene units in the 4-position of the pyridine ring. The two-step procedure afforded the molecules bpp[n]helicene (n = 4, 5 and 6) and methyl-bpp[4]helicene, abbreviated as 4, 5, 6 and 4m respectively, with overall good yields. This series of ligands shows fluorescence in the violet region, with a red shift of the emission when increasing the number of aromatic rings in the helicene unit. The tridentate fluorophores have been reacted with Re(CO) 5 Cl and [Ru(terpy)Cl 3 ] to prepare a series of transition metal complexes formulated as [Re I (n)(CO) 3 Cl] (n = 4 and 5) and [Ru II (n)(terpy)](PF 6 ) 2 (n = 4, 4m, 5 and 6). The compounds [a] MOLTECH-4807 Scheme 1. Bpp[n]helicene ligands investigated in the present study.Full Paper 4, 4m, 5 and 6). The photophysical properties of the ligands and complexes have been investigated. Results and Discussion Synthesis and Crystal Structures of the LigandsThe synthetic procedure for the N-donor helicene-based ligands 4, 4m, 5 and 6 is described in Scheme 2 and Scheme 3. The preparation of bpp[n]helicene (n = 4, 5, 6) ligands has been achieved via a two steps procedure from racemic 2-bromo-[n]helicenes, synthesized according to literature reports (Scheme 2). [13] First, a Suzuki coupling between 2,6-dichloropyridine-4-boronic acid pinacol ester and bromo[n]helicene afforded molecules 1, 2 and 3 with excellent yields. These precursors were subsequently reacted with sodium pyrazolate to afford bpp[n]helicene ligands 4, 5 and 6 as racemic mixtures.Precursor 1 has also been reacted with 3-methyl-pyrazole to prepare the ligand methyl-bpp[4]helicene 4m (Scheme 3). This reaction provided two isomers as a consequence of the delocal-Scheme 2. Synthetic procedure for ligands 4, 5 and 6.Scheme 3. Synthetic procedure for ligand 4m.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Helicene Bis(pyrazol‐1‐yl)pyridine Ligands for Luminescent Transition‐Metal Complexes

et al. 2019

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“…Proline presents a rigid core which tends to limit the number of available conformations and leads in nature to helical structure such as collagen whose symmetry of the supramolecular structure is compatible with efficient SHG response [13][14][15][16]. Nevertheless, besides molecules such as substituted helicenes and helicene-like compounds [17,18] and other oligomeric helical strands [19,20], obtaining polar material structure with a helical structure remains difficult to achieve [21]. In this study, we propose the synthesis and computational characterization of two novel proline derivatives which yield polar and helical isomorphous crystals.…”

Section: Introductionmentioning

confidence: 99%

Polar and Helical Isomorphous Crystals of Proline Derivatives: Influence of a Fluorine Atom on the Electric Susceptibility

et al. 2021

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Two novel nonlinear optical isomorphous crystals of proline derivatives with alkyne functionality have been obtained (Boc-L-ProNH(CH2)2CCH and Boc-cis-4-fluoro-L-ProNH(CH2)2CCH). Both derivatives, which differ only by the substitution of a H atom to a F atom, adopt the same polar and columnar right-handed helix arrangement in the crystalline state. In addition, adjacent polar helical columns all point in the same direction, thus generating a macrodipole and a crystalline system conducive for second harmonic generation (SHG) properties. This isomorphous crystal system constitutes an interesting tool to study the effect of the fluorine atom on the dipole moment and on the first hyperpolarizability. Starting from the PBC optimized geometries of the crystals, the macroscopic second-order nonlinearity, χ(2), of the newly synthesized crystals has been estimated by quantum chemical calculations. These χ(2) responses are of the same order of magnitude as those of inorganic proline derivatives while smaller than those observed in crystals of push–pull π-conjugated molecules. Graphic Abstract

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“…1−5 In view of the importance of the time-domain THz spectroscopy technique and density functional theory (DFT)based theoretical approach help us to study the structure− properties and correlation of HEMs. 17,18 Our group has also explored different types materials such as LT/SIGaAs-based photoconductive antenna and organic and semiconductor crystals for THz generation and its application in time-domain spectroscopy of HEMs. 19−22 Because tetrazole derivatives show superior energetic properties as compared to the other five-membered azole moieties because of high contents of nitrogen and higher value of positive heat of formation, their physical properties are comparable with premium explosives like Research department explosive (RDX) and 2,4,6-trinitrotoluene (TNT).…”

Section: ■ Introductionmentioning

confidence: 99%

Time-Domain Terahertz Spectroscopy and Density Functional Theory Studies of Nitro/Nitrogen-Rich Aryl-Tetrazole Derivatives

et al. 2020

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The paper reports the time-domain THz spectroscopy studies of noncentrosymmetric energetic nitro/ nitrogen-rich aryl-tetrazole high-energy molecules. The fingerprint spectra in the THz domain reveal the role of different functional groups attached to position "1" of the tetrazole moiety, which controls the energetic properties. These responses are deliberated through density functional theory (DFT) calculations. The synthesized aryl-tetrazoles exhibit high positive heat of formation (369−744 kJ/mol), high detonation velocities, and pressures (D v : 7734−8298 m·s −1 ; D p : 24−28 GPa) in comparison to the noncentrosymmetric 2,4,6-trinitrotoluene (TNT). These compounds exhibit variation in the refractive indices and absorption between 0.1 and 2.2 THz range. The DFT studies at the molecular and single-crystal level (using plane wave pseudo potential method) endorse in detecting these bands (with ∼1% deviation). The calculated vibrational frequencies and linear optical properties are found to have good agreement with the experimental data in UV−visible and THz regions.

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Terahertz radiation and second-harmonic generation from a single-component polar organic ferroelectric crystal

Abstract: A single-component polar organic ferroelectric crystal produces THz and second-harmonic radiation.

Cited by 33 publications

References 31 publications

Helicene Bis(pyrazol‐1‐yl)pyridine Ligands for Luminescent Transition‐Metal Complexes

Helicene Bis(pyrazol‐1‐yl)pyridine Ligands for Luminescent Transition‐Metal Complexes

Polar and Helical Isomorphous Crystals of Proline Derivatives: Influence of a Fluorine Atom on the Electric Susceptibility

Time-Domain Terahertz Spectroscopy and Density Functional Theory Studies of Nitro/Nitrogen-Rich Aryl-Tetrazole Derivatives

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