Polyhedral-based nonlinear optical materials (original) (raw)
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Structure-Property Relationships in Organic Nonlinear Optical Materials
MRS Proceedings, 1999
ABSTRACTTuning the degree of bond-length alternation in organic nonlinear optical materials is a powerful paradigm for the design of organic materials with large molecular hyperpolarizabilities (β). Several research groups have employed this paradigm in the design and synthesis of NLO materials incorporating donor-acceptor polyenes. Increased bond-length alternation in polyenes leads to decreased barriers to rotation about C=C bonds and, hence, increased conformational flexibility. Since the degree of bond-length alternation is solvent dependent, so is the degree of conformational flexibility. In an effort to probe the influence of conformational flexibility on NLO response, we synthesized a series of simple donor-acceptor polyenes that are either conformationally flexible (la, 2a, 3a) or rigid (1b, 2b, 3b). For each pair of molecules ZINDO sum-over-states calculations predict a larger value of βμ, for the conformationally flexible isomer, but EFISH measurements (CHCl3) display mixe...
…, 1997
2 ) dppe, X 2 ) C≡C, Y 2 ) (E)-CH)CH (12), C≡C (18); L 2 ) dppe, X 2 ) (E)-CH)CH, Y 2 ) C≡C , (E)-CH)CH (16); L 2 ) dppm, X 2 ) C≡C, Y 2 ) (E)-CH)CH (13); L 2 ) dppm, X 2 ) (E)-CH)CH, Y 2 ) C≡C (15), (E)-CH)CH (17)] are reported, the latter being donorbridge-acceptor complexes varying in bridge composition by replacement of yne with E-ene linkages, together with their cyclic voltammetric data, linear optical, and quadratic nonlinear optical response data. Ru II/III oxidation potentials increase on replacing yne linkage by E-ene linkage at the phenylene adjacent to the metal center, and on replacing dppe by dppm co-ligands. The low-energy optical absorption maxima occur in the region 20400-23300 cm -1 and are metal-to-ligand charge-transfer (MLCT) in origin; these bands undergo a blue-shift upon π-bridge lengthening by addition of phenyleneethynylene units, and on replacing E-ene linkages by yne linkages. Time-dependent density functional theory calculations on model complexes have suggested assignments for the low-energy bands. The optical spectra of selected oxidized species contain low-energy ligand-to-metal charge transfer (LMCT) bands centered in the region 9760-11800 cm -1 . Quadratic molecular nonlinearities from hyper-Rayleigh scattering (HRS) studies at 1064 nm reveal an increase in the two-level-corrected 0 value on π-bridge lengthening, a trend that is not seen with values because of the blue-shift in λ max for this structural modification. Replacing yne linkages by E-ene linkage at the phenylene adjacent to the metal center or dppm co-ligand by dppe results in an increase in and 0 values. In contrast, quadratic molecular nonlinearities by HRS at 1300 nm or electric field-induced secondharmonic generation (EFISH) studies at 1907 nm do not afford clear trends. Houbrechts, S.; Kauranen, M.; Clays, K.; Persoons, A.
Semi-empirical calculations of the nonlinear optical properties of polycyclic aromatic compounds
Chemical Physics, 1994
A systematic study of factors influencing nonlinear optical properties, in particular the second hyperpolarizability ( y) , is conducted for a series of polycyclic aromatic hydrocarbons (PAHs). The HOMO-LUMO gap, polarizability (cu), first hyperpolarizability ( p), and second hyperpolarizability of polycyclic aromatic compounds are computed by using semi-empirical MNDO-FF calculation implemented in the MOPAC package. For linear polyacenes, the linear and nonlinear properties and total resonance energy are found to increase while the HOMO-LUMO gap and resonance energy per electron decrease as the number of six-membered rings increases. For nonlinear PAHs, the chain topology should be taken into account. An empirical formula is given to relate the computed ( y) and (cu ) . 0301-0104/94/S 07.00 0 1994 Elsevier Science B.V. All rights reserved. SSDZ 0301-0104(93)E0387-B
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
2-(4-Fluorophenyl)-1-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole (fpmpdi) was synthesised and its structure was characterized by 1 H, 13 C, mass, elemental analysis and X-ray techniques. It belongs to monoclinic crystal system having the lattice dimensions of monoclinic with point group, P 21 /c; a = 8.5132 (1)Å, b = 9.5128 (2)Å, c = 19.2610 (3)Å,ˇ= 96.798 (2). Since (fpmpdi) is highly sensitive to different external stimulations such as UV irradiation, heat, increasing pressure and changing the environmental pH causing color change and so they can be used as a "multi-way" optically switchable material. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg 2+ , Pb 2+ and Cu 2+ and this was suggested to result from the suppression of radiationless transitions from the n-* state in the chemosensors. The optimized geometrical parameters obtained by DFT calculation is in good agreement with single crystal XRD data. The Mulliken, NBO charge analysis and the HOMO-LUMO energies were also calculated. The molecular electrostatic potential surface (MEP) and first static hyperpolarisability have also been employed theoretically which reveal that the fpmpdi have non-linear optical (NLO) behavior with non-zero values. Ground and excited states DFT calculations were carried out in order to find out dipole moment and energy.
Physical Chemistry Research, 2020
Density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations were employed to investigate the electronic and nonlinear optical properties of some substituted C2Bn −2Hn (n = 14 −17) carboranes. Li, Na, K, F, Cl, Br are used as substituents. The carboranes substituted with alkali metal show considerably large first hyperpolarizability values than those of un-substituted ones. NLO response of the halogen-substituted systems is slightly enhanced. The well-known two-level model theory is investigated through TD-DFT approach to understand the origin of NLO response. This study indicates that alkali-metal substituted carboranes may be appropriate for nonlinear optical (NLO) applications.
Ab initio study of nonlinear optical properties of aromatic fused rings
Chemical Physics Letters, 2013
ABSTRACT The nonlinear optical properties of benzene, naphthalene, anthracene, and pyrene are investigated. Static and dynamic polarizability, α(-ω; ω), and second hyperpolarizability, corresponding to dc electric-field-induced Kerr effect (DCKE), intensity dependent refractive index (IDRI), dc electric field-induced second harmonic generation (EFISHG), and third harmonic generation (THG) have been calculated. The calculated α and γ show good agreement with the available theoretical and gas-phase experimental data. The second hyperpolarizabilities exhibit the following trend: γ(THG) > γ(EFISHG) > γ(IDRI) ˜ γ(DCKE) > γ(static). We find that the second hyperpolarizabilities increase as the number of rings in the system increases in either dimension, but the magnitude of increase is more pronounced along the molecular chain axis.
Second-Order Nonlinear Optical Organic Materials: Recent Developments
Springer Series in Optical Sciences, 2000
This chapter presents an overview of the current status of second-order nonlinear optical organic materials for their use in photonic applications such as optical frequency converters and electro-optic modulators. Special emphasis is placed on the material aspects and a thorough discussion of presently available substances. The potential of organic materials for third-order nonlinear optical applications has been presented in detail in Chap. 2. Earlier reviews of organic nonlinear optical materials covering different physical and material aspects can be found in [3.1-8]. Section 3.1 presents a brief introduction to important nonlinear optical and electro-optic effects, while Sect. 3.2 discusses basic material issues relevant for second-order effects. In Sect. 3.3 we discuss the nonlinearities on a molecular scale presenting comprehensive tables. Section 3.4 is devoted to an overview on the macroscopic properties of single crystals and polymers. The advantages and disadvantages of both material systems are discussed and critically confronted with inorganic dielectrics and semiconductors. Section 3.5 deals with the potential utilization of the presented materials and effects: we present a selection of the most promising applications. Some of the organic devices have already matured to a point of commercial availability. In Sect. 3.6 we discuss the issue of stability of the materials, focusing on optical damage in single crystals and orientational relaxation of poled polymers. Finally in Sect. 3.7 we summarize our findings and give an outlook on future work and materials development. 3.1 Nonlinear Optical and Electro-Optic Effects Linear and nonlinear optical effects can be described in terms of the linear polarization pL and the nonlinear polarization pNL induced by the electric field (3.1) This series is truncated because the terms higher than second-order are beyond the scope of this chapter. Some of the higher-order effects are discussed in Chap 2. (3.1) also defines the susceptibility tensors X(n), which contain all the information about the optical properties of the respective material.
Organometallics, 2002
2 ) dppe, X 2 ) C≡C, Y 2 ) (E)-CH)CH (12), C≡C (18); L 2 ) dppe, X 2 ) (E)-CH)CH, Y 2 ) C≡C , (E)-CH)CH (16); L 2 ) dppm, X 2 ) C≡C, Y 2 ) (E)-CH)CH (13); L 2 ) dppm, X 2 ) (E)-CH)CH, Y 2 ) C≡C (15), (E)-CH)CH (17)] are reported, the latter being donorbridge-acceptor complexes varying in bridge composition by replacement of yne with E-ene linkages, together with their cyclic voltammetric data, linear optical, and quadratic nonlinear optical response data. Ru II/III oxidation potentials increase on replacing yne linkage by E-ene linkage at the phenylene adjacent to the metal center, and on replacing dppe by dppm co-ligands. The low-energy optical absorption maxima occur in the region 20400-23300 cm -1 and are metal-to-ligand charge-transfer (MLCT) in origin; these bands undergo a blue-shift upon π-bridge lengthening by addition of phenyleneethynylene units, and on replacing E-ene linkages by yne linkages. Time-dependent density functional theory calculations on model complexes have suggested assignments for the low-energy bands. The optical spectra of selected oxidized species contain low-energy ligand-to-metal charge transfer (LMCT) bands centered in the region 9760-11800 cm -1 . Quadratic molecular nonlinearities from hyper-Rayleigh scattering (HRS) studies at 1064 nm reveal an increase in the two-level-corrected 0 value on π-bridge lengthening, a trend that is not seen with values because of the blue-shift in λ max for this structural modification. Replacing yne linkages by E-ene linkage at the phenylene adjacent to the metal center or dppm co-ligand by dppe results in an increase in and 0 values. In contrast, quadratic molecular nonlinearities by HRS at 1300 nm or electric field-induced secondharmonic generation (EFISH) studies at 1907 nm do not afford clear trends. Houbrechts, S.; Kauranen, M.; Clays, K.; Persoons, A.
Current Opinion in Solid State and Materials Science, 1996
Over the past two years, the field of molecular nonlinear optics has benefited from both upstream rejuvenation (the emergence of new molecular engineering guidelines) and downstream application-oriented breakthroughs, helping to bring the field closer to industrial developments. In the fundamentals areas, traditional perspectives based on the paranitroaniline 'molecular diode' template are being enlarged to encompass three-dimensional multicharge transfer 'multipolar' systems with dipolarless 'octupoles', demanding that earlier models and experiments be thoroughly revisited. Furthermore, the relevance of polar structures primarily targeted towards quadratic nonlimear optics has been extended to cubic all-optical processes based on a cascaded sequence of quadratic processes. In the application domain, progress in crystal growth is best illustrated by the demonstration of low threshold pulsed near-IR optical parametric oscillators based on stable organic or organomineral crystals. Functionalized polymers have confirmed their current supremacy as organic optoelectronic device materials with the reports of low voltage electro-optic modulation in integrated waveguide structures and high modulation bandwidth.