Nonlinear Optical Properties Of Chromophores Research Articles

Theoretical investigations of the electronic structure, spectroscopic (IR, Raman and UV–Vis), optoelectronic, thermodynamic and nonlinear optical properties of chromophores of 2-styrylquinoline and 2-(3-nitrostyryl)quinoline

Theoretical investigations of the electronic structure, spectroscopic (IR, Raman and UV–Vis), optoelectronic, thermodynamic and nonlinear optical properties of chromophores of 2-styrylquinoline and 2-(3-nitrostyryl)quinoline

The effect of the additional phenyl moiety on the linear and quadratic nonlinear optical properties of chromophores with vinyl-quinoxalinone-vinyl π-bridge

Four novel push-pull tricyanofuran-based chromophores with vinylene-quinoxalinone-vinylene π-conjugated bridge and aniline type donor with phenyl moiety either introduced into the donor/acceptor as substituent or fused with aniline in carbazole and phenothiazine structures have been synthesized and their linear and nonlinear optical properties were systematically investigated by UV–Vis spectroscopy and DFT calculations. Addition of benzene ring as substituent to the chromophore leads to moderate (22–36 pm/V) macroscopic NLO activity of composite chromophore/PMMA materials, while guest-host polymers doped with chromophores with fused heterocyclic donor moiety demonstrate higher d33 values up to 47 pm/V. Chromophore-containing polymer films preserve more than 90% of d33 after 1000 h at ambient temperature.

Ferrocene appended 1,8-naphthalimide chromophores: Synthesis, theoretical, the effect of phenyl substitution on aggregation-induced enhanced emission and second-order nonlinear optical studies

A new ferrocene appended linear donor-π-acceptor (D-π-A) type 1,8-naphthalimide chromophores [FcPhNap-n-butyl (1) and Fc(Ph)2Nap-n-butyl (2)] have been synthesized and characterized using various analytical and spectroscopic techniques. The chromophores 1 and 2 show the one-electron transfer process, which was examined through cyclic voltammetric (CV) method. The solvatochromic studies show red shift by increasing the solvent polarity from non-polar to polar for both the chromophores 1 and 2, due to the better stabilization of the more polarized excited state than the ground state in the polar solvent. The fluorescence studies show low fluorescence emission, which was enhanced by aggregation in THF/water mixture when the water ratio is increased upto 60%, due to the restricted intramolecular rotation (RIR) process in the aggregated state. Also, the quantum yield increases 3.4 (1) and 6.8 (2) times in the aggregation induced enhanced emission (AIEE) state than THF solution for both the chromophores [THF/AIEE = 0.05/0.17 for 1 and 0.03/0.22 for 2]. The second-order non-linear optical properties of the chromophores 1 and 2 were studied using Kurtz and Perry powder technique, chromophore 2 shows 1.2 times higher SHG efficiency than 1, owing to the presence of additional phenyl group in 2, which further supports the effective charge transfer process from donor to acceptor. Furthermore, optical and non-linear optical properties of chromophores 1 and 2 were analyzed by DFT/TD-DFT calculations using different functionals (B3LYP, long-range corrected CAM-B3LYP and LC-BLYP) with 6–31+G** level of theory. The B3LYP functional shows higher hyperpolarizability values [β0 = 109.2 × 10-30 esu (1), 299.7 × 10-30 esu (2)], due to the overestimation of the dipole moment, polarizability and hyperpolarizabilities between the donor–π–acceptor systems in B3LYP-hybrid functional, which leads to incorrect long-range charge transfer.

Tunable linear and nonlinear optical properties of chromophores containing 3,7-(di)vinylquinoxalinone core by modification of receptors moieties

To study the linear and nonlinear optical properties of chromophores with 3,7-(di)vinylquinoxalinone core, excitation energies, dipole moments, polarizabilities, the first and second hyperpolarizabilities as well as TPA cross-sections of four chromophores with different receptors in vacuum and chloroform solvent were calculated by DFT method and response theory. Two methods of the Hellmanne-Feynman theorem and the McRae equation were used to estimate the difference of the dipole moment between the excited state and the ground state. The linear polarizability and the first hyperpolarizability were calculated by the derivative method, and the second hyperpolarizability was calculated by the finite difference method. It is found that the numerical size and order of the above polarizability and hyperpolarizability were verified by using the few-state model. By studying charge-transfer excited states and the transition matrix element, the internal mechanism of TPA and transition channels were revealed. Results demonstrated that chromophore TCP with acceptor [5-dicyanomethylene-2-oxo-4-cyano-2,5-dihydropyrrol-3-yl] possesses a more obvious NLO coefficient value, and TCF with 5,5-dimethyl-2- dicyanomethylene-3-cyano-2,5-dihydrofuran-4-yl possesses the largest TPA cross-section. The current investigation is expected to provide theoretical support for the development of chromophores with 3,7-(di)vinylquinoxalinone π-electron bridge in NLO materials.

Enhancement of electro-optic properties of nonlinear optical chromophores by introducing pentafluorobenzene group into the donor and π-bridge

Two isophorone-based chromophores A-B has been synthesized and investigated based on diethylaminophenyl donor and tricyanovinyldihydrofuran or phenyl-trifluoromethyltricyanofuran acceptors. The chromophores were modified with a bulky pentafluorobenzene group covalently attached to both the donor and bridge section of the chromophores to prevent close packing of molecules, which benefit the polarization efficiency. The ultraviolet absorption, Density functional theory (DFT) calculation, thermal stabilities and electro-optic activities of these chromophores were systematically studied. The chromophores A-B exhibited good thermal stabilities with the decomposition temperatures (Td) higher than 220 °C. Most importantly, the rigid steric hindrance groups can effectively reduce intermolecular electrostatic interactions to translate the hyperpolarizabilities of chromophore into large electro-optic (EO) coefficients (r33). Polymers doped with 30 wt% chromophore A-B have been poled to afford ultrahigh electro-optic coefficient (r33) of 115 pm/V and 213 pm/V, respectively at 1.31 μm, which is higher than that of analogue chromophores which without isolation groups.

Design, synthesis, and properties of nonlinear optical chromophores based on a verbenone bridge with a novel dendritic acceptor

A polyenic chromophore containing a new dendritic tricyanofuran acceptor has been synthesized for achieving improved polar order in poled polymers.

Nonlinear optical properties of chromophores with indolizine donors: Theoretical study

New class of nonlinear optical chromophores with donors containing indolizine moiety is proposed. Dipole moment and first hyperpolarizability values of the chromophores, which are analogs of FTC, CLD and OLD chromophores, containing 1-methyl-2-phenylindolizin-3-yl (MPI-3) or 3-methyl-2-phenylindolizin-1-yl (MPI-1) donors (instead of diethylaminophenyl), 3-cyano-2-dicyanomethylene-5,5-dimethyl-1,5-dihydrofuran-4-yl (TCF) acceptor, and 2,5-divinylthiophene, octatetraene and 2,2′-divinylbithiophene π-electron bridge, are calculated by DFT technique. Chromophores with named donors and acceptors and 3,7-divinylquinoxalin-2-one π-electron bridge are also studied. In most cases higher values of first hyperpolarizability were obtained for chromophores with MPI-3 donor, this being in accordance with the electron density distribution in these fragments. The change of dimethylaniline donor fragment for indolizine one results in the growth of the first hyperpolarizability values. This observation holds also for chromophores with divinylquinoxalinone π-electron bridge, in which higher values of first hyperpolarizability are obtained when the donor moiety is connected through vinylene group at position 3 rather than at position 7 of the quinoxalinone system.

Significant Effect of Bromo Substituents on Nonlinear Optical Properties of Polymer and Chromophores

Four chromophores containing bromo substituents, a ployimide with bromo-containing chromophores, four reference functional polyimides, and fourteen reference chromophores were synthesized for studying effect of bromo substituents on nonlinear optical (NLO) properties of materials and chromophores. The results of hyper-Rayleigh scattering and UV-vis spectra show that static first molecular hyperpolarizability (beta(0)) values of bromo-containing chromophores are 1.24-5.75 times as beta(0) of the corresponding chloro-containing chromophores (Hammett constants sigma of chloro and bromo groups are same) without causing a visible shift of the absorption band to longer wavelength. UV-vis spectra and the results of Maker Fringe method show that the polyimide with chromophores containing bromo substituents exhibits a good optical transparency and a much higher macroscopic nonlinear optical coefficient (d(33) = 20.1 pm/V) than the reference polyimides containing nitro (d(33) = 9.6 pm/V) and cyano (d(33) = 8.9 pm/V) groups in spite of nitro and cyano groups being strong electron acceptors. d(33) of polyimide with chloro-containing chromophores is very small. Therefore, this paper suggests an effective strategy for improving the NLO properties of polymeric materials and chromophores without reducing optical transparency in designing NLO polymers and chromophores. On the basis of quantum chemistry calculations, the reasons of effect of bromo substituents on NLO properties of chromophores and materials were discussed.

Theory-inspired development of organic electro-optic materials

Real-time, time-dependent density functional theory (RTTDDFT) and pseudo-atomistic Monte Carlo–molecular dynamics (PAMCMD) calculations have been used in a correlated manner to achieve quantitative definition of structure/function relationships necessary for the optimization of electro-optic activity in organic materials. Utilizing theoretical guidance, electro-optic coefficients (at telecommunication wavelengths) have been increased to 500 pm/V while keeping optical loss to less than 2 dB/cm. RTTDDFT affords the advantage of permitting explicit treatment of time-dependent electric fields, both applied fields and internal fields. This modification has permitted the quantitative simulation of the variation of linear and nonlinear optical properties of chromophores and the electro-optic activity of materials with optical frequency and dielectric permittivity. PAMCMD statistical mechanical calculations have proven an effective means of treating the full range of spatially-anisotropic intermolecular electrostatic interactions that play critical roles in defining the degree of noncentrosymmetric order that is achieved by electric field poling of organic electro-optic materials near their glass transition temperatures. New techniques have been developed for the experimental characterization of poling-induced acentric order including a modification of variable angle polarization absorption spectroscopy (VAPAS) permitting a meaningful correlation of theoretical and experimental data related to poling-induced order for a variety of complex organic electro-optic materials.

Synthesis and nonlinear optical properties of chromophores for photorefractive polymer materials

The synthesis and nonlinear optical (NLO) properties of a series of nitrostilbene-, dinitrostilbene-, and dicyanomethylenedihydrofuran-based chromophores potentially useful in photorefractive multifunctional polymers are reported. Electronic absorption spectra have been measured in different solvents. Electric field induced second harmonic (EFISH) generation results show that the 2-dicyanomethylen-3-cyano-5,5-dimethyl-2,5-dihydrofuran moieties lead to the best NLO performances. Dinitrophenyl-based chromophores have shown a reduced nonlinear response as compared with the mononitro analogues. Nonlinear optical properties of a selected nitro–dinitro couple have been also determined theoretically.

Synthesis and NLO Properties of Chromophores with 1,8‐Dimethoxy‐9,10‐dihydroanthracene and Thiobarbituric acid Moieties

AbstractThe new chromophore molecules with nonlinear optical (NLO) properties were prepared by Knoevenagel condensation from 4,5‐diformyl‐1,8‐dimethoxy‐9,10‐dihydroanthracene and thiobarbituric acid derivatives in the presence of piperidine and acetic acid. In these chromophores, the ring‐locked triene employed as a conjugation bridge and the thiobarbituric acid moiety was as an electron acceptor in a D‐π‐A units. The solvatochromism and UV spectra indicate that they have higher second‐order nonlinear polarizability μβ values than the corresponding reference compound, without causing a large red shift of the charge transfer band.

Relationship between structure and nonlinear optical properties of new bisazo chromophores. Theoretical and experimental study

Two new bisazo chromophores—derivatives of bis-2,2-(4-hydroxyphenyl)propane (bisphenol A), heterocyclic amines (2-aminobenzothiazole, and 2-amino-6-nitrobenzothiazole) and aniline—were synthesized. Nonlinear optical properties of these chromophores were studied by solvatochromic method (obtained compounds have βCT value ∼10−29 esu). Dependence among the structure of molecules, their dipole moments, and first hyperpolarizabilities was considered on the basis of semi-empirical calculations. A correlation between the measured and calculated β values was studied. The NLO chromophores were used as special monomers to synthesize copolyarylates. The basic characterization of obtained polymers was carried out.

Synthesis and Nonlinear Optical Properties of Chromophores with 1,8‐Dimethoxy‐9,10‐dihydroanthracene and Ring‐locked Triene

Abstract The new chromophore molecules with nonlinear optical (NLO) properties were prepared by Knoevenagel condensation from 1,8‐dimethoxy‐4,5‐diformyl‐9,10‐dihydroanthracene and isophorone derivative in the presence of piperidine and acetic acid. In these chromophore, the ring‐locked trienes were employed as the conjugation bridge and electron acceptor in D‐π‐A units. The key intermediate dialdehyde was conveniently prepared via a three step reaction, in which 1,8‐dimethoxyanthraquinone was reduced with zinc/acetic acid and sodium/ethanol successively, followed by formylation with 1,1‐dichlorodimethyl ether in the presence of TiCl4. The solvatochromism indicate that they have higher second‐order nonlinear hyperpolarizability μβ values than the corresponding reference compound, without red shift of the charge transfer band.

Design and synthesis of push-pull chromophores for second-order nonlinear optics derived from rigidified thiophene-based pi-conjugating spacers.

Two series of push-pull chromophores built around thiophene-based pi-conjugating spacers rigidified either by covalent bonds or by noncovalent intramolecular interactions have been synthesized and characterized by UV-vis spectroscopy, electric field induced second harmonic generation (EFISH) and differential scanning calorimetry. Comparison of the linear and second-order nonlinear optical properties of chromophores based on a covalently bridged dithienylethylene (DTE) spacer with those of their analogues based on open chain DTE shows that the rigidification of the spacer produces a considerable bathochromic shift of the absorption maximum together with a dramatic enhancement of the molecular quadratic hyperpolarizability (mu beta) which reaches values among the highest reported so far. A second series of NLO-phores has been derived from a 2,2'-bi(3,4-ethylenedioxythiophene) (BEDOT) pi-conjugating spacer. As indicated by X-ray and UV-vis data, rigidification of the spacer originates in that case, from noncovalent intramolecular interactions between sulfur and oxygen atoms. Again, comparison with the parent compounds based on an unsubstituted bithiophene spacer reveals a marked red shift of the absorption maximum and a large enhancement of mu beta. In an attempt to distinguish the contribution of the electronic and geometrical effects of the ethylenedioxy group, a third series of NLO-phores based on 3,4-ethylenedioxythiophene (EDOT) and 3,4-dihexyloxythiophene spacers has been synthesized. Comparison with compounds based on unsubstituted thiophene shows that, despite a red shift of lambda(max), introduction of alkoxy groups leads to a decrease of mu beta. Theoretical calculations indicate that this effect results from a decrease of the dipole moment (mu) caused by the auxiliary electron-donor alkoxy groups on the thiophene ring. In contrast, replacement of BT by BEDOT produces an increase of mu, which associated with the noncovalent rigidification of the BT system accounts for the observed enhancement of mu beta.

Synthesis and properties of nonlinear optical chromophores and polymers containing 6-nitroquinoline as π-electron acceptor

Two nonlinear optical (NLO) methacrylate monomers, 2-methyl-acrylic acid 2-(ethyl-{4-[2-(6-nitro-quinolin-2-yl)-vinyl]-phenyl}-amino)-ethyl ester (5) and 2-methyl-acrylic acid 6-{3-[2-(6-nitro-quinolin-2-yl)-vinyl]-carbazol-9-yl}-hexyl ester (7) were newly synthesized and copolymerized with methylmethacrylate to give NLO polymers, P1 and P2. These polymers were well soluble in organic solvents and showed glass transition temperatures at 145 °C and 114 °C, respectively. The number average molecular weights (Mn) were 26,600 for P1 and 9,300 for P2. The SHG coefficients (d33) of corona-poled films of P1 and P2 measured with 1.064 μm Nd-YAG laser were 32.2 pm/V and 17.6 pm/V, respectively.